TWI398338B - Compensation method for optics mold - Google Patents

Description

Optical mold processing compensation method

The invention relates to an optical mold processing compensation method. In particular, the method compensates for the wavefront error of an optical system.

With the development of optical industry and optoelectronic technology, a variety of optical components and optoelectronic systems have emerged according to different needs, and optical lenses are one of the indispensable components in various optical systems. In addition to the astronomical telescopes and cameras that are well known to the general public, applications in digital cameras, laser printers, photocopiers, and projectors have also become popular, and the requirements for the quality and precision of optical lenses are increasing. The higher the height.

At present, industrial optical lenses are distinguished by the use of materials and their manufacturing methods, and there are three main types of conventional glass lens polishing and polishing, molded glass lenses and plastic injection molding. The traditional lens grinding and polishing method uses a series of rounding, forming, grinding, polishing, centering and other procedures to make the lens. Not only the processing process is slow but also involves a lot of technology, especially the aspheric surface is not easy to make. . Secondly, in the method of manufacturing an aspherical lens, glass molding processing and plastic injection molding technology have been used in the industry, and both of the above techniques are formed by using a mold and a mold by compression molding or injection molding.

It is also necessary to tell the story. At present, for the mold processing part in the aspherical lens, the aspherical lens design parameters are also input into the computer numerical control (CNC) to process the mold core, and then input to the CNC diamond lathe for correction. Machining to cut out the mirror shape desired by the user.

It should be noted that the requirements for the shape accuracy of the lens are generally determined by the use of the lens, such as low precision such as spectacle lenses, high precision such as CD player read heads, etc., usually requiring a shape accuracy of 10 μm. It is even smaller or smaller between 0.1 μm. Therefore, in the design of the mold core, it is necessary to consider the effects of shrinkage, warpage, deformation, internal stress and the like which are generated during the molding or injection process.

However, unfortunately, in the lens manufacturing process, the factors affecting the shape of the lens are complicated, and it is difficult to consider in the design of the mold. Therefore, the compensation for the deformation of the lens is the lens molding and plastic injection molding. A very important job in the production method. Traditionally, a molded glass lens or a plastic injection lens is placed on a 3D contour scanner, and the contour of the optical lens is scanned by a 3D contour scanner, and the scanned contour is obtained by linear regression. The contour shape is used to know the dimensional error between the calculated value of the lens shape and the design value, and then the mold compensation is performed according to the error. This compensation method requires compensation for the two faces of each lens of the lens (or optical system), and the compensation effect can only be applied to a single lens. The compensation process takes a long time and cannot compensate for the systematic error caused by the lens assembly.

In a nutshell, the precision of aspherical glass lenses has a very important relationship with the performance of optical systems. In the process of mold core processing, if the error compensation technology of the mold is not done well, the lenses produced are different from the design values. The assembled optical system does not meet the performance specifications. But even if the accuracy of all lenses meets the design requirements, optical assembly may also produce errors. Poor, resulting in reduced optical system performance.

Therefore, if there is a method for processing compensation of the mold, not only compensation for the optical element (lens or machine member) but compensation for the optical system or the optical instrument, the optical component manufacturing error and the optical system assembly error can be And compensation processing.

Therefore, the object of the present invention is to provide an optical mold processing compensation method, using an interferometer as a measuring tool to measure the wavefront error of the optical lens, wherein the wavefront error can be represented by a Zernike polynomial, which is an optical system lens. Manufacturing errors and assembly errors. Then, the wavefront error is reversely input into the optical design software, and the optical software optimization function is used to adjust some lens shape parameters or lens pitches, so that the optical system is adjusted by partial lens shape parameters or lens spacing, and its wavefront and reverse input. The wavefront error is consistent, that is, the adjustment of the lens shape parameters or the lens pitch in the optical system can compensate for the wavefront error measured by the interferometer. In this way, the optical system can be designed to meet the design requirements in the case of adjusting one or several optical components, and the previous method of performing mold compensation for each optical component without guaranteeing the quality of the assembled optical system can be improved.

According to the concept of the present invention, an optical mold processing compensation method is proposed, which comprises the steps of: (a) obtaining an prototype of an optical system according to an optical design result; and (b) measuring a prototype wave of the optical system. Wavefront error; (c) back-feeding the wavefront error back to an optical design software and designing the selected portion of the optical design software The optical system is optimized to obtain a set of design parameters; and (d) an optical mold kernel correction is performed based on the difference between the set of design parameters and the optical design result.

In order to further illustrate the techniques, means and functions of the present invention in order to achieve the intended purpose, reference should be made to the detailed description of the invention and the accompanying drawings. The drawings are to be considered in all respects as illustrative and not restrictive

The traditional mold error compensation is compensated for the contour of a single mirror, and there is no compensation for optical system errors such as dimensional error and assembly error of the machine components. The accuracy of a single lens is no better, and the overall performance of the optical system cannot be guaranteed. Therefore, the present invention proposes an optical mold processing compensation method suitable for use in an optical component or a basic component (optical lens) of an optical instrument. The following is a detailed description of the invention.

