JP2007033263A - On-board measuring method of shape error of micro recessed surface shape, and measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-board measuring method of a shape error of a micro recessed surface shape capable of measuring the shape error of a micro recessed surface in non-contact at high speed and high accuracy, and also to provide its measuring device. <P>SOLUTION: The measuring device comprises: an objective lens 23 facing the micro recessed surface 22; a light source module 25 for emitting converged light; a lens barrel 28 for making the optical axis 26 of the converged light and the axial center 27 common; an imaging element 29; a micro lens array 31 arranged between the lens barrel 28 and the imaging element 29; and a computer. The lens barrel 28 has two lenses 41 and 42 having a confocal, and a pinhole 44 arranged at the confocal. A measuring system is constituted so as to match condensing position of the converged light condensed through the objective lens 23 with the center of curvature of the micro recessed surface 22. The shape error of the micro recessed surface 22 is calculated based on the difference between the center of gravity position of each of light columns that are reflected from the micro recessed surface and formed on the imaging element 29 by the micro lens array 31 and the center of gravity position of a light column when a previously determined micro recessed surface 22 has an ideal shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a precise on-machine measurement method and measurement apparatus for minute concave surface shape errors for the purpose of improving precision and efficiency in precision machining.

  Conventionally, precision machining has been performed for processing of a minute concave shape. In this case, if there is an error caused by a tool movement error or an attachment error in a machine tool, it causes a problem in machining, such as deterioration in machining shape accuracy and tool life. In this regard, the object to be measured is removed from the machine tool, the shape error of the minute concave shape is measured, and the rework is performed by correcting the movement error and the mounting error of the tool causing the error. .

  For example, in a stylus type contour shape measuring instrument, a cross-sectional shape error of a micro concave surface is measured by scanning the stylus in one direction while contacting the object to be measured, and then the stylus is moved away from the micro concave surface to the original position. The micro-concave surface error is measured over the entire micro-concave surface by repeatedly measuring the shape error of the new section by moving slightly in the direction perpendicular to the return scanning direction.

The non-contact optical autofocus measuring instrument measures the cross-sectional shape error of the micro concave surface by scanning in one direction while automatically focusing the objective lens that emits the laser on the micro area of the micro concave surface. Is repeated over a plurality of cross sections to measure over the entire concave surface.
In the laser microscope and the laser probe type measuring device, the cross-sectional shape error is measured by scanning the laser beam in one horizontal direction as a stylus of light.

Furthermore, in an interferometer using a white light source and a Twiman-Green interferometer for measuring a microsphere concave surface, the shape error of the entire microconcave surface is measured at once.
In addition to the above, many methods for measuring the shape error of a minute concave surface using a laser beam or a stylus have been developed and used.

Patent Document 1 discloses an example of a non-contact dimension measurement method using laser autofocus. Patent Document 2 discloses an example of a stylus type contour shape measuring method and an apparatus therefor.
Patent No.3180091 Patent No. 3025413

  By the way, in the method of measuring a minute concave surface shape error using the above-mentioned stylus type contour shape measuring instrument, it takes time to measure the shape error for each cross section, and the measurement result in the direction perpendicular to the stylus scanning direction. Is unreliable. In addition, there is a problem that the object to be measured can be scratched with a stylus for contact measurement.

The method of measuring a minute concave surface shape error using a non-contact optical automatic focus measuring instrument has the same problem as the stylus type contour shape measuring instrument except that it is non-contact and cannot be scratched.
The method using the laser microscope and the laser probe type measuring device has the same problem as the stylus type contour shape measuring device except that it is non-contact and cannot be scratched.

  In addition, the method using an interferometer using a white light source or a Twiman-Green interferometer for measuring microspherical concave surfaces is not a common optical path interferometer, so it is a harsh measurement environment that suppresses temperature changes, air fluctuations, vibrations, etc. Issues that control is required, time is required for calculation, and minute scratches that are likely to occur in ultra-precision cutting are magnified by the magic mirror effect. was there.

  FIG. 12 and FIG. 13 show the processed shape of the workpiece 3 targeted by the present invention. This processed shape is a minute concave surface 2 having a radius of curvature R from the ball center 4 and having a rotationally symmetric shape around the central axis 1 (see FIG. 12). FIG. 13 is a cross section taken along the line AA in FIG. When such a minute concave surface 2 is precision machined, for example, a shaving method or a milling method is performed.

