WO2021102620A1 - Long-distance large field of view iris optical imaging device and method - Google Patents

Abstract

A long-distance large field of view iris optical imaging device (100), comprising: an iris optical tracking system, comprising a 3D depth imaging unit; an iris zoom focusing optical imaging system, comprising an optical zoom focusing lens assembly (120) and an ultra-high resolution image imaging sensor (122), used for executing adjustments of a focal length and/or a focusing position of iris imaging according to a 3D physical space point coordinate, the ultra-high resolution image imaging sensor (122) being physically imaged; an LED illumination light source radiation system, comprising a radiation intensity solid angle and/or radiation intensity direction angle and used for executing, according to the 3D physical space point coordinate, the combined control in response to the matching relation among fields of view of the iris zoom focusing optical imaging system corresponding to different working radiuses/distances; and an image processing and drive control system (150), used for achieving the driving and feedback control among system units. The device and an imaging method thereof can ensure the constancy of the irradiance in a large field of view.

Description

Device and method for long-distance large-field-of-view iris optical imaging Technical field

The present invention relates to the technical field of optical imaging, in particular to a device and method for long-distance large-field iris optical imaging.

Background technique

Known iris imaging devices have the following drawbacks. The imaging time of acquiring images in a long working distance and large working field of view scene exceeds 1-3s, and the user cannot maintain a consistent and relatively static state for such a long time, due to the image iris diameter Requires a large magnification requirement of >200pixel, resulting in a very slight movement that can cause the field of view of the iris imaging system to be readjusted, zoom focus, and illumination.

In addition, traditional ranging includes software mapping the iris diameter or binocular distance, because the error is too large due to the variation of the population that is greater than 20%, and the accurate working distance information cannot be provided, which directly affects the overall performance. The same is true for physical measurements such as infrared, ultrasound, and tof. The distance is too large to provide accurate working distance information under the scenes of long working distance and large working field of view. At the same time, the known technology has image quality such as depth of field, image brightness, image relative illuminance, illuminating light source radiation intensity, and iris irradiance of the eye. In the scene of long working distance and large working field of view, the consistency cannot be guaranteed, and even the difference is several times. The traditional lighting source is adjusted with the inverse square of the working distance, and the radiation intensity of the non-constant light source (such as the range of 2 to 3 times the working distance, The angle of view changes by 2 to 3 times, and the radiation intensity changes by 4 to 9 times), resulting in the inability to meet the requirements of constant field of view and radiation illuminance in a large range at the same time.

The traditional improved imaging field of view uses a mechanical pan/tilt structure, which leads to complex control, low positioning error accuracy, low stability and reliability, serious problems in power consumption, volume and noise life, and time-consuming imaging after waiting for the adjustment of the pan/tilt position Very severe imaging speed is very slow.

Therefore, in view of the above-mentioned technical problems in the scenes of long working distance and large working field of view in the prior art, a device and method for long-distance and large field of view iris optical imaging are needed.

Summary of the invention

One aspect of the present invention is to provide a device for optical imaging of a long-distance iris with a large field of view, the device comprising:

Iris optical tracking system, iris zoom focusing optical imaging system, LED illumination light source radiation system, image display feedback system, image processing and drive control system;

The iris optical tracking system includes a 3D depth imaging unit for performing 3D physical space point coordinate acquisition;

The iris zoom focusing optical imaging system includes an optical zoom focusing lens group and an ultra-high-resolution image imaging sensor, which is used to perform focal length and/or focus position adjustment of iris imaging according to 3D physical space point coordinates, and ultra-high-resolution image imaging Sensor physical imaging;

The LED illuminating light source radiation system includes a solid angle of radiation intensity and/or a direction angle of radiation intensity, which is used to perform response to different working radii/distances corresponding to the iris zoom focusing optical imaging system between the field of view angles according to the 3D physical space point coordinates. Combination control of matching relationships;

The image display feedback system includes a display screen for real-time display of current images and/or status information;

The image processing and drive control system is connected to the iris optical tracking system, the iris zoom focusing optical imaging system, the LED illumination light source radiation system, and the image display feedback system, and realizes the drive and feedback control between each system unit.

The imaging field angle of the 3D depth imaging unit is greater than or equal to the imaging field angle of the iris zoom focusing optical imaging system.

Preferably, the 3D depth imaging unit includes 3D TOF depth imaging or structured light depth imaging, or binocular stereo vision imaging.

Preferably, the ultra-high resolution image imaging sensor has a resolution of at least 8K.

Preferably, the radiation intensity direction angle of the LED illumination light source radiation system satisfies the relationship: ψ=arctan(D/R), where,

Defined in the angle between the center line corresponding to the peak direction of the radiation intensity of the LED illumination light source radiation system and the optical axis of the iris zoom focusing optical imaging system, D is the optical center of the LED illumination light source radiation system and the optical center of the iris zoom focusing optical imaging system Distance, R is the working radius of the iris zoom focusing optical imaging system.

Preferably, the solid angle of the radiation intensity of the LED illumination light source radiation system satisfies the relationship: Ω(ω)=4π*sin ² (ω) unit steradian sr, where,

ω=arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/((1+β)*EFLiris))=arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/(β* R)), ω is the half field angle of the iris zoom focusing optical imaging system,

PXiris is the pixel resolution in the X horizontal direction of the iris zoom focusing optical imaging system,

PYiris is the Y vertical pixel resolution of the iris zoom focusing optical imaging system,

EFLiris is the focal length position,

β=PR*PSiris, PR is the image resolution of the physical diameter of the iris,

PSiris is the pixel unit resolution of the ultra-high resolution image imaging sensor of the iris zoom focusing optical imaging system,

R is the working radius of the iris zoom focusing optical imaging system.

