CN115183699A - Rapid relative measurement method and device for rear-mounted spectroscopic pupil differential confocal curvature radius - Google Patents
Rapid relative measurement method and device for rear-mounted spectroscopic pupil differential confocal curvature radius Download PDFInfo
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Abstract
The invention discloses a method and a device for rapidly and relatively measuring a rear-mounted pupil differential confocal curvature radius, and belongs to the technical field of optical precision measurement. The invention selects a known curvature radius R from the same batch of tested elements 0 As a template S 0 Scanning at the confocal position to obtain a differential confocal light intensity response curve and a linear segment fitting equation thereof; sequentially clamping the tested piece S n Mapping the collected differential light intensity values to a linear segment fitting equation to realize S n Defocus amount Δ z n Fast measurement without scanning; by Δ z n And R 0 Calculating to obtain the curvature radius R of the measured element n . The invention can realize the rapid high-precision measurement of the curvature radius of N spherical elements in the same batch only by 1 time of scanning and N times of repeated clamping, and compared with the existing high-precision curvature radius measurement method, the invention can retain the differential confocal high-precision measurementThe method can obviously improve the measurement efficiency and the processing efficiency and precision of the large-batch spherical elements.
Description
Technical Field
The invention relates to a method and a device for rapidly and relatively measuring a rear-mounted beam splitting pupil differential confocal curvature radius, belonging to the technical field of optical precision measurement.
Background
Spherical optical elements are used in a large number of optical systems such as medical inspection, digital cameras, etc., and thus have a great demand and throughput. The precision of the curvature radius of the spherical optical element directly determines the performance of the optical system, so the detection precision of the spherical optical element has great significance in the field of optical measurement.
At present, the curvature radius measuring method can be divided into a contact type and a non-contact type:
common contact measurement methods include a template method, a sphere diameter gauge method, a three-coordinate method, a laser tracking method and the like. The template method and the sphere diameter instrument method are simple and convenient to operate, and the measuring speed is high. However, the template method is influenced by the self precision of the template and the stress change between the measured mirrors, the measurement precision is not high, and the measurement precision is influenced by subjective factors of measuring personnel; the accuracy of the sphericity diameter method is only 30ppm, and the accuracy of the method decreases as the curvature radius value increases. The three-coordinate method is to scan the measured spherical surface to obtain the best fitting sphere as the measurement result of the curvature radius, and the measurement precision is 20ppm. However, this method is not suitable for small radius of curvature measurement and the measurement efficiency is low. The laser tracking method is only suitable for measuring spherical elements with large calibers, and the measuring flow is more complicated. The contact measurement methods all have the inherent defect that the surface of a measured sample is easy to scratch.
Non-contact measurement methods mainly include geometric optics methods and interferometry. The geometrical optical method comprises a knife edge shadow method, an auto-collimation method and the like. The method for measuring the curvature radius value by the knife edge shadow method is simple and convenient to operate, but the measurement precision is not high and is only 50ppm. The autocollimation method is only suitable for measuring the curvature radius of the large-caliber element, and the precision is 500ppm when the curvature radius of more than 5m is measured. For interferometry, it is a highly accurate measurement method widely used at present. According to the classical interference method, a cat eye position and a confocal position of a measured spherical surface are respectively focused by using a phase measurement interferometer, so that the radius of curvature to be measured is obtained, and the measurement precision can reach 10ppm. On the basis, jan.K. et al propose an absolute interferometric fast detection method based on wavelength tuning phase shift, and the measurement precision is 10ppm. However, the interference method has the problems that the posture adjustment process is complicated, the interference fringes need to be stabilized for a long time after the card is installed, and the like, and in addition, the interference fringes are easily interfered by the environment factors such as air flow, temperature, vibration and the like, so the method has low efficiency.
The inventor provides a laser differential confocal curvature radius measuring method in 2010, and the method utilizes the characteristic that an absolute zero point of a differential confocal light intensity response curve accurately corresponds to a measuring beam focus to focus a cat eye position and a confocal position of a measured surface respectively so as to obtain the curvature radius to be measured. The method has the precision of 5ppm, but still needs to scan and fix the focus of two points of the cat eye position and the confocal position, and needs to perform a more complicated posture adjustment process. The process efficiency therefore remains to be further improved.
