TWI402711B - System and method for analyzing errors of aspheric lens - Google Patents

Description

Aspheric mirror error analysis system and method

The invention relates to an error analysis system and method, in particular to an error analysis system and method for an aspherical mirror surface.

Quality is one of the important factors for a company to maintain its long-term development ability. How to ensure and improve product quality is an important part of corporate activities. In order to improve and ensure the quality of the products, it is essential to carry out inspections on the products. By verifying the quality information of the products and their manufacturing processes, the manufacturing process of the products is controlled according to this information--correction and compensation activities are carried out. The rate of waste defective products and repaired products is minimized to ensure the stability of the product quality formation process and the consistency of the products produced.

The pursuit of higher manufacturing precision has always been the goal of the manufacturing industry. The improvement of manufacturing precision depends not only on machine tools, tools and numerical control technology, but also on the measurement accuracy and the error analysis of the measurement data that can be achieved by the test methods used in the manufacturing system. Since aspherical mirror elements are more and more widely used in optical design, higher requirements are placed on the detection of aspherical surface parameters and the evaluation of aspherical surface quality. With the development of modern open CNC technology, the computer's software resources and powerful computing power are effectively utilized to analyze the error of the measured data, thereby improving the processing precision of the product.

However, the original error analysis of the measured data cannot automatically derive the design data and the measured data for comparison, and the error analysis data cannot be visually reflected in the error analysis process.

In view of the above, it is necessary to provide an aspherical mirror error analysis system and method, which can automatically analyze the error between the measurement data of the aspherical mirror workpiece and the design data, and intuitively reflect the error curve and related data.

An aspherical mirror error analysis system for performing error analysis on measurement data and design data of an aspherical mirror workpiece, comprising: a data acquisition module for acquiring design data and measurement data of the workpiece; and an error analysis module For generating a design curve based on the design data, and generating a measurement curve according to the measurement data, performing coordinate transformation on the measurement curve, converting the coordinates of the measurement point in the measurement curve from the measurement coordinate system to the aspherical mirror coordinate system, and calculating the design curve and The error between the measured curves after the coordinate transformation, the error analysis data is acquired and an error curve is generated according to the error analysis result; and the output module is used for outputting the error analysis data and the error curve.

An aspherical mirror error analysis method for error analysis of measurement data and design data of an aspherical mirror workpiece, the method is used for controlling a machine to measure a workpiece, and the method comprises the following steps: acquiring design data and measurement data of the workpiece The measurement curve is generated according to the measurement data, and the design curve is generated according to the design data; the coordinate transformation is performed on the measurement curve, and the coordinate of the measurement point in the measurement curve is converted from the measurement coordinate system to the aspherical mirror coordinate system; the design curve and the coordinate transformation are calculated. The magnitude of the error between the measured curves; the error analysis data is acquired; the error curve is generated based on the error analysis data; and the error analysis data and the error curve are output.

Compared with the prior art, the aspherical mirror error analysis system and method can automatically analyze the error between the measurement data of the aspherical mirror workpiece and the design data, and generate an error curve and related data that can be visually reflected. Correction data is generated to guide the correction of the aspherical mirror surface workpiece, thereby improving machining accuracy and measurement accuracy.

For ease of understanding, the following is a brief description of the technical terms involved in the present invention: aspherical surface: a curved surface having different radii of points on the surface, and the basic surface shape is a quadric surface, which is a rotationally symmetric surface. The aspherical optical equations are listed below, where Z is the axis of rotation; C = 1/R, where R is the radius of curvature of the aspherical apex; k = 1 - e, where e is the eccentricity; Ai is the polynomial of the higher aspherical surface Coefficient, indicating the deviation of the aspheric surface from the reference quadric:

As shown in FIG. 1, it is a hardware architecture diagram of a preferred embodiment of the aspherical mirror error analysis system of the present invention. The aspherical mirror error analysis system 2 (hereinafter referred to as "the present system 2") is constructed in the computer 1, and the computer 1 further includes a storage device 3. The computer 1 is connected to the machine table 4, so that the system 2 can acquire relevant data of the workpiece to be measured from the machine table 4, thereby performing error analysis on the measurement data to determine whether the processing of the workpiece is qualified. The machine 4 can be a computer numerical control (CNC, Computer Numerical Control) machine tool with a measurement function such as a numerical control machine tool or a measurement machine tool.

The system 2 provides an operation interface for displaying design data, measurement data, parameters of various settings, fitting curves, and analysis results. The user can perform related operations through the operation interface, for example, loading required data into the system 2, inputting parameter values, and viewing error analysis results.

The storage device 3 is configured to store various types of data, including design data, measurement data, parameters and corresponding parameter values, analysis results, and the like.

As shown in FIG. 2, it is a functional module diagram of the aspherical mirror error analysis system of the present invention. The system 2 is installed in the computer 1, and mainly comprises five functional modules, namely: a data acquisition module 21, an error analysis module 22, a fitting module 23, a correction data generation module 24, and an output module 25. .

