WO2025057765A1 - Projection optical system, image projection device, and eyepiece device - Google Patents

Abstract

The present invention achieves both stabilization of operation of a deflection mirror and miniaturization of a device.　The present art provides a projection optical system, etc., comprising a first lens group that has at least one lens and condenses light projected from a light source to a position of a primary imaging point that is an image of the light source, a deflection mirror that causes light to scan from the first lens group, and a second lens group that has at least one lens and forms an image of light from the deflection mirror at a position of a secondary image formation point that is an image of the primary image formation point, the focal point of the second lens group on the light source side being positioned in the vicinity of the emission position of a principal ray of light on the deflection mirror.

Description

Projection optical system, image projection apparatus, and eyepiece device

The technology disclosed herein (hereinafter also referred to as "the technology") relates to a projection optical system, an image projection device, and an eyepiece device.

A technology has been developed that projects images by scanning a light beam from a light source in two dimensions using a deflection mirror.

For example, Patent Document 1 discloses a technology relating to "a projection optical system comprising, in order from the light source side to the projection side along the optical axis, a first lens group having at least one lens and a positive focal length, which focuses light from the light source onto a primary image point which is an image of the light source, a deflector which scans the light from the first lens group, and a second lens group having at least one lens and a positive focal length, which focuses light from the deflector onto a secondary image point which is an image of the primary image point, the first lens group forming the primary image point between the first lens group and the second lens group along the optical axis."

Patent document 1 explains that by shortening the distance between the deflection mirror and the primary image point, the effective diameter of the deflection mirror can be made smaller, which has the advantage of making the device more compact and preventing costs from increasing.

International Publication No. 2018/110448

The size of the image projected by the projection optical system is generally larger than the lens group that makes up the projection optical system. As a result, the image light emitted from this lens group often diverges as it travels. Therefore, the smaller the image size to be projected, the smaller the deflection mirror's angle tends to be. If the deflection mirror's angle becomes extremely small, there is a risk that the operation of the deflection mirror will become unstable. For this reason, it is necessary to ensure a certain degree of deflection angle.

To ensure a certain degree of deflection angle, for example, the image light emitted from the lens group that constitutes the projection optical system may be converged. In this case, the deflection angle of the deflection mirror becomes relatively large.

However, in this case, the area through which the chief ray of each light beam passes on the exit surface of this lens group becomes larger than the size of the image to be projected. This may result in an increase in the size of the projection optical system.

The main objective of this technology is to provide a projection optical system that achieves both stable operation of the deflection mirror and compactness of the device.

This technology is
a first lens group having at least one lens and configured to focus light projected from a light source onto a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
There is provided a projection optical system, in which a focal point of the second lens group on the light source side is located near an emission position of a chief ray of light from the deflection mirror.
When the direction from the deflection mirror toward the second lens group is defined as positive,
A distance from a focal point of the second lens group on the light source side to a light emission position on the deflection mirror may be −1% or more and 2% or less of a focal length of the second lens group.
The first lens group may have a focal length of 2.0 mm or greater.
The focal length of the second lens group may be 24 mm or less.
The distance on the optical axis from the exit surface of the second lens group to the secondary image point may be 500 mm or less.
The chief rays of the respective light beams projected from the second lens group may be substantially parallel.
The first lens group may include a combination of a positive lens and a negative lens.
The second lens group may include a combination of a positive lens and a negative lens.
The light projected from the light source may be a laser light.
The light source is
A first light source unit that projects light in a first wavelength band;
A second light source unit that projects light in a second wavelength band;
and a third light source unit that projects emission light in a third wavelength band.
the first wavelength band is a wavelength band corresponding to red,
the second wavelength band is a wavelength band corresponding to green,
The third wavelength band may be a wavelength band corresponding to blue color.
In addition, this technology:
A projection optical system;
an eyepiece device disposed in front of an observer's eye,
The projection optical system comprises:
a first lens group having at least one lens and configured to focus light projected from a light source onto a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
a focal point of the second lens group on the light source side is located in the vicinity of an emission position of a chief ray of light on the deflection mirror,
An image projection apparatus is provided, wherein the eyepiece device projects light from the projection optical system onto the observer's retina.
The focal point on the light source side of the eyepiece device may be positioned at the position of the secondary image point.
The ocular device may be a contact lens type device.
In addition, this technology:
An eyepiece device disposed in front of an eye of an observer and projects light from a projection optical system onto a retina of the observer,
The projection optical system comprises:
a first lens group having at least one lens and configured to focus light projected from a light source onto a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
An eyepiece device is provided in which the focal point of the second lens group on the light source side is located near the exit position of the chief ray of light from the deflection mirror.

This technology makes it possible to stabilize the operation of the deflection mirror while also miniaturizing the device. Note that the effects described here are not necessarily limited to those described herein, and may be any of the effects described in this disclosure.

1 is a schematic diagram showing an example of the configuration of a projection optical system 10 according to a comparative example of the present technology. 1 is a schematic diagram showing an example of the configuration of a projection optical system 10 according to a comparative example of the present technology. 1 is a schematic diagram illustrating an example of the configuration of a projection optical system 10 according to an embodiment of the present technology. 2 is a schematic diagram showing a state of a light beam in the comparative example shown in FIG. 1 . 3 is a schematic diagram showing a state of a light beam in the comparative example shown in FIG. 2 . FIG. 4 is a schematic diagram showing the state of a light beam in the embodiment shown in FIG. 3. 1 is a schematic diagram showing a configuration example of an eyepiece device 20 according to an embodiment of the present technology. 11 is a graph showing a correlation between a focal length f3 of an eyepiece device 20 according to an embodiment of the present technology and a numerical aperture θ of a light beam projected by the eyepiece device 20. 11 is a graph showing a correlation between a distance D2 from a second lens group 2 to a secondary image plane P2 according to an embodiment of the present technology and a numerical aperture θ of a light beam projected by an eyepiece device 20. 1 is a graph showing paraxial calculations of the focal lengths of a first lens group 1 and a second lens group 2 according to an embodiment of the present technology. 11 is a graph showing an example of a simulation result of the projection optical system 10 according to an embodiment of the present technology. 11 is a graph showing an example of a simulation result of the projection optical system 10 according to an embodiment of the present technology. 11 is a graph showing an example of a simulation result of the projection optical system 10 according to an embodiment of the present technology. 1 is a schematic diagram illustrating an example of the configuration of a projection optical system 10 according to an embodiment of the present technology. 1 is a schematic diagram illustrating an example of the configuration of an image projection device 100 according to an embodiment of the present technology. 1 is a schematic diagram illustrating an example of the configuration of an image projection device 100 according to an embodiment of the present technology.