Preferably, the LED illumination light source radiation system and the iris focal length focusing optical imaging system are configured as:

The combined imaging mode of global pixel exposure (integration) and illumination radiation in the synchronization pulse external trigger or the synchronization pulse internal trigger mode in the combination of the filter, in which:

The synchronization pulse exposure (integration) time and the synchronization pulse illumination radiation time Tpulse<m/(PR*speed) of the combined imaging mode,

speed is the predetermined controlled movement speed, in m/s,

PR is the image resolution of the physical diameter of the iris,

m is the pixel scale of the motion blur image that is predetermined to be controlled, the unit is pixel;

The synchronization pulse exposure (integration) frequency and the synchronization pulse illumination radiation frequency Fpulse of the combined imaging mode, the synchronization pulse illumination radiation frequency Fpulse=[10, 30] Hz,

The LED illuminating light source radiation system generates synchronous pulsed illuminating radiation on the surface of the iris. The irradiance Tpulse*Fpulse*Eiris(ω)<10mw/cm ² /s,

Eiris(ω) is the irradiance on the surface of the iris.

Another aspect of the present invention is to provide a method for long-distance large-field-of-view iris optical imaging, the method comprising:

The image processing and drive control system implements the drive and feedback control process between the iris optical tracking system, the iris zoom focusing optical imaging system, the LED illumination light source radiation system, and the image display feedback system:

a. Feedback control of the iris optical tracking system. The 3D depth imaging unit of the iris optical tracking system obtains the 3D coordinates of the key points of the iris, and converts the relative coordinates to 3D physical space points to achieve real-time synchronous iris optical imaging tracking;

b. Feedback control of the iris zoom focusing optical imaging system and ultra-high-resolution image imaging sensor, according to the 3D physical space point coordinates, realize real-time synchronization of the feedback control of the focal length and/or focus position of the optical zoom focusing lens group, and ultra-high-resolution images Physical imaging of imaging sensor;

c. Feedback control LED illumination light source radiation system, according to 3D physical space point coordinates, realize real-time synchronization response to different working radius/distance corresponding to the iris zoom focus optical imaging system's matching relationship between the field of view angle of the LED illumination light source radiation intensity direction Feedback control of angle and/or solid angle of LED illumination light source radiation intensity;

d. Feedback control The image display feedback system displays the current image and/or status information in real time;

The image display feedback system realizes real-time synchronous display that the current image is an infrared image imaged by a 3D depth imaging unit, an RGB visible light unit imaging image or an iris zoom focusing optical imaging image.

Preferably, the feedback control iris imaging tracking system includes:

a1. Define the field of view FOVface and effective imaging focal length EFLface of the 3D depth imaging unit according to the predetermined working field of view FOV:

EFLface=[(PXface ² +PYface ² ) ^1/2 *PSface/2]/tan(FOVface/2)

PXface is the X horizontal pixel resolution of the 3D depth imaging unit;

PYface is the Y vertical pixel resolution of the 3D depth imaging unit;

PSface is the pixel unit resolution of the 3D depth imaging unit;

FOVface is the field of view angle of the 3D depth imaging unit, FOVface=FOV;

EFLface is the effective imaging focal length of the 3D depth imaging unit.

a2. Define the key points of the 3D depth imaging unit to control the acquisition of the iris:

a21. Obtain the brightness (infrared gray scale) image Ii(x, y) and the depth distance image Iz(x, y) of the 3D depth imaging unit;

a22. Detect the face area in the brightness image Ii(x,y), and further locate the center coordinates of the left and right eyes (xl, yl) and (xr, yr) in the face area;

a23. Obtain the depth distance information of the positions corresponding to the coordinates of the left and right eye centers in the depth distance image Iz(x,y),

z=[Iz(xl,yl)+lz(xr,yr)]/2

or

z=Iz((xl+xr)/2, (yl+yr)/2);

a24. Generate key reference points for the image side of the 3D depth imaging unit,

KPface(xe,ye,z): KPface(xe,ye,z)=KPface((xl+xr-PXface)/2*PSface, (yl+yr-PYface)/2*PSface,z);

a25. Generate the key reference point KPface(Xe,Ye,Ze) of the 3D depth imaging unit object: KPface(Xe,Ye,Ze)=KPface(xe*z/EFLface,ye*z/EFLface,z).

a3. Establish the object key reference point coordinates of the 3D depth imaging unit KPface (Xe, Xe, Ze) relative to the 3D physical space point Piris (X, Y, Z) coordinate transformation of the iris zoom focusing optical imaging system, Piris (X, Y) , Z)=(Xe-Xoffset, Xe-Yoffset, Ze-Zoffset),

(Xoffset, Yoffset, Zoffset) is the 3D physical position coordinate offset of the 3D depth imaging unit relative to the iris zoom focusing optical imaging system.

Preferably, the feedback control iris zoom focusing optical imaging system includes:

b1. Perform synchronization control of the focal length and focus parameters of the iris zoom and focus optical imaging system;

b11. Perform the control of the focal length parameters of the iris zoom and focus optical imaging system to achieve a predetermined magnification that keeps the focal position constant, that is, the same imaging iris diameter,

Focus position EFLiris=R*β/(1+β)R=(X ² +Y ² +Z ² ) ^1/2 ,

Among them, β=PR*PSiris, and PR is the image-side resolution of the physical diameter of the iris,

The pixel unit resolution of the image imaging sensor of the PSiris iris zoom focusing optical imaging system,

R is the working radius of the iris zoom focusing optical imaging system;

b2. Perform the focus parameter control of the iris zoom focusing optical imaging system to achieve the focus position within the depth of field of the image side.

Focus position FOCUS=β*[R-kDOF, R+kDOF],

Among them, the control range of k steps, DOF=2*FNO*SOC*(1+β)/β ² , where FNO is the aperture parameter of the iris zoom focusing optical imaging system,

SOC is the minimum physical spot resolution parameter of the iris zoom focusing optical imaging system.

