CN114199525A - Integrated lens measuring device and measuring method thereof - Google Patents
Integrated lens measuring device and measuring method thereof Download PDFInfo
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- CN114199525A CN114199525A CN202111507063.2A CN202111507063A CN114199525A CN 114199525 A CN114199525 A CN 114199525A CN 202111507063 A CN202111507063 A CN 202111507063A CN 114199525 A CN114199525 A CN 114199525A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G01B11/00—Measuring arrangements characterised by the use of optical techniques
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Abstract
The invention provides an integrated lens measuring device and a measuring method thereof.A ultraviolet light structured light information displayed on an ultraviolet light liquid crystal display enters a first camera set after being reflected by one side surface of a lens to be measured, and meanwhile, a visible light structured light information displayed on the ultraviolet light visible light conversion liquid crystal display enters the first camera set after being refracted by two surfaces of the lens to be measured; and ultraviolet light structural light information displayed on the ultraviolet light and visible light conversion liquid crystal display enters the second camera set after being reflected by the surface on the other side of the lens to be detected. And respectively calculating the three-dimensional appearances of the two surfaces of the lens under the same coordinate system by means of the camera imaging parameter calibration result and the light reflection law, so that the lens thickness information can be obtained by difference. In addition, the camera observes the visible structure light information of the liquid crystal display converted from the ultraviolet light and the visible light through two-time refraction of the two surfaces of the lens, and the refractive index of the lens can be solved according to the refraction law and geometric constraint.
Description
Technical Field
The invention relates to the field of optics, in particular to a lens measuring device and method.
Background
Phase measurement deflection is a non-contact surface shape detection technology based on structured light coding, phase shift technology and wavefront reconstruction algorithm. However, for transparent elements, when internal reflection exists, reflection of light simultaneously exists at the front and rear surfaces, which affects accurate extraction of fringe phases. The conventional method for measuring the lens surface by phase measurement deflection usually adopts a method for roughening or blackening the lower surface of the element to pre-treat the transparent element to be measured, however, the method can only measure one of the upper surface and the lower surface of the transparent element. Even if the upper and lower surfaces of the transparent element are inverted for measurement, the coordinate systems of the upper and lower surfaces of the transparent element obtained by the two measurements are not uniform, and thus the thickness information of the lens element cannot be obtained.
Aiming at most organic resin and glass materials, the material has good absorption effect on ultraviolet rays. To address this problem, Sprenger D et al (Faber C, Seraphim M, G.
UV-Deflectometry:No parasitic reflections[C]Dgao 2010,111: a 19) first proposed an ultraviolet light deflection using an ultraviolet light source, a movable slit and a camera making up the system. However, this method requires moving the slit several positions in the horizontal and vertical directions to realize the scanning of the light bar formed by the uv light source through the slit on the lens surface, which takes a long time for measurement and has a complicated structure. Meanwhile, whether the central position of the light bar can be accurately extracted is also a decisive factor influencing whether the measurement result is accurate.
Wang, R et al (Li, d., Li, l., Xu, k., Tang, l., Chen, p., & Wang, Q. (2018). Surface shape measurement of longitudinal plane measurement, optical Engineering,57(10),104104.) propose a method using fourier transform to eliminate aliasing of the information of the upper and lower surfaces of the lens while reflecting fringes, however, this method is only suitable for thicker plate transparent elements.
Lampalzer R et al (Method and apparatus for the same and the same surface normal of preferred specific objects: U.S. Pat. No. 8,284,392[ P ].2012-10-9.) disclose a phase shift deflection technique covering the visible, infrared and ultraviolet bands, which is used to measure one of a specular surface or a transparent member. And it thinks that the structured light display device is a plane, however, the display device such as a liquid crystal display is often not an ideal plane, and there is a certain flatness deviation.
Disclosure of Invention
The purpose of the invention is as follows: the integrated lens measuring device and the measuring method thereof under the same coordinate system are provided, and the measuring result is accurate.
The technical scheme is as follows: an integrated lens measuring device comprises a first camera set and an ultraviolet light liquid crystal display which are arranged on one side of a lens to be measured, and a second camera set and an ultraviolet light and visible light conversion liquid crystal display which are correspondingly arranged on the other side of the lens to be measured;
the ultraviolet light structured light information displayed on the ultraviolet light liquid crystal display enters the first camera set after being reflected by the surface of one side of the lens to be tested, and meanwhile, the visible light structured light information displayed on the ultraviolet light visible light conversion liquid crystal display enters the first camera set after being refracted by the two surfaces of the lens to be tested; and ultraviolet light structural light information displayed on the ultraviolet light and visible light conversion liquid crystal display enters the second camera set after being reflected by the surface on the other side of the lens to be detected.