Below, a preferred embodiment for implementing the present technology will be described with reference to the drawings. Note that the embodiment described below is an example of a representative embodiment of the present technology, and does not limit the scope of the present technology. In addition, the present technology can be combined with any of the following examples and their variations.

In the following description of the embodiments, configurations may be described using terms that include "approximately", such as "approximately parallel" and "approximately perpendicular". For example, "approximately parallel" does not only mean completely parallel, but also means that it is substantially parallel, that is, it includes a state that is deviated from a completely parallel state by, for example, about a few percent. The same applies to other terms that include "approximately". In addition, each figure is a schematic diagram, and is not necessarily an accurate depiction. The scale of the drawings has been exaggerated to make the characteristics of the technology easier to understand. Therefore, it should be noted that the scale of the drawings and the scale of the actual device are not necessarily the same.

Unless otherwise specified, in the drawings, "top" means the upper direction or upper side in the drawing, "bottom" means the lower direction or lower side in the drawing, "left" means the left direction or left side in the drawing, and "right" means the right direction or right side in the drawing. In addition, in the drawings, the same or equivalent elements or members are given the same reference numerals, and duplicate explanations are omitted.

The explanation will be given in the following order.
1. First embodiment of the present technology (example 1 of projection optical system)
(1) Comparative Example (2) Overview of the Present Embodiment (3) Passage Area of Chief Ray (4) Direct Retinal Imaging (5) Simulation 2. Second Embodiment of the Present Technology (Example 2 of Projection Optical System)
3. Third embodiment of the present technology (example of image projection device)
4. Fourth embodiment of the present technology (example of eyepiece device)

[1. First embodiment of the present technology (example 1 of projection optical system)]
(1) Comparative Example
In order to describe the problem to be solved by the present technology, a comparative example of the present technology will be described first with reference to Fig. 1. Fig. 1 is a schematic diagram showing an example of the configuration of a projection optical system 10 according to the comparative example of the present technology.

As shown in FIG. 1, the projection optical system 10 includes a first lens group 12, a deflection mirror 3, and a second lens group 2. This projection optical system 10, together with a light source 4, constitutes an image projection device 100.

The light source 4 includes a light source section 41 and at least one lens (e.g., a collimator lens) 42.

The first lens group 12 has a positive focal length overall. The first lens group 12 has at least one lens, and focuses the light projected from the light source 4 at the position of the primary image point P1, which is the image of the light source 4.

Note that when light is collected or diffused by an optical system, refraction and reflection of light rays occur. This can result in deviation (aberration) from the original ideal imaging point. For this reason, the first lens group 12 does not necessarily have to collect light at the position of the primary imaging point P1, and may collect light near the position of the primary imaging point P1. The same applies to the secondary imaging point P2 described below.

The deflection mirror 3 scans the light from the first lens group 12. The deflection mirror 3 rotates or tilts around an axis. When light that has passed through the primary image point P1 is irradiated onto the deflection mirror 3, the angle of the deflection mirror 3 is controlled to reflect the light in a specific direction. By controlling the angle of the deflection mirror 3, the light can be scanned. For example, when the light is scanned horizontally by rotating the deflection mirror 3, the position of the light moves from left to right. Similarly, it can also be scanned vertically by tilting it.

An example of the deflection mirror 3 is a MEMS (Micro-Electro-Mechanical Systems Mirror) mirror. A MEMS mirror is a mirror with a fine mechanical structure, and can be made to vibrate and rotate minutely using an electrical signal. This makes it possible to scan the emitted light and form an image.

The elements that make up the deflection mirror 3 are not limited to MEMS mirrors, but may be, for example, a galvanometer. A galvanometer is a device that scans the emitted light by minutely vibrating a mirror using an electrical signal. By controlling the position of the mirror, the direction of the light can be changed, making it possible to scan the emitted light.

The second lens group 2 has a positive focal length overall. The second lens group 2 has at least one lens (for example, lens 21) and focuses the light from the deflection mirror 3 at a secondary image point (secondary image plane) P2, which is an image of the primary image point P1.

In this comparative example, the focal point P3 on the light source 4 side of the second lens group 2 and the emission position P4 of the chief ray L of light on the deflection mirror 3 are located apart. Specifically, the emission position P4 of the chief ray L of light on the deflection mirror 3 is located closer to the second lens group 2 than the focal point P3 on the light source 4 side of the second lens group 2.

As a result, each of the chief rays of the multiple light beams projected from the second lens group 2 is in a divergent state, expanding as it travels. This makes the size of the second lens group 2 that constitutes the projection optical system 10 smaller than the size of the image projected by the projection optical system 10. As a result, it is possible to project a high-resolution image while miniaturizing the projection optical system 10.

The smaller the image size to be projected, the smaller the swing angle of the deflection mirror 3 tends to be. For example, when the image light from the projection optical system 10 is projected onto the observer's retina, the image size becomes very small and the swing angle of the deflection mirror 3 also becomes very small.

In order to project a high-resolution image while stabilizing the operation of the deflection mirror 3, it is preferable to make the deflection angle of the deflection mirror 3 relatively large. If the deflection angle of the deflection mirror 3 is smaller than, for example, ±3 degrees, the operation of the deflection mirror 3 may become unstable.

In order to make the deflection angle of the deflection mirror 3 relatively large, the optical system may be adjusted so that the chief rays of the multiple light beams projected by the projection optical system 10 each travel while converging. This will be explained with reference to FIG. 2. FIG. 2 is a schematic diagram showing an example of the configuration of a projection optical system 10 according to a comparative example of this technology.

As shown in FIG. 2, the focal point P3 on the light source 4 side of the second lens group 2 and the emission position P4 of the chief ray of light on the deflection mirror 3 are located apart. Specifically, the emission position P4 of the chief ray of light on the deflection mirror 3 is located farther from the second lens group 2 than the focal point P3 on the light source 4 side of the second lens group 2.

As a result, each of the chief rays of the multiple light beams projected from the second lens group 2 travels while converging. As a result, it is possible to project an image smaller in size than the second lens group 2 while maintaining a relatively large swing angle of the deflection mirror 3.