Disclosure of Invention
In order to solve the problem of low efficiency of high-precision measurement of the curvature radius of spherical elements in batches, the invention mainly aims to provide a method and a device for quickly and relatively measuring the curvature radius of a rear-mounted split-pupil differential confocal device.
The purpose of the invention is realized by the following technical scheme.
The invention discloses a rapid and relative measurement method for the rear-mounted pupil differential confocal curvature radius, which can realize rapid and high-precision measurement of the curvature radius of a spherical element and comprises the following specific steps:
the method comprises the following steps: selecting a sample plate S in the same batch as the tested mirror in batch elements 0 Nominal values of the parameters of the elements of the template and N identical batches of measured mirrors S 1 -S N The same is true.
The element parameters include radius of curvature, caliber, surface reflectivity.
Step two: using post-pupil differentialConfocal focusing system at S 0 Scanning near the confocal position, carrying out differential processing on the collected light intensity signals to obtain a differential confocal curve, and carrying out linear fitting on a linear section of the curve to obtain a fitting straight line l diff (z) according to l diff (z) axial position coordinate of zero point S 0 The device is accurately positioned at the confocal position, and the accurate focusing of the element to be measured is realized.
Step three: take down S from vertical fixture 0 And sequentially mounting the tested lens S n N = 1-N, the process guarantees S by the self-gravity of the test mirror n The repeated spatial positioning of (2). Acquisition card S using postposition pupil differential confocal fixed focus system n The differential light intensity value is then mapped to l diff (z) further obtaining defocus amount Δ z n And the rapid measurement of batch components is ensured.
Step four: by using conversion relation, the curvature radius R of the sample plate is calibrated 0 And defocus amount Δ z n Calculating the measured curvature radius R n The method not only can keep the advantages of differential confocal high-precision measurement, but also can obviously improve the measurement efficiency, thereby realizing the high-efficiency, quick and convenient detection of the curvature radius of the spherical element.
Preferably, the implementation method of the step four is as follows: using the conversion relation shown in the following formula to calibrate the curvature radius R of the sample plate 0 And defocus amount Δ z n Calculating the measured curvature radius R n 。
Wherein R is 0 For calibrating the sample plate S 0 Radius of curvature of (2), R n Is the radius of curvature of the sample to be measured, Δ z n Representative calibration sample plate sphere center O 0 And the center of the sphere O of the sample to be measured n Axial offset between, D F To support the chucking diameter of the chuck. The advantages of differential confocal high-precision measurement are kept, and the measurement efficiency is obviously improved.
Preferably, the implementation method of the step four is as follows: using the conversion relation shown in the following formula to calibrate the sample plateRadius of curvature R 0 And defocus amount Δ z n Calculating the measured curvature radius R n The method not only can keep the advantages of differential confocal high-precision measurement, but also can obviously improve the measurement efficiency, thereby realizing the high-efficiency, quick and convenient detection of the curvature radius of the spherical element.
Wherein R is 0 For calibrating the sample plate S 0 Radius of curvature of (2), R n Is the radius of curvature of the sample to be measured, Δ z n Representative calibration sample plate sphere center O 0 And the center of the sphere O of the sample to be measured n Axial offset between, D F To support the chucking diameter of the chuck.
The invention discloses a rapid relative measurement method for a rear-mounted pupil differential confocal curvature radius. According to the detected elliptic light spots, virtual pinhole front focuses vph1 and virtual pinhole rear focuses vph2 are symmetrically arranged in a circular detection area at the position of an optical axis, namely on two sides of a virtual pinhole confocal point. The gray value integral in the virtual needle hole is used as detection light intensity, the axial light intensity response of the two virtual needle holes is detected and differential processing is carried out to obtain a differential confocal response curve, and the differential light intensity value I of the detected piece diff (Δz n ) Expressed as:
I diff (Δz n )＝I vph2 (Δz n )-I vph1 (Δz n )
wherein, I vph1 (Δz n ) Expressed as the light intensity value at the virtual pinhole front focus vph1, I vph2 (Δz n ) The light intensity value at the virtual pinhole front focus vph2. And obtaining a fitting straight line with a high slope and a long linear range through linear fitting so as to ensure the measurement precision and the measurement range of the curvature radius.
