CN118111681B - Low-cost high-precision optical lens group parameter measurement method and system - Google Patents
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Abstract
The invention relates to the technical field of optical lens group parameter measurement, and discloses a low-cost high-precision optical lens group parameter measurement method and a system. Although the mode jump output of the wave number can cause the side lobe of the interference signal to be too high, the invention can reduce the interference of the side lobe of the interference signal by the optical lens group parameter measuring method, and the peak frequency of the interference signal can be extracted more easily, thereby solving the problem of phase aliasing. The optical path structure of the optical lens group parameter measurement system is simple, and the operation steps are simple. The optical lens group parameter measurement system does not need to specially design a wave number monitoring light path, and can greatly reduce hardware cost. The optical lens group parameter measurement system can be used for perspective measurement of a plurality of groups of lenses through one experiment, and the measurement efficiency of the optical lens group parameters can be greatly improved.
Description
Technical Field
The invention relates to the technical field of optical lens group parameter measurement, in particular to a low-cost high-precision optical lens group parameter measurement method and system.
Background
Today, with rapid development of manufacturing industry, various optical components are widely used in the industrial field, and the requirements of researchers on various high performance indexes of optical lenses are continuously increasing. Therefore, the market demand for high-precision and high-standard lens specifications is expanding, and the development of optical lens detection technology is being promoted. However, most of the detection technologies on the market at present aim at measuring various performance indexes of one lens once, and cannot measure a plurality of lenses in a perspective manner, so that the efficiency is low.
The conventional lens detection schemes are as follows: contact surface three-dimensional profilometry, laser triangulation, structured light measurement.
The three-dimensional contour measurement method of the contact surface is that the probe head is driven by a mechanical device to carry out point-by-point scanning measurement, and the precision can reach the nanometer level. However, the measurement time is long, and the measured piece is easily damaged.
The laser triangulation method is to project a linear light source onto the surface of a to-be-measured piece, the to-be-measured object moves along the axial direction of the light source, and then the three-dimensional contour information of the surface of the to-be-measured piece is obtained through the geometric relationship between the light source, the to-be-measured piece and the acquisition equipment.
The structured light measurement method is to project a light source to the surface of a measured object at a certain angle, reflect the light to form characteristic points on the surface of the measured object, and acquire the three-dimensional profile of the measured object by using a triangulation method according to a marked space coordinate system and related parameters.
Although the measurement technology can detect the three-dimensional contour shape of the surface of the object, the lens group cannot be measured in a perspective manner.
Wavelength swept interferometry is a novel interferometry method, and has rapid development and great potential. The technology can detect the three-dimensional contour information of an object in the depth direction, has micron-level resolution and millimeter-level imaging depth, and can realize the non-contact nondestructive single experimental perspective measurement of the three-dimensional morphology of the surfaces of a plurality of lens groups. However, this technique has a limitation that a mode-free hopping wavelength bandwidth as wide as possible is required, which requires high requirements for various hardness indexes of the light source and is expensive. The specific principle is as follows:
The measurement of the wavelength sweep interference technology in the x and y directions in space is based on the optical microscopic imaging principle, the measurement precision and resolution mainly depend on the design of an optical system, and the error can be greatly reduced by manual design. But the measurement accuracy and profile resolution in the depth z direction is mainly determined by the bandwidth of the laser wavenumber scan. Since the chromatographic resolution of wavelength swept interferometry is inversely proportional to the bandwidth of the laser wavenumber sweep, the bandwidth of the laser wavenumber sweep must be sufficiently wide to obtain ultra-high resolution and imaging depth.
Two corresponding solutions are:
1. An ultra wide bandwidth swept source is used.
2. The semiconductor laser has the advantages of small volume, low cost and continuous tuning without mode hopping in the wave number tuning range.
However, the ultra-wide bandwidth laser has the disadvantages of high cost, huge volume, complex structure and complicated operation steps, and is not beneficial to the construction of an optical path hardware system.
A temperature-tunable distributed feedback structure (DFB) semiconductor laser is adopted, if the temperature-tunable distributed feedback structure (DFB) semiconductor laser exceeds the wave number tuning range, a chromatographic interference signal with mode hopping is brought, so that a side lobe of the interference signal is too high, and an error is brought to subsequent signal demodulation.