The shaving method is a method in which a single crystal diamond tool having a nose radius R is used to feed in a direction perpendicular to the central axis while controlling the cutting.
The milling method is a method in which a diamond ball end mill having a ball radius R is used to rotate around its axis.

  In the shaving method, it is necessary to perform at least simultaneous two-axis control in the direction perpendicular to the minute concave surface and the cutting direction or the rotation direction, and high-precision relative motion is required. In addition, since the motion trajectory is complicated, there is a problem that the shape of the diamond tool feeding direction and the shape perpendicular to the feeding direction are generated separately.

  On the other hand, in the milling method, due to the chucking error of the ball end mill and the eccentricity of the cutting edge, the ball end mill makes a movement that swings around the rotation axis. As a result, there is a problem that a minute concave surface having a curvature radius R ′ different from the requested curvature radius R is processed.

  In order to precisely machine a minute concave surface by these machining methods, it has been attempted to accurately measure a motion such as tool feed, cutting, or rotation, and to correct the motion error to zero as much as possible. . However, when the shape error becomes submicron or less, it becomes difficult not only to measure and correct each motion accurately, but also strongly influenced by other motions. For this reason, it is indispensable to perform correction processing by measuring a minute concave shape error and estimating each movement error from the shape error.

However, all of the measurement methods and measuring instruments described above require measurement with a measuring instrument that is different from the machine tool, so the measurement environment and processing environment are different, or the measurement object must be removed and reattached after measurement. There are problems such as the occurrence of mounting errors due to the above, and the time required for setup. For this reason, when machining shape accuracy such as micron or submicron is required,
a. Measuring the micro concave shape error,
b. Trial cutting with the corrective motion calculated from the error,
If it is not repeatedly performed, the required machining shape accuracy cannot be ensured.

  In view of the above-described points, the present invention provides a micro-concave surface shape error measuring method and measuring apparatus capable of measuring a micro-concave surface shape error at high speed and high accuracy without contact and capable of being measured on a precision processing machine. The purpose is to provide.

  A shape error on-machine measuring method for a micro concave surface according to the present invention includes an objective lens facing a micro concave surface to be measured, a light source module having a light source and emitting focused light, an optical axis and an axis of the focused light. A lens barrel having a common lens, an image sensor, a microlens array disposed between the lens barrel and the image sensor, and a computer having an arithmetic processing function. And a pinhole arranged confocally, and the measurement system is configured with the same focusing position of the focused light focused through the objective lens and the center of curvature of the minute concave surface. , Taking in the light beam reflected from the minute concave surface reaching the image sensor and formed by the micro lens array, and the beam position when the center of gravity of each light beam on the image sensor and the minute concave surface obtained in advance are in an ideal shape of From the difference between the heart position, and calculates the fine concave shape error.

  A shape error on-machine measuring method for a micro concave surface according to the present invention includes an objective lens facing a micro concave surface for measurement, a light source module having a light source and emitting focused light, and a micro light source between the light source and the objective lens. A microlens array that is arranged at a position that does not affect the reflected light from the concave surface to form a light beam, a lens barrel that shares the optical axis and axis of the focused light, an image sensor, and a computer having an arithmetic processing function The lens barrel includes two lenses having a confocal point and a pinhole arranged at the confocal point, and a condensing position of focused light condensed through the objective lens, and a minute concave surface The measurement system is configured with the same center of curvature, and the computer captures the light beam reflected from the minute concave surface that reaches the image sensor. The center of gravity of the light beam on the image sensor and the minute concave surface obtained in advance Is From the difference between the position of the center of gravity of the beam column for a shape, and calculates the fine concave shape error.

  A micro-concave surface shape error measuring apparatus according to the present invention includes an objective lens facing a micro-concave surface to be measured, a light source module having a light source and emitting focused light, an optical axis and an axis of the focused light A lens barrel having a common lens, an image sensor, a microlens array disposed between the lens barrel and the image sensor, and a computer having an arithmetic processing function. And a pinhole arranged confocally, and the measurement system is configured by the same focusing position of the focused light focused through the objective lens and the center of curvature of the minute concave surface. , Taking in the light beam reflected from the minute concave surface reaching the image sensor and formed by the micro lens array, and the beam position when the center of gravity of each light beam on the image sensor and the minute concave surface obtained in advance are in an ideal shape From the difference between the position of the center of gravity, characterized in that it comprises so as to calculate the fine concave shape error.