The invention discloses a rapid relative measurement method for a rear-mounted pupil differential confocal curvature radius, which sets a threshold value I ts And judging whether the defocusing amount is in the linear response interval. Sample plate S 0 The light intensity response I of the virtual pinhole obtained by scanning vph1 、I vph2 Summing to obtain light intensity response sum I sum ：
I sum ＝I vph1 +I vph2
Wherein, I vph1 Expressed as the light intensity value at the virtual pinhole front focus vph1, I vph2 The light intensity value at the virtual pinhole front focus vph2 is shown.
When the measured piece S n Collected single point light intensity response and I sumn >I ts When the differential light intensity value is in the linear response interval, namely the measured piece does not exceed the measuring range, the next measurement can be carried out; when the measured piece S n Collected single point light intensity response and I sumn <I ts When the differential light intensity value is out of the linear response interval, namely the measured piece exceeds the measuring range, the information that the measured piece cannot be measured is returned. Thus according to I sum Whether or not it is greater than I ts To realize the over-range judgment.
The invention discloses a method for quickly and relatively measuring the rear-mounted pupil differential confocal curvature radius, which adopts a vertical annular clamping structure to ensure that a sample plate and each measured piece can be quickly and stably clamped by means of self gravity, and ensures that wefts corresponding to the same rise height on a spherical surface (namely contact lines of the spherical elements and the annular clamping device) can be repeatedly positioned at the same spatial position after spherical elements in the same batch are clamped. For the measurement of the concave spherical surface, the excircle of the annular fixture is contacted with the measured spherical surface; for convex spherical surface measurement, the inner circle of the annular fixture is in contact with the measured spherical surface.
The invention also discloses a device for rapidly and relatively measuring the differential confocal curvature radius of the rear split pupil, which is used for realizing the method for rapidly and relatively measuring the differential confocal curvature radius of the rear split pupil. The device for rapidly and relatively measuring the rear spectral pupil differential confocal curvature radius comprises a rear spectral pupil differential confocal module, a motion control and monitoring module and an attitude adjusting module. The rear-mounted pupil differential confocal module uses a D-shaped diaphragm to set light spots on a CCD detection surface into virtual pinhole positions, and performs differential processing on axial light intensity response of the virtual pinhole positions, so that accurate focusing of a detected element is realized. The postposition pupil differential confocal module comprises a point light source, a collimating mirror, a reflecting mirror, a converging mirror, a D-shaped diaphragm, a microscope objective and a photoelectric detector CCD.
The motion control module drives a lead screw to drive the high-precision air floatation guide sleeve to move along the direction of an optical axis by using a servo motor, and simultaneously monitors position information in real time by using a grating ruler to complete scanning and position data acquisition. The motion control module comprises a servo motor, a lead screw, a high-precision air floatation guide sleeve, a high-precision air floatation guide rail and a grating ruler. The attitude adjusting module adjusts the spatial positions of the standard converging mirror and the measured mirror by using the two-dimensional adjusting frame, so that the centers of the standard converging mirror and the measured mirror coincide with the optical axis, and the absolute measuring process of the curvature radius is converted into the relative measurement based on the sample plate. The pose adjustment process utilizes a ring fixture to quickly and accurately position the object to be measured at the confocal location of the particular template. The attitude adjusting module comprises a two-dimensional adjusting frame and an annular clamp.
Has the advantages that:
1. the invention discloses a method and a device for rapidly and relatively measuring the differential confocal curvature radius of a rear-mounted pupil, wherein scanning is carried out at the confocal position of a spherical element with a known curvature radius, and a fitting equation of a linear section of the spherical element is obtained through differential confocal scanning; and then, clamping the spherical element to be measured, collecting single-point differential light intensity, and mapping the single-point differential light intensity into a linear segment fitting equation, so that the rapid non-scanning measurement of the defocus amount of the spherical element to be measured is realized, and the problem that the conventional method for measuring the curvature radius of the spherical optical element is difficult to meet the measurement requirement of large batch and high speed is solved.
2. The invention discloses a method and a device for rapidly and relatively measuring a rear-mounted beam-splitting pupil differential confocal curvature radius. The invention converts the absolute measurement process of the curvature radius into the relative measurement based on the sample plate. The invention can not only keep the advantages of differential confocal high-precision measurement, but also obviously improve the measurement efficiency and improve the processing efficiency and precision of large-batch spherical elements.