Two corresponding solutions are:
1. A random fourier transform method.
2. Phase compensation method.
The problems of the method are that the optical path of the light source wave number sequence needs to be monitored with high precision, but the optical path has strict requirements on hardware and is high in price, and the experimental error caused by the wave number is also monitored.
In addition, the random fourier transform requires a very narrow range of mode hops for the light source output and is poorly generalized.
The phase compensation method compensates the problem that the random Fourier method requires a narrow mode jump range, but needs high-precision mode jump data as prior information, so that extremely high hardware requirements are provided for the optical path for monitoring the light source wave number sequence and the whole imaging system.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a low-cost high-precision optical lens group parameter measurement method.
In order to achieve the above purpose, the technical scheme provided by the invention is as follows:
A low-cost high-precision optical lens group parameter measurement method comprises the following steps:
Setting up an optical lens group parameter measurement system, wherein the system comprises a mode jump laser, a temperature controller, a laser power controller, a beam splitting prism, a reference plane, a telecentric lens detector, an optical lens group with a lens bracket and a computer; the optical lens group with the lens bracket is respectively distributed in the four side directions of the beam splitting prism; the mode-jump laser is opposite to the optical lens group with the lens bracket; the telecentric lens detector is opposite to the reference plane; the reference plane is provided with a virtual shadow under the action of the beam-splitting prism, and the virtual shadow is positioned between the beam-splitting prism and the optical lens group with the lens bracket; the temperature controller and the laser power controller are both connected with the mode-jump laser; the computer is connected with the telecentric lens detector;
calibrating an optical lens group parameter measurement system, and obtaining a calibration coefficient;
After the laser parameters of the mode-jump laser are regulated by the temperature controller and the laser power controller, the mode-jump laser emits laser beams which respectively irradiate the surface of each optical lens of the optical lens group and the reference plane under the action of the beam splitting prism, the reflected light of the front surface and the rear surface of each optical lens of the optical lens group and the reflected light of the reference plane are mutually overlapped to form interference, an interference signal is received by the telecentric lens detector and transmitted to the computer, and the interference signal is analyzed and processed by the computer to finally obtain the parameters of the optical lens group;
the computer analyzing and processing the interference signal comprises the following steps:
Removing the direct current component from the interference signal to obtain a light intensity signal;
obtaining a corresponding power spectrum and frequency based on the light intensity signal, thereby obtaining a power spectrum-frequency diagram;
the phase position of the front surface and the back surface of each optical lens of the optical lens group is obtained based on the power spectrum-frequency diagram;
the obtained phases are respectively input into a least square method for spatial demodulation to obtain unwrapped data;
And solving parameters of corresponding optical lenses in the optical lens group by combining the nonlinear least square fitting equation and unwrapped data.
Further, the power spectrumThe calculation formula of (2) is as follows:
（2）
In the formula (2), the amino acid sequence of the compound, In order to be of an angular frequency,For the number of signal points,Is the firstThe point of the input signal is the point of the input signal,Is the signal pointIn correspondence with the moment of sampling,The sample mean and the sample variance are respectively,For a time-shift invariant, which shifts the time origin by a constant, the power spectrumAnd the method is kept unchanged, and the following formula is satisfied:
（3）；
Frequency of The calculation formula of (2) is as follows: （4）。
Further, the step of calculating the phase of the front and rear surfaces of each optical lens of the optical lens group based on the power spectrum-frequency diagram comprises the following steps:
Finding out the corresponding frequency under each peak value from the power spectrum-frequency diagram, and extracting the phase under the corresponding peak value through the following formula:
the discrete signal of the interference sequence of one pixel point of the interference pattern is set as follows:
（5）
In the formula (5), the amino acid sequence of the compound, For amplitude, ω is the angular frequency,Is the phase of the interference signal;
after being simplified by Euler's formula The interference signals of the individual points are:
（6）
in the formula (6), the amino acid sequence of the compound, Is the bottom of the natural logarithm,Is an imaginary unit;
further reduce equation (6):
（7）
Inputting discrete signals and angular frequency of an interference spectrum sequence into a formula (7), and inputting a calculated result into a formula (8) to obtain a phase:
（8）
In the formula (8), the amino acid sequence of the compound, For the imaginary part of the corresponding value,Is the real part of the corresponding value.