  A shape error on-machine measuring device having a micro concave shape according to the present invention includes an objective lens facing a micro concave surface to be measured, a light source module having a light source and emitting focused light, and a micro concave surface between the light source and the objective lens. A microlens array that is arranged at a position that does not affect the reflected light from the lens and forms a light beam, a lens barrel that shares the optical axis and axis of the focused light, an image sensor, and a computer having an arithmetic processing function, The lens barrel has two lenses having a confocal point and a pinhole arranged at the confocal point, and a condensing position of the condensed light condensed through the objective lens, and a curvature of the minute concave surface The measurement system is configured with the same center, and the computer captures the light beam reflected from the minute concave surface reaching the image sensor, and the position of each center of gravity of the light beam on the image sensor and the minute concave surface obtained in advance are ideal From the difference between the position of the center of gravity of the beam column for a Jo, characterized by comprising to calculate the fine concave shape error.

A diffraction grating can be used instead of the above-described microlens.
As the barycentric position of the light beam when the micro concave surface obtained in advance is an ideal shape, the barycentric position calculated in advance by a computer can be used. Alternatively, as the center of gravity position of the light beam when the micro concave surface obtained in advance is an ideal shape, the shape accuracy exceeds the required specification of the object to be measured with the focal point position of the objective lens and the center position of curvature arranged the same. It is possible to use the position of the center of gravity of the light beam of the reflected light from the spherical mirror or the plane mirror perpendicular to the optical axis placed at the focal position of the objective lens.

  According to the on-machine measuring method and measuring apparatus for a minute concave surface according to the present invention, a geometrical optical element that is resistant to disturbances such as temperature changes, air fluctuations, and vibrations by arranging a microlens array or a diffraction grating. Measurement can be performed, and measurement can be performed at a higher speed than measurement methods such as scanning and interference. In addition, by arranging a lens barrel consisting of two lenses and a pinhole serving as a spatial frequency filter arranged at the confocal point, reflected light affected by scratches on a minute concave surface is removed by this pinhole. The shape error can be measured with high accuracy.

  The micro concave surface shape error measuring method and measuring apparatus according to the present embodiment is a geometric optical that is resistant to disturbances such as temperature change, air fluctuation, and vibration by inserting a micro lens array or a diffraction grating. Measurement can be performed, and the measurement speed can be increased compared to measurement methods such as scanning and interference. Further, by inserting a spatial frequency filter, it is possible to limit the reflected light under the influence of scratches that are particularly problematic on a minute concave surface, and to measure the shape error with high accuracy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 and FIG. 2 show an embodiment of a micro-concave shape error measuring apparatus according to the present invention and the principle configuration thereof. The measuring apparatus 21 according to the present embodiment includes an objective lens 23 facing a micro concave surface 22 to be measured, a light source module 25 having a light source 24 and emitting focused light, an optical axis 26 and an axis 27 of the focused light. A lens barrel 28, a solid-state imaging device in this example, a CCD solid-state imaging device 29, and means for dividing light arranged between the lens barrel 28 and the CCD solid-state imaging device 29 into a plurality of spots For example, a microlens array 31 and a computer (not shown) having an arithmetic processing function are provided.

  That is, the objective lens 23, the light source module 25, the lens barrel 28, the microlens array 31, and the CCD solid-state imaging device 29 are arranged with a common optical axis in this order, and these are all covered with the cover 33. (See FIG. 1). The output of the CCD solid-state imaging device 29 is taken into a computer in which an image monitor and an image acquisition device are incorporated, a so-called personal computer.

  In this example, the light source module 25 includes a laser light source 24, a polarizing plate 34, a collimator lens 35, a right-angle prism 36, a polarizing beam splitter 37, and a quarter wavelength plate 38. The lens barrel 28 includes two lenses 41 and 42 having a confocal point, a pinhole 44 disposed at the confocal position (in this example, a pinhole plate 43 disposed to have the pinhole 44 at the focal position), and It is comprised. Here, the lens 41 on one polarization beam splitter 37 side is configured as a Fourier transform lens, and the lens 42 on the other microlens array 31 side is configured as an inverse Fourier transform lens. The pinhole plate 43 functions as a spatial frequency filter.