However, in this configuration example, there is a risk that the range through which the chief rays of each light beam pass on the exit surface of the second lens group 2 may be larger than the image size on the secondary image plane P2. This may result in a larger size of the second lens group 2, which may lead to an increase in the size of the projection optical system 10.

(2) Overview of this embodiment
Therefore, the present technology provides a projection optical system in which the chief rays of each light beam projected from the second lens group are approximately parallel by specifying the positional relationship between the focal point on the light source side of the second lens group and the emission position of the chief ray of light on the deflection mirror.

Specifically, this technology provides a projection optical system that includes a first lens group having at least one lens and focusing light projected from a light source at a position of a primary image point that is an image of the light source, a deflection mirror that scans the light from the first lens group, and a second lens group having at least one lens and focusing the light from the deflection mirror at a position of a secondary image point that is an image of the primary image point, the light source side focal point of the second lens group being located near the emission position of the chief ray of light on the deflection mirror.

An example of the configuration of the projection optical system 10 according to one embodiment of the present technology will be described with reference to FIG. 3. FIG. 3 is a schematic diagram showing an example of the configuration of the projection optical system 10 according to one embodiment of the present technology.

As shown in FIG. 3, the projection optical system 10 includes a first lens group 12, a deflection mirror 3, and a second lens group 2. Note that the contents of each component that were explained above with reference to FIG. 1 etc. will not be explained again.

The first lens group 12 preferably has a combination lens of a positive lens and a negative lens. When the first lens group 12 collects light from the light source 4, the chromatic aberration of each wavelength of the light source 4 can be corrected by using a combination lens of a positive lens and a negative lens for correcting chromatic aberration on the collecting side lens. To correct chromatic aberration, for example, a combination of glass lenses with different Abbe numbers can be used for the positive and negative lenses.

Alternatively, the first lens group 12 may be composed of only multiple positive single lenses, and the on-axis chromatic aberration may be corrected by adjusting the distance between the light source 4 and the first lens group 12. In this case, costs can be reduced because a combination lens for correcting chromatic aberration is not used. In this case, the lenses in the first lens group 12 do not have to be made of glass; using plastic lenses, for example, would further reduce costs.

The second lens group 2 preferably has a combination lens of a positive lens and a negative lens. By using at least one combination lens of a positive lens and a negative lens, chromatic aberration of magnification that occurs off-axis can be corrected. With the preferred configuration of the first lens group 12 described above, it is possible to correct axial chromatic aberration, but it is difficult to correct chromatic aberration over the entire off-axis angle of view, so it is preferable to correct chromatic aberration in the second lens group 2. By using at least one combination lens of a positive lens and a negative lens in the second lens group 2, chromatic aberration of each wavelength of the light source 4 can be corrected.

Furthermore, it is preferable that the second lens group 2 has at least one transmitting surface having a free-form shape. If an axisymmetric lens is used for the second lens group 2, there is a risk that distortion will occur in the two-dimensionally scanned image. By using a lens having a free-form shape, this distortion is optically corrected, and a good image can be obtained.

Also, the projected image may be adjusted in a direction perpendicular to the optical axis by moving at least one of the lenses in the first lens group 12 and the second lens group 2 in a direction perpendicular to the optical axis. This allows the projected image to be moved in a plane perpendicular to the optical axis.

The light source 4 emits light whose intensity is modulated based on image data. The light projected from the light source 4 is preferably laser light. Laser light has high light brightness and consistent wavelength characteristics, making it suitable for projecting clear, bright images onto the retina. Laser light has features such as a high contrast ratio, a wide color gamut, and high resolution.

In this configuration example, the focal point P3 on the light source 4 side of the second lens group 2 is located near the emission position P4 of the chief ray of light on the deflection mirror 3. As a result, the chief ray L of each light beam projected from the second lens group 2 becomes approximately parallel. The chief ray of each light beam that is now approximately parallel is focused by, for example, an eyepiece device (not shown) placed in front of the observer's eye, and projected onto the observer's retina.

With this technology, the chief rays of each light beam projected from the second lens group 2 become nearly parallel, so that a large swing angle of the deflection mirror 3 can be ensured even when the size of the projected image is small. This makes it possible to stabilize the operation of the deflection mirror 3. Furthermore, compared to the comparative example (see FIG. 2) in which the chief rays of the multiple light beams projected from the second lens group 2 each progress while converging, the device can be made more compact. In other words, it is possible to achieve both stabilization of the operation of the deflection mirror and miniaturization of the device. This effect also occurs in the other embodiments described below. Therefore, repeated description may be omitted in the explanation of the other embodiments.

[(3) Area through which the chief ray passes]
The state of the light beam in each of the comparative example and this embodiment will be described with reference to FIGS.

FIG. 4 is a schematic diagram showing the state of light beams in the comparative example shown in FIG. 1. FIG. 4A shows the state of the chief ray of the light beam that passes through the outermost part of the image light projected from the second lens group 2, among the multiple light beams contained in the image light projected from the second lens group 2. As shown in FIG. 4A, the chief ray of each light beam projected from the second lens group 2 spreads as it travels. The chief ray of each light beam is then refracted by the eyepiece device 20 placed in front of the observer's eye, and is guided to the eyeball E.

In Figure 4B, the dashed line indicates the pass area A1 of the chief ray of each light beam on the exit surface of the second lens group 2. On the exit surface of the second lens group 2, the pass area of each light beam is the sum of the pass area A1 of the chief ray of each light beam shown in the dashed line and the spread of the light beam passing through the outermost part of the image light. In other words, the length of the pass area of each light beam is the sum of the diagonal length r1 of the pass area of the chief ray shown in the dashed line and the beam diameter r2 of the light beam passing through the outermost part of the image light.

In FIG. 4C, the dashed line indicates the area A2 through which the chief ray of each light beam passes at the secondary image point (secondary image plane) P2. At the secondary image plane P2, each light beam is in a condensed state. Therefore, the size of the area A2 through which the chief ray of each light beam passes is approximately the same as the size of the image projected by the projection optical system 10.

As shown in Figure 4A, in this comparative example, each of the chief rays of the multiple light beams projected from the second lens group 2 expands as it travels. Therefore, as shown in Figures 4B and 4C, the passage area A1 of the chief ray of each light beam on the exit surface of the second lens group 2 is smaller than the passage area A2 of the chief ray of each light beam at the secondary image point (secondary image plane) P2.