Further, when the optical lens group comprises an optical wedge, the optical wedge parameter is obtained by combining the nonlinear least square fitting equation and unwrapped data, and the method comprises the following steps:
And respectively inputting unwrapped phases of the front surface and the rear surface of the optical wedge into a nonlinear least square fitting plane equation to respectively obtain normal vectors of corresponding planes, and then calculating the two normal vectors to obtain an included angle of the two planes to obtain the inclination angle of the optical wedge.
Further, when the optical lens group includes a plano-convex lens, the method for calculating plano-convex lens parameters by combining the nonlinear least square fitting equation and unwrapped data includes:
Calculating the data obtained after the convex surface unwrapping of the plano-convex lens by adopting a nonlinear least square fitting spherical equation to obtain the pre-curvature radius of the analog quantity;
and then multiplying the pre-curvature radius by a calibration coefficient to obtain the curvature radius.
Further, when the optical lens group includes a plano-convex lens, the method further includes, in combination with the nonlinear least squares fitting equation and unwrapped data, obtaining plano-convex lens parameters, including:
Fitting plane data by using nonlinear least square fitting polynomials to the data after plane unwrapping of the plano-convex lens; and then taking the fitted plane data as the reference plane and the data of the plane unwrapped by the plano-convex lens, calculating standard deviation, converting the unit into radian, and obtaining flatness data.
Further, when calibrating the optical lens set parameter measurement system, the grid reticle is placed at the lens support for fixing the optical lens set, and the lens support is set within the focal length range of the telecentric lens detector.
In order to achieve the above objective, the present invention further provides a low-cost and high-precision optical lens set parameter measurement system, which is used for implementing the low-cost and high-precision optical lens set parameter measurement method, and the system comprises a mode-jump laser, a temperature controller, a laser power controller, a beam splitting prism, a reference plane, a telecentric lens detector, an optical lens set with a lens bracket, and a computer;
The mode jump laser, the reference plane, the telecentric lens detector and the optical lens group with the lens bracket are respectively arranged in the directions of four side surfaces of the beam splitting prism;
The mode-jump laser is opposite to the optical lens group with the lens bracket;
the telecentric lens detector faces the reference plane;
The reference plane is provided with a virtual shadow under the action of the beam-splitting prism, and the virtual shadow is positioned between the beam-splitting prism and the optical lens group with the lens bracket;
the temperature controller and the laser power controller are both connected with the mode-jump laser;
the computer is connected with the telecentric lens detector.
Compared with the prior art, the technical scheme has the following principle and advantages:
the mode-hopping laser is applied to the parameter measurement of the optical lens group, has low price and small volume, can work at high speed and has wider wave number mode-hopping output bandwidth. Although the mode jump output of the wave number can cause the side lobe of the interference signal to be too high, the interference of the side lobe of the interference signal can be reduced by the optical lens group parameter measurement method, and the peak frequency of the interference signal can be extracted more easily, so that the problem of phase aliasing is solved.
The optical path structure of the optical lens group parameter measurement system is simple, and the operation steps are simple.
The optical lens group parameter measurement system does not need to specially design a wave number monitoring light path, and can greatly reduce hardware cost.
The optical lens group parameter measurement system can be used for perspective measurement of a plurality of groups of lenses through one experiment, and the measurement efficiency of the optical lens group parameters is greatly improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the services required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the figures in the following description are only some embodiments of the present invention, and that other figures can be obtained according to these figures without inventive effort to a person skilled in the art.