  The remaining one focal plane a of the two lenses 41 and 42 constituting the lens barrel 28 and the one focal array of the microlens array 31 coincide with each other (see FIG. 3). In addition, the CCD solid-state imaging device 29 is disposed so that the imaging surface c is positioned in front of or behind the other focal array b of the microlens array 31 so as to be orthogonal to the optical axis (see FIG. 3). The other focal position of the other two lenses 41 and 42 constituting the lens barrel 28 is matched with the focal position of the objective lens 23.

  Next, a measurement method for measuring the shape error of the minute concave surface of the object to be measured according to the present embodiment using the measurement device 21 will be described.

  In the present embodiment, the minute concave surface shape 22 of the DUT 20 is a concave spherical shape. The measuring device 21 shown in FIG. 2 is arranged with respect to an object to be measured (hereinafter referred to as an object to be measured) 20 so that the focal point of the objective lens 23 and the center of curvature of the concave spherical shape 22 coincide. In the laser light emitted from the laser light source 24 of the light source module 25 in the measuring device 21, for example, only a vibration component parallel to the paper surface of FIG. 2 is transmitted through the polarizing plate 34 and becomes parallel light by the collimator lens 35 and is a right angle prism 36. Through the polarization beam splitter 37. The laser light totally reflected by the polarization beam splitter 37 passes through the quarter wavelength plate 38 to become circularly polarized light and enters the objective lens 23.

  The laser beam becomes a focused spherical wave by the objective lens 23 to be focused, and then irradiated to the minute concave spherical surface 22 having a center of curvature at a position coincident with the focal point of the objective lens 23. The laser light reflected by the minute concave spherical surface 22 becomes reversely rotated circularly polarized light, is transmitted again through the objective lens 23 while having information on the shape error of the minute concave spherical surface 22 and scratches, and then vibrates by the quarter wavelength plate 38. The direction is perpendicular to the paper surface of the figure and enters the polarization beam splitter 37. The returned laser light incident on the polarization beam splitter 37 passes through the polarization beam splitter 37 and enters the lens 41 of the lens barrel 28.

  The laser beam is Fourier-transformed by the lens 41, and only the scratch component from the laser beam is removed by the pinhole 44 arranged at the focal point. That is, the scratch light component reflected by the scratch formed in the concave spherical shape 22 (the light component reflected by the uneven surface having a high spatial frequency) is focused on a position away from the pin hole 44 so as to focus on a pinhole (so-called It does not pass through the (spatial frequency filter) 44 and is therefore removed by this pinhole plate 43. The laser light transmitted through the pinhole 44 is subjected to inverse Fourier transform by the lens 42, and a wavefront having a shape error component of the minute concave spherical surface 22 is reproduced. The reproduced wavefront laser light is incident on the microlens array 31, divided into a plurality of beam arrays corresponding to the pitch interval of the microlenses, and incident on the CCD solid-state imaging device 29, thereby obtaining a spot array image.

  Then, after the spot row image acquired by the CCD solid-state imaging device 29 is taken into a personal computer, the shape error of the minute concave spherical surface 22 is calculated.

  Next, the procedure for calculating the shape error of the minute concave spherical surface 22 from the spot row image will be described with reference to FIGS. FIG. 5 is a flowchart showing the procedure, FIG. 6 is a spot / disturbance light discrimination, FIG. 7 is a center of gravity discrimination for each spot, FIG. 8 is a center of gravity position map example, and FIG. An explanation of the integration direction is shown. The acquired image is described as a bitmap image.

  First, as shown in FIG. 5, in step S <b> 1, binarization (brightening of brightness and darkness) is performed with a threshold value that can distinguish individual spots from the spot row image. In step S1, as shown in FIG. 6, a binarized region 46 where many bright pixels 45 are gathered and a region 47 where few bright pixels 45 are gathered are obtained.