3. The invention discloses a method and a device for quickly and relatively measuring the rear-mounted pupil differential confocal curvature radius, which adopt a vertical annular clamping structure to ensure that a sample plate and each measured piece can be quickly and stably clamped by means of self gravity, and ensure that wefts (namely contact lines of spherical elements and annular clamping devices) corresponding to the same rise on a spherical surface can be repeatedly positioned at the same spatial position after spherical elements of the same batch are clamped, and the quick, high-precision and non-contact detection of the curvature radius of N spherical elements can be realized only by one-time scanning measurement and N-time single clamping measurement. The invention can solve the problem of low production and manufacturing efficiency of the existing optical element, meet the detection requirements in large-scale processing and assembling processes and improve the detection efficiency of the curvature radius.
Drawings
FIG. 1 is a flow chart of the rapid relative measurement of the rear-mounted pupil differential confocal curvature radius of the present invention;
FIG. 2 is a schematic diagram of the present invention based on a rear-mounted spectroscopic differential confocal detection;
FIG. 3 is a graph of a curvature radius versus measurement geometry model for a concave spherical surface according to example 1 of the present invention;
FIG. 4 is a graph of the curvature radius versus the measurement geometry for a convex spherical surface in example 2 of the present invention;
fig. 5 is a diagram of a method and an apparatus for fast relative measurement of a posterior spectroscopic pupil differential confocal curvature radius for a concave spherical surface according to embodiment 1 of the present invention;
fig. 6 is a diagram of the method and apparatus for fast relative measurement of the posterior pupil differential confocal curvature radius of a convex spherical surface according to embodiment 2 of the present invention;
wherein: 1-point light source, 2-polarizing beam splitter, 3-collimating mirror, 4-reflector, 5-D diaphragm, 6-microobjective, 7-optical detector CCD, 8-adjusting frame, 9-converging mirror, 10-clamp, 11-motor, 12-lead screw, 13-grating reading head, 14-air-floating guide sleeve, 15-air-floating guide rail, 16-grating ruler and 17-sample plate S 0 18-measured element S n 19-virtual pinhole front focus vph1, 20-virtual pinhole rear focus vph2, 21-front Jiao Guangjiang I vph1 22-post Jiao Guangjiang I ph2 23-differential confocal light intensity curve, 24-fitting straight line l diff (z), 25-defocus amount delta z, 26-differential confocal single-point light intensity value I diff (Δz)。
Detailed Description
The invention is further illustrated by the following figures and examples.
Example 1
As shown in fig. 5, the method and apparatus for fast and relatively measuring the rear split pupil differential confocal curvature radius includes a rear split pupil differential confocal module, a motion control and monitoring module, and an attitude adjustment module. The rear-mounted pupil differential confocal module uses a D-shaped diaphragm 5 to set light spots on a CCD detection surface 7 into virtual pinhole positions, and performs differential processing on axial light intensity response of the virtual pinhole positions, so that accurate focusing of a detected element is realized. The postposition pupil differential confocal module comprises a point light source 1, a collimating mirror 3, a reflecting mirror 4, a converging mirror 9, a D-shaped diaphragm 5, a microscope objective 6 and a photoelectric detector CCD7.
The motion control module drives the screw 12 to drive the high-precision air-floatation guide sleeve 14 to move along the optical axis direction by using a servo motor, and simultaneously monitors position information in real time by using the grating ruler 16 to complete scanning and position data acquisition. The motion control module comprises a servo motor 11, a lead screw 12, a high-precision air-floating guide sleeve 14, a high-precision air-floating guide rail 15 and a grating ruler 16. The attitude adjusting module uses a two-dimensional adjusting frame 8 to adjust the spatial positions of the standard converging mirror 9 and the measured mirror 18, so that the centers of the standard converging mirror and the measured mirror coincide with the optical axis, and the absolute measuring process of the curvature radius is converted into the relative measurement based on a sample plate. The pose adjustment process utilizes the ring fixture 10 to quickly and accurately position the object under test at the confocal location of the particular template. The attitude adjusting module comprises a two-dimensional adjusting frame 8 and an annular clamp 10.