In the measuring device, the lens to be measured can be considered not only as an absolute planar structure but also as a three-dimensional structure having a surface shape.
Further, the ultraviolet wavelength range displayed on the ultraviolet liquid crystal display and the ultraviolet-visible light conversion liquid crystal display is 10-400 nm, and the ultraviolet wavelength range belongs to OKP-1, PMMA, soda-lime glass and other lens commonly-used manufacturing materials and can almost completely absorb the ultraviolet light in the wave band.
Further, the ultraviolet light liquid crystal display and the ultraviolet light-visible light conversion liquid crystal display include a liquid crystal display using an ultraviolet lamp tube as a backlight, a liquid crystal display using an ultraviolet Light Emitting Diode (LED) as a backlight, a liquid crystal display using an ultraviolet light emitting lamp bead (LED) as a backlight, a liquid crystal display using an ultraviolet projector (DLP) as a backlight, or a liquid crystal display using an ultraviolet Organic Light Emitting Diode (OLED) for self-luminescence.
Further, a light homogenizing film, a light homogenizing lens or a light guide plate is arranged on the ultraviolet light liquid crystal display and the ultraviolet light and visible light conversion liquid crystal display and used for enabling the screen brightness to be more uniform.
Furthermore, at least one ultraviolet light liquid crystal display and at least one ultraviolet light and visible light conversion liquid crystal display are arranged.
Further, the realization of the ultraviolet light and visible light conversion process of the ultraviolet light and visible light conversion liquid crystal display comprises switching an ultraviolet light backlight light source and a visible light backlight light source at the back of the liquid crystal screen.
Further, the ultraviolet light and visible light conversion liquid crystal display can be replaced by an independent ultraviolet light liquid crystal display and a visible light liquid crystal display.
An integrated lens measurement method comprising the steps of:
(1) building a measuring device, and calibrating and position debugging the measuring device;
(2) displaying ultraviolet light structured light information on an ultraviolet light liquid crystal display, carrying out absolute phase expansion on the ultraviolet light structured light information which is collected by a first camera group and is subjected to reflection modulation by the surface on one side of a lens, and solving that ultraviolet light rays received by each pixel of the first camera group are emitted by a certain position of the ultraviolet light liquid crystal display;
(3) solving the surface shape of one side surface of the lens by utilizing a camera imaging model, a system geometric relation and a reflection law;
(4) displaying ultraviolet light structural light information on an ultraviolet light and visible light conversion liquid crystal display, carrying out absolute phase expansion on the ultraviolet light structural light information which is collected by a second camera set and is subjected to reflection modulation by the surface on the other side of a lens, and solving that ultraviolet light rays received by each pixel of the second camera set are emitted by a certain position of the ultraviolet light and visible light conversion liquid crystal display;
(5) solving the surface shape of the surface on the other side of the lens by using a camera imaging model, a system geometric relation and a reflection law;
(6) the surface shapes of the two sides of the lens are known, and the difference between the two surface shapes is used for obtaining the thickness of the lens;
(7) displaying visible light structured light information on an ultraviolet light and visible light conversion liquid crystal display, carrying out absolute phase expansion on the visible light structured light information which is collected by a first camera group and is subjected to refraction modulation by surfaces on two sides of a lens, and solving that visible light rays received by each pixel of the first camera group are emitted by a certain position of the ultraviolet light and visible light conversion liquid crystal display;
(8) and solving a refraction angle according to the surface shapes of the two side surfaces of the measured lens and the refraction law, taking the system geometric relation and the refraction law as constraints, and solving the refraction index of the lens by optimizing or violently searching the refraction index.
Further, the positions of the display pixels shot by each pixel of the camera set correspondingly are obtained by adopting a time phase unwrapping algorithm in the steps (2), (4) and (7)
Further, in the step (3) and (5), the ray corresponding to a certain pixel of the camera group internal reference camera can be obtained through camera internal reference calibration, the height is searched on the ray, so that the incident ray and the emergent ray correspondingly received by other cameras in the camera group at the height meet the reflection law and the normal vectors of all cameras in the camera group at the point are consistent, the lens height corresponding to the pixel is obtained, the lens heights corresponding to all pixels of the reference camera are found, and finally the surface shape of the side surface corresponding to the lens is obtained.