  Next, in step S2, binarized images exceeding the threshold value are adjacent to at least the required number of points described later (one bright unit pixel 45 on the imaging surface c of the CCD solid-state image sensor 29 is adjacent). A point image other than the existing point image is regarded as disturbance light, and the point image (region 47) regarded as disturbance light is erased from the image as shown in FIG. Here, when the score is 10% or less of the maximum score, it is regarded as ambient light. In the process of step S2, at this time, a group of images exceeding the remaining threshold value is regarded as one spot (corresponding to the region 46), and the number thereof is counted, and the minute shape having the ideal shape calculated in advance. If the number is the same as the number of spots in the case of the concave spherical surface 22, the process proceeds to the next process, that is, step S3. If the number is not the same, the binarization level is changed and the binarization process (step S1) is repeated.

Next, in step S3, the center of gravity in the X direction (horizontal direction) on the image is calculated for each spot. The center of gravity in the X direction in each spot is obtained by a weighted average using the number of bits in the Y direction (vertical direction) having a luminance equal to or higher than the threshold value in each bit in the X direction in the spot as a weight. For example, referring to FIG. 7, when X = 5 (the fifth pixel number), there are two bright pixels in the Y direction, when X = 6, there are four bright pixels in the Y direction, and when X = 7, the bright pixels in the Y direction. pixels are 6, Ming pixels .. in X = 17 Y direction one is, next, on the basis of this finding the center of gravity position X _G in the X direction from the following equation 1. For even Y-direction of the center of gravity position Y _G, similarly determined from weighted average weighed by the number of bits X direction having a luminance greater than or equal to the threshold in the individual bits in the Y direction in the spot. In this way, the center-of-gravity position G (X _G , Y _G ) in each spot is obtained.

ここで、
Ｋｐ．Ｋｑ：白点（明の画素）の総数である。
Ｘｐ：Ｘ方向の白点（明の画素）の数である。
Ｙｑ：Ｙ方向の白点（明の画素）の数である。

here,
Kp. Kq: the total number of white spots (bright pixels).
Xp: the number of white spots (bright pixels) in the X direction.
Yq: the number of white points (bright pixels) in the Y direction.

  In this way, the center-of-gravity position map 59 of each spot 58 (see the mark ●) shown in FIG. 8 is created.

  The center-of-gravity position map 59 is compared with the center-of-gravity position map 61 of each spot 60 in the case of a minute concave spherical surface having an ideal shape calculated in advance by a personal computer (see circles in FIG. 8). The inclination of the shape error of the minute concave spherical surface actually measured is calculated from the difference ΔX, ΔY in the center of gravity position for each spot 58.

  Although the shape error of the minute concave spherical surface can be calculated by trapezoidal integration of the difference for each gravity center position, in order to suppress the influence of the integration error, as shown in FIG. 1 and two paths 2 in the direction of Y → X are performed separately, and the average is defined as the shape error of the minute concave spherical surface. The shape error W is obtained by the equation (2).

ここで、
ΔＸ，ΔＹ：理想形状のときのスポット重心位置と実際のスポット重心位置との差である。
δｘｎ−１，δｙｍ−１：ｎとｎ−１のスポット間隔、ｍとｍ−１のスポット間隔である。
ｄ：理想のスポット間隔である。

here,
ΔX, ΔY: The difference between the spot centroid position in the ideal shape and the actual spot centroid position.
δxn−1, δym−1: the spot interval between n and n−1, and the spot interval between m and m−1.
d: Ideal spot interval.

  In the above example, the measurement method and the measurement device according to the present embodiment are applied to the measurement of the shape error of the minute concave spherical surface. However, when measuring the shape error of a non-concave spherical surface such as a paraboloid other than the concave spherical surface. It can also be applied to. That is, in this embodiment, it is possible to measure the shape error of a minute concave surface including a minute concave spherical surface and a minute non-concave spherical surface.

  The measuring device 21 configured as described above is mounted on a precision machine tool as shown in FIG. FIG. 4 is an example applied to a portal milling machine equipped with the measuring device (so-called shake measuring device) 21 shown in FIG. In FIG. 4, reference numeral 71 denotes a portal milling machine as a whole, and a machining table 72 is disposed on the portal milling machine 51 so as to reciprocate in one direction (arrow a direction), and is placed on the machining table 72. A plurality of concave shapes 22 are processed on the upper surface of the workpiece 73 (corresponding to the workpiece 20 in FIG. 2). On the other hand, it is supported above corresponding to the work piece 73 and can reciprocate in the vertical direction (arrow b direction) and reciprocate in the horizontal direction (arrow c direction) with respect to the surface of the work table 72 as shown in FIG. A measuring device (runout measuring device) 21 having the configuration is attached so that the objective lens 23 faces the workpiece 73.