Preferably, the feedback control LED illumination light source radiation system includes:

c1. Perform the direction and angle parameter control of the radiation intensity of the illumination light source of the LED illumination light source radiation system

The radiation direction angle of the LED illumination light source ψ = arctan (D/R),

Defined as the angle between the center line corresponding to the peak direction of the radiation intensity of the LED illumination light source radiation system and the optical axis of the iris zoom focusing optical imaging system, D is the optical center of the LED illumination light source radiation system and the optical center of the iris zoom focusing optical imaging system Distance, R is the working radius of the iris zoom focusing optical imaging system;

c2. Perform parameter control of the solid angle of the LED illumination light source radiation intensity of the LED illumination light source radiation system,

The solid angle of the radiant intensity of the LED lighting source Ω(ω)=4π*sin ² (ω) unit steradian sr, where,

ω=arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/((1+β)*EFLiris))=arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/(β* R)), ω is the half field angle of the iris zoom focusing optical imaging system,

PXiris is the pixel resolution in the X horizontal direction of the iris zoom focusing optical imaging system,

PYiris is the Y vertical pixel resolution of the iris zoom focusing optical imaging system,

EFLiris is the focal length position,

β=PR*PSiris, PR is the image resolution of the physical diameter of the iris,

PSiris is the pixel unit resolution of the ultra-high resolution image imaging sensor of the iris zoom focusing optical imaging system,

R is the working radius of the iris zoom focusing optical imaging system.

The device and method for long-distance and large-field-of-view iris optical imaging provided by the present invention can simultaneously realize constant field of view and radiation illuminance in a large range, and has the following advantages:

1. Constant magnification is the same iris diameter of the imaged image.

2. Respond to the imaging speed within 0.1s within the field of view, working distance and depth of field.

3. Constant imaging depth of field.

4. Constant imaging image brightness.

5. Constant imaging image relative contrast.

6. Constant total light power radiated by the LED lighting source system.

7. Constant irradiance of the eye iris, and meets the upper limit of eye biological safety radiation.

8. The moving speed up to 1m/s is not affected by motion blur, and resists the interference of various ambient light>10,000lux noise conditions.

9. There is no mechanical moving parts, high reliability and stability, and the working distance is greater than 1m, and the field of view range is greater than 60 degrees.

It should be understood that the foregoing general description and the subsequent detailed description are exemplary descriptions and explanations, and should not be used as a limitation on the content claimed by the present invention.

Description of the drawings

With reference to the accompanying drawings, more objectives, functions and advantages of the present invention will be clarified by the following description of the embodiments of the present invention, in which:

Fig. 1 schematically shows a schematic diagram of a device for optical imaging of a long-distance large field of view iris in an embodiment of the present invention.

Reference signs:

100 Long-distance and large field of view iris optical imaging device,

110 3D depth imaging unit infrared VCSEL light source,

111 The infrared imaging lens and image imaging sensor of the depth imaging unit,

114 Visible light RGB image imaging unit,

115 The field of view of the 3D depth imaging unit is the predetermined working field of view FOVface,

116 The predetermined near-end working radius Rnear,

117 The predetermined near-end working distance Znear,

118 The predetermined remote working radius Rfar,

119 The predetermined remote working distance Zfar,

120 The zoom focus imaging lens group of the iris zoom focus optical imaging system,

121 The filter of the iris zoom focusing optical imaging system,

122 Ultra-high resolution image imaging sensor of iris zoom focusing optical imaging system,

123 protection window,

124 iris zoom focus optical imaging system's near-end working radius/distance Rnear/Znear field of view FOViris-near,

125 iris zoom focusing optical imaging system's far-end working radius/distance Rfar/Zfar field of view FOViris-far,

126 The near-end working radius/distance Rnear/Znear imaging area of the object plane of the iris zoom focusing optical imaging system,

127 The far-end working radius/distance Rfar/Zfar imaging area of the object plane of the iris zoom focusing optical imaging system,

When the 130L/130R is at the far end working radius/distance Rfar/Zfar, the LED illuminating light source radiates the LED illuminating light source on the left and right sides of the system,

When the 131L/131R is in the near-end working radius/distance Rnear/Znear, the LED illuminating light source radiates the left and right side LED illuminating light source of the system,

When the 132L/132R is at the far end working radius/distance Rfar/Zfar, the solid angle of the left/right illuminating light source radiation intensity of the LED illumination light source radiation system is matched with the far end working radius/distance Rfar/Zfar of the iris zoom focusing optical imaging system Field of view FOViris-far,

When the 133L/133R is in the near-end working radius/distance Rnear/Znear, the solid angle of the left/right illuminating light source radiation intensity of the LED illumination light source radiation system is matched with the near-end working radius/distance of the iris zoom focusing optical imaging system. Field of view FOViris-near,

When the 134L/134R is in the near-end working radius/distance Rnear/Znear, the left/right illuminating light source radiation intensity direction angle of the LED illumination light source radiation system is matched with the near-end working radius/distance Rnear/Znear of the iris zoom focusing optical imaging system,

When the 135L/135R is at the far end working radius/distance Rfar/Zfar, the left/right illuminating light source radiation intensity direction angle of the LED illumination light source radiation system matches the far end working radius/distance Rfar/Zfar of the iris zoom focusing optical imaging system,

150 Image processing and drive control system,

160 Image display feedback system.

Detailed ways

By referring to exemplary embodiments, the objects and functions of the present invention and methods for achieving these objects and functions will be clarified. However, the present invention is not limited to the exemplary embodiments disclosed below; it can be implemented in different forms. The essence of the description is only to help those skilled in the relevant art to comprehensively understand the specific details of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference signs represent the same or similar components or the same or similar steps.

Example one:

As shown in FIG. 1, a schematic diagram of the principle of a long-distance large-field iris optical imaging device in an embodiment of the present invention. According to this embodiment of the present invention, a long-distance large-field iris optical imaging device 100 includes: iris optics Tracking system, iris zoom focusing optical imaging system, LED illumination light source radiation system, image display feedback system 160, image processing and drive control system 150.

The iris optical tracking system includes a 3D depth imaging unit.

The 3D depth imaging unit can adopt 3D TOF depth imaging or structured light depth imaging (for example, 940nm infrared VCSEL light source 110, imaging lens and image imaging sensor 111), or binocular stereo vision imaging (LED illumination light source, 2 groups installed at a fixed interval) The parameter symmetrical imaging lens and image imaging sensor) provide depth image information.