As can be seen from the above aspects of the present invention, the present invention has the following significant advantages:
1. ultraviolet light was introduced to measure the lens. The characteristic that the lens material almost completely absorbs wavelength ultraviolet light is fully utilized, the influence of reflected light on the bottom surface of the lens on the upper surface is eliminated by utilizing ultraviolet irradiation, and the accurate measurement of the upper surface and the lower surface of the lens is realized. An ultraviolet light/visible light conversion liquid crystal display is arranged at the bottom of the lens to display visible light, and then the camera can refract the observed visible structural light information twice through the upper surface and the lower surface of the lens. With the three-dimensional appearance of the upper and lower surfaces of the lens in the same coordinate system, the lens thickness information can be obviously obtained by difference. Because the upper and lower surfaces of the lens are measured, the camera can observe the visible structure light information of the ultraviolet light/visible light conversion liquid crystal display through twice refraction of the upper and lower surfaces of the lens, and the refractive index of the lens can be solved according to the refraction law and geometric constraint.
2. By utilizing the characteristic that the pixels of the liquid crystal display are arranged in rows and columns at equal intervals, the liquid crystal display can be used for projecting accurate stripe image information more conveniently and accurately, and the accuracy of a subsequent measurement result is further ensured.
3. The method comprises the steps of firstly, collecting ultraviolet structural light displayed by the ultraviolet liquid crystal display after the ultraviolet structural light is reflected and modulated by the upper surface of the lens by using a camera, and obtaining the position of a pixel of the ultraviolet liquid crystal display corresponding to light rays shot by each pixel of the camera through an absolute phase obtained by resolving stripe phases. Due to the characteristic that the pixels of the liquid crystal display are arranged in rows and columns at equal intervals, the two-dimensional size physical coordinates of the light emergent points on the ultraviolet liquid crystal screen can be obtained according to the positions of the pixels on the premise that the pixel intervals are known. And further utilizing the calibration result of the ultraviolet liquid crystal screen relative to the position of the camera and the surface shape calibration result of the ultraviolet liquid crystal screen to obtain the three-dimensional size physical coordinate of the light emergent point on the ultraviolet liquid crystal screen. And secondly, collecting ultraviolet structure light displayed by the ultraviolet light/visible light conversion liquid crystal display after the ultraviolet light/visible light conversion liquid crystal display is subjected to reflection modulation by the lower surface of the lens by using a camera, and obtaining the pixel position of the ultraviolet light/visible light conversion liquid crystal display corresponding to the light rays shot by each pixel of the camera through the absolute phase obtained by resolving the fringe phase. Due to the characteristic that the pixels of the liquid crystal display are arranged in rows and columns at equal intervals, on the premise of knowing the pixel interval, the two-dimensional size physical coordinate of the light emergent point on the ultraviolet/visible light conversion liquid crystal display can be obtained according to the pixel position. And further utilizing the calibration result of the ultraviolet light/visible light conversion liquid crystal display relative to the position of the camera and the surface shape calibration result of the ultraviolet light/visible light conversion liquid crystal display to obtain the three-dimensional size physical coordinate of the light ray emergent point on the ultraviolet light/visible light conversion liquid crystal display. And respectively calculating the three-dimensional shapes of the upper surface and the lower surface of the lens by a computer by means of a camera imaging parameter calibration result and a light reflection law. The upper and lower surfaces of the lens are located in the same coordinate system, and the lens thickness information can be obtained by differentiating. And acquiring visible structure light displayed by the ultraviolet light/visible light conversion liquid crystal display after refraction and modulation on the upper surface and the lower surface of the lens by using a camera, and obtaining the pixel position of the ultraviolet light/visible light conversion liquid crystal display corresponding to light rays shot by each pixel of the camera through an absolute phase obtained by phase calculation. Due to the characteristic that the pixels of the liquid crystal display are arranged in rows and columns at equal intervals, on the premise of knowing the pixel interval, the two-dimensional size physical coordinate of the light emergent point on the ultraviolet/visible light conversion liquid crystal display can be obtained according to the pixel position. And further utilizing the calibration result of the ultraviolet light/visible light conversion liquid crystal display relative to the position of the camera and the surface shape calibration result of the ultraviolet light/visible light conversion liquid crystal display to obtain the three-dimensional size physical coordinate of the light ray emergent point on the ultraviolet light/visible light conversion liquid crystal display. And calculating the refractive index of the lens by a computer by means of a camera imaging parameter calibration result and a light refraction law.
