TW201918689A - Method and system for measuring processing quality of optical component including splitting and segmenting an ideal planar light - Google Patents

Abstract

A method for measuring a processing quality of an optical component includes: providing an ideal planar light having a standard wavefront; making the ideal planar light after splitting pass through a processed curved surface of an optical component in the forward and reverse directions to obtain a wavefront to be measured due to the aberration from the standard wavefront; segmenting the wavefront to be measured; detecting the wavefront to be measured after the segmentation to obtain a discrete distribution of a plurality of light spots to be measured; and calculating local phases and high-order aberrations based on the local phase distributions of light sports to be measured. Then the aberration wavefront is reconstructed, so as to calculate an actual curvature of the processed curved surface of the optical component to obtain the processing quality of the optical component.

Description

 Measuring system and method for optical component processing quality  

The invention relates to a measuring system and method for processing quality of an optical component, in particular to a measuring system and method for processing quality of an optical component, which can measure the imaging quality of the optical component on-line, confirm the processing quality of the component, and thereby reduce the amount of shutdown and offline. Measuring time.

Generally, the optical quality of the processed optical component 2' (for example, the lens, as shown in FIG. 1) is mostly determined by a contact method to confirm the surface roughness and shape accuracy of the optical component, whether it is an optical component in the visible light band or an invisible light band. Optical components, common contact measuring equipment (such as free-form surface profilometer, UA3P) always confirm the surface roughness and shape accuracy of optical components through multiple finishing methods through gradual finishing and measurement, but It is easy to affect the positioning accuracy, actual machining accuracy and time consuming due to multiple loading and unloading, and the surface roughness and shape accuracy of the optical component do not truly reflect the imaging quality of the optical component.

At present, optical manufacturers propose a set of research frameworks with high accuracy and objective display of optical components and lens system characteristics by wavefront measurement method. In addition to the accuracy and reliability of the instrument, you can customize the programmed test sequence through reliable software, plus a wide range of applications and ultra-precise autofocus or precision mechanical focusing platform to select the perfect function and design for multi-band, increase Measurement speed and accuracy of optical parameters. However, this series of wavefront measurement systems are still in offline measurement, which can only be used for quality inspection of finished products, and cannot be used as the basis for online confirmation of optical component processing quality during processing.

In view of this, there is a need to provide a measurement system and method for confirming the processing quality of optical components on-line to solve the aforementioned problems.

The main object of the present invention is to provide a measuring system and method for processing quality of an optical component, which can measure the imaging quality of the optical component on-line, and thereby confirm the processing quality of the optical component, so as to reduce the off-line offline measurement time.

To achieve the above object, the present invention provides a method for measuring the processing quality of an optical component, comprising: providing an ideal planar light having a standard wavefront; and passing the ideal planar light after splitting through the first and second directions The curved surface of the optical component is such that the standard wavefront aberration becomes the wavefront to be measured; the wavefront to be measured is divided; the wavefront to be measured after the segmentation is sensed, and the discrete distribution of the plurality of light spots to be measured is known; The localized phase and high-order aberrations of the light-receiving spots are calculated, and the aberration wavefront is reconstructed, thereby calculating the curvature of the processed curved surface of the optical element, thereby obtaining the processing quality of the optical component.

The invention further provides a measuring system for processing quality of an optical component, comprising: a light source for providing a desired planar light having a standard wavefront; and a beam splitter for splitting the ideal planar light into an optical component Wherein the optical component is disposed on a reflector, and the ideal planar light is split in a forward direction through one of the optical components to form a curved surface, and then reflected by the reflector to pass through the processed curved surface a second time in the reverse direction. So that the standard wavefront aberration is the wavefront to be measured; a wavefront segmentation unit for dividing the wavefront to be measured passing through the beam splitter; an image sensor disposed after the wavefront segmentation unit End, the sensing wavefront after the segmentation is sensed, and the distribution of the plurality of light spotes to be detected is obtained through the arrayed discrete spot extraction; and a data analysis module is electrically connected to the image sensor, And an algorithm for calculating each local phase and high-order aberration according to the local distributions of the light spots to be measured, and then reconstructing the aberration wavefront, thereby calculating the processed surface of the optical component Actual curvature The processing quality of the optical element.