FIG. 1 is a diagram of the optical path of a low cost high precision optical lens set parameter measurement system according to the present invention;
FIG. 2 is a schematic flow chart of a low-cost high-precision optical lens set parameter measuring method according to the present invention;
FIG. 3 is an interference pattern experimentally collected in an embodiment of the present invention;
FIG. 4 is a power spectrum versus frequency plot obtained in an embodiment of the present invention;
Fig. 5 is a phase diagram of the front and rear surfaces of an optical wedge and the surface of a plano-convex lens in an embodiment of the present invention (a is the phase diagram of the front surface of the optical wedge, b is the phase diagram of the rear surface of the optical wedge, c is the phase diagram of the plane of the plano-convex lens, and d is the phase diagram of the convex surface of the plano-convex lens);
FIG. 6 is an unwrapped graph of the front and rear surfaces of an optical wedge and the surface of a plano-convex lens (a is an unwrapped graph of the front surface of an optical wedge, b is an unwrapped graph of the rear surface of an optical wedge, c is a planar unwrapped graph of a plano-convex lens, d is a convex unwrapped graph of a plano-convex lens) according to an embodiment of the present invention;
FIG. 7 is a fitted view of the front and rear surfaces of a 6' optical wedge in an embodiment of the present invention.
Reference numerals:
A 1-mode-hop laser; 2-a temperature controller; 3-a laser power controller; 4-a beam-splitting prism; 5-a reference plane R; 6-a telecentric lens detector; 7-wedge; 8-plano-convex lenses; 9-computer.
Detailed Description
The invention is further illustrated by the following examples:
as shown in fig. 1, the system for measuring parameters of an optical lens set with low cost and high precision according to the present embodiment includes a mode-jump laser 1, a temperature controller 2, a laser power controller 3, a beam splitting prism 4, a reference plane R5, a telecentric lens detector 6, an optical lens set with a lens support (including an optical wedge 7 with an inclination angle of 6' and a plano-convex lens 8 with a focal length of 1500), and a computer 9;
The mode-jump laser 1, the reference plane R5, the telecentric lens detector 6 and the optical lens group with the lens bracket are respectively arranged in the four side directions of the beam-splitting prism 4; the mode-jump laser 1 is opposite to the optical lens group with the lens bracket; telecentric lens detector 6 is opposite to reference plane R5; the reference plane R5 is formed with a virtual image under the action of the beam splitting prism 4, the virtual image being located between the beam splitting prism 4 and the optical lens group with the lens support; the temperature controller 2 and the laser power controller 3 are connected with the mode-jump laser 1; the computer 9 is connected to the telecentric lens detector 6. The lens holder is disposed within the focal length of telecentric lens detector 6.
In addition, the embodiment also provides a low-cost high-precision optical lens group parameter measurement method, as shown in fig. 2, the working principle of which comprises the following steps:
s1, constructing the optical lens group parameter measurement system;
S2, calibrating an optical lens group parameter measurement system (converting the pixel value of the acquired interference signal after unwrapping into a real physical quantity) and obtaining a calibration coefficient;
In the present step, the step of the method,
A grid reticle produced by Hengyang optics is adopted, the model is GH-YP0105, the line number is 25 multiplied by 25, the line width is 0.01mm, and the interval between each line is 0.2mm. The grid pattern can be clearly obtained in the computer 9 by placing the grid reticle at the lens support and starting the mode-jump laser 1, because the lens support is arranged in the focal length range of the telecentric lens, and the resolution of the system in the transverse direction and the longitudinal direction is 3.985 mu m/pixels finally obtained by using a related calibration method.
And (3) preparing a standard plano-convex lens component with known parameters, comparing the standard plano-convex lens component with the optical lens group, and measuring the plano-convex lens with the focal length of 1000 in the calibration process to obtain a calibration coefficient. The calibration coefficient of the plano-convex lens experiment is 1.2934.
S3, placing the optical lens group on a lens bracket at a measuring position of an optical lens group parameter measuring system (the optical wedge 7 with the position relation of an inclination angle of 6' is arranged in front, and the plano-convex lens 8 with the focal length of 1500 is arranged in back);
S4, adopting A mode-jump laser 1 of (laser wavelength) =635 nm, a laser power controller 3 is set at ILD (laser current) =55ma, a laser temperature controller 2 is set to rise from 25 ℃ to 38 ℃ at uniform speed, and a telecentric lens detector 6 collects and saves 1000 interference patterns at a speed of 30 frames per second, as shown in fig. 3; (in the process, the mode-jump laser 1 emits laser beams, the laser beams respectively irradiate on the front and back surfaces of the optical wedge 7 with the inclination angle of 6' and the plane and the convex surface of the plano-convex lens 8 with the focal length of 1500 and the reference plane R5 under the action of the beam-splitting prism 4, and the reflected light of the front and back surfaces of the optical wedge 7 and the plane and the convex surface of the plano-convex lens 8 and the reflected light of the reference plane R5 are mutually overlapped to form interference);
S5, reading 1000 interference patterns, and removing direct current components from the interference signals to obtain light intensity signals;
the light intensity signal is expressed as:
(1)
In the formula (1), the components are as follows, For the intensity of light, subscriptAndEach of the interface layers is respectively arranged on the substrate,In order for the number of surfaces to participate in the interference,For the initial phase position,Is the number of waves to be used,Is the firstReflected light inside the surface andOptical path difference of reflected light inside the individual surfaces.