When the device is used for measuring the curvature radius of the elements in batches, a differential confocal curve is obtained by adopting a rear-mounted beam splitting pupil differential confocal detection technology, and as shown in figure 2, measurement light reflected by the elements to be measured passes through a D-shaped diaphragm 5 and a microscope objective 6 and is imaged on a CCD7 detection surface. A circular detection area is arranged at the position of an optical axis of the detected elliptic light spot, and a front focus vph1 of a virtual pinhole 19 and a rear focus vph2 of the virtual pinhole 20 are symmetrically arranged at two sides of a confocal point. The gray value integral in the virtual needle hole is used as detection light intensity, the axial light intensity response of the two virtual needle holes is detected and differential processing is carried out, a differential confocal response curve 23 is obtained, and a fitting straight line with high slope and long linear range is obtained through linear fitting, so that the curvature radius measurement precision and the measurement range are ensured.
A method and a device for quickly and relatively measuring the rear-arranged beam splitting pupil differential confocal curvature radius are disclosed, wherein a vertical annular clamping device 10 is adopted to ensure that a sample plate and each measured piece can be quickly and stably clamped by means of self gravity, and to ensure that wefts (namely contact lines of spherical elements and the annular clamping device) corresponding to the same rise on a spherical surface can be repeatedly positioned at the same spatial position after spherical elements in the same batch are clamped. As shown in figures 5 and 6, the device can measure concave and convex spherical surfaces. For concave spherical surface measurement, the outer circle of the annular fixture is in contact with the measured spherical surface, as shown in fig. 3; for convex sphere measurement, the inner circle of the ring fixture is in contact with the measured sphere, as shown in fig. 4.
The calibration sample plate and the element to be measured are respectively arranged on the same fixture by utilizing the device, and the spherical center position of the calibration sample plate and the element to be measured can deviate delta z in the optical axis direction due to the small difference of the curvature radiuses of the calibration sample plate and the element to be measured n By the defocus amount of (2), and further by the defocus amount [ Delta ] z n And obtaining the curvature radius to be measured.
The measurement procedure for the concave spherical surface is as follows:
the method comprises the following steps: a sample plate 17 of the same lot as the test mirrors is selected from the batch of components, and the nominal values of the component parameters of the sample plate are the same as those of the N test mirrors 18 of the same lot. The element parameters include radius of curvature, caliber, surface reflectivity.
Step two: scanning is carried out near the confocal position of the sample plate 17 by using a rear-mounted beam splitting pupil differential confocal focusing system, differential processing is carried out on the collected light intensity signals to obtain a differential confocal curve 23, linear fitting is carried out on the linear section of the curve to obtain a fitting straight line 24, the sample plate 17 is accurately positioned at the confocal position according to the axial position coordinate of a zero point 24, and accurate focusing of the element to be measured is realized.
Step three: the sample plate 17 is taken down from the vertical fixture and the tested lens 18 is sequentially clamped, and the repeated spatial positioning of the tested lens 18 is ensured by the gravity of the tested lens in the process. For concave spherical surface measurement, the outer circle of the annular fixture is in contact with the measured spherical surface. The differential light intensity value after the clamped measured lens 18 is collected by the rear-mounted pupil differential confocal focusing system and is mapped to a fitting straight line 24 to obtain a defocusing amount 25, as shown in fig. 3.
Step four: according to D F Is 29.980mm, from the calibrated template radius of curvature R 0 = -39.1042mm and defocus Δ z 1 =0.0097mm, using
Formula, calculating to obtain R 1 And (4) the mark of which is-39.0963 mm, and is the curvature radius of the concave spherical surface of the tested element.
Example 2
As shown in fig. 6, the method and apparatus for fast and relative measurement of the rear-split pupil differential confocal curvature radius are similar to those shown in fig. 5 for the curvature radius of the convex spherical surface.
The measurement procedure for convex spherical surface is as follows:
the method comprises the following steps: a sample plate 17 of the same lot as the test mirrors is selected from the batch of components, and the nominal values of the component parameters of the sample plate are the same as those of the N test mirrors 18 of the same lot. The element parameters include radius of curvature, caliber, surface reflectivity.
Step two: scanning is carried out near the confocal position of the sample plate 17 by using a rear-mounted beam splitting pupil differential confocal focusing system, differential processing is carried out on the collected light intensity signals to obtain a differential confocal curve 23, linear fitting is carried out on the linear section of the curve to obtain a fitting straight line 24, and the sample plate 17 is accurately positioned at the confocal position according to the axial position coordinate of a zero point of 24.