As described above, the size of the passing area A2 is approximately the same as the size of the image projected by the projection optical system 10. As the projected image size becomes smaller, the size of the passing area A1 at the exit surface of the second lens group 2 becomes smaller, and the swing angle of the deflection mirror 3 also tends to become smaller. As the swing angle of the deflection mirror 3 becomes smaller, there is a risk that the operation of the deflection mirror 3 will become unstable.

FIG. 5 is a schematic diagram showing the state of light beams in the comparative example shown in FIG. 2. As shown in FIG. 5A, in this comparative example, the chief rays of the multiple light beams projected from the second lens group 2 each travel while converging. Therefore, when the size of the image to be projected is fixed, as shown in FIGS. 5B and 5C, the passage area A1 of the chief ray of each light beam on the exit surface of the second lens group 2 is larger than the passage area A2 of the chief ray of each light beam at the secondary image point (secondary image plane) P2. This may result in the projection optical system 10 becoming larger.

FIG. 6 is a schematic diagram showing the state of the light beams in the present embodiment shown in FIG. 3. As shown in FIG. 6A, in this embodiment, the chief rays of the multiple light beams projected from the second lens group 2 are each approximately parallel. Therefore, when the size of the image to be projected is fixed, as shown in FIGS. 6B and 6C, the passage area A1 of the chief ray of each light beam on the exit surface of the second lens group 2 is approximately the same size as the passage area A2 of the chief ray of each light beam at the secondary image point (secondary image plane) P2. This makes it possible to achieve both stable operation of the deflection mirror 3 and compactness of the device.

[(4) Direct Retinal Imaging]
The projection optical system 10 according to this embodiment can be used, for example, in a retinal imaging type image projection device, which is also called an image projection device based on Maxwellian vision.

When light enters the pupil and reaches the retina, photoreceptor cells inside the retina detect the light and convert it into nerve signals. These nerve signals are sent via the optic nerve to the brain, where the brain interprets them to help us recognize the scenes and objects we see.

In order to allow an observer to view an image, a retinal projection type image projector projects an image onto the observer's retina and forms an image on the retina. To form an image on the retina, an eyepiece device is often placed in front of the observer's eye. As shown in FIG. 6A, when the chief rays of each light beam projected from the second lens group 2 are approximately parallel, the chief rays of each light beam are refracted to the focal position of the eyepiece device.

Examples of the eyepiece device 20 include a lens, a half mirror, a prism, an optical fiber, and a diffraction element. In this embodiment, the eyepiece device 20 can be a contact lens type device. A contact lens type device is a thin, transparent lens that is attached directly to the surface of the eyeball. A contact lens type device has, for example, a diffraction grating or a hologram lens, and projects light from the projection optical system 10 onto the observer's retina by utilizing principles such as light diffraction and interference.

In particular, unlike when viewing an object directly, retinal projection image projection devices form an image on the observer's retina using an eyepiece device. For this reason, the focal position on the retina side of the eyepiece device needs to be located near the crystalline lens. In other words, the focal length of the eyepiece device needs to be short, on the order of a few mm.

This eyepiece device will be described with reference to FIG. 7. FIG. 7 is a schematic diagram showing an example configuration of an eyepiece device 20 according to one embodiment of the present technology.

As shown in FIG. 7, each light beam projected from the second lens group 2 is focused at a secondary image point P2, and then projected onto the eyepiece device 20 while expanding. The eyepiece device 20 acts, for example, as a lens, and guides each light beam to the pupil E1 and retina E2.

At this time, it is preferable that the focal point on the light source side of the eyepiece device 20 is located at the position of the secondary image point P2. This allows the eyepiece device 20 to guide each light beam to the pupil E1 in a substantially parallel state. Each light beam guided to the pupil E1 is refracted by the crystalline lens and forms an image on the retina E2. Note that the position of the focal point of the eyepiece device 20 does not necessarily have to coincide with the position of the secondary image point P2, and some deviation is acceptable.

The resolution of an image is determined by the degree to which each light beam is focused on the retina. The resolution of an image can be increased by increasing the degree to which each light beam is focused. In order to increase the degree to which the light beam is focused on the retina, it is preferable to increase the beam diameter (exit pupil) of each light beam projected onto the eyeball. In order to increase this beam diameter, it is preferable to increase the numerical aperture θ.

The beam diameter of each light beam projected onto the eyeball is determined by the numerical aperture θ of each light beam projected from the second lens group 2 and the focal length of the eyepiece device 20. If the focal length of the eyepiece lens is f, then the beam diameter of the light beam projected from the eyepiece device 20 is approximately 2fθ.

As mentioned above, the focal position on the retina side of the ocular device 20 needs to be located near the crystalline lens. Therefore, if the ocular device 20 is, for example, a contact lens type device, the distance from the ocular device 20 to the crystalline lens is short, and therefore the focal length of the ocular device 20 is inevitably short.

Here, the relationship between the focal length of the eyepiece device 20 and the numerical aperture θ of the light beam projected by the eyepiece device 20 will be described with reference to FIG. 8. FIG. 8 is a graph showing the correlation between the focal length f3 of the eyepiece device 20 according to one embodiment of the present technology and the numerical aperture θ of the light beam projected by the eyepiece device 20.

In FIG. 8, the horizontal axis indicates the focal length f3 of the eyepiece device 20. The vertical axis indicates the numerical aperture θ of the light beam projected by the eyepiece device 20. The legend on the right side of the graph indicates the beam diameter (exit pupil) of the light beam projected by the eyepiece device 20.

When the beam diameter is 0.15 mm or less, the image resolution drops significantly. Therefore, it is preferable that the beam diameter is 0.15 mm or more. When the eyepiece device 20 is a contact lens type device, its focal length can be about 8 mm. In this case, it can be seen from this graph that in order to allow the observer to view a high-resolution image, the numerical aperture θ needs to be 0.01 or more.

In order to set the numerical aperture θ to 0.01 or more, it is necessary to increase the beam diameter of each light beam projected from the second lens group 2. In particular, when the distance on the optical axis from the second lens group 2 to the secondary image plane P2 (projection distance) is set long, in order to project high-resolution image light, it is necessary to increase the beam diameter of each light beam projected from the second lens group 2. This will be explained with reference to FIG. 9. FIG. 9 is a graph showing the correlation between the distance D2 from the second lens group 2 to the secondary image plane P2 and the numerical aperture θ of the light beam projected by the eyepiece device 20 according to one embodiment of the present technology.