As can be seen from equation (1), the amplitude and the intensity of lightProportional to frequencyAnd optical path differenceProportional to the ratio.
After the light intensity signal is obtained, the corresponding power spectrum and frequency are obtained based on the light intensity signal, so that a power spectrum-frequency diagram is obtained;
Power spectrum The calculation formula of (2) is as follows:
（2）
In the formula (2), the amino acid sequence of the compound, In order to be of an angular frequency,For the number of signal points,Is the firstThe point of the input signal is the point of the input signal,Is the signal pointIn correspondence with the moment of sampling,The sample mean and the sample variance are respectively,For a time-shift invariant, which shifts the time origin by a constant, the power spectrumAnd the method is kept unchanged, and the following formula is satisfied:
（3）；
Frequency of The calculation formula of (2) is as follows: （4）；
The obtained power spectrum-frequency diagram is shown in fig. 4, and the four peak signals respectively correspond to the interference signals S1R, S R generated by the reference plane R5 and the front and rear surfaces S1, S2 of the optical lens assembly wedge 7, and the interference signals S3R, S R generated by the reference plane R5 and the front and rear surfaces S3, S4 of the plano-convex lens 8.
S6, finding out the corresponding frequency under each peak value from the power spectrum-frequency diagram, and extracting the phase under the corresponding peak value through the following formula to obtain the front and back surface phase diagrams of the optical wedge 7 and the front and back surface phase diagrams of the plano-convex lens 8, as shown in FIG. 5;
the discrete signal of the interference sequence of one pixel point of the interference pattern is set as follows:
（5）
In the formula (5), the amino acid sequence of the compound, In order to be amplitude-value,Is the phase of the interference signal;
after being simplified by Euler's formula The interference signals of the individual points are:
（6）
in the formula (6), the amino acid sequence of the compound, Is the bottom of the natural logarithm,Is an imaginary unit;
further reduce equation (6):
（7）
Inputting discrete signals and angular frequency of an interference spectrum sequence into a formula (7), and inputting a calculated result into a formula (8) to obtain a phase:
（8）
In the formula (8), the amino acid sequence of the compound, For the imaginary part of the corresponding value,Is the real part of the corresponding value.
S7, inputting the obtained phases into a least square method space for demodulation to obtain unwrapped data, as shown in FIG. 6;
S8, the unwrapped phases of the front surface and the rear surface of the optical wedge 7 are respectively input into a nonlinear least square fitting plane equation to respectively obtain normal vectors of corresponding planes, and then the two normal vectors are calculated to obtain an included angle of the two planes. As shown in fig. 7, the calculated data of the inclination angle of the wedge 7 is 6.4546'. The standard error given by the authorities is + -1 ', and the experimental error is 0.4546', so that the experimental error is within the allowable range, and the experimental result is reliable.
S9, fitting the data obtained after the convex surface of the plano-convex lens 8 is unwrapped with a spherical equation by a nonlinear least square method to obtain a pre-curvature radius 599.2263mm of an analog quantity, wherein the pre-curvature radius is still not small difference from a theoretical curvature radius 775.2mm given by a manufacturer, the simulated pre-curvature radius is required to be multiplied by a calibration coefficient obtained in the step S2, and the curvature radius of the analog quantity is 775.0393mm and the error is-0.1607 mm;
S10, fitting the plane unwrapped data of the plano-convex lens 8 into plane data by using a nonlinear least square fitting polynomial. Calculating standard deviation by taking the fitted plane data as a reference plane and the data of the plane unwrapped plano-convex lens 8, converting the unit into radian, obtaining flatness data of 27.3169, which is commonly used in manufacturers The quality of 20 is high-precision, the center wavelength of the laser in this experiment is 635nm20=31.75. The plane of the plano-convex lens 8 is also of high precision quality.