  In this portal milling machine 71, after processing a desired minute concave spherical surface 22 on the workpiece 73, the measuring device (runout measuring device) 21 is lowered to a predetermined position with respect to the minute concave surface to be measured on the machine. The mutual position with the minute concave surface in the horizontal plane is set. Thereafter, the shape error of the minute concave spherical surface 2 is measured, the shape error is fed back, and the grinding means of the portal milling machine is finely adjusted to finally process the minute concave spherical surface 22 where the shape error becomes as small as possible. To do.

  According to the measurement method and the measurement apparatus according to the above-described embodiment, the geometrical optical measurement with the microlens array 31 inserted does not affect the minute concave surface 22 without being affected by disturbances such as temperature change, air fluctuation, and vibration. The shape error can be measured at high speed without contact. Further, by inserting the lens barrel 28 in which the pinhole 44 as a spatial frequency filter is inserted, the reflected light affected by the scratches that cause a problem on the minute concave surface 22 can be removed, and measurement is performed with high accuracy. be able to. Moreover, since it can be directly measured on a precision machine tool, it enables further high-speed and high-precision measurement. In particular, it is possible to accurately measure a shape error of submicron or less.

  FIG. 10 shows another embodiment of the measuring apparatus according to the present invention. The measuring device 81 of the present embodiment is configured by arranging a microlens array 31 that forms a spot row at a position between the laser light source 24 and the objective lens 23 and that does not affect the reflected light from the minute concave surface 22. That is, in this example, the microlens array 31 is arranged between the laser light source 24 and the polarizing plate 34 so that the spot row is formed first. Since other configurations are the same as those in FIG. 2, the corresponding portions are denoted by the same reference numerals, and redundant description is omitted.

  Also in the measurement apparatus of the present embodiment, the shape error of the minute concave surface can be measured at high speed and high accuracy in a non-contact manner, as described in the embodiment of FIG.

  FIG. 11 shows another embodiment of the measuring apparatus according to the present invention. The measuring device 84 according to the present embodiment uses the focal position of the objective lens 23 as a means for obtaining in advance the position of the center of gravity of the ideally shaped spot (ray) row, instead of obtaining it beforehand by calculation in the personal computer. A spherical mirror 85 having the same curvature center position, that is, a spherical mirror 85 having a shape accuracy higher than the required specification of the object to be measured is arranged, and the barycentric position of the spot row of reflected light from the spherical mirror 85 is used. The For example, the spherical mirror 85 is replaced with the minute concave surface 22 to be measured, and is placed at the same position or the same center of curvature. In the spherical mirror 85 of FIG. 11, an example with a large curvature radius is shown. As another means for obtaining in advance the barycentric position of the ideal-shaped spot (ray) array, the spot array of the reflected light from the plane mirror 86 placed at the focal position of the objective lens 23, that is, the plane mirror 86 perpendicular to the optical axis, It is configured to use the center of gravity position. Since other configurations are the same as those in FIG. 2, the same reference numerals are given to the corresponding portions, and redundant description is omitted. At the time of measurement, the spherical mirror 85 or the plane mirror 86 is removed.

  The good point of the method of FIG. 11 is that the center of gravity of the ideally shaped spot row can be obtained after assembling the optical system, so that all the effects of mounting errors can be canceled. Of course, the shape error of the minute concave surface can be measured at high speed and high accuracy without contact, as in the embodiment of FIG.

  Further, in each of the above-described embodiments, a configuration in which a diffraction grating is arranged instead of the microlens array may be employed. As an example of this diffraction grating, vertical and horizontal slit rows are overlapped and a spot row is formed by using a transmission hole at the intersection of both slits. Alternatively, a spot array can be formed using a fiber grating (fiber diffraction grating).

