DE2436819A1 - DEVICE FOR OBSERVING A SCALE DIVISION - Google Patents

Description

Dr. lUrhtrt Schol, _ρΠΒ? ■

J afcitauiralt r; - ⁵ TTr """""^ _r

\ er s / \ n / RJ Applicant: fcj. V. Philips Uioeilcimperuubrieken 19-7-7 ■ ')

File No.j PHB-32.359

ig from. July 29, 1974.

"Device for observing a scale division".

The Erf inciting relates to a device for observing a scale division. If a scale division is required in conventional telescopes and microscopes, this is attached in the plane of a real image of the scene or object that is being observed, which ensures that
that both the scale division and the image are set together sharply in the focal plane, so that they transmit without parallax by means of a chi ie s

Eyepiece can be observed. A problem
results when there is no real picture in the instrument

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PIIB 32359

is produced. This is with a Fei'nrohr with a one-time Enlargement of the case, essentially only must consist of a window through which a scene at a certain distance with the eye is observed. Even then, a scale division may still be necessary in order to determine angles in the field of view to be able to measure. Such measurements can be the primary task of a telescope with a single magnification be.

According to a first aspect, the invention provides a device for observing a scale division, which consists of a transparent υ ρ bic element with a spherical hollow surface on which a partially * wise reflective layer is attached, and off there is a scale division which has the shape of part of a sphere leading to said surface is concentric and has a radius of curvature, which is approximately equal to half the radius of curvature of this Surface is.

The scale division can be done directly with the

Eye or with any other image observation device, e.g., a television camera, whose entrance pupil on the common center of curvature the surface and the scale division is centered. But it is also possible that between the image observation device and the device for observation

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A telescope is attached to the scale division, the entrance pupil of which is centered on the described Iveise
is. The transparent optical element can be a toilet of another optical system zlxt ¹ simultaneous observation of the image on which the scale division is superimposed
will form. The element can, for example _{, be} a meniscus lens with a low negative power which reproduces the image of a scene lying at a relatively great distance at a distance at which it is easy to observe

ι
can be. However, the element can also be a part

form any other optical system in which one
Graduation is required.

In a second aspect, the invention provides an observation device of the type in which a Scale division is superimposed and that from a first

■ ι
and a second meniscus element, the

first meniscus element has a gz-outer curvature a radius
as the second meniscus element, while both surfaces of the second meniscus element and the hollow surface of the first meniscus element have a common center of focus and the convex
Surface of the first meniscus element in such
Mass from concentricity to the aforementioned
Finishes that differ from the combination of the two
Meniscus elements have an optical strength that
for pleasant direct observation of a scene

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with an eye that is in the said common center of curvature is located while a partially reflective layer on the said hollow Surface of the first meniscus element attached and a spherical scale division between the meniscus elements is arranged, the central point of the common curvature is concentric, the scale division having such a radius of curvature that it is dxirch Reflection in the reflective layer without effort can be observed with the eye.

With the help of one device after the second Aspect can be a scene with a scale division superimposed on it for the delivery of information, e.g. in relation to the position of a part of the observed scene in relation to another part of the same can be observed. That The observer's eye is located in the area of the center of curvature. The scale division can be based on the the hollow surface of the second minus element closest to the observer's eye is applied, in this surface may be etched or placed in the vicinity of this surface.

Such an instrument is a single magnification telescope and essentially consists in itself from a window through which a scene can be observed. Rays of light that come from far away reaping parts of the observed scene,

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reach the eye of the observer with almost no distraction. The main ray from any point in the scene runs near the center of curvature of the surfaces and is therefore perpendicular to these surfaces. This means that this ray is not from the optical system is deflected so that the scene is observed without distortion over an extended field of view " will.

Such a device also behaves like a concentric meniscus system according to Bouwers when observing the scale division. By making the radius of curvature of the concentric graduation smaller than that of the partially reflective surface, rays of light originating from a point on the graduation and moving away from the observer's eye are reflected from the partially reflective hollow surface of the first meniscus element and partially collimated. After passing through the meniscus element closest to the eye, the light beam reaches the observer's eye and can generate an illusory image of the scale graduation at a distant point, which is superimposed on the image of the scene generated by the telescope. In this case, too, the main ray of the bundle generating the image of the scale graduation runs more or less through the center of curvature of the surface

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perpendicular to these surfaces.