In FIG. 9, the horizontal axis indicates the distance (projection distance) D2 on the optical axis from the second lens group 2 to the secondary image plane P2. The vertical axis indicates the numerical aperture θ of the light beam projected by the eyepiece device 20. The legend on the right side of the graph indicates the maximum value [mm] of the area through which the chief ray passes on the exit surface of the second lens group 2.

The projection optical system 10 according to this embodiment can be built into, for example, a wristwatch-type device. The eyepiece device 20 according to this embodiment can be, for example, a contact lens-type device. Therefore, the distance (projection distance) D2 on the optical axis from the second lens group 2 constituting this wristwatch-type device to the secondary image plane P2 may exceed, for example, 500 mm. Furthermore, the size of the image observed by the observer needs to be smaller than the size of the contact lens-type device. In other words, the area through which the chief ray passes on the exit surface of the second lens group 2 needs to be smaller than the size of the contact lens-type device. As a specific example, the length of the area through which the chief ray passes on the exit surface of the second lens group 2 needs to be 10 mm or less.

As shown in Figure 9, when the projection distance D2 exceeds 500 mm, it becomes difficult to keep the area through which the chief ray passes at the exit surface of the second lens group 2 to 10 mm or less while setting the numerical aperture θ on the vertical axis to 0.01 or more. Therefore, in order to achieve both stable operation of the deflection mirror and compactness of the device while allowing the observer to view a high-resolution image, it is preferable that the distance on the optical axis from the exit surface of the second lens group 2 to the secondary image point P2 be 500 mm or less.

(5) Simulation
As described above, the present technology specifies the positional relationship between the focal point of the second lens group 2 on the light source 4 side and the emission position of the chief ray of light on the deflection mirror 3. In order to confirm the preferred arrangement position of the deflection mirror 3, the inventor performed a simulation. First, in order to determine the preconditions for the simulation, a paraxial calculation was performed on the focal lengths of the first lens group 12 and the second lens group 2 when the numerical aperture θ of the light beam projected from the second lens group 2 is 0.010 and the projection distance is 200 mm or more and 500 mm or less. The calculation result will be described with reference to FIG. 10. FIG. 10 is a graph showing the paraxial calculation of the focal lengths of the first lens group 12 and the second lens group 2 according to an embodiment of the present technology.

In FIG. 10, the horizontal axis indicates the focal length f1 of the first lens group 12. The vertical axis indicates the focal length f2 of the second lens group 2. The legend on the right side of the graph indicates the projection distance [mm].

In this graph, the focal length f1 values range from 1.5 to 6.5. If the focal length f1 value is reduced, the radius of curvature of each lens that makes up the first lens group 12 must be reduced. However, if the radius of curvature of the lenses is made extremely small, it becomes difficult to process each lens. To facilitate lens processing, it is preferable that the focal length f1 of the first lens group 12 is 2.0 mm or greater.

Based on the results of this paraxial calculation, the simulation prerequisites were set as follows:

<Prerequisites>
(a) Distance D2 from the exit surface of the second lens group 2 to the secondary image plane P2: 500 mm
(b) Numerical aperture θ of the light beam projected from the second lens group 2: 0.01
(c) Focal length f1 of the first lens group 12: 2.3 mm
(d) Focal length f2 of the second lens group 2: 22.0 mm
(e) Length of the area through which the chief ray passes on the secondary image plane P2: 5 mm (2.5 mm on each side); (f) No aberration occurs at the focal points of the first lens group 12 and the second lens group 2.

The simulation results based on this precondition will be described with reference to Figs. 11 and 12. Figs. 11 and 12 are graphs showing an example of the simulation results of the projection optical system 10 according to one embodiment of the present technology.

In FIG. 11, the horizontal axis represents the distance D1 from the focal point on the light source side of the second lens group 2 to the emission position of the chief ray of light on the deflection mirror 3, normalized by the focal length f2 of the second lens group 2. The direction from the deflection mirror 3 toward the second lens group 2 is considered positive. The vertical axis represents the deflection angle α (one side) [deg] of the deflection mirror 3.

When the value on the horizontal axis is positive (greater than 0), the chief ray of each light beam reflected by the deflection mirror 3 travels in a divergent direction when projected from the second lens group 2. In this case, in order to ensure the length (5 mm) of prerequisite condition (e), it is necessary to reduce the swing angle α of the deflection mirror 3.

On the other hand, when the horizontal axis value is negative (less than 0), the smaller the horizontal axis value, the greater the change in the swing angle α of the deflection mirror 3 (the inclination of the swing angle α). This indicates that there is a large change in the projected image size relative to a perturbation in the distance from the focal point on the light source side of the second lens group 2 to the emission position of the chief ray of light on the deflection mirror 3.

As mentioned above, in order to achieve both stable operation of the deflection mirror 3 and compactness of the device, it is preferable that the chief rays of each light beam projected from the second lens group 2 are approximately parallel. In order for the chief rays of each light beam projected from the second lens group 2 to be approximately parallel, it is preferable that the focal point P3 on the light source 4 side of the second lens group 2 coincides with the emission position P4 of the chief ray of light on the deflection mirror 3, as shown in Figure 3. In other words, it is preferable that the value on the horizontal axis in Figure 11 is 0.

However, the focal point P3 on the light source 4 side of the second lens group 2 and the emission position P4 of the chief ray of light on the deflection mirror 3 do not necessarily have to coincide. The focal point P3 on the light source 4 side of the second lens group 2 may be located near the emission position P4 of the chief ray of light on the deflection mirror 3.

Specifically, as shown in FIG. 11, when the direction from the deflection mirror 3 toward the second lens group 2 is defined as positive, the distance D1 from the focal point P3 of the second lens group 2 on the light source 4 side to the emission position P4 of the chief ray of light on the deflection mirror 3 may be -1% to 2% of the focal length f2 of the second lens group 2. If it can be kept within this range of -1% to 2%, it is possible to keep the change within 1 degree from the swing angle of the deflection mirror 3 when the focal point P3 of the second lens group 2 on the light source 4 side and the emission position P4 of the chief ray of light on the deflection mirror 3 are aligned. This makes it possible to make the respective light beams projected from the second lens group 2 approximately parallel.