The iris zoom focusing optical imaging system includes an optical zoom focusing lens group 120, an optical filter 121, and an ultra-high resolution image imaging sensor 122.

The LED illuminating light source radiation system includes the combined control of the solid angle of the radiant intensity of the LED illuminating light source and/or the direction and angle of the radiant intensity.

The image display feedback system 160 includes a display screen for real-time display of current images and/or status information.

The imaging field angle 115 of the 3D depth imaging unit is greater than or equal to the imaging field angle 124/125 of the iris zoom focusing optical imaging system.

The ultra-high resolution image imaging sensor 122 has a resolution of at least 8K.

The image processing and drive control system 150 is connected to the iris optical tracking system, the iris zoom focusing optical imaging system, the LED illumination light source radiation system, and the image display feedback system, and realizes the drive and feedback control between each system unit.

According to this embodiment of the present invention, a method for long-distance large-field-of-view iris optical imaging includes: the image processing and drive control system executes the drive and feedback control process between each system unit as follows:

a. Feedback control of the iris imaging tracking system, through the 3D depth imaging unit to obtain the 3D coordinates of the key points of the iris, and convert the relative coordinates to 3D physical space points to achieve real-time synchronous iris optical imaging tracking.

b. Feedback control of the iris zoom focusing optical imaging system, according to the 3D physical space point coordinates, real-time synchronization of the feedback control of the focal length and focus position of the optical zoom focusing lens group, and the physical imaging feedback control of the ultra-high resolution image imaging sensor.

c. Feedback control LED illumination light source radiation system, according to 3D physical space point coordinates, realize real-time synchronization response to different working radius/distance corresponding to the iris zoom focus optical imaging system's matching relationship between the field of view angle of the LED illumination light source radiation intensity direction Feedback control of angle and/or solid angle of LED illumination light source radiation intensity.

d. Feedback control The image display feedback system displays the current image and/or status information in real time.

The image display feedback system realizes real-time synchronous display of the current image as an infrared brightness image imaged by a 3D depth imaging unit, an RGB visible light unit image or an iris zoom focusing optical image.

According to the embodiment of the present invention, the specific steps include:

a1. Define the field of view FOVface115 and the effective imaging focal length EFLface of the 3D depth imaging unit according to the predetermined working field of view FOV.

EFLface=[(PXface ² +PYface ² ) ^1/2 *PSface/2]/tan(FOVface/2),

PXface is the X horizontal pixel resolution of the 3D depth imaging unit, pixel;

PYface is the Y vertical pixel resolution of the 3D depth imaging unit, pixel;

PSface is the pixel unit resolution of the 3D depth imaging unit, um/pixel;

FOVface is the field of view of the 3D depth imaging unit, FOVface=FOV;

EFLface is the effective imaging focal length of the 3D depth imaging unit, mm.

Typical parameters are calculated as follows:

PXface=640pixels, PYface=480pixels, PSface=5.6um/pixel, FOVface=FOV=77 degrees, EFLface=2.8mm.

a2. Define the 3D depth imaging unit to control and acquire the key points of the iris.

a21. Obtain the brightness (infrared gray scale) image Ii(x, y) and the depth distance image Iz(x, y) of the 3D depth imaging unit.

a22. Detect the face area in the brightness image Ii(x, y), and further locate the center coordinates (xl, yl) and (xr, yr) of the left and right eyes in the face area.

At present, the well-known deep learning-based convolutional neural network CNN cascade model can reliably and accurately realize the functions of face region detection and eye positioning.

Specifically, in order to improve the performance of detecting and positioning eyes, this embodiment adopts the independent or combined visible light RGB image imaging unit 114 to perform calibration and registration of the 3D depth imaging unit and the visible light RGB image imaging unit 114 in advance, and then further detect the face area in the RGB image And human eye positioning improves accuracy and reliability. In addition, the RGB imaging unit can be used to detect the face when the device is in the standby state and trigger the system to enter the normal working state, thereby reducing the standby power consumption of the system. Furthermore, the image formed by the visible light RGB image imaging unit is used in the image display feedback system to display the current image in real time.

a23. Obtain the depth distance information of the positions corresponding to the coordinates of the left and right eye centers in the depth distance image Iz(x,y),

z=[Iz(xl,yl)+lz(xr,yr)]/2,

or

z=Iz((xl+xr)/2, (yl+yr)/2).

a24. Generate 3D depth imaging unit image side key reference point KPface(xe,ye,z): KPface(xe,ye,z)=KPface((xl+xr-PXface)/2*PSface, (yl+yr-PYface) )/2*PSface,z).

a25. Generate the key reference point KPface (Xe, Ye, Ze) of the 3D depth imaging unit object: KPface (Xe, Ye, Ze) = KPface (xe*z/EFLface, ye*z/EFLface, z).

a3. Establish the key reference point coordinates of the 3D depth imaging unit KPface (Xe, Xe, Ze) relative to the 3D physical space point Piris (X, Y, Z) coordinate transformation of the iris zoom focusing optical imaging system,

Piris(X, Y, Z)=(Xe-Xoffset, Xe-Yoffset, Ze-Zoffset),

Among them, (Xoffset, Yoffset, Zoffset) is the 3D physical position coordinate offset of the 3D depth imaging unit relative to the iris zoom focusing optical imaging system.

Perform synchronization control of the focal length and focus parameters of the iris zoom and focus optical imaging system, including:

b1. Perform the focal length parameter control of the iris zoom focusing optical imaging system to achieve a predetermined magnification that keeps the focal position constant, that is, the same imaging iris diameter.

Focus position EFLiris=R*β/(1+β)R=(X ² +Y ² +Z ² ) ^1/2

Among them, β=PR*PSiris PR is the physical diameter of the iris and the image resolution pixel/mm, such as a typical 20pixels/mm. The pixel unit resolution of the ultra-high resolution image imaging sensor of the PSiris iris zoom focusing optical imaging system is um/pixel, As a typical 3um/pixel, β=0.06.