Light-i originating from a point in the scene Rays are made to diverge from the two meniscus elements because each meniscus element is one is weakly negative lens. This means that the image observed by the observer is not in infinity is located, but rather close to the observer lies. In a practical embodiment this Abs band are generally of the order of 0.4 m, what for

a pleasant observation a little too close isb. Dtirch one little deviation from the state of concentricity of the anterior and posterior surfaces of one of the Meniscus elements, this element can be made positive to a slight extent, whereby there is a partial compensation for the negative strength of the other meniscus element, thereby creating the image in any one Distance from the observer can be brought. A generally accepted distance is close to 1 m. To minimize the negative strength of the two meniscus elements in the concentric state make, it is advisable to choose their thickness as small as possible. In a practical embodiment, can the first meniscus element will be weakly positive, while the second will be purely concentric and thus weakly negative is.

The two meniscus elements inevitably lead

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lent a slight negative spherical aberration, which, in the case of the element closest to the eye, has a corrective effect on the positive spherical aberration ', which is inserted from the hollow surface, which acts as a mirror for the scale dividing image. The magnitude of the aberration is, however, when observed with the eye in daylight due to the smaller dimension of the pupil of the eye so small that the Images are not significantly affected. At a low light level, the eye pupil becomes enlarged, thereby observing the images with a high level of aberration; with such With low light levels, however, the performance of the eye has already deteriorated considerably.

The image of the scale division can also be at the same distance from the eye as the image of the scene " be shown by the fact that the radius of curvature of the 'scale division of half the radius of curvature of the partially reflective layer is chosen slightly different. If the radius is the "scale division, if is also chosen to be concentric to the layer, larger than half the radius of this layer, this will be radiation beams reflected from a point on the scale division to the eye of the observer diverge, as a result of which it appears to originate from a point which lies beyond the layer at a finite distance.

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By a suitable choice of the radius of the scale division one can map the scale division with that of the scene collapse. This will result in errors the parallax is kept as small as possible when reading the scale division.

The scale division can have many forms, e.g. by etching in the convex surface of the second meniscus element or by vapor deposition in vacuum or chemical processes. The lines of the scale division can be reflective or diffusing and can therefore be with light emanating from the scene or with appropriate light Anointed positions outside the field of vision Light originating from light sources are illuminated. When the scale division is part of the surface of the second Meniscal element forms, the raditis must have this surface be calculated with the greatest care so that they are at the correct distance from the partial reflective layer is located to ensure that the mapping of the graduation in the same Distance as the image of the scene appears from the observer. The scale division can also change the shape a pointer, wire, grid, beta light strip, or other self-luminescent Have source in close proximity to the convex surface of the second meniscus elemerit

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can be attached. A display device of these Art must have the shape of the surface of a sphere, the center of curvature of which more or less corresponds to the Points of curvature of the optical surfaces coincide, while this device, if movable, moves the surface thereof Ball must follow. When using a movable display device, this can be with a movable one.

Window connected to an illuminated scale fx-ei

- ι

lays on the same sphere as the display device, but located on the edge of the field of view and therefore on the same reflective surface Way the pointer will be observed. However, the window can also be stationary while the illuminated one Scale is connected to the moving pointer. the

ι Scale can e.g. in degrees or radians or in meters

be calibrated per kilometer.

One must take into account that the scale division is arranged in the optical system in such a way that that they come from the scene and the light. Partial illustration of the light generating the scale division shields. As long as the lines of the scale division are not too thick and really quite close to the eye, does the mentioned extent of the shielding have no disruptive consequences.

The one to be generated with this device

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Field of view can be larger than 90 °. Practical difficulties with respect to the production of the individual parts and the scale interval to make it likely that a field of view in the order of 6o ° is a reasonable ₀ Venn example, in a particular device, a horizontal field of view of 6o ° and a vertical field of view of, for example, 20 ° required this can easily be achieved by appropriately machining the edges of the meniscus elements or by using masks.