Next, FIG. 12 will be described. In FIG. 12, the horizontal axis represents the focal point P3 of the second lens group 2 on the light source 4 side, as in FIG.
It is a value obtained by normalizing a distance D1 from the deflection mirror 3 to an emission position P4 of the chief ray of light on the deflection mirror 3 by the focal length f2 of the second lens group 2. The direction from the deflection mirror 3 toward the second lens group 2 is defined as positive. The vertical axis indicates the maximum value W of the length of the area through which the chief ray passes on the emission surface of the second lens group 2 when the center of the emission surface is used as a reference.

In Figure 12, when the value on the horizontal axis is negative (less than 0), the chief ray of each light beam reflected by the deflection mirror 3 travels in a converging direction when projected from the second lens group 2. In this case, to ensure the assumed image length (5 mm), it is necessary to increase the area through which the chief ray passes on the exit surface of the second lens group 2.

When the direction from the deflection mirror 3 toward the second lens group 2 is defined as positive, it is preferable that the distance from the focal point P3 on the light source 4 side of the second lens group 2 to the emission position P4 of the chief ray of light on the deflection mirror 3 is between -1% and 2% of the focal length of the second lens group 2. If it can be kept within this range of between -1% and 2%, the value on the vertical axis can be kept to about +1 mm from the state where the focal point P3 on the light source 4 side of the second lens group 2 and the emission position P4 of the chief ray of light on the deflection mirror 3 are aligned. This makes it possible to make the chief rays of each light beam projected from the second lens group 2 approximately parallel.

Next, the correlation between the focal length f2 of the second lens group 2 and the swing angle α of the deflection mirror 3 when the focal point P3 on the light source 4 side of the second lens group 2 coincides with the emission position P4 of the chief ray of light on the deflection mirror 3 will be described with reference to FIG. 13. FIG. 13 is a graph showing an example of a simulation result of the projection optical system 10 according to an embodiment of the present technology.

The assumptions for this simulation are that the numerical aperture θ of the light beam projected from the second lens group 2 is 0.01, and the length of the area through which the chief ray passes on the secondary image plane P2 is 5 mm (2.5 mm on each side).

In FIG. 13, the horizontal axis is the focal length f2 [mm] of the second lens group 2. The vertical axis is the deflection angle α (one side) [deg] of the deflection mirror 3. The legend on the right side of the graph indicates the projection distance [mm].

As shown in Figure 13, even if the projection distance (200, 300, 400, 500, 600) is different, the graph draws almost the same curve. In other words, it can be seen that the swing angle α of the deflection mirror 3 is almost not affected by the projection distance, but is affected by the focal length f2 of the second lens group 2 shown on the horizontal axis.

In addition, in this simulation, the numerical aperture θ of the light beam projected from the second lens group 2 is set to 0.01 as a prerequisite, but the swing angle α of the deflection mirror 3 is not affected by this numerical aperture θ. In other words, the swing angle α of the deflection mirror 3 is affected by the focal length f2 of the second lens group 2 and the length of the area through which the chief ray passes on the secondary image plane P2. In this example, if the focal length f2 of the second lens group 2 is 24 mm or less, the swing angle α of the deflection mirror 3 will be ±3 degrees or more, and the operation of the deflection mirror 3 will be stable.

Of course, the length of the area through which the chief ray passes at the secondary image plane P2 will vary depending on the focal length of the eyepiece device 20 and the required angle of view. However, if the focal length f2 of the second lens group 2 is 24 mm or less, it is possible to keep the swing angle α of the deflection mirror 3 within a range that does not interfere with its operation.

The above description of the projection optical system according to the first embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical inconsistency.

[2. Second embodiment of the present technology (example 2 of the projection optical system)]
In order to project a color image, the light source may include a first light source unit that projects an emission light of a first wavelength band, a second light source unit that projects an emission light of a second wavelength band, and a third light source unit that projects an emission light of a third wavelength band. This will be described with reference to Fig. 14. Fig. 14 is a schematic diagram showing a configuration example of a projection optical system 10 according to an embodiment of the present technology.

As shown in FIG. 14, the light source 4 may include a first light source unit 41R that projects emitted light in a first wavelength band, a second light source unit 41G that projects emitted light in a second wavelength band, and a third light source unit 41B that projects emitted light in a third wavelength band. Note that the number of light source units is not particularly limited.

More specifically, the first wavelength band may be a wavelength band corresponding to red, the second wavelength band may be a wavelength band corresponding to green, and the third wavelength band may be a wavelength band corresponding to blue. This allows the image projection device 100 to allow the observer to view a full-color image. The wavelength band corresponding to red may be, for example, approximately 620 to 750 nm. The wavelength band corresponding to green may be, for example, approximately 500 to 550 nm. The wavelength band corresponding to blue may be, for example, approximately 430 to 500 nm.

The light source 4 further includes, for example, lenses 42R, 42G, and 42B. The lens 42R makes the emitted light of the first wavelength band projected by the first light source unit 41R approximately parallel. Similarly, the lens 42G makes the emitted light of the second wavelength band projected by the second light source unit 41G approximately parallel. The lens 42B makes the emitted light of the third wavelength band projected by the third light source unit 41B approximately parallel.

In this embodiment, mirror 51 and dichroic mirrors 52 and 53 are used as a multiplexing optical system. This multiplexing optical system multiplexes the emitted light of each wavelength band onto the same optical axis and emits it to the first lens group 12.

The mirror 51 is disposed on the optical axis of the first light source unit 41R and the lens 42R. The mirror 51 reflects the light of the first wavelength band projected from the first light source unit 41R.

The dichroic mirror 52 is disposed on the optical axis of the second light source unit 41G and the lens 42G. The dichroic mirror 52 transmits the light of the first wavelength band projected from the first light source unit 41R and reflects the light of the second wavelength band projected from the second light source unit 41G.

The dichroic mirror 53 is disposed on the optical axis of the third light source unit 41B and the lens 42B. The dichroic mirror 53 reflects the light of the first wavelength band projected from the first light source unit 41R, reflects the light of the second wavelength band projected from the second light source unit 41G, and transmits the light of the third wavelength band projected from the third light source unit 41B.