This embodiment has the following advantages:
the mode-hopping laser 1 is applied to the parameter measurement of the optical lens group, and the mode-hopping laser 1 has low price, small volume, high-speed operation and wider wave number mode-hopping output bandwidth. Although the mode jump output of the wave number can cause the side lobe of the interference signal to be too high, the interference of the side lobe of the interference signal can be reduced by the optical lens group parameter measurement method, and the peak frequency of the interference signal can be extracted more easily, so that the problem of phase aliasing is solved.
The optical path structure of the optical lens group parameter measurement system is simple, and the operation steps are simple.
The optical lens group parameter measurement system does not need to specially design a wave number monitoring light path, and can greatly reduce hardware cost.
The optical lens group parameter measurement system can be used for perspective measurement of a plurality of groups of lenses through one experiment, and the measurement efficiency of the optical lens group parameters is greatly improved.
The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, so variations in shape and principles of the present invention should be covered.
Claims (8)
1. The method for measuring the parameters of the optical lens group with low cost and high precision is characterized by comprising the following steps:
Setting up an optical lens group parameter measurement system, wherein the system comprises a mode jump laser, a temperature controller, a laser power controller, a beam splitting prism, a reference plane, a telecentric lens detector, an optical lens group with a lens bracket and a computer; the optical lens group with the lens bracket is respectively distributed in the four side directions of the beam splitting prism; the mode-jump laser is opposite to the optical lens group with the lens bracket; the telecentric lens detector is opposite to the reference plane; the reference plane is provided with a virtual shadow under the action of the beam-splitting prism, and the virtual shadow is positioned between the beam-splitting prism and the optical lens group with the lens bracket; the temperature controller and the laser power controller are both connected with the mode-jump laser; the computer is connected with the telecentric lens detector;
calibrating an optical lens group parameter measurement system, and obtaining a calibration coefficient;
After the laser parameters of the mode-jump laser are regulated by the temperature controller and the laser power controller, the mode-jump laser emits laser beams which respectively irradiate the surface of each optical lens of the optical lens group and the reference plane under the action of the beam splitting prism, the reflected light of the front surface and the rear surface of each optical lens of the optical lens group and the reflected light of the reference plane are mutually overlapped to form interference, an interference signal is received by the telecentric lens detector and transmitted to the computer, and the interference signal is analyzed and processed by the computer to finally obtain the parameters of the optical lens group;
the computer analyzing and processing the interference signal comprises the following steps:
Removing the direct current component from the interference signal to obtain a light intensity signal;
obtaining a corresponding power spectrum and frequency based on the light intensity signal, thereby obtaining a power spectrum-frequency diagram;
the phase position of the front surface and the back surface of each optical lens of the optical lens group is obtained based on the power spectrum-frequency diagram;
the obtained phases are respectively input into a least square method for spatial demodulation to obtain unwrapped data;
And solving parameters of corresponding optical lenses in the optical lens group by combining the nonlinear least square fitting equation and unwrapped data.
2. The method for measuring parameters of an optical lens set with low cost and high precision according to claim 1, wherein the power spectrum P (ω) is calculated as follows:
In the formula (2), ω is angular frequency, N is the number of signal points, x k is the kth input signal point, t k is the time of sampling corresponding to the signal point x k, Σ 2 is the sample mean and sample variance, respectively, τ is the time-shift invariant, which keeps the power spectrum P (ω) unchanged when the time origin shifts by a constant, satisfying the following formula:
The calculation formula of the frequency f is as follows:
3. The method for measuring parameters of an optical lens set with low cost and high accuracy according to claim 2, wherein the step of obtaining the phase of the front and rear surfaces of each optical lens of the optical lens set based on the power spectrum-frequency map comprises:
Finding out the corresponding frequency under each peak value from the power spectrum-frequency diagram, and extracting the phase under the corresponding peak value through the following formula:
the discrete signal of the interference sequence of one pixel point of the interference pattern is set as follows:
y(N)＝Acos(ωN+φ) (5)
in the formula (5), A is amplitude, omega is angular frequency, and phi is the phase of an interference signal;
The interference signals of N points after being simplified by Euler formulas are as follows:
In the formula (6), e is the bottom of natural logarithm, and j is an imaginary unit;
further reduce equation (6):
inputting discrete signals and angular frequency of an interference spectrum sequence into a formula (7), and inputting a calculated result into a formula (8) to obtain a phase:
in the equation (8), im is the imaginary part of the corresponding value, and Re is the real part of the corresponding value.