Step three: the sample plate 17 is taken down from the vertical fixture and the tested lens 18 is sequentially clamped, and the repeated spatial positioning of the tested lens 18 is ensured by the gravity of the tested lens in the process. For convex spherical surface measurement, the inner circle of the annular fixture is in contact with the measured spherical surface. The differential light intensity value after the clamped measured lens 18 is collected by the rear-mounted pupil differential confocal focusing system and is mapped to a fitting straight line 24 to obtain a defocusing amount 25, as shown in fig. 4.
Step four: according to D F Measured value of (1) is 29.986mm, measured by calibrating the radius of curvature R of the sample plate 0 =39.1mm and defocus amount deltaz 2 =0.0303mm, using
Formula (II) to obtain R 2 And =39.10644mm, which is the curvature radius of the convex spherical surface of the tested element.
While the invention has been described in connection with specific embodiments thereof, it will be understood that these should not be construed as limiting the scope of the invention, which is defined in the following claims, and any variations which fall within the scope of the claims are intended to be embraced thereby.
Claims (7)
1. The rapid relative measurement method for the differential confocal curvature radius of the postposition pupil is characterized in that: comprises the following steps of (a) preparing a solution,
the method comprises the following steps: selecting a sample plate S in the same batch as the tested mirror in batch elements 0 Nominal values of the parameters of the elements of the template and N identical batches of measured mirrors S 1 -S N The same;
the element parameters comprise curvature radius, caliber and surface reflectivity;
step two: using a postposition pupil differential confocal focusing system at S 0 Scanning near the confocal position, carrying out differential processing on the collected light intensity signals to obtain a differential confocal curve, and carrying out linear fitting on a linear section of the curve to obtain a fitting straight line l diff (z) according to l diff (z) axial position coordinate of zero point S 0 The device is accurately positioned at a confocal position to realize accurate focusing of the element to be detected;
step three: take down S from vertical fixture 0 And sequentially clamping the tested lenses S n N = 1-N, the process guarantees S by the self-gravity of the test mirror n The repeated spatial localization of (a); acquisition card S using postposition pupil differential confocal fixed focus system n The differential light intensity value is then mapped to l diff (z) further obtaining defocus amount Δ z n The rapid measurement of batch elements is ensured;
step four: by using conversion relation, the curvature radius R of the sample plate is calibrated 0 And defocus amount Δ z n Computing quiltMeasuring radius of curvature R n The method not only can keep the advantages of differential confocal high-precision measurement, but also can obviously improve the measurement efficiency, thereby realizing the high-efficiency, quick and convenient detection of the curvature radius of the spherical element.
2. The method for fast relative measurement of the posterior spectroscopic differential confocal radius of curvature of claim 1, wherein: obtaining a differential confocal curve by adopting a postposition spectral pupil differential confocal detection technology, and imaging measurement light reflected by a measured element on a CCD detection surface through a D-shaped diaphragm and a microscope objective; according to the detected elliptic light spots, a virtual pinhole front focus vph1 and a virtual pinhole rear focus vph2 are symmetrically arranged in a circular detection area at the position of an optical axis, namely on two sides of a virtual pinhole confocal point; the gray value integral in the virtual needle hole is used as detection light intensity, the axial light intensity response of the two virtual needle holes is detected and differential processing is carried out to obtain a differential confocal response curve, and the differential light intensity value I of the detected piece diff (Δz n ) Expressed as:
I diff (Δz n )＝I vph2 (Δz n )-I vph1 (Δz n )
wherein, I vph1 (Δz n ) Expressed as the light intensity value at the virtual pinhole front focus vph1, I vph2 (Δz n ) The light intensity value at the virtual pinhole front focus vph2 is obtained; and obtaining a fitting straight line with a high slope and a long linear range through linear fitting so as to ensure the measurement precision and the measurement range of the curvature radius.