As shown in Figure 1, R is a predetermined working radius, including a predetermined proximal working radius Rnear116, a predetermined distal working radius Rfar118,

The predetermined working distance Z includes a predetermined near-end working distance Znear117 and a predetermined far-end working distance Zfar119.

For example, the typical parameters near-end working radius Rnear=1m, and far-end working radius Rfar=2m, respectively EFLiris=56.6mm and 113.2mm.

Considering that the actual user moves involuntarily while ensuring the speed and adjustment frequency, the optical zoom operation can be performed after the R interval is changed by a certain predetermined range. If you keep the same focal length relative to the range of 5-10cm, this design is reasonable, and the iris diameter itself also varies from person to person.

b2. Perform the focus parameter control of the iris zoom focusing optical imaging system to achieve the focus position within the depth of field of the image side.

Focus position FOCUS=β*[R-kDOF, R+kDOF]

Among them, k step number control range, k=[1, 2], step length is STEP=β*DOF, such as k=2, including -2STEP, -STEP, 0, +STEP, 2STEP, a total of 5 ranges, DOF= 2*FNO*SOC*(1+β)/β ² , where FNO is the aperture parameter of the iris zoom focusing optical imaging system, the parameter range is [PF, 2PF], PF=PSiris/(1um/pixel); SOC is The minimum physical spot resolution parameter of the iris zoom focusing optical imaging system. The typical value of the parameter is SOC=2*PSiris*1pixel, and the maximum value DOF=21.2mm.

Due to the error of the depth information, the iris zoom focusing optical imaging system has a precision mechanical error in the actual manufacturing process, individual deviations, etc., resulting in 2k+1 times the step size control position, the step size is β*DOF, generally 3-5 steps. The range is completely in the predetermined image-side focus position, ensuring that the focus position is within the object depth of field range of +-DOF/2 (equivalent, within the image-side depth of field range of +-β*DOF/2), and at the same time such a small number of control steps The number can be guaranteed to be completed in 0.1s.

The above-mentioned design of the present invention guarantees a constant range of depth of field, and at the same time realizes that the focus position is within the range of depth of field of the image plane.

Ideal aspheric optical glass/plastic hybrid 2 liquid lens liquid lenses independently control the focal length EFLiris and focus FOCUS respectively. The above design requires both focal length and focus position to be converted to the correspondingly designed imaging optical system. The diopter of the 2 liquid lenses is the unit specification Compared with the complex cam curve control driven by traditional stepping motors, the liquid lens has a diopter and voltage/current corresponding linear response optical property relationship, which can greatly simplify the driving control process, and this design can greatly reduce the overall imaging The number of system components (12-16 pieces in 3-4 groups).

At the same time, there are no mechanical transmission parts driven by traditional screw or gear connection, no service life limit, and the control accuracy and repeatability are also substantially improved.

In practice of the present invention, the current liquid lens has a limited clear aperture typically such as 6-10mm, and a limited diopter range -10 to +20 diopters, the wavefront error increases to λ/10 at large diopters, but Attributable to the FNO value and long focal length application requirements of the depth of field, it is suitable for the iris zoom focusing optical imaging system. Optical designers can use the characteristics of liquid lens to optimize the design of the optical path. For example, select the appropriate exit entrance pupil in the optical path and design the FNO to solve the clear aperture. The initial design of the zoom part of the optical system is to set the zoom liquid lens to work at 0 diopter optical power. The far end working radius/distance corresponds to the maximum focal length. The initial design of the focusing part of the optical system is to set the focusing liquid lens to work at the image plane position corresponding to the far end working radius/distance when the focusing liquid lens is at 0 diopter optical power.

Perform parameter control of the LED illumination light source radiation intensity direction angle and/or LED illumination light source radiation intensity solid angle parameter control of the LED illumination light source radiation system, and realize that the coordinates of different 3D physical space points respond to the iris focal length corresponding to different working radius/distance focusing optics The matching of the relationship between the field of view angle ranges of the imaging system is shown in Figure 1.

c1. Execute the parameter control of the direction and angle of the illuminating light source radiation intensity of the LED illuminating light source radiation system.

Radiation direction angle of LED lighting source ψ = arctan(D/R)

Defined as the angle between the center line corresponding to the peak direction of the radiation intensity of the LED illumination light source radiation system and the optical axis of the iris zoom focusing optical imaging system, D is the optical center of the LED illumination light source radiation system and the optical center of the iris zoom focusing optical imaging system Distance, R is the working radius of the iris zoom focusing optical imaging system.

The equivalent definition is the angle ψ'between the center line corresponding to the peak direction of the radiation intensity of the LED illumination light source radiation system and the object plane of the iris zoom focusing optical imaging system, ψ=90-ψ'.

C2. Perform parameter control of the solid angle of the LED lighting source radiation intensity of the LED lighting source radiation system.

The solid angle of the radiant intensity of the LED lighting source Ω(ω)=4π*sin ² (ω) unit sphere degree sr

ω=arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/((1+β)*EFLiris))=arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/(β* R))

ω is the half field angle of the iris zoom focusing optical imaging system.

PXiris is the pixel resolution in the X horizontal direction of the iris zoom focusing optical imaging system, pixel.

PYiris is the Y vertical pixel resolution of the iris zoom focusing optical imaging system, pixel.

The radiant intensity peak value Ipeak of the LED illumination light source radiation system, Ipeak=OP/Ω(ω) unit mw/sr.

OP is the total optical power of the radiation system of the LED lighting source, mw.

The solid angle Ω(ω) of the radiation intensity of the LED illumination light source defines the solid angle distributed in the corresponding range of the radiation intensity peak direction when the ratio of the radiation intensity Iρ of the LED illumination light source radiation system to the peak radiation intensity Ipeak is equal to ρ.

ρ=Iρ/Ipeak, ρ is the relative illuminance of light radiation received by the imaging image surface of the predetermined custom iris focal length focusing optical imaging system, such as 0.5 or 0.707, higher means the relative illuminance is more evenly distributed.