The present invention provides a measurement method for confirming the manufacturing quality and final image quality of an optical component (e.g., a lens) on a processing apparatus (e.g., a turning machine). A microarray component (such as a microlens array or an annular slit array) is mounted on the front end of the image sensor to cause the incident wavefront to generate a discrete spot distribution through the microarray element (eg, a microlens array or an annular slit array). A differential is obtained to obtain the slope change value, and then the image sensor is used to image and analyze the local wavefront of the optical component to be tested, and the numerical difference is analyzed to further reverse the processing quality of the optical component, which is a fast and direct optical component. Quality control method.

The invention has the following advantages: First, the invention can measure the imaging quality of the optical component on-line: the wavefront reconstruction of the optical component imaging through the wavefront sensing information, which directly corresponds to the imaging quality, and can be returned to the optical component processing quality confirmation. Reduce downtime offline measurement time and increase equipment utilization rate. Secondly, the present invention establishes a non-contact measurement method: avoiding the conventional contact measurement device that always measures the surface roughness and shape accuracy of the component in multiple loading and unloading manners, which easily leads to measurement error. It is also easy to cause poor positioning accuracy.

The above and other objects, features, and advantages of the present invention will become more apparent from the accompanying drawings.

1‧‧‧Measurement system for optical component processing quality

11‧‧‧Light source

111‧‧‧Ideal flat light

112‧‧‧Standard wavefront

112’‧‧‧ Wavefront to be tested

12‧‧‧ Spectroscope

13‧‧‧ Wavefront splitting unit

131‧‧‧Microlens array

132‧‧‧Circular Slit Array

14‧‧‧Image sensor

141‧‧‧Standard light spot

141’‧‧‧Spots to be tested

15‧‧‧Data Analysis Module

2‧‧‧Standard optical components

2'‧‧‧Optical components

21‧‧‧Standard machined surface

21'‧‧‧Masked surface

3‧‧‧ reflector

S100~S500‧‧‧Steps

1 is a schematic perspective view of a conventional optical component.

2 is a flow chart of a method of measuring the quality of an optical component in accordance with an embodiment of the present invention.

3a and 3b are schematic diagrams showing the configuration of a measuring system for processing quality of an optical component according to an embodiment of the present invention.

Figure 4 shows a schematic diagram of the generation of a single microlens displacement.

Figure 5 shows a schematic diagram of wavefront reconstruction.

Fig. 6 is a view showing the configuration of a measuring system for processing quality of an optical component according to another embodiment of the present invention.

Figure 7 shows a measurement system for processing quality of an optical component according to an embodiment of the present invention integrated into a hand-held device.

2 is a flow chart of a method of measuring the quality of an optical component in accordance with an embodiment of the present invention. The method for measuring the processing quality of the optical component includes: step S100: providing a perfect planar light having a standard wavefront; and step S200: passing the ideal planar light after splitting through an optical component in the forward and reverse directions Machining the curved surface so that the standard wavefront aberration becomes the wavefront to be measured; step S300: dividing the wavefront to be measured; step S400: sensing the wavefront to be measured after the segmentation, and extracting through the arrayed discrete spot Obtaining a discrete distribution of the plurality of light spots to be tested; and step S500: calculating local and high-order aberrations according to respective local distributions of the light-receiving light points, and then reconstructing the aberration wavefront, thereby deriving the The actual curvature of the curved surface of the optical component, thereby obtaining the processing quality of the optical component. The processing quality includes surface roughness, shape accuracy, and internal stress distribution.