An additional extension of the device is obtained in that an auxiliary telescope with a from 1 different magnification is arranged in such a way that that its entrance pupil is in the area of the center of curvature of the meniscus elements. This makes it possible to view the scene at a different magnification to be observed with a map of the scale division superimposed on it. Also can if the auxiliary telescope is rotatable about its entrance pupil, all restrictions in the field of view by the possibility a sequential observation can be removed. The brightness of the with the help of such an auxiliary telescope (if it has a high magnification) observed Scene can be compared to the brightness obtained with just a single-magnification telescope decreased because the exit pupil of the

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Fernrohi ^ es with a single magnification smaller than that Can be the entrance pupil of the auxiliary telescope. this could result in the exit pupil of the entire system becoming smaller than the pupil of the eye, whereby the apparent concealment of the scene is reduced.

This reduction in brightness relates

refer to "the use of an auxiliary daylight telescope. It is also possible for the auxiliary telescope to be an image intensifier tube or an infrared imager for use in low light conditions or at. Finding Infrared Images Contains. With such an infrared system, of course meniscus elements permeable to infrared radiation are used will.

The invention * will hereinafter be exemplified explained in more detail with reference to the drawing. Show it:

1 shows a telescope with a single magnification,

Fig. 2 shows the way in which the scale division observed with one of the telescopes ΛίΧΓα,

3 shows the influence of the negative strength of the meniscus elements on the telescope according to FIG. 1,

4 shows a modified embodiment of the telescope according to FIG. 1, with which a comfortable observation distance is obtained, and

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FIG. 5 shows in detail the "mode of operation of the telescope according to FIG. H when observing the scale division.

The type of construction and the mode of operation of the scale graduation monitoring device are initially described in general with reference to FIGS. 1 and 2. A first meniscus element 1 has concentric spherical front and rear surfaces 2 and 3, respectively. The surfaces 2 and 3 have a center of curvature 7. The surface 3, the hollow surface, is provided with a partially reflective layer 8. The second meniscus element h has concentric spherical front and rear surfaces 5 and 6, both of which also have the center of curvature 7. The spherical scale graduation 9 has the same center of curvature 7 and a radius of curvature which is equal to half the radius of curvature of the surface 3. In this example, the surface 5 adjoins the scale division 9. The pupil 10 of the observer's eye is located close to the common center of curvature 7 of all surfaces mentioned and the scale division.

Fig. 1 shows the graduation observation device, as a telescope with a single magnification acts that a bundle of parallel rays 11, which from a relatively distant, puxikt-shaped source in the scene originates, receives.

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The main ray of the beam I 1 passes through the Krümmungsraittelpunkt 7 · Irn general it can be said that the beam without deflection, and chgeht parallel by the two meniscus elements 1 and h hinduz ^ and the pupil 10 of the eye of Beobachters.mit a certain weakening due to the layer 8 reached. The main ray of a corresponding radiation bundle 12, which originates from another relatively distant, point-shaped source in the scene, also passes through the center of curvature 7 at a certain angle to the bundle 11. The bundle 1 ~ 2 is, however, in exactly the same way treated as the bundle 11, so that the scene is observed by the observer with a single magnification and without distortion.

Fig. 2 shows the graduation observation device which produces an image, a graduation, focused at infinity, for the observer's eye. The figure shows a beam cone 14 which diverges from a point 13 on the scale graduation 9 and is incident on the partially reflecting layer 8. The rays · 1'k are reflected with reduced light intensity in the form of a parallel bundle 15 because the point 13 lies in the focal point of the hollow mirror surface 8. The main ray of the bundle 15 passes through the center of curvature 7 and reaches the pupil 10 of the observer's eye. That

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Eye sees point 13 focused and at infinity so as superimposed on the distant scene.