4. The method for measuring parameters of an optical lens set with low cost and high precision according to claim 1, wherein when the optical lens set comprises an optical wedge, the step of obtaining the optical wedge parameters by combining a nonlinear least square fitting equation and unwrapped data comprises the steps of:
And respectively inputting unwrapped phases of the front surface and the rear surface of the optical wedge into a nonlinear least square fitting plane equation to respectively obtain normal vectors of corresponding planes, and then calculating the two normal vectors to obtain an included angle of the two planes to obtain the inclination angle of the optical wedge.
5. The method for measuring parameters of an optical lens set with low cost and high precision according to claim 1, wherein when the optical lens set comprises a plano-convex lens, the step of obtaining plano-convex lens parameters by combining a nonlinear least squares fitting equation and unwrapped data comprises:
Calculating the data obtained after the convex surface unwrapping of the plano-convex lens by adopting a nonlinear least square fitting spherical equation to obtain the pre-curvature radius of the analog quantity;
and then multiplying the pre-curvature radius by a calibration coefficient to obtain the curvature radius.
6. The method for measuring parameters of an optical lens set with low cost and high precision according to claim 5, wherein when the optical lens set comprises a plano-convex lens, the method for calculating the plano-convex lens parameters by combining a nonlinear least squares fitting equation and unwrapped data further comprises:
Fitting plane data by using nonlinear least square fitting polynomials to the data after plane unwrapping of the plano-convex lens; and then taking the fitted plane data as the reference plane and the data of the plane unwrapped by the plano-convex lens, calculating standard deviation, converting the unit into radian, and obtaining flatness data.
7. A low cost, high accuracy optical lens set parameter measurement method as claimed in claim 1, wherein the grid reticle is placed at a lens mount for holding the optical lens set, the lens mount being disposed within a focal length of the telecentric lens probe, when the optical lens set parameter measurement system is calibrated.
8. A low-cost high-precision optical lens group parameter measurement system for realizing the low-cost high-precision optical lens group parameter measurement method according to any one of claims 1-7, which is characterized by comprising a mode jump laser, a temperature controller, a laser power controller, a beam splitting prism, a reference plane, a telecentric lens detector, an optical lens group with a lens bracket and a computer;
The mode jump laser, the reference plane, the telecentric lens detector and the optical lens group with the lens bracket are respectively arranged in the directions of four side surfaces of the beam splitting prism;
The mode-jump laser is opposite to the optical lens group with the lens bracket;
the telecentric lens detector faces the reference plane;
The reference plane is provided with a virtual shadow under the action of the beam-splitting prism, and the virtual shadow is positioned between the beam-splitting prism and the optical lens group with the lens bracket;
the temperature controller and the laser power controller are both connected with the mode-jump laser;
the computer is connected with the telecentric lens detector.
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| CN107764197A (en) * | 2017-10-16 | 2018-03-06 | 长春理工大学 | A kind of optical system axial direction parameter measuring apparatus and method |
| CN109855743A (en) * | 2019-01-04 | 2019-06-07 | 北方工业大学 | Device and method for measuring large-size optical plane by double-frequency laser heterodyne interference phase |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107764197A (en) * | 2017-10-16 | 2018-03-06 | 长春理工大学 | A kind of optical system axial direction parameter measuring apparatus and method |
| CN109855743A (en) * | 2019-01-04 | 2019-06-07 | 北方工业大学 | Device and method for measuring large-size optical plane by double-frequency laser heterodyne interference phase |
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