3a and 3b are schematic diagrams showing the configuration of a measuring system for processing quality of an optical component according to an embodiment of the present invention. Referring to FIG. 3a and FIG. 3b, the optical component processing quality measurement system 1 includes a light source 11, a beam splitter 12, a wavefront splitting unit 13, an image sensor 14, and a data analysis module 15. The light source 11 is used to provide a desired planar light 111 having a standard wavefront 112. The beam splitter 12 is used to split the ideal planar light 111 into an optical element 2' (or standard optical element 2). The optical element 2' (or standard optical element 2) may be a lens in the visible light band or in the invisible light band. The light source 11 can be combined to provide ideal planar light 111 in the visible light band or in the invisible light band according to the optical element 2' (or the standard optical element 2) having a visible light band or an invisible light band.

The optical element 2' (or the standard optical element 2) is disposed on a reflector 3, and the ideal planar light 111 after splitting passes through the optical element 2' (or the standard optical element 2) in a forward direction to process the curved surface 21 '(or the standard machined surface 21), which is then reflected by the reflector 3 and passes through the machined surface 21' (or the standard machined surface 21) a second time in the reverse direction, so that the standard wavefront 112 becomes untested due to aberration Wavefront 112' (or still the standard wavefront 112 with no aberrations). The wavefront segmentation unit 13 is configured to divide the wavefront 112' (or standard wavefront 112) through the beam splitter 12. The image sensor 14 is disposed at the rear end of the wavefront dividing unit 13 for sensing the divided wavefront 112' after the segmentation and knowing the distribution of the plurality of light spotes 141' (or the standard light spot 141). The image sensor 14 can be, for example, a CCD (Charge Coupled Device) or a Complementary Metal-Oxide Semiconductor (CMOS).

The data analysis module 15 is electrically connected to the image sensor 14 and has an algorithm for calculating local and high-order aberrations according to the local distributions of the light-detecting spots 141'. Then, the aberration wavefront is reconstructed, thereby calculating the actual curvature of the processed curved surface 21' of the optical element 2', and measuring the processing quality of the optical element 2'. The processing quality includes surface roughness, shape accuracy, and internal stress distribution.

For example, the algorithm of the data analysis module 15 is a Hartmann-Shack measurement method for measuring the wavefront aberration of the optical component to be tested, because the wavefront aberration can be expressed by a mathematical polynomial pattern, such as a Zernike polynomial, etc. In order to accurately analyze the magnitude of each aberration, the wavefront aberration is fitted by the Zernike polynomial, and the equation (1) is as follows:

It can be seen from the above equation that the wavefront aberrations can be expressed by the k-order Zernike polynomial. Since the Zernike polynomial has orthogonality and rotation invariance in the unit circle, the present invention chooses to fit the wavefront aberration by the Zernike polynomial, C ₁ , C ₂ , C ₃ equations, etc. is the Zernike coefficient, the magnitude of each aberration can be analyzed by coefficients, Z ₁ , Z ₂ , Z _{3 ,} etc. are polynomials for expressing various aberrations, and the polynomial of each aberration is Table 1.

It can be known from equation (1) that the Zernike polynomial fitting wavefront aberration must return the Zernike coefficient back to the Zernike polynomial, so the Zenrike coefficient plays a key role in wavefront reconstruction. Firstly, the optical energy distribution of the image sensor 14 is obtained by optical ray tracing, and the position of the center of gravity is calculated by the centroid method, and the displacement between the position of the center of gravity of the ideal wavefront and the position of the center of gravity of the wavefront to be measured is analyzed, because of the Zernike bias. The differential is the local slope of the wavefront, which is proportional to the displacement of the center of gravity. Therefore, the Zernike coefficient can be inversely derived from this relationship, and the Zernike coefficient is obtained by returning to the Zernike polynomial to reconstruct the wavefront aberration to be measured.