The first lens group 12 focuses the approximately parallel light from the combining optical system at the position of the primary image point P1. The focal point P3 on the light source 4 side of the second lens group 2 is located near the emission position P4 of the chief ray of light on the deflection mirror 3. The light from the lens 21 is scanned two-dimensionally by the deflection mirror 3, passes through the second lens group 2, and is focused on the secondary image plane P2.

The elements that make up the combining optical system are not limited to these. For example, the combining optical system may be made up of a dichroic prism, a polarizing beam splitter (PBS), a polarizing beam combiner (PBC), a half mirror, an interference filter, etc.

Note that the technology for emitting light in multiple wavelength bands to project a color image is not necessarily limited to this configuration. For example, the light source may be a single light source unit that emits light in multiple wavelength bands. As a specific example, a laser diode array can be used to emit light in multiple wavelength bands from a single chip. Alternatively, light in multiple wavelength bands can be generated from a single chip by introducing luminescent substances of different colors into a liquid or gas and exciting each of them to emit light.

The above description of the projection optical system according to the second embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

3. Third embodiment of the present technology (example of image projection device)
The image projection device according to this embodiment will be described with reference to Fig. 15. Fig. 15 is a schematic diagram showing an example of the configuration of an image projection device 100 according to an embodiment of the present technology.

As shown in FIG. 15, the image projection device 100 includes a projection optical system 10 and an eyepiece device 20 that is placed in front of the observer's eye.

In this configuration example, the projection optical system 10 is built into a wristwatch-type device, which is an example of the image projection device 100. The observer can change the image projected by the image projection device 100 via a display provided in the wristwatch-type device 100.

Each light beam projected from the projection optical system 10 is imaged at a secondary imaging point and then projected onto the eyepiece device 20 while expanding. The eyepiece device 20 projects the light from the projection optical system 10 onto the observer's retina E1.

The eyepiece device 20 may be, for example, a glasses-type device, but is preferably a contact lens-type device. Glasses-type devices need to be adapted to the shape of each individual's face. On the other hand, contact lens-type devices do not require this, and can provide a comfortable fit and sensation to everyone.

In addition, the contact lens type eyepiece device 20 has lenses that are worn directly on the eye, so it can project light more directly onto the retina. On the other hand, in the case of glasses type devices, there is a possibility that the frame and lens thickness may interfere, resulting in restrictions on light transmission.

When the eyepiece device 20 is a glasses-type device, the eyepiece device 20 may have, for example, a half mirror, a prism, a lens, an optical fiber, a diffraction element, etc. In particular, the eyepiece device 20 may have a diffraction element, such as a holographic optical element, a Fresnel lens, a reflective diffraction grating, or a transmissive diffraction grating. A diffraction element can diffuse or converge light by utilizing the diffraction effect of light. By having a diffraction element, for example, the eyepiece device 20 can be simplified. Compared to other optical elements with complex optical configurations, such as lens arrays, a diffraction element can realize a simple and compact device design.

An example of the configuration of the image projection device 100 according to this embodiment will be described with reference to FIG. 16. FIG. 16 is a schematic diagram showing an example of the configuration of the image projection device 100 according to one embodiment of the present technology.

As shown in FIG. 16, the image projection device 100 includes at least a projection optical system 10, a light source 4, and a control unit 30.

The projection optical system 10 includes a first lens group 12, a deflection mirror 3, and a second lens group 2.

The first lens group 12 has at least one lens and focuses the light projected from the light source 4 at the position of the primary image point P1, which is the image of the light source 4.

The deflection mirror 3 scans the light from the first lens group 12.

The second lens group 2 has at least one lens (e.g., lens 21) and focuses the light from the deflection mirror 3 at the position of the secondary image point P2, which is an image of the primary image point P1.

At this time, the focal point of the second lens group 2 on the light source 4 side is located near the emission position of the chief ray of light on the deflection mirror 3.

The control unit 30 has a light source control unit 31 and a scanning control unit 32. The light source control unit 31 controls the light emission of the light source 4 based on image data. The scanning control unit 32 controls the scanning direction and scanning timing of the deflection mirror 3 based on image data. For example, a microcontroller, a driver integrated circuit (IC), a signal generation circuit, etc. can be used as the control unit 30.

Note that the image projection device 100 incorporating the projection optical system 10 is not limited to the wristwatch type device shown in FIG. 16.

The above description of the image projection device according to the third embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical inconsistency.

[4. Fourth embodiment of the present technology (example of eyepiece device)]
As shown in FIG. 15 etc., the present technology provides an eyepiece device 20 that is placed in front of the observer's eye and projects light from a projection optical system 10 onto the observer's retina.

The eyepiece device 20 may be, for example, a glasses-type device, but is preferably a contact lens-type device. Glasses-type devices need to be adapted to the shape of each individual's face. On the other hand, contact lens-type devices do not require this, and can provide a comfortable fit and sensation to everyone.

In addition, the contact lens type eyepiece device 20 has lenses that are worn directly on the eye, so it can project light more directly onto the retina. On the other hand, in the case of glasses type devices, there is a possibility that the frame and lens thickness may interfere, resulting in restrictions on light transmission.

When the eyepiece device 20 is a glasses-type device, the eyepiece device 20 may have, for example, a half mirror, a prism, a lens, an optical fiber, a diffraction element, etc. In particular, the eyepiece device 20 may have a diffraction element, such as a holographic optical element, a Fresnel lens, a reflective diffraction grating, or a transmissive diffraction grating. A diffraction element can diffuse or converge light by utilizing the diffraction effect of light. By having a diffraction element, for example, the eyepiece device 20 can be simplified. Compared to other optical elements with complex optical configurations, such as lens arrays, a diffraction element can realize a simple and compact device design.

As shown in FIG. 16 etc., the projection optical system 10 that projects light onto this eyepiece device 20 includes a first lens group 12, a deflection mirror 3, and a second lens group 2.

The first lens group 12 has at least one lens and focuses the light projected from the light source 4 at the position of the primary image point P1, which is the image of the light source 4.

The deflection mirror 3 scans the light from the first lens group 12.

The second lens group 2 has at least one lens (e.g., lens 21) and focuses the light from the deflection mirror 3 at the position of the secondary image point P2, which is an image of the primary image point P1.

At this time, the focal point of the second lens group 2 on the light source 4 side is located near the emission position of the chief ray of light on the deflection mirror 3.

The above description of the eyepiece device according to the fourth embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical inconsistency.