Essentially, the solid angle of the radiant intensity of the LED lighting source produces the radiant illuminance Eiris on the surface of the iris, Eiris(ω,ψ)=OP/(Ω(ω)*R ² )*cos ³ (ψ).

When ω is small enough, sin ² (ω)=tan ² (ω) is satisfied.

As shown in Figure 1, the near-end working radius/distance Rnear/Znear field of view FOViris-near124 of the iris zoom focusing optical imaging system. The far-end working radius/distance Rfar/Zfar field of view FOViris-far125 of the iris zoom focusing optical imaging system. The iris zoom focuses the near-end working radius/distance Rnear/Znear of the object plane imaging area 126 of the optical imaging system. The far-end working radius/distance Rfar/Zfar imaging area 127 of the object plane of the iris zoom focusing optical imaging system. At the far end working radius/distance Rfar/Zfar, the LED illumination light source radiates the left and right sides of the LED illumination light source 130L/130R of the system. At the near end working radius/distance Rnear/Znear, the LED illumination light source radiates the left and right side LED illumination light sources 131L/131R of the system. At the far end working radius/distance Rfar/Zfar, the solid angle of the radiation intensity of the left/right illuminating light source of the LED illumination light source radiation system is matched with the far end working radius/distance Rfar/Zfar field of view angle of the iris zoom focusing optical imaging system FOViris-far132L/132R. At the near end working radius/distance Rnear/Znear, the solid angle of the radiation intensity of the left/right illuminating light source of the LED illumination light source radiation system is matched with the near-end working radius/distance Rnear/Znear field of view angle of the iris zoom focusing optical imaging system FOViris-near133L/133R. In the near-end working radius/distance Rnear/Znear, the left/right illuminating light source radiation intensity direction angle of the LED illumination light source radiation system matches the near-end working radius/distance Rnear/Znear134L/134R of the iris zoom focusing optical imaging system. At the far end working radius/distance Rfar/Zfar, the left/right illuminating light source radiation intensity direction angle of the LED illumination light source radiation system matches the far end working radius/distance Rfar/Zfar135L/135R of the iris zoom focusing optical imaging system.

The present invention can realize the essentially constant total light power of the LED illumination light source radiation system, by dynamically changing the radiation intensity of the LED illumination light source, the light radiation intensity of the solid angle distribution is changed by the same amount, regardless of the iris zoom focusing optical imaging. How the system changes in the far/near-end working radius [Rfar, Rnear]/distance [Zfar, Znear] and the corresponding field of view [FOViris-far, FOViris-near], according to the formula Eiris(ω, ψ) is kept close to constant , And can fully match the working radius/distance and the corresponding iris optical zoom focusing optical imaging system's field of view angle.

It can be proved that for an imaging image surface with an iris focal length focusing optical imaging system, the light radiation illuminance Eimage is received.

According to the formula Eimage(ω,ψ)=1/16/(1+β) ² *cos ⁴ (Φ)*μ*Eiris(ω,ψ)/FNO ² ,

When ω is small enough to satisfy cos ⁴ (Φ)=1, Φ is the imaging incident angle of the iris focal length focusing optical imaging system, Φ=[0,ω], and μ is the optical reflectivity of the iris biological tissue.

Eimage is constant, that is, the imaged image brightness Iimage is constant.

Iimage=QE*Tpulse*Eimage*ADC*G

QE is the photon-electronic quantum conversion efficiency unit e-/(mw*um ² )/s, G is the unit conversion gain unit mv/e-, and ADC is the analog voltage/digital brightness conversion unit LSB/mv.

At present, traditional CMOS SENSOR technology performs photon-electronic quantum conversion using PD silicon-based photodiodes, which are not efficient. Cutting-edge QF quantum film or OPF organic photosensitive film technologies have natural high quantum conversion efficiency for infrared photons, and global shutter. The properties are ideally preferred.

At the same time, it can be proved that the relative illuminance ρ of the imaging image surface of the iris focal length focusing optical imaging system is constant, ρ=Eedge/Ecenter=Iρ/Ipeak, Eedge is the irradiance at the edge of the imaging image surface (the edge of the field of view) Eedge=Eimage(ω,ψ)*ρ, Ecenter is the irradiance at the center of the imaging image plane (the center of the field of view), Ecenter=Eimage(ω,ψ) means that the brightness of the imaging image has a constant relative contrast.

In the present invention, the LED illuminating light source radiation system is controlled by an array combination with different radiation direction angles and radiation intensity solid angles, so as to match the corresponding iris focal length and focus the field of view angle range of the optical imaging system [FOViris-far, FOViris-near], Working radius range [Rfar, Rnear], or working distance range [Zfar, Znear].

In the present invention, the LED illumination light source radiation system and the iris focal length focusing optical imaging system are combined and configured to have a combined control response to the synchrotron radiation intensity direction angle and the radiation intensity solid angle, so as to realize the response of the LED illumination light source radiation system in different 3D physical space points. The corresponding matching relationship between the field of view angles of the iris zoom focusing optical imaging system corresponding to different working radii/distances, meets the constant imaging image brightness within the predetermined working field of view and working distance, and the constant imaging image contrast, constant The radiant power of the LED lighting source system and the constant irradiance of the iris of the eye.

In order to eliminate the motion blur caused by the user's motion in actual use, due to such a large optical magnification, even a moving speed below 10cm/s can cause very obvious image motion blur interference, which affects the recognition performance.

In the present invention, the LED illumination light source radiation system and the iris focal length focusing optical imaging system are configured as a global pixel exposure (integration) and illumination radiation combined imaging mode of synchronous pulse external triggering or synchronous pulse internal triggering.

Among them, the synchronization pulse exposure (integration) time and the synchronization pulse illumination radiation time Tpulse<m/(PR*speed), speed is the predetermined controlled movement speed such as 1m/s, m is the predetermined controlled motion blur image pixel scale, m< 10pxiels.

Synchronous pulse exposure (integration) frequency and synchronous pulse illumination radiation frequency Fpulse, Fpulse=[10,30]Hz, LED illumination light source radiation system generates synchronous pulse illumination radiation on the iris surface irradiance Tpulse*Fpulse*Eiris(ω)< 10mw/cm2/s to ensure that the eye radiation biological safety is met.