Referring to FIG. 3a again, after the standard wavefront 112 without aberration passes through the microlens array 131 of the wavefront segmentation unit 13, the image sensor 14 is focused on the image sensor 14 to generate an array of standard spots 141; FIG. 3b, the wavefront to be measured 112' having aberrations, after being focused by the microlens array 131 of the wavefront segmentation unit 13, the image sensor 14 is focused on the image sensor 14 to be an array of the spot to be measured 141'. The standard spot 141 of the wavefront 112 and the spot to be measured 141' of the wavefront 112' to be measured will generate a displacement amount Δy, and FIG. 4 shows a schematic diagram of the displacement amount of a single microlens, wherein the focal length is f.

Since the wavefront variation corresponding to each microlens is different after the wavefront to be measured, the wavefront to be measured is divided by the microlens array, and the displacement amount corresponding to each microlens is different. Therefore, the incident wavefront slope corresponding to each microlens can be obtained by dividing the displacement variation on the image sensor 14 by the focal length. Since the wavefront aberration of the present invention is fitted by the Zernike polynomial, the Zernike polynomial is partially differentiated. The wavefront slope can also be obtained, so this correspondence can be organized into the following equation (2).

It is known from equation (2) that the displacement amount of the image sensor 14 is proportional to the wavefront slope, and the displacement of the X-direction and the Y-direction on the image sensor 14 is known to be divided by the focal length of the microlens, and is substituted. The appropriate coordinates can be organized into the following matrix relationships:

Observing the matrix relationship of the above formula, the Zernike coefficient corresponding to the wavefront aberration can be obtained by using the inverse matrix. In the present invention, the matrix relation is written as A=ZC, and the Zernike coefficient can be obtained by using equation (3).

The Zernike coefficient is obtained back into the Zernike polynomial, and the wavefront aberration is fitted.

The present invention mainly reconstructs the wavefront aberration of the optical component 2 by Hartmann-Shack, since the reconstructed wavefront aberration is reconstructed by the displacement of the position of the center of gravity of the light spot to be measured 141' sensed by the image sensor 14. The amount of displacement is mainly the amount of difference between the standard spot 141 and the spot to be measured 141'. The standard wavefront of the present invention is a reflected wavefront after a light beam is incident on the standard optical element 2 without aberrations, and its wavefront is focused by the microlens array as a standard spot 141, as shown in Fig. 3a. The wavefront to be tested of the present invention is a reflected wavefront after the light beam is incident on the optical element 2' with aberration, and the wavefront reflected from the optical element 2' is the wavefront aberration containing the aberration, via After the microlens array is focused, it can be obtained as the spot to be measured 141', as shown in Fig. 3b. The present invention reconstructs the Zernike coefficient by fitting the beam to the standard optical element 2 without aberration and the reflected wavefront of the optical element 2' containing the aberration, and fitting the wavefront aberration of the optical element (see FIG. 5). In this case, the curvature of the processed curved surface 21' of the optical element 2' is derived, and the processing quality of the optical element 2' is measured. The processing quality includes surface roughness, shape accuracy, and internal stress distribution.

In another embodiment, the method for measuring the quality of the optical component of the present invention can be used as an effective measurement method for confirming the quality of in-visible optical components (for example, 锗 lenses). Referring to FIG. 6, the wavefront segmentation unit 13 includes an annular slit array 132 that replaces the microlens array. Through the annular slit array 132, the angle/spatial resolution is insufficient, and the invisible band measurement is often supported, which often affects the measurement accuracy due to image interference of the microlens array.

In yet another embodiment, the optical component processing quality measurement system of the present invention can be integrated into a handheld device. Referring to FIG. 7, the handheld device 1' includes a light source 11, a beam splitter 12, a wavefront splitting unit 13, an image sensor 14, and a data analysis module 15. An optical element 2' is disposed on a jig 30 of a turning machine, one of which is in planar contact with the optical element 2', which plane acts as a reflector 3.

The present invention provides a measurement method for confirming the manufacturing quality and final image quality of an optical component (e.g., a lens) on a processing apparatus (e.g., a turning machine). A microarray component (such as a microlens array or an annular slit array) is mounted on the front end of the image sensor to cause the incident wavefront to generate a discrete spot distribution through the microarray element (eg, a microlens array or an annular slit array). A differential is obtained to obtain the slope change value, and then the image sensor is used to image and analyze the local wavefront of the optical component to be tested, and the numerical difference is analyzed to further reverse the processing quality of the optical component, which is a fast and direct optical component. Quality control method.