The data acquisition module 21 is configured to acquire required data, including design data, measurement data, and the like. For example, for the acquisition of measurement data, a timer board and a counter board can be installed in the computer, and the timer board and the counter board respectively provide a timer and a counter, and the timer and the counter follow the machine 4 The two axes of the upper coordinate system (such as the X axis and the Z axis, or the Y axis and the Z axis) are linked or the three axes (such as the X axis, the Y axis and the Z axis) are linked to generate a motion trajectory and generate related parameters, and the random table The measurement of the workpiece by the probe on the 4, the data acquisition module 21 acquires each measurement data, the measurement path of the probe, and the like.

According to the specific conditions of different measuring devices, the main errors generated in the measurement include position error, such as: positioning error of the measuring origin, and measurement of the misalignment error between the coordinate system and the aspherical mirror coordinate system. Because in the ultra-precision machining, the value of the above error is small, and the measurement data is too large, it is not suitable to analyze by the graph, and the position error is corrected by numerically solving the error. The coordinate transformation can be performed by the following formula (1), where x and z are measurement points, and x' and z' are coordinate points of the transformed measurement points: x '= x * cos θ - z * sin θ - Dx z '= x * sin θ + z * cos θ - dy m =tan θ

The error analysis module 22 is configured to generate a measurement curve according to the measurement data, and generate a design curve according to the design data, and perform coordinate transformation on the measurement curve by using a preset formula (1).

The error analysis module 22 is further configured to calculate a magnitude of an error between the design curve and the coordinate curve after the coordinate transformation, obtain error analysis data, and generate an error curve. The calculated error includes calculating the magnitude of the face shape error (also referred to as "shape error"), which includes the peak-to-valley value (PV value) and the wavefront root mean square value (RMS value). Wherein, the PV value is the difference between the maximum error value and the absolute value of the minimum error value.

The fitting module 23 is configured to fit the error analysis data by the least square method, and minimize the error between the design data and the measurement data to obtain the optical parameters of the aspherical mirror.

The fitting module 23 can perform smoothing and denoising processing on the acquired error analysis data before fitting. The smoothing and denoising processing of the data can be performed by means of neighborhood averaging method, low pass filtering, median filtering, mean filtering, frequency domain filtering, and the like. For example, median filtering uses a sliding window with an odd number of points to replace the value of the center point of the window with the median of the points in the window. Its function is to make the difference between the gray values of the surrounding primitives larger. Replace with a primitive that is close to the surrounding primitive value, eliminating isolated noise points.

The least squares method is a mathematical optimization technique that seeks the best function matching of a set of data by minimizing the sum of the squares of the errors. For fitting the line, make the error analysis data as close as possible to a plane parallel to the xoy plane and as close as possible to a line parallel to the x-axis; for a circle or plane, make the error analysis data as far as possible parallel to the xoy plane In-plane.

The correction data generating module 24 is configured to preset a correction parameter, and generate correction data according to the error curve for correcting the workpiece. The correction data generation module 24 may generate correction data according to the error curve before fitting, or may generate correction data according to the fitted error curve. The correction parameter and the correction data are correction data generated for the design parameters and design data of the workpiece, and are used for reworking the workpiece to reduce the error between the design data and the measurement data, thereby realizing the aspherical mirror workpiece. High precision machining.

The output module 25 is configured to output various types of data to the storage device 3, and output corresponding data files for reference by the user. The various types of data include: design data, measurement data, design curves, measurement curves, error analysis data, error curves, correction parameters, and correction data. The data file can include a combination of one or more of the above data. The output data or data file can be displayed in the operation interface provided by the system 2.

Data files can be output in different formats, for example, data files with mod as the last code name, data files with omm as the last code name, and data files with txt as the last code name. Data files of different formats can be identified and called by different systems or devices.

As shown in FIG. 3, it is a flow chart of a preferred embodiment of the aspherical mirror error analysis method of the present invention. First, in step S2, the data acquisition module 21 acquires design data and loads the design data into the system 2.

In step S4, the data acquisition module 21 acquires each measurement data, including data such as coordinate values of the measurement points and the number of measurement points.

In step S6, the error analysis module 22 generates a measurement curve based on the measurement data, and generates a design curve according to the design data. In step S8, the error analysis module 22 performs coordinate transformation on the measurement curve by using a preset formula (1), thereby reducing the position error. In the measurement process, according to the specific conditions of different measuring devices, the position error generated in the measurement includes: the positioning error of the measurement origin, and the misalignment error between the coordinate system and the aspherical mirror coordinate system, so coordinate transformation of the measurement curve The position error can be reduced.

In step S10, the error analysis module 22 calculates the magnitude of the error between the design curve and the coordinate curve after the coordinate transformation, acquires the error analysis data, and generates an error curve. The calculated error includes calculating the magnitude of the surface shape error including the peak-to-valley value (PV value) and the wavefront rms value (RMS value), wherein the PV value is the absolute value of the maximum error value and the minimum error value. The difference between the values.