4. In the aspect of precision, because the three-dimensional appearance of the structured light projection equipment is considered, the measurement results of the upper surface and the lower surface of the lens and the thickness of the lens are more accurate.
Drawings
FIG. 1 is a schematic structural diagram of a measuring device according to the present invention;
FIG. 2 is a schematic view of the principle of measuring the upper surface of a lens;
FIG. 3 is a schematic view of the principle of measuring the lower surface of a lens;
FIG. 4 is a schematic view of the principle of lens refractive index measurement;
FIG. 5 is a diagram showing calibration results of relative position relationships among four cameras, an ultraviolet liquid crystal display and an ultraviolet/visible light conversion liquid crystal display of the measuring device;
FIG. 6 is a diagram showing the calibration result of the UV LCD surface profile;
FIG. 7 is a diagram illustrating the calibration result of UV/visible light conversion LCD surface shape;
FIG. 8 is a schematic diagram showing the measurement results of the upper surface profile of the lens;
FIG. 9 is a diagram illustrating the measurement result of the surface shape of the lower surface of the lens;
FIG. 10 is a graph showing lens thickness measurements;
FIG. 11 is a graph showing the lens refractive index measurement results.
Detailed Description
An integrated lens measuring device, as shown in fig. 1, includes four cameras (two cameras 1, 2 as a first camera set, two cameras 3, 4 as a second camera set), an ultraviolet liquid crystal display 5, an ultraviolet/visible light converting liquid crystal display 6, a lens 8 to be measured, and a computer 7 connecting all the cameras 1, 2, 3, 4, the ultraviolet liquid crystal display 5 and the ultraviolet/visible light converting liquid crystal display 6. Wherein, the cameras 1, 2, 3 and 4 are ultraviolet enhanced cameras and can simultaneously sense visible light and ultraviolet light, and the ultraviolet light wave band covers 365 nm; the computer 7 is used for controlling the display of the structured light information of the two liquid crystal displays 5 and 6 and the image acquisition control of the four cameras 1, 2, 3 and 4, and calculating to obtain a measurement result; the wavelength of ultraviolet light displayed on the ultraviolet light liquid crystal display 5 is 365nm, an ultraviolet LED is used as backlight, and the resolution is 1920 multiplied by 1080; the wavelength of ultraviolet light displayed on the ultraviolet light/visible light conversion liquid crystal display 6 is 365nm, an ultraviolet LED and a white light LED are used as backlight, and the resolution is 1920 x 1080; the lens 8 to be measured has uniform refractive index, thickness of about 10mm and is made of polycarbonate.
The four cameras 1, 2, 3, 4, the ultraviolet liquid crystal display 5, and the ultraviolet/visible light composite liquid crystal display 6 are fixed by mechanical means so as to maintain the relative positional relationship. The two cameras 1 and 2 and the ultraviolet light liquid crystal display 5 of the first camera set are arranged above the lens 8 to be tested, and the two cameras 3 and 4 and the ultraviolet light/visible light composite liquid crystal display 6 of the second camera set are arranged below the lens 8 to be tested. Two cameras 3 and 4 of a second camera set are correspondingly arranged under the first camera set, and an ultraviolet light/visible light conversion liquid crystal display 6 is correspondingly arranged under an ultraviolet light liquid crystal display 5. The ultraviolet light structural light displayed on the ultraviolet light liquid crystal display 5 enters the first camera set through structural light information after being reflected by the upper surface of the lens 8 to be tested, and the visible light structural light displayed on the ultraviolet light/visible light composite liquid crystal display 6 simultaneously enters the first camera set through structural light information after being refracted by the upper surface and the lower surface of the lens 8 to be tested; and the ultraviolet light structural light displayed by the ultraviolet light/visible light composite liquid crystal display 6 enters the second camera set through the structural light information after the ultraviolet light structural light is reflected by the lower surface of the lens 8 to be tested.