Furthermore, the iris focal length focusing optical imaging system realizes the global pixel exposure (integration) and the combined imaging mode of the illumination radiation in the synchronization pulse external trigger or the synchronization pulse internal trigger mode under the combination of the filter. Anti-interference performance under various light interference conditions. Such as outdoor solar environment up to 10,000 lux or more.

The ultra-high-resolution image imaging sensor of the present invention has a resolution of at least 8K, which is above 8000*4000. Considering such ultra-high-resolution bandwidth and frame rate are limited, the present invention can use binning or subsampling in image quality processing. The imaging mode improves the preprocessing speed of image imaging quality.

Due to the fact that the image imaging sensor cannot increase the resolution indefinitely, and further expand the field of view angle, the present invention adopts multiple groups of iris focal length focusing optical imaging system arrays to achieve the corresponding group of several times to increase the field of view angle. It can be equivalently understood as the angle of view corresponding to the resolution of the corresponding multiple.

The protective window 123 can be made of full-transmission tempered optical glass, or more preferably, a filter that reflects visible light below 700nm and transmits infrared light from 700-900nm, which can protect the internal optical components while the user cannot observe the internal structure by reflecting visible light Provide users with visual feedback in their natural state. Furthermore, filtering visible light can increase the focal length of the iris and focus the optical imaging system to eliminate interference with external non-imaging wavelength stray light, and further improve the image quality SNR.

The invention provides a long-distance large-field-of-view iris optical imaging device and method, which simultaneously realizes the constant viewing angle and radiation illuminance in a large range.

In combination with the description and practice of the present invention disclosed herein, other embodiments of the present invention are easily conceived and understood by those skilled in the art. The description and embodiments are only considered to be exemplary, and the true scope and spirit of the present invention are defined by the claims.

Claims (10)