3. The method for fast relative measurement of the posterior spectroscopic differential confocal radius of curvature of claim 1, wherein: by setting the threshold value I ts Judging whether the defocusing amount is in a linear response interval; sample plate S 0 Light intensity response I of virtual pinhole obtained by scanning processing vph1 、I vph2 Summing to obtain light intensity response sum I sum ：
I sum ＝I vph1 +I vph2
Wherein, I vph1 Expressed as the light intensity value at the virtual pinhole front focus vph1, I vph2 The light intensity value at the virtual pinhole front focus vph2 is obtained;
when the measured piece S n Collected single point light intensity response and I sumn >I ts When the differential light intensity value is in the linear response interval, namely the measured piece does not exceed the measuring range, the next measurement can be carried out; when the tested piece S n Collected single point light intensity response and I sumn <I ts When the differential light intensity value is out of the linear response interval, namely the measured piece exceeds the measuring range, the information that the measured piece cannot be measured is returned; thus according to I sum Whether or not it is greater than I ts To realize the over-range judgment.
4. The method for fast relative measurement of the posterior spectroscopic differential confocal radius of curvature of claim 1, wherein: the vertical annular clamping structure is adopted to ensure that the sample plate and each tested piece can be quickly and stably clamped by means of self gravity, and the wefts corresponding to the same rise height on the spherical surface can be repeatedly positioned at the same spatial position after the spherical surface elements in the same batch are clamped; for the measurement of the concave spherical surface, the excircle of the annular fixture is contacted with the measured spherical surface; for convex spherical surface measurement, the inner circle of the annular fixture is in contact with the measured spherical surface.
5. The method for fast relative measurement of the posterior pupil differential confocal curvature radius according to claim 1, 2, 3 or 4, characterized in that: the implementation method of the fourth step is that,
using the conversion relation shown in the following formula to calibrate the curvature radius R of the sample plate 0 And defocus amount Δ z n Calculating the measured curvature radius R n ；
Wherein R is 0 For calibrating the sample plate S 0 Radius of curvature of (2), R n Is the radius of curvature of the sample to be measured, Δ z n Representative calibration sample plate sphere center O 0 And the center of the sphere O of the sample to be measured n Shaft betweenTo the offset, D F The diameter of the clamp for supporting the clamp; the advantages of differential confocal high-precision measurement are retained, and the measurement efficiency is obviously improved.
6. The method for fast relative measurement of the posterior pupil differential confocal curvature radius according to claim 1, 2, 3 or 4, characterized in that: the implementation method of the fourth step is that,
using the conversion relation shown in the following formula to calibrate the curvature radius R of the sample plate 0 And defocus amount Δ z n Calculating the measured curvature radius R n The advantages of differential confocal high-precision measurement can be kept, the measurement efficiency can be obviously improved, and the curvature radius of the spherical element can be efficiently, quickly and conveniently detected;
wherein R is 0 For calibrating the sample plate S 0 Radius of curvature of (2), R n Is the radius of curvature of the sample to be measured, Δ z n Representative calibration sample plate sphere center O 0 And the center of the sphere O of the sample to be measured n Axial offset between, D F To support the chucking diameter of the chuck.
7. The device for rapidly and relatively measuring the differential confocal curvature radius of the postposition pupil is characterized in that: the device comprises a rear-mounted pupil differential confocal module, a motion control and monitoring module and an attitude adjusting module; the rear-mounted pupil differential confocal module uses a D-shaped diaphragm to set light spots on a CCD detection surface as virtual pinhole positions, and performs differential processing on axial light intensity response of the light spots to realize accurate focusing of a detected element; the rear pupil differential confocal module comprises a point light source, a collimating mirror, a reflecting mirror, a converging mirror, a D-shaped diaphragm, a microscope objective and a photoelectric detector CCD;
the motion control module drives a lead screw to drive a high-precision air floatation guide sleeve to move along the direction of an optical axis by using a servo motor, and simultaneously monitors position information in real time by using a grating ruler to finish scanning and position data acquisition; the motion control module comprises a servo motor, a lead screw, a high-precision air floatation guide sleeve, a high-precision air floatation guide rail and a grating ruler; the attitude adjusting module adjusts the spatial positions of the standard converging mirror and the measured mirror by using a two-dimensional adjusting frame, so that the centers of the standard converging mirror and the measured mirror are superposed with an optical axis, and the absolute measuring process of the curvature radius is converted into relative measurement based on a sample plate; in the posture adjusting process, the ring-shaped clamp is used for quickly and accurately positioning the measured piece at the confocal position of the sample plate; the attitude adjusting module comprises a two-dimensional adjusting frame and an annular clamp.
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