The method for measuring the surface shapes, the thicknesses and the refractive indexes of the two surfaces of the integrated lens by adopting the measuring device comprises the following specific steps:
(1) building a measuring device:
the ultraviolet light liquid crystal display 5 and the two cameras 1 and 2 of the first camera set are placed in the direction facing the upper surface of the lens 8 to be measured, so that the two cameras 1 and 2 can observe the structured light information of the ultraviolet light displayed on the ultraviolet light liquid crystal display 5, which enters the cameras 1 and 2 after being reflected and modulated by the upper surface of the lens 8. The other two cameras 3 and 4 and the ultraviolet light/visible light composite liquid crystal display 6 are placed in the direction facing the lower surface of the lens 8, so that the two cameras 1 and 2 of the first camera set can observe the visible light information entering the cameras 1 and 2 after the visible light displayed by the ultraviolet light/visible light composite liquid crystal display 6 is refracted and modulated on the upper surface and the lower surface of the lens 8, and meanwhile, the two cameras 3 and 4 of the second camera set below can observe the structured light information entering the cameras 3 and 4 after the ultraviolet light displayed on the ultraviolet light/visible light composite liquid crystal display 6 is reflected and modulated on the lower surface of the lens 8.
(2) Calibrating the built measuring device:
in order to realize the surface shape measurement of the lens 8, the four cameras 1, 2, 3 and 4, the ultraviolet liquid crystal display 5 and the ultraviolet/visible light composite liquid crystal display 6 need to be calibrated. Firstly, internal reference calibration of small hole imaging models of four cameras 1, 2, 3 and 4 is completed through Zhang Zhengyou calibration, and imaging parameter calibration results of the four cameras 1, 2, 3 and 4 are shown in a table 1:
TABLE 1 Camera imaging parameters
In the table, (u)0,v0) As the principal point coordinates, f, of the pinhole modelx、fyIs a horizontal and vertical focal length, k1、k2、k3As radial distortion coefficient, p1、p2Is the tangential distortion coefficient.
The measurement of the relative position relationship of the four cameras 1, 2, 3 and 4, the ultraviolet light liquid crystal display 5 and the ultraviolet light/visible light composite liquid crystal display 6 and the calibration of the surface shapes of the liquid crystal displays 5 and 6 are finished through a point light source microscope measuring head in the three-coordinate measuring machine. The calibration results of the relative position relationship between the four cameras 1, 2, 3, 4, the uv-lcd 5 and the uv/visible-lcd 6 are shown in fig. 5, the calibration results of the surface shape of the uv-lcd 5 are shown in fig. 6, and the calibration results of the surface shape of the uv/visible-lcd 6 are shown in fig. 7.
(3) And (3) completing debugging of the measuring device:
and fixing and packaging the calibrated four cameras 1, 2, 3 and 4, the ultraviolet light liquid crystal display 5 and the ultraviolet light/visible light conversion liquid crystal display 6 to form the measuring device.
(4) The measuring device is placed in a position where the lens 8 can be measured:
adjusting the positions of the components of the measuring device to enable the two cameras 1 and 2 of the first camera set to simultaneously observe ultraviolet light structured light information displayed on the ultraviolet light liquid crystal display 5 through the reflection of the upper surface of the lens 8 and observe visible light structured light information displayed on the ultraviolet light/visible light composite liquid crystal display 6 through the refraction of the upper surface and the lower surface of the lens 8; the two cameras 3 and 4 of the second camera set can observe the ultraviolet light structured light information displayed on the ultraviolet light/visible light composite liquid crystal display 6 through reflection of the lower surface of the lens 8.