It is a schematic block diagram which shows one Embodiment of the shape error on-machine measuring device of a minute concave shape which concerns on this invention. It is a fundamental lineblock diagram of one embodiment of a shape error on-machine measuring device of the shape of a minute concave concerning the present invention. It is an enlarged view of the principal part of FIG. It is a block diagram which shows one Embodiment of the precision machine tool which mounts the measurement apparatus on the shape error machine of the minute concave shape which concerns on this invention. It is a flowchart which shows the procedure of the shape error calculation of the minute concave spherical surface concerning this invention. It is explanatory drawing with which it uses for description of discrimination | determination of a spot and disturbance light. It is explanatory drawing with which it uses for description of the gravity center discrimination | determination of a spot. It is a gravity center position map figure which shows the example of a gravity center position map. It is explanatory drawing which shows the integration path | route at the time of calculating the shape error based on this invention by trapezoidal integration. It is a schematic block diagram which shows other embodiment of the shape error on-machine measuring device of a micro concave surface shape which concerns on this invention. It is a schematic block diagram which shows other embodiment of the shape error on-machine measuring device of a micro concave surface shape which concerns on this invention. It is a schematic perspective view which shows the micro concave surface made into a process target. It is sectional drawing on the AA line of FIG.

Explanation of symbols

20 .. Object to be measured, 21, 81, 84 .. Micro concave surface shape error measuring device, 22 .. Micro concave surface, 23 .. Objective lens, 24 .. Laser light source, L. 25 .. Light source module, 26 .. Optical axis, 27 .. Center axis, 28 .. Lens barrel, 29 .. Solid-state imaging device, 31 .. Micro lens array, 34. .., right angle prism, 37 .. polarizing beam splitter, 38 .. 1/4 wavelength plate, 41, 42 ... lens, 43 ... pinhole plate, 44 ... pinhole, 45 ... solid-state image sensor Unit pixel, 46... Area considered as spot, 47... Area considered as disturbance, 58 .. actual measured spot centroid position, 59 .. actual measured spot centroid position map, 60.・ Spot center of gravity of ideal shape , 61 ... of the ideal shape spot position of the center of gravity map

Claims (12)