A device for long-distance and large-field-of-view iris optical imaging is characterized in that the device comprises: Iris optical tracking system, iris zoom focusing optical imaging system, LED illumination light source radiation system, image display feedback system, image processing and drive control system; The iris optical tracking system includes a 3D depth imaging unit for performing 3D physical space point coordinate acquisition; The iris zoom focusing optical imaging system includes an optical zoom focusing lens group and an ultra-high-resolution image imaging sensor, which is used to perform focal length and focus position adjustment of iris imaging according to 3D physical space point coordinates. The ultra-high-resolution image imaging sensor is physically Imaging The LED illuminating light source radiation system includes a solid angle of radiation intensity and/or a direction angle of radiation intensity, which is used to perform response to different working radii/distances corresponding to the iris zoom focusing optical imaging system between the field of view angles according to the 3D physical space point coordinates. Combination control of matching relationships; The image display feedback system includes a display screen for real-time display of current images and/or status information; The imaging field angle of the 3D depth imaging unit is greater than or equal to the imaging field angle of the iris zoom focusing optical imaging system; The image processing and drive control system is connected to the iris optical tracking system, the iris zoom focusing optical imaging system, the LED illumination light source radiation system, and the image display feedback system, and realizes the drive and feedback control between each system unit. The device according to claim 1, wherein the 3D depth imaging unit comprises 3D TOF depth imaging or structured light depth imaging, or binocular stereo vision imaging. The device according to claim 1, wherein the ultra-high resolution image imaging sensor has a resolution of at least 8K. The device according to claim 1, wherein the radiation intensity direction angle of the LED illumination light source radiation system satisfies the relationship: ψ=arctan(D/R), wherein, Defined in the angle between the center line corresponding to the peak direction of the radiation intensity of the LED illumination light source radiation system and the optical axis of the iris zoom focusing optical imaging system, D is the optical center of the LED illumination light source radiation system and the optical center of the iris zoom focusing optical imaging system Distance, R is the working radius of the iris zoom focusing optical imaging system. The device according to claim 1, wherein the solid angle of the radiation intensity of the LED illumination light source radiation system satisfies the relationship: Ω(ω)=4π*sin ² (ω) unit sphere degree sr, wherein, ω=arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/((1+β)*EFLiris)) = Arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/(β*R)), ω is the half field of view of the iris zoom focusing optical imaging system, PXiris is the pixel resolution in the X horizontal direction of the iris zoom focusing optical imaging system, PYiris is the Y vertical pixel resolution of the iris zoom focusing optical imaging system, EFLiris is the focal length position, β=PR*PSiris, PR is the image resolution of the physical diameter of the iris, PSiris is the pixel unit resolution of the ultra-high resolution image imaging sensor of the iris zoom focusing optical imaging system, R is the working radius of the iris zoom focusing optical imaging system. The device according to claim 1, wherein the LED illumination light source radiation system and the iris focal length focusing optical imaging system are configured as: The combined imaging mode of global pixel exposure (integration) and illumination radiation in the synchronization pulse external trigger or the synchronization pulse internal trigger mode in the combination of the filter, in which: The synchronization pulse exposure (integration) time and the synchronization pulse illumination radiation time Tpulse<m/(PR*speed) of the combined imaging mode, speed is the predetermined controlled movement speed, in m/s, PR is the image resolution of the physical diameter of the iris, m is the pixel scale of the motion blur image that is predetermined to be controlled, the unit is pixel; The synchronization pulse exposure (integration) frequency and the synchronization pulse illumination radiation frequency Fpulse of the combined imaging mode, the synchronization pulse illumination radiation frequency Fpulse=[10, 30] Hz, The LED illuminating light source radiation system generates synchronous pulsed illuminating radiation on the surface of the iris. The irradiance Tpulse*Fpulse*Eiris(ω)<10mw/cm ² /s, Eiris(ω) is the irradiance on the surface of the iris. A method for long-distance and large-field-of-view iris optical imaging is characterized in that the method includes: The image processing and drive control system implements the drive and feedback control process between the iris optical tracking system, the iris zoom focusing optical imaging system, the LED illumination light source radiation system, and the image display feedback system: a. Feedback control of the iris optical tracking system. The 3D depth imaging unit of the iris optical tracking system obtains the 3D coordinates of the key points of the iris, and converts the relative coordinates to 3D physical space points to achieve real-time synchronous iris optical imaging tracking; b. Feedback control of the iris zoom focusing optical imaging system, according to the 3D physical space point coordinates, to achieve real-time synchronization of the feedback control of the focal length and/or focus position of the optical zoom focusing lens group, and the feedback control of the physical imaging of the ultra-high resolution image imaging sensor; c. Feedback control LED illumination light source radiation system, according to 3D physical space point coordinates, realize real-time synchronization response to different working radius/distance corresponding to the iris zoom focus optical imaging system's matching relationship between the field of view angle of the LED illumination light source radiation intensity direction Feedback control of angle and/or solid angle of LED illumination light source radiation intensity; d. Feedback control The image display feedback system displays the current image and/or status information in real time; The image display feedback system realizes real-time synchronous display that the current image is an infrared image imaged by a 3D depth imaging unit, an RGB visible light unit imaging image or an iris zoom focusing optical imaging image. The method according to claim 7, wherein the feedback control of the iris imaging tracking system comprises: a1. Define the field of view FOVface and effective imaging focal length EFLface of the 3D depth imaging unit according to the predetermined working field of view FOV: EFLface=[(PXface ² +PYface ² ) ^1/2 *PSface/2]/tan(FOVface/2) PXface is the X horizontal pixel resolution of the 3D depth imaging unit; PYface is the Y vertical pixel resolution of the 3D depth imaging unit; PSface is the pixel unit resolution of the 3D depth imaging unit; FOVface is the field of view angle of the 3D depth imaging unit, FOVface=FOV; EFLface is the effective imaging focal length of the 3D depth imaging unit. a2. Define the key points of the 3D depth imaging unit to control the acquisition of the iris: a21. Obtain the brightness (infrared gray scale) image Ii(x, y) and the depth distance image Iz(x, y) of the 3D depth imaging unit; a22. Detect the face area in the brightness image Ii(x,y), and further locate the center coordinates of the left and right eyes (xl, yl) and (xr, yr) in the face area; a23. Obtain the depth distance information of the positions corresponding to the coordinates of the left and right eye centers in the depth distance image Iz(x,y), z=[Iz(xl,yl)+lz(xr,yr)]/2 or z=Iz((xl+xr)/2, (yl+yr)/2); a24. Generate key reference points for the image side of the 3D depth imaging unit, KPface(xe,ye,z): KPface(xe,ye,z)=KPface((xl+xr-PXface)/2*PSface, (yl+yr-PYface)/2*PSface,z); a25. Generate the key reference point KPface(Xe,Ye,Ze) of the 3D depth imaging unit object: KPface(Xe,Ye,Ze)=KPface(xe*z/EFLface,ye*z/EFLface,z). a3. Establish the object key reference point coordinates of the 3D depth imaging unit KPface (Xe, Xe, Ze) relative to the 3D physical space point Piris (X, Y, Z) coordinate transformation of the iris zoom focusing optical imaging system, Piris (X, Y) , Z)=(Xe-Xoffset, Xe-Yoffset, Ze-Zoffset), (Xoffset, Yoffset, Zoffset) is the 3D physical position coordinate offset of the 3D depth imaging unit relative to the iris zoom focusing optical imaging system. The method according to claim 7, wherein the feedback control of the iris zoom focusing optical imaging system comprises: b1. Perform synchronization control of the focal length and focus parameters of the iris zoom and focus optical imaging system; b11. Perform the control of the focal length parameters of the iris zoom and focus optical imaging system to achieve a predetermined magnification that keeps the focal position constant, that is, the same imaging iris diameter, Focus position EFLiris=R*β/(1+β)R=(X ² +Y ² +Z ² ) ^1/2 , Among them, β=PR*PSiris, and PR is the image-side resolution of the physical diameter of the iris, The pixel unit resolution of the image imaging sensor of the PSiris iris zoom focusing optical imaging system, R is the working radius of the iris zoom focusing optical imaging system; b2. Perform the focus parameter control of the iris zoom focusing optical imaging system to achieve the focus position within the depth of field of the image side. Focus position FOCUS=β*[R-kDOF, R+kDOF], Among them, the control range of k steps, DOF=2*FNO*SOC*(1+β)/β ² , where FNO is the aperture parameter of the iris zoom focusing optical imaging system, SOC is the minimum physical spot resolution parameter of the iris zoom focusing optical imaging system. The method according to claim 7, wherein the feedback control of the LED illumination light source radiation system comprises: c1. Perform the direction and angle parameter control of the radiation intensity of the illumination light source of the LED illumination light source radiation system The radiation direction angle of the LED illumination light source ψ = arctan (D/R), Defined as the angle between the center line corresponding to the peak direction of the radiation intensity of the LED illumination light source radiation system and the optical axis of the iris zoom focusing optical imaging system, D is the optical center of the LED illumination light source radiation system and the optical center of the iris zoom focusing optical imaging system Distance, R is the working radius of the iris zoom focusing optical imaging system; c2. Perform parameter control of the solid angle of the LED illumination light source radiation intensity of the LED illumination light source radiation system, The solid angle of the radiant intensity of the LED lighting source Ω(ω)=4π*sin ² (ω) unit steradian sr, where, ω=arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/((1+β)*EFLiris)) = Arctan((PXiris ² +PYiris ² ) ^1/2 /2*PSiris/(β*R)), ω is the half field of view of the iris zoom focusing optical imaging system, PXiris is the pixel resolution in the X horizontal direction of the iris zoom focusing optical imaging system, PYiris is the Y vertical pixel resolution of the iris zoom focusing optical imaging system, EFLiris is the focal length position, β=PR*PSiris, PR is the image resolution of the physical diameter of the iris, PSiris is the pixel unit resolution of the ultra-high resolution image imaging sensor of the iris zoom focusing optical imaging system, R is the working radius of the iris zoom focusing optical imaging system.

Images