The invention has the following advantages: First, the invention can measure the imaging quality of the optical component on-line: the wavefront reconstruction of the optical component imaging through the wavefront sensing information, which directly corresponds to the imaging quality, and can be returned to the optical component processing quality confirmation. In turn, the downtime offline measurement time is reduced, and the equipment utilization rate is improved. Secondly, the present invention establishes a non-contact measurement method: avoiding the conventional contact measurement device that always measures the surface roughness and shape accuracy of the component in multiple loading and unloading manners, which easily leads to measurement error. It is also easy to cause poor positioning accuracy.

In the above, it is merely described that the present invention is an embodiment or an embodiment of the technical means for solving the problem, and is not intended to limit the scope of implementation of the present invention. That is, the equivalent changes and modifications made in accordance with the scope of the patent application of the present invention or the scope of the invention are covered by the scope of the invention.

Claims (10)

 A method for measuring the processing quality of an optical component, comprising the steps of: providing a desired planar light having a standard wavefront; and splitting the ideal planar light after splitting through the processed surface of an optical component in the forward and reverse directions. The standard wavefront aberration is made into the wavefront to be measured; the wavefront to be measured is segmented; the wavefront to be measured after the segmentation is sensed, and the discrete distribution of the plurality of spot to be measured is known through the arrayed discrete spot extraction And calculating the local phase and the high-order aberration according to the local distributions of the light-measuring points, and then reconstructing the aberration wavefront, thereby calculating the actual curvature of the processed surface of the optical component, thereby obtaining the The processing quality of optical components.    The method for measuring the processing quality of an optical component according to claim 1, wherein the processing quality includes surface roughness, shape accuracy, and internal stress distribution.    The method for measuring the processing quality of an optical component according to the first aspect of the invention, wherein the measuring method of the processing quality of the optical component is used as a measuring method for confirming the processing quality of the invisible lens.    A measuring system for processing quality of an optical component, comprising: a light source for providing a desired planar light having a standard wavefront; and a beam splitter for splitting the ideal planar light into an optical component, wherein the optical The component is disposed on a reflector, and the ideal planar light is split into a curved surface through one of the optical components in a forward direction, and then reflected by the reflector and passed through the processed curved surface a second time in the reverse direction, so that the standard The wavefront is the wavefront to be measured due to the aberration; a wavefront segmentation unit is used to divide the wavefront to be measured through the beam splitter; an image sensor is disposed at the rear end of the wavefront segmentation unit for Sensing the divided wavefront after the segmentation, and learning the discrete distribution of the plurality of light spots to be measured through the arrayed discrete spot extraction; and a data analysis module electrically connected to the image sensor and having a The algorithm is configured to calculate each local phase and high-order aberration according to the local distributions of the light spots to be measured, and then reconstruct the aberration wavefront to calculate the actual curvature of the processed surface of the optical component. Obtaining the optics The processing quality of the components.    A measuring system for processing quality of an optical component according to claim 4, wherein the wavefront dividing unit comprises a microarray element.    A measuring system for processing quality of an optical component according to claim 5, wherein the microarray element is a microlens array or an annular slit array.    The measuring system for processing quality of an optical component according to claim 4, wherein the processing quality comprises surface roughness, shape accuracy, and internal stress distribution.    The measuring system for optical component processing quality according to claim 4, wherein the optical component processing quality measuring system is integrated into a handheld device.    The measuring system for processing quality of an optical component according to claim 4, wherein the optical component is a lens of visible light or invisible light.    The measurement system for optical component processing quality according to claim 4, wherein the algorithm of the data analysis module is a Hartmann-Shack measurement method for measuring the wavefront aberration of the optical component to be tested.