As shown in Figure 1, this figure is a flow chart of the method of compensation. First, in step 100, a prototype of an optical system (optical lens) is obtained according to an optical design result, wherein the optical design result is an optical lens (hereinafter referred to as a lens) set according to a user's request. Parameters, such as the shape parameter of a lens and the position of each component in the optical system (which will define the position and orientation of a lens in the optical system, such as the position of the lens, the lens and another lens) The parameters of the pitch, the inclination of the lens, etc., and the material from which the optical lens is made. Furthermore, as is well known, the aforementioned prototype of the optical system mentioned It is also an original type of optical system. In the process of building a new design optical system, it is inevitable that there are still unpredictable problems. Therefore, before starting mass production of the optical system products, The prototype of the optical system is necessary to test and feel the function of the newly designed optical system.

Step 110: Measure the wavefront error of the prototype of the optical system, and the instrument used in the wavefront error of the prototype of the optical system. In this embodiment, an interferometer is used. Comprehensibly, the interferometer is typically used to measure the surface condition of a spherical or planar mirror (also, the surface shape error of the planar lens and the spherical lens (convex and concave) optical components), through collimated laser light passing through The standard wavefront (planar wavefront or spherical wavefront) formed by a standard lens (planar or spherical standard lens) is compared with the surface of the lens to form an interference pattern, and the mirror surface shape of the lens can be known by analyzing the interference pattern. Error and other conditions. Similarly, it can also be used to measure the wavefront error of the optical system. As with the measurement of the surface shape error, the interference pattern can be analyzed to know the system wavefront error. This wavefront error is caused by the shape error (mirror shape error, lens eccentricity and tilt, optical component size error and eccentricity) generated by the optical components in the optical system and system assembly errors. Generally, the Zernike function can be used. Said.

Step 120: Negative feedback of the wavefront error of the prototype of the optical system to an optical design software such as Zemax, Code-V or OSLO for analysis (also inputting the obtained Zernike function to The optical design software), and selecting a plurality of design parameters in the optical design software to perform the optical system optimization to obtain a set of settings Calculating parameters, and selecting a plurality of lens shape parameters and a plurality of lens position parameters in selecting a plurality of design parameters, wherein the lens shape parameter is a radius of curvature, an aspheric coefficient, or a lens of the lenses thickness. The aforementioned lens positional parameters are parameters that define the position and orientation of the lenses in the optical system, such as the position of the lens, the spacing between the lens and another lens, the inclination of the lens, and the like. As shown in Figures 2A and 2B, the optical software optimization function is used to adjust the design parameters of one or several lenses in the optical system, so that the wavefront of the compensated optical system coincides with the reversal of the prototype of the optical system. Wavefront error to compensate for errors accumulated in the original optical system due to fabrication and assembly.

Step 130: Perform an optical mold kernel correction according to the difference between the design parameters of the group and the optical design result.

In step 130, after correcting the optical mold, if the correction is not good, the process returns to step 120 to obtain another set of design parameters for further optical mold compensation.

Finally, it should also be mentioned that among the options of the plurality of design parameters selected in step 120 may be one of a plurality of lens shape parameters and a plurality of lens position parameters or a combination of the two parameters.

The above is a detailed description of the present invention, and is not intended to limit the scope of the present invention. The present invention is modified by those skilled in the art, and is not intended to be protected by the scope of the patent application. By.

100‧‧‧According to an optical design result to obtain the prototype of an optical system

110‧‧‧Measure the wavefront error of the prototype of the optical system

120‧‧‧ Inverting the wavefront error back to an optical design software, and selecting a part of the design parameters in the optical design software to optimize the optical system, so that the wavefront and the reverse input of the optical system Wavefront error phase Match to get a set of design parameters as well as

130‧‧‧An optical model correction based on the difference between the design parameters of the group and the optical design results

Figure 1 is a flow chart showing the processing method of the optical mold processing of the present invention. Figure. 2A and 2B are schematic diagrams showing the input reverse wavefront error in the prototype of an optical system and an optical design, respectively.

100‧‧‧Prototype of an optical system based on an optical design result

110‧‧‧Measure the wavefront error of the prototype of the optical system

120‧‧‧ Inverting the wavefront error back to an optical design software as an optical system optimization target, and selecting a part of the design parameters in the optical design software as a variable parameter to optimize the optical system to obtain One Optical system in which the wavefront is matched with the optimization target as well as

130‧‧‧According to the difference between the design parameters of the optimization results and the design parameters of the optical design results, an optical model correction

Claims (6)

An optical mold processing compensation method, the method comprising: (a) obtaining an optical system prototype according to an optical design result, wherein the prototype comprises at least two optical components and machine components; (b) measuring the prototype Wavefront error of the prototype of the optical system; (c) negative feedback of the wavefront error to an optical design software, and selecting a plurality of design parameters for the optical system in the optical design software Optimizing to match the wavefront of the optical system with the wavefront error of an inverse input to obtain a set of design parameters; and (d) the difference between the design parameters of the set and the optical design result To perform an optical mold repair. The method of claim 1, wherein the optical system is a lens. The method of claim 1, wherein in the step (c), the design parameters are one of a plurality of lens shape parameters and positional parameters of the plurality of lenses or a combination of the two parameters. The method of claim 3, wherein the lens shape parameters are a radius of curvature of the lenses, an aspheric coefficient, and a thickness of the lens. The method of claim 3, wherein the lens positional parameters define a position and a square of the lens in the optical system. Parameters such as the position of the lens, the spacing between the lens and the other lens, the angle of inclination of the lens, and the like. The method of claim 3, wherein in step (d), if the optical mold is not properly corrected, returning to step (c), the optical system optimization is continued to obtain another set of designs. parameter.