Fig. 3 shows the mode of operation of the telescope with a single enlargement in detail. The meniscus elements 1 and h correspond to those according to FIG. 1. The bundle of parallel rays 16, originating from a distant point in the scene, converges after passing through the surface 2, but then diverges more strongly on exiting the element 1 over the surface 3. In this way the element 1 creates something diverging fret J., which means that it has a low negative strength. Something similar happens in the same sense when the bundle 16 then passes through the element k , so that the divergence of the bundle 16 is increased. The negative strength of the element k is greater than that of the element 1 due to the smaller radii of curvature of the surfaces 5 and 6. As a result, the bundle 16 seems to originate from a point 17 which can be relatively close to the telescope. The distant scene thus appears at a finite distance that can be too small for comfortable observation.

Fig. H shows how the apparent observation distance can be increased. The radius of curvature of the surface 2 is reduced, whereby the positive strength of the surface 2 is increased. The divergence of the bundle 16 when leaving the element ^ is now

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diminishes or has even turned into convergence. The diverging effect of the element h has remained unchanged, as a result of which the final divergence of the bundle is smaller than in FIG. 3. In this way, the bundle 16 now appears to diverge from a point further away

18 in Fig. H. The greater curvature of the surface 2 can be selected such that the point 18, the apparent observation point of a distant scene, comes to lie at a comfortable observation distance,

FIG. 5 shows how the apparent observation distance of the scale division can be changed and, in particular, can be made the same as that of the scene. In FIG. 5, the conical radiation bundle ] k diverges from a point 13 of the graduation 9 and is incident on the partially reflecting layer 8 on the hollow surface 3 of the element 1. The reflected beam

19 can be made converging or diverging to a small extent by moving the graduation 9 over a small distance from the element 1 or towards this element from a nominal position in the focal point of the hollow mirror surface 8. The scale division is kept concentric to the center point 7 so that the radius of curvature is changed with such a movement. The divergence or convergence of the bundle 19 can be made the same as the bundle 2 1 in FIG. H by choosing the correct position for the scale

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will. In FIG. 5, the image 20 of the point 13 of the scale division when observed through the element k appears to be at the same distance as the apparent observation point. 18 of the removed scene in Fig. H.

Details of a practical embodiment of a graduation observer with a field of view of 60 ° will now be given. The material for the two meniscus elements can be "crown" glass with a low refractive index, but the choice of materials is not critical and there is a large group of glasses and clear plastics suitable for this purpose. The first meniscus element has an axial thickness of 5 "and the radius of the convex surface is 50 ^{± 25 mm and that} of the hollow surface 49.75 mm. For the second meniscus element, the radii of curvature of the convex and hollow surfaces are 25> 0 min or 22.0 mm, so that the thickness is 3 mm. The graduation is made by engraving on the convex surface of the second meniscus element. The hollow surface of the first meniscus element is covered with a very thin layer of aluminum, whereby the semipermeable layer is obtained.

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Claims (1)

PHB 32359 19-7.7 ^ Patent claims : Λ.J Device for observing a scale division, characterized in that it consists of a transparent optical element with a spherical hollow surface on which a partially reflective layer is applied, and of a scale division which has the shape of part of a sphere which is concentric with said surface and has a radius of curvature which is approximately equal to half the radius of curvature of this surface. 2o observation instrument of the type in which the Scale division is superimposed, which contains a first and a second meniscus element, characterized in that, that the first meniscus element has a larger radius of curvature than the second meniscus element, wherein the two surfaces of the second meniscus element and the hollow surface of the first meniscus element become one common curvature instincts point out, while the convex surface of the first meniscus element of concentricity to said surfaces in such Mass deviates, so that the combination of the two meniscus elements receives an optical strength that is pleasant for a direct observation of a scene with one eye located in said common center of curvature is suitable, on the hollow surface of the first meniscus element a partially reflective 509809/0753. ■ PHB 32359 19. 7. 7 '* • constant layer is angebriicht, while a spherical scale division, which is concentric with the common center of curvature, located between the two Meniskuseiementen, said graduation having such a radius of curvature that by reflection in said layer, the scale division without An ₁ -strengung with this Eye can be observed. 3. Device according to claim 2, characterized in that the graduation is located on one of the two surfaces of the second meniscus element. H. Device according to Claim 1 or 2, characterized in that the scale division contains a pointer which can be moved in the spherical surface of the scale division. • 509809/0753 4S Emptied