An objective lens facing the micro concave surface for measurement;
A light source module having a light source and emitting focused light;
A lens barrel having a common optical axis and axis of the focused light;
An image sensor;
A microlens array disposed between the lens barrel and the imaging device;
A computer having an arithmetic processing function,
The lens barrel has two lenses having a confocal point, and a pinhole arranged at the confocal point,
A condensing position of the focused light condensed through the objective lens and a center of curvature of the minute concave surface are configured to constitute a measurement system,
The computer captures a light beam reflected by the micro concave surface reaching the image sensor and formed by the micro lens array,
A shape error of the micro concave surface is calculated from a difference between each barycentric position of the light beam on the image sensor and a barycentric position of the light beam when the micro concave surface obtained in advance has an ideal shape. Measuring method of on-machine error of minute concave shape. The remaining one focal plane of the two lenses of the lens barrel and the one focal array of the microlens array,
The imaging element is arranged so as to be orthogonal to the optical axis in front of or behind the other focal array of the microlens array,
The other focal position of the two lenses of the lens barrel is matched with the focal position of the objective lens,
The shape error machine for a minute concave surface according to claim 1, wherein the position of the center of gravity calculated in advance by the computer is used as the barycentric position of the ray train when the minute concave surface obtained in advance is an ideal shape. Upper measurement method. An objective lens facing the micro concave surface for measurement;
A light source module having a light source and emitting focused light;
A microlens array that is disposed between the light source and the objective lens and that does not affect the reflected light from the minute concave surface to form a light beam row;
A lens barrel having a common optical axis and axis of the focused light;
An image sensor;
A computer having an arithmetic processing function,
The lens barrel has two lenses having a confocal point, and a pinhole arranged at the confocal point,
A condensing position of the focused light condensed through the objective lens and a center of curvature of the minute concave surface are configured to constitute a measurement system,
The computer captures a light beam reflected from the minute concave surface reaching the image sensor,
A shape error of the micro concave surface is calculated from a difference between each barycentric position of the light beam on the image sensor and a barycentric position of the light beam when the micro concave surface obtained in advance has an ideal shape. Measuring method of on-machine error of minute concave shape. Arranging a collimator lens for collimating the light beam;
The imaging element is disposed so as to be orthogonal to the optical axis forward or backward from the remaining focal plane of the two lenses of the lens barrel,
The other focal position of the two lenses of the lens barrel is matched with the focal position of the objective lens,
The shape error machine for a minute concave surface according to claim 3, wherein the position of the center of gravity calculated in advance by the computer is used as the barycentric position of the ray train when the minute concave surface obtained in advance is an ideal shape. Top measurement method. 5. The micro-concave shape error measurement method according to claim 1, wherein a diffraction grating is used instead of the micro lens array. As the barycentric position of the ray train when the micro concave surface obtained in advance is an ideal shape,
A spherical mirror having a shape accuracy higher than the required specification of an object to be measured placed with the focal position of the objective lens being the same as the center of curvature, or a plane mirror perpendicular to the optical axis placed at the focal position of the objective lens The shape error on-machine measurement method of a minute concave shape according to any one of claims 1 to 5, wherein the position of the center of gravity of the ray train of reflected light from the center is used. An objective lens facing the micro concave surface for measurement;
A light source module having a light source and emitting focused light;
A lens barrel having a common optical axis and axis of the focused light;
An image sensor;
A microlens array disposed between the lens barrel and the imaging device;
A computer having an arithmetic processing function,
The lens barrel has two lenses having a confocal point, and a pinhole arranged at the confocal point,
The measurement system is configured by concentrating the condensing position of the focused light condensed through the objective lens and the center of curvature of the minute concave surface,
The computer captures a light beam reflected by the micro concave surface reaching the image sensor and formed by the micro lens array,
The shape error of the minute concave surface is calculated from the difference between each barycentric position of the light beam on the image sensor and the barycentric position of the light beam when the minute concave surface obtained in advance has an ideal shape. A micro-concave surface shape error on-machine measuring device characterized by the above. The remaining one focal plane of the two lenses of the lens barrel is matched with one focal array of the microlens array,
The imaging element is arranged to be orthogonal to the optical axis in front of or behind the other focal array of the microlens array,
The other focal position of the two lenses of the lens barrel is adjusted to the focal position of the objective lens,
The micro concave surface shape according to claim 7, wherein the gravity center position calculated in advance by the computer is used as the barycentric position of the light beam when the micro concave surface obtained in advance is an ideal shape. Form error measuring device. An objective lens facing the micro concave surface for measurement;
A light source module having a light source and emitting focused light;
A microlens array that is disposed between the light source and the objective lens and that does not affect the reflected light from the minute concave surface to form a light beam row;
A lens barrel having a common optical axis and axis of the focused light;
An image sensor;
A computer having an arithmetic processing function,
The lens barrel has two lenses having a confocal point, and a pinhole arranged at the confocal point,
The measurement system is configured by concentrating the condensing position of the focused light condensed through the objective lens and the center of curvature of the minute concave surface,
The computer captures a light beam reflected from the minute concave surface reaching the image sensor,
The shape error of the minute concave surface is calculated from the difference between each barycentric position of the light beam on the image sensor and the barycentric position of the light beam when the minute concave surface obtained in advance has an ideal shape. A micro-concave surface shape error on-machine measuring device characterized by the above. A collimator lens is arranged to make the light beam parallel,
The imaging element is arranged so as to be orthogonal to the optical axis forward or backward from the remaining one focal plane of the two lenses of the lens barrel,
The other focal position of the two lenses of the lens barrel is adjusted to the focal position of the objective lens,
10. The micro concave surface shape according to claim 9, wherein the gravity center position calculated in advance by the computer is used as the barycentric position of the light beam when the micro concave surface obtained in advance is an ideal shape. Form error measuring device. 12. The micro-concave shape on-machine error measuring apparatus according to claim 7, wherein a diffraction grating is used instead of the micro lens array. As the barycentric position of the ray train when the micro concave surface obtained in advance is an ideal shape,
A spherical mirror having a shape accuracy higher than the required specification of an object to be measured placed with the focal position of the objective lens being the same as the center of curvature, or a plane mirror perpendicular to the optical axis placed at the focal position of the objective lens The shape error on-machine measuring device having a minute concave shape according to any one of claims 7 to 11, wherein the position of the center of gravity of the ray train of the reflected light from is used.

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