Note that the embodiments of this technology are not limited to the above-mentioned embodiments, and various modifications are possible without departing from the spirit of this technology. The specific values, shapes, materials (including compositions), etc. described in each embodiment are merely examples, and are not intended to be limiting.

The present technology can also be configured as follows.
[1]
a first lens group having at least one lens and configured to focus light projected from a light source at a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
a focal point of the second lens group on the light source side is located near an emission position of a chief ray of light from the deflection mirror.
[2]
When the direction from the deflection mirror toward the second lens group is defined as positive,
a distance from a focal point of the second lens group on the light source side to a light emission position on the deflection mirror is equal to or greater than −1% and equal to or less than 2% of a focal length of the second lens group;
The projection optical system according to [1].
[3]
The focal length of the first lens group is 2.0 mm or more.
The projection optical system according to any one of claims 1 to 2.
[4]
The focal length of the second lens group is 24 mm or less.
The projection optical system according to any one of [1] to [3].
[5]
a distance on the optical axis from the exit surface of the second lens group to the secondary image point is 500 mm or less;
The projection optical system according to any one of [1] to [4].
[6]
The chief rays of the respective light beams projected from the second lens group are substantially parallel.
The projection optical system according to any one of [1] to [5].
[7]
the first lens group has a combination of a positive lens and a negative lens;
The projection optical system according to any one of [1] to [6].
[8]
the second lens group has a combination of a positive lens and a negative lens;
The projection optical system according to any one of [1] to [7].
[9]
The light projected from the light source is a laser light.
The projection optical system according to any one of [1] to [8].
[10]
The light source is
A first light source unit that projects light in a first wavelength band;
A second light source unit that projects light in a second wavelength band;
a third light source unit that projects emission light in a third wavelength band,
The projection optical system according to any one of [1] to [9].
[11]
the first wavelength band is a wavelength band corresponding to red,
the second wavelength band is a wavelength band corresponding to green,
The third wavelength band is a wavelength band corresponding to blue.
The projection optical system according to [10].
[12]
The light source is a single light source unit that emits light of multiple wavelength bands.
The projection optical system according to any one of [1] to [9].
[13]
A projection optical system;
an eyepiece device disposed in front of an observer's eye,
The projection optical system comprises:
a first lens group having at least one lens and configured to focus light projected from a light source onto a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
a focal point of the second lens group on the light source side is located in the vicinity of an emission position of a chief ray of light on the deflection mirror,
An image projection apparatus, wherein the eyepiece device projects light from the projection optical system onto the observer's retina.
[14]
A focal point on the light source side of the eyepiece device is disposed at the position of the secondary image point.
The image projection device according to [13].
[15]
The ocular device is a contact lens type device.
The image projection device according to [13] or [14].
[16]
An eyepiece device disposed in front of an eye of an observer and projects light from a projection optical system onto a retina of the observer,
The projection optical system comprises:
a first lens group having at least one lens and configured to focus light projected from a light source onto a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
An eyepiece device, wherein the focal point of the second lens group on the light source side is located near the emission position of the chief ray of light on the deflection mirror.

100 Image projection device 10 Projection optical system 1 First lens group 2 Second lens group 3 Deflection mirror 4 Light source 41R First light source section 41G Second light source section 41B Third light source section 20 Eyepiece device 30 Control section 31 Light source control section 32 Scanning control section P1 Primary image point P2 Secondary image point P3 Focus of second lens group on the light source side P4 Emergence position of chief ray on deflection mirror A1 Passage area of chief ray on exit surface of second lens group A2 Passage area of chief ray on secondary image surface θ Numerical aperture α Swing angle of deflection mirror f1 Focal length of first lens group f2 Focal length of second lens group f3 Focal length of eyepiece device E Eyeball E1 Pupil E2 Retina

Claims (15)

a first lens group having at least one lens and configured to focus light projected from a light source onto a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
a focal point of the second lens group on the light source side is located near an emission position of a chief ray of light from the deflection mirror. When the direction from the deflection mirror toward the second lens group is defined as positive,
a distance from a focal point of the second lens group on the light source side to a light emission position on the deflection mirror is equal to or greater than −1% and equal to or less than 2% of a focal length of the second lens group;
The projection optical system according to claim 1 . The focal length of the first lens group is 2.0 mm or more.
The projection optical system according to claim 1 . The focal length of the second lens group is 24 mm or less.
The projection optical system according to claim 1 . a distance on the optical axis from the exit surface of the second lens group to the secondary image point is 500 mm or less;
The projection optical system according to claim 1 . The chief rays of the respective light beams projected from the second lens group are substantially parallel.
The projection optical system according to claim 1 . the first lens group has a combination of a positive lens and a negative lens;
The projection optical system according to claim 1 . the second lens group has a combination of a positive lens and a negative lens;
The projection optical system according to claim 1 . The light projected from the light source is a laser light.
The projection optical system according to claim 1 . The light source is
A first light source unit that projects light in a first wavelength band;
A second light source unit that projects light in a second wavelength band;
a third light source unit that projects emission light in a third wavelength band,
The projection optical system according to claim 1 . the first wavelength band is a wavelength band corresponding to red,
the second wavelength band is a wavelength band corresponding to green,
The third wavelength band is a wavelength band corresponding to blue.
The projection optical system according to claim 10. A projection optical system;
an eyepiece device disposed in front of an observer's eye,
The projection optical system comprises:
a first lens group having at least one lens and configured to focus light projected from a light source onto a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
a focal point of the second lens group on the light source side is located in the vicinity of an emission position of a chief ray of light on the deflection mirror,
An image projection apparatus, wherein the eyepiece device projects light from the projection optical system onto the observer's retina. A focal point on the light source side of the eyepiece device is disposed at the position of the secondary image point.
The image projection device according to claim 12. The ocular device is a contact lens type device.
The image projection device according to claim 12. An eyepiece device disposed in front of an eye of an observer and projects light from a projection optical system onto a retina of the observer,
The projection optical system comprises:
a first lens group having at least one lens and configured to focus light projected from a light source onto a position of a primary image point which is an image of the light source;
a deflection mirror that scans the light from the first lens group;
a second lens group having at least one lens and configured to focus the light from the deflection mirror at a secondary image point which is an image of the primary image point;
An eyepiece device, wherein the focal point of the second lens group on the light source side is located near the emission position of the chief ray of light on the deflection mirror.