In step S12, the fitting module 23 fits the error analysis data by the least squares method, and minimizes the error between the design data and the measurement data to obtain the optical parameters of the aspherical mirror. The acquired error analysis data can be smoothed and denoised by the fitting module 23 before fitting. The smoothing and denoising processing of the data can be performed by means of neighborhood averaging method, low pass filtering, median filtering, mean filtering, frequency domain filtering, and the like.

In step S14, the correction data generation module 24 presets the correction parameters, and generates correction data according to the fitted error curve for correcting the workpiece. The correction parameter and the correction data are correction data generated for the design parameters and design data of the workpiece, and are used for reworking the workpiece to reduce the error between the design data and the measurement data, thereby realizing the aspherical mirror workpiece. High precision machining.

In step S16, the output module 25 outputs various types of data to the storage device 3, and outputs corresponding data files to the user for reference, and ends the process. The various types of data include: design data, measurement data, design curves, measurement curves, error analysis data, error curves, correction parameters, and correction data. The data file can include a combination of one or more of the above data. The output data or data file can be displayed in the operation interface.

In addition, in other embodiments, the fitting of the error curve in step S12 may be omitted, and the correction data generating module 24 may generate correction data according to the unfitted error curve. By fitting the measured data, more accurate optical parameters can be obtained, thereby realizing the optical parameters of the aspherical mirror in the reverse direction.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and equivalent modifications or variations made by those skilled in the art in light of the spirit of the present invention are It should be covered by the following patent application.

computer. . . 1

Aspherical mirror error analysis system. . . 2

Data acquisition module. . . twenty one

Error analysis module. . . twenty two

Fitting module. . . twenty three

Correct the data generation module. . . twenty four

Output module. . . 25

Storage device. . . 3

Machine. . . 4

1 is a hardware architecture diagram of a preferred embodiment of the aspherical mirror error analysis system of the present invention.

2 is a functional block diagram of the aspherical mirror error analysis system of the present invention.

3 is a flow chart of a preferred embodiment of the aspherical mirror error analysis method of the present invention.

Aspherical mirror error analysis system. . . 2

Data acquisition module. . . twenty one

Error analysis module. . . twenty two

Fitting module. . . twenty three

Correct the data generation module. . . twenty four

Output module. . . 25

Claims (10)

An aspherical mirror error analysis system for error analysis of measurement data and design data of an aspherical mirror workpiece, the system comprising: a data acquisition module for acquiring design data and measurement data of the workpiece; an error analysis module, It is used to generate a design curve according to the design data, and generate a measurement curve according to the measurement data, coordinately transform the measurement curve, convert the coordinate of the measurement point in the measurement curve from the measurement coordinate system to the aspherical mirror coordinate system, calculate the design curve and coordinates The magnitude of the error between the transformed measurement curves, the error analysis data is acquired, and an error curve is generated according to the error analysis result; and an output module is configured to output the error analysis data and the error curve. The aspherical mirror error analysis system of claim 1, wherein the system further comprises a fitting module for fitting the error analysis data by using a least squares method, by comparing the design data with the measurement data. The error is minimized to obtain the optical parameters of the aspherical mirror. For example, in the aspherical mirror error analysis system described in claim 1, the fitting module is further configured to perform smoothing and denoising processing on the acquired error analysis data. For example, in the aspherical mirror error analysis system described in claim 1, the system further includes a correction data generation module for preset correction parameters, and generating correction data according to the error curve for correction processing. For example, in the aspherical mirror error analysis system described in claim 1, the error magnitude calculated by the error analysis module includes a peak-to-valley value of the error curve and a wavefront root mean square value. An aspherical mirror error analysis method for error analysis of measurement data and design data of an aspheric mirror workpiece, the method comprising the steps of: acquiring design data and measurement data of the workpiece; generating a measurement curve according to the measurement data, and according to the design Data generation design curve; coordinate transformation of the measurement curve, transform the coordinate of the measurement point in the measurement curve from the measurement coordinate system to the aspherical mirror coordinate system; calculate the error between the design curve and the coordinate curve after the coordinate transformation; Obtain error analysis data; generate an error curve based on the error analysis data; and output error analysis data and an error curve. For example, the aspherical mirror error analysis method described in claim 6 further includes the following steps: performing the smoothing and denoising processing on the acquired error analysis data after the step of acquiring the error analysis data. The method for analyzing an aspherical mirror error according to claim 6 of the patent application scope, after the step of acquiring error analysis data, the method further comprises the steps of: fitting the error analysis data by using a least square method; and design data and measurement data The error between them is minimized to obtain the optical parameters of the aspherical mirror. The method for analyzing an aspherical mirror error according to item 6 of the patent application scope, the method further comprising the steps of: preset a correction parameter; and after the step of generating an error curve according to the error analysis data, according to the error curve and the preset correction parameter The correction data is generated for correcting the workpiece. For example, in the aspherical mirror error analysis method described in claim 6, the calculated error magnitude includes a peak-to-valley value of the error curve and a wavefront root mean square value.