(5) The method comprises the steps of utilizing cameras 1 and 2 of a first camera set to collect ultraviolet stripe structure light information displayed by an ultraviolet liquid crystal display 5 after the ultraviolet stripe structure light information is reflected and modulated by the upper surface of a lens 8, and obtaining the position of an ultraviolet liquid crystal display pixel X shot by each pixel X of the cameras 1 and 2 by using a time phase unwrapping algorithm in Huntley J M, Saldner H.Temporal phase-unwrapting algorithm for automatic interferometric interaction analysis [ J ]. Applied Optics,1993,32(17):3047 3052 ]:
in the present embodiment, 10 sets of single frequency stripes I of 1 to 10 are projected on the uv-lcd 5 according to the time-phase unwrapping algorithm1(x) Wherein each set of stripes is solved for a wrapped phase φ (x) wrapped between [ - π, + π) by a four-step phase shift method as in equation (1):
wherein n is the number of phase shift steps;
the position relation of each pixel X of the camera corresponding to the 5 pixels X of the ultraviolet liquid crystal display can be the absolute phase after the wrapping phase phi (X) is unwrapped
To obtain the absolute phase
The relationship to the wrapped phase φ (x) is as follows:
to obtain the coefficient k (x) in equation (2), the absolute phase at frequency t is defined by the phase relationship between different sets of frequency stripes
The relationship to wrapped phase φ (x, t) is as follows:
the relationship f (X) between the position of the screen pixel X and each pixel X of the corresponding camera at the 10 th set of frequencies can be calculated by equation (4):
where the coefficient v (x,10) can be calculated by equation (5), where round (·) denotes rounding the decimal fraction:
(6) solving the three-dimensional shape information of the upper surface of the lens 8:
to obtain pixel x in camera 1 of fig. 21The corresponding lens 8 height is an example.
By calibrating the internal parameters of the camera 1, the pixel x can be obtained1Corresponding ray l1Camera 1 pixel x obtained by absolute phase1Corresponding to the screen point P of the UV LCD 51. At ray l1At a certain height Z, pixels x are taken from the camera 1 according to the law of reflection1Height Z, corresponding screen point P1The normal vector 1 of the surface can be calculated. In addition, at this height, according to the internal reference calibration result of the camera 2, the corresponding pixel x can be obtained2 Camera 2 pixels x obtained by absolute phase2Corresponding screen point P2. And then 2 pixels x by the camera according to the law of reflection2Height Z, corresponding screen point P2The normal vector 2 of the surface can be calculated. Judging whether the curved surface normal vector 1 and the curved surface normal vector 2 are superposed or not, and if so, determining that the point is the pixel x1The height of the lens 8 is corresponding to the surface shape S of the upper surface of the lens 81(x) (ii) a If they do not coincide, continue on the ray l1Other heightsThe calculation is carried out until a coincidence point of the two normal vectors is found. All the pixel points in all the cameras 1 are traversed, and the surface shape S of the upper surface of the lens 8 can be finally obtained1(x)。
In the example of fig. 2, pixel x is known1Ray l1And pixel x1Corresponding screen point P1At a ray l1Upper search for different heights ZA，ZB，ZC… …, obtaining different heights Z according to the internal reference calibration result of the camera 2A，ZB，ZCDifferent pixels x corresponding to the lower camera 22A，x2B，x2CPixel x2ACorresponding screen point P2APixel x2BCorresponding screen point P2BPixel x2CCorresponding screen point P2C… … are provided. It can be seen that the height ZAAnd a height ZCThe normal vector 1 of the curved surface represented by the arrow with the solid line is not consistent with the normal vector 2 of the curved surface represented by the arrow with the dotted line, so that the two points are not the pixel x1Corresponding to the height of the lens 8, at a height ZBThe normal vector 1 of the curved surface is consistent with the normal vector 2 of the curved surface, namely the point is the pixel x1Corresponding to the height of the lens 8.
Finding the lens heights corresponding to all pixels in the camera 1 according to the process, and finally obtaining the surface shape S of the upper surface of the lens 81(x) The results are shown in FIG. 8.
(7) And collecting ultraviolet stripe structure light information displayed by an ultraviolet light/visible light liquid crystal display 6 after the ultraviolet light/visible light liquid crystal display is reflected and modulated by the lower surface of a lens 8 by using cameras 3 and 4 of a second camera set:
and (5) projecting 10 groups of single-frequency ultraviolet stripes of 1 to 10 on the ultraviolet/visible light liquid crystal display 6 according to the method in the step (5), wherein the relation between the position of the pixel X of the ultraviolet/visible light liquid crystal display 6 and each pixel X of the camera corresponding to the pixel X can be obtained by a time phase unwrapping algorithm in a formula (4).
(8) Solving the three-dimensional shape information of the lower surface of the lens 8:
to obtain pixel x in camera 3 of fig. 33The corresponding height Z of the lens 8 is taken as an example, and the method is the same as the step (6).
Through the calibration of the camera 3 internal referenceObtain pixel x3Corresponding ray l3Camera 3 pixels x obtained by absolute phase3Corresponding to the screen point P of the ultraviolet light/visible light conversion liquid crystal display 63. At ray l3At a certain height Z, pixels x are taken from the camera 1 according to the law of reflection3Height Z, corresponding screen point P3The normal vector 1 of the surface can be calculated. In addition, at this height, according to the internal reference calibration result of the camera 4, the corresponding pixel x can be obtained4 Camera 4 pixels x obtained by absolute phase4Corresponding screen point P4. And then 4 pixels x by the camera according to the law of reflection4Height Z, corresponding screen point P4The normal vector 2 of the surface can be calculated. Judging whether the curved surface normal vector 1 and the curved surface normal vector 2 are superposed or not, and if so, determining that the point is the pixel x3The height of the lens 8 is corresponding to the surface shape S of the lower surface of the lens 82(x) (ii) a If they do not coincide, continue on the ray l3And performing calculation on other heights until a coincidence point of the two normal vectors is found. All the pixel points in all the cameras 3 are traversed, and the surface shape S of the lower surface of the lens 8 can be finally obtained2(x)。
In the example of fig. 3, pixel x is known3Ray l3And pixel x3Corresponding screen point P3At a ray l3Upper search for different heights ZA，ZB，ZC… …, obtaining different heights Z according to the internal reference calibration result of the camera 4A、ZB、ZCDifferent pixels x corresponding to the lower camera 44A，x4B，x4CPixel x4ACorresponding screen point P4APixel x4BCorresponding screen point P4BPixel x4CCorresponding screen point P4C… … are provided. It can be seen that the height ZAAnd a height ZCThe normal vector 1 of the curved surface represented by the arrow with the solid line is not consistent with the normal vector 2 of the curved surface represented by the arrow with the dotted line, so that the two points are not the pixel x3Corresponding to the height of the lens 8, at a height ZBThe normal vector 1 of the curved surface is consistent with the normal vector 2 of the curved surface, namely the point is the pixel x3Corresponding to the height of the lens 8.
All pixel pairs in the camera 3 are found according to the above processThe height of the lens is required to finally obtain the surface shape S of the lower surface of the lens 82(x) The results are shown in FIG. 9.
(9) Solving the thickness of the lens 8;
the thickness information d (x) of the lens 8 can be obtained by subtracting the three-dimensional shapes of the upper and lower surfaces of the lens 8 according to the formula (6), and the result is shown in fig. 10:
d(x)＝S1(x)-S2(x) (6)
(10) the camera 1 is used for collecting the visible light stripe structure light information displayed by the ultraviolet light/visible light composite liquid crystal display 6 after the refraction modulation of the upper surface and the lower surface of the lens 8:
and (5) projecting 10 groups of single-frequency visible light stripes of 1 to 10 on the ultraviolet/visible light liquid crystal display 6, wherein the relation between the position of the pixel X of the ultraviolet/visible light liquid crystal display 6 and each pixel X of the corresponding camera 1 and 2 can be obtained by a time phase unwrapping algorithm in the formula (4).
(11) Solving lens 8 refractive index information:
to obtain pixel x in camera 1 of fig. 41The corresponding refractive index of the lens 8 is taken as an example. In the measurement result of the upper surface of the lens 8, the pixel x can be obtained1Corresponding to the upper surface point Z of the lens 8. The camera 1 collects the visible light structured light information displayed by the ultraviolet light/visible light composite liquid crystal display after the ultraviolet light/visible light composite liquid crystal display is modulated by the refraction of the upper surface and the lower surface of the lens 8, and the pixel x can be obtained1Corresponding to the pixel point p on the screen. The lower surface profile of the lens 8 is known from the measurement results. A different refractive index of the lens 8 results in a pixel x1The position of the corresponding lower surface point z of the lens 8 is different. As in fig. 4, the wrong index of refraction may result in x1The lower surface point z of the lens 8, which should correspond to this, is erroneously calculated as z'. At this time, pixel x is represented by the law of refraction1The corresponding on-screen pixel point is p'. The refractive index n (x) of the lens 8 obtained by solving through nonlinear optimization according to the system geometric relationship and the refraction law as constraints is shown in fig. 11.
Claims (10)
1. An integrated lens measuring device is characterized by comprising a first camera set and an ultraviolet light liquid crystal display which are arranged on one side of a lens to be measured, and a second camera set and an ultraviolet light and visible light conversion liquid crystal display which are correspondingly arranged on the other side of the lens to be measured;
the ultraviolet light structured light information displayed on the ultraviolet light liquid crystal display enters the first camera set after being reflected by the surface of one side of the lens to be tested, and meanwhile, the visible light structured light information displayed on the ultraviolet light visible light conversion liquid crystal display enters the first camera set after being refracted by the two surfaces of the lens to be tested; and ultraviolet light structural light information displayed on the ultraviolet light and visible light conversion liquid crystal display enters the second camera set after being reflected by the surface on the other side of the lens to be detected.
2. The integrated lens measurement device according to claim 1, wherein the ultraviolet light wavelength range displayed on the ultraviolet light liquid crystal display and the ultraviolet light-visible light conversion liquid crystal display is 10-400 nm.
3. The integrated lens measurement device according to claim 1, wherein the uv-lcd and uv-vis lcd comprises an lcd using uv lamps as backlight, an lcd using uv leds as backlight, an lcd using uv light bulbs as backlight, an lcd using uv projectors as backlight, or an lcd using uv oleds for self-illumination.
4. The integrated lens measurement device according to claim 1, wherein a light homogenizing film, a light homogenizing lens or a light guiding plate is disposed on the uv-lcd and the uv-vis conversion lcd.
5. The integrated lens measurement device of claim 1, wherein at least one of the UV-LCD and the UV-VIS LCD is provided.
6. The integrated lens measurement device of claim 1, wherein the uv-vis lcd comprises a uv-and a vis-a-vis backlight source behind a switching lcd.
7. The integrated lens measurement device of claim 1, wherein the uv-vis lcd is replaceable with separate uv-and vis-lcd displays.
8. The measurement method of the integrated lens measurement device according to claim 1, comprising the steps of:
(1) building a measuring device, and calibrating and position debugging the measuring device;
(2) displaying ultraviolet light structured light information on an ultraviolet light liquid crystal display, carrying out absolute phase expansion on the ultraviolet light structured light information which is collected by a first camera group and is subjected to reflection modulation by the surface on one side of a lens, and solving that ultraviolet light rays received by each pixel of the first camera group are emitted by a certain position of the ultraviolet light liquid crystal display;
(3) solving the surface shape of one side surface of the lens by utilizing a camera imaging model, a system geometric relation and a reflection law;
(4) displaying ultraviolet light structural light information on an ultraviolet light and visible light conversion liquid crystal display, carrying out absolute phase expansion on the ultraviolet light structural light information which is collected by a second camera set and is subjected to reflection modulation by the surface on the other side of a lens, and solving that ultraviolet light rays received by each pixel of the second camera set are emitted by a certain position of the ultraviolet light and visible light conversion liquid crystal display;
(5) solving the surface shape of the surface on the other side of the lens by using a camera imaging model, a system geometric relation and a reflection law;
(6) the surface shapes of the two sides of the lens are known, and the difference between the two surface shapes is used for obtaining the thickness of the lens;
(7) displaying visible light structured light information on an ultraviolet light and visible light conversion liquid crystal display, carrying out absolute phase expansion on the visible light structured light information which is collected by a first camera group and is subjected to refraction modulation by surfaces on two sides of a lens, and solving that visible light rays received by each pixel of the first camera group are emitted by a certain position of the ultraviolet light and visible light conversion liquid crystal display;
(8) and solving a refraction angle according to the surface shapes of the two side surfaces of the measured lens and the refraction law, taking the system geometric relation and the refraction law as constraints, and solving the refraction index of the lens by optimizing or violently searching the refraction index.
9. The measurement method of the integrated lens measurement device of claim 8, wherein the step (2), (4) and (7) adopts a time phase unwrapping algorithm to obtain the position of each pixel of the camera set corresponding to the captured image element of the display.
10. The measuring method of the integrated lens measuring device according to claim 8, wherein in the step (3) (5), the ray corresponding to a certain pixel of the camera set internal reference camera is obtained through calibration of the camera internal reference, and the height is searched on the ray, so that the incident ray and the emergent ray received by other cameras in the camera set at the height correspondingly satisfy the reflection law and satisfy the coincidence of normal vectors of all cameras in the camera set at the point, the lens height corresponding to the pixel is obtained, the lens heights corresponding to all pixels of the reference camera are found, and finally the surface shape of the corresponding side surface of the lens is obtained.
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