JP2005172459A - Grid pattern projection shape measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high accuracy in measurement by adjusting the stripe contrast, even when measuring an object which is translucent for the wavelength of the projection light, by constituting the line width ratio of a light opaque region and a light transparent region of reference grid to be adjustable, as well as constituting the reference grid for projecting the grid pattern onto the object with a binary grid. <P>SOLUTION: The projection grid 40 is composed of two elementary grids 41, 43 in which each opaque grid lines 45, 47 are overlapping. The two component grids 41, 43 are so constituted that they are relatively slidable in a lateral direction perpendicular to the grid lines 45, 47, by means of a uniaxial moving stage 49. By this lateral sliding, the projection grid 40 can vary, in the line width ratio of the light opaque region B and the light transparent region W. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention projects a predetermined lattice pattern onto a measurement object, and measures the shape of the measurement object based on a fringe pattern generated when the lattice pattern undergoes deformation according to the shape of the measurement object. The present invention relates to a pattern projection shape measuring apparatus.

  Conventionally, as this type of lattice pattern projection shape measuring apparatus, a moire apparatus that performs shape measurement by moire topography is known. This moire device irradiates a reference grating (reference grating) to create a shadow on the object to be measured, and observes the moire fringes generated by viewing the deformed grating formed by the shadow through the reference grating. An image of a grid irradiation type (substance grid type) (see Patent Document 1 below) and a first reference grid (projection grid) for projection are projected onto the object to be measured, and a deformation formed by this image There is a lattice projection type (see Patent Document 2 below) that observes moire fringes generated by forming a lattice image on a second reference lattice (imaging lattice) for observation.

  In addition, as other lattice pattern projection shape measuring apparatus, a device that directly analyzes the shape of a measured object from a striped pattern of a deformed lattice (see Patent Document 3 below), or a plurality of lattices in the direction of the lattice lines of each other It is known that a pattern of moire fringes generated by tilting and overlaying is projected on a measured object, and the shape of the measured object is analyzed based on the deformation of the moire fringe pattern (see Patent Document 4 below). Yes.

  In order to improve the measurement accuracy in such a lattice pattern projection shape measuring apparatus, it is desirable that the light intensity distribution of the lattice pattern projected onto the measurement object changes in a sine wave shape. Conventionally, a grating (sine wave grating, pseudo sine wave grating, corrected sine wave grating) configured so that the light transmittance distribution of the reference grating changes in a sine wave shape is formed to achieve more accurate shape measurement. However, such a sine wave grating is more expensive than a so-called binary grating (binary grating) in which the light transmittance distribution changes in a binary manner.

JP-A-4-147001 Japanese Utility Model Publication No. 55-97408 Japanese Patent Laid-Open No. 11-83454 JP 2002-81923 A JP 2000-105109 A "Application of Moire Topography to Medical Dentistry" MEDICAL IMAGING TECHNOLOGY Vol.5 No.1 (1987) 5: 1-5: 2

  By the way, for example, when measuring a human body or ceramics with a moire device, there is a phenomenon that the contrast of the moire fringes is greatly reduced such that the moire fringes look bright overall and the difference between light and dark (black and white) is not clear. Patent Document 1). This is because if the object to be measured is semi-transmissive to the wavelength of the light source to be used, the light undergoes internal scattering in the object to be measured, and this internal scattering (particularly backscattering among them) causes the object to be measured. It is thought that the major factor is that the light intensity distribution of the projected grating pattern is broken and it is impossible to obtain a sinusoidal wave pattern.

  The phenomenon in which the fringe contrast decreases when measuring a human body or the like is also observed in other shape measuring apparatuses using lattice pattern projection in addition to the moire apparatus, which is a major factor for reducing the measurement accuracy. Conventionally, there has been proposed a technique for changing the amplitude and bias intensity of a sinusoidal grating pattern projected on the object to be measured by changing the pitch and width of the grating lines in the sinusoidal grating according to the shape of the object to be measured. (See Patent Document 3 above).

  However, there has been proposed a technique that can optically solve the problem of reduction in fringe contrast, which is thought to be mainly caused by internal scattering of the object to be measured, in a form that can deal with a plurality of objects to be measured having different levels of internal scattering. There wasn't.

  The present invention has been made in view of such circumstances, and even when measuring an object to be measured that has translucency with respect to the wavelength of the light source to be used, the fringe contrast is adjusted to achieve high measurement. It is an object of the present invention to provide a lattice pattern projection shape measuring apparatus capable of obtaining accuracy.

In order to solve the above problems, a lattice pattern projection shape measuring apparatus according to the present invention is:
A pair of non-transparent grid lines and translucent grid lines that are adjacent to each other, and each of the pair has a substantially constant line width in at least one direction over the entire length, and is parallel to the above direction without a gap. The shape of the object to be measured is based on a fringe pattern generated by projecting a plurality of pairs of grid patterns of the first reference grating onto the object to be measured and subjecting the lattice pattern to deformation according to the shape of the object to be measured. In a lattice pattern projection shape measuring apparatus for measuring
The first reference grating is a binary grating in which the transmittance of the projection light changes approximately in a binary manner between the opaque grating line and the transparent grating line.
The pair of pitches is not changed, and the ratio of the line width of the light-transmitting grid lines and the light-transmitting grid lines constituting the pitches is variable in the direction.

In the present invention, the first reference grating is configured by superposing the two element gratings having the same pair of pitches so that the lattice lines are parallel to each other, and the two elements The line width ratio may be changed by relatively shifting the lattice in the direction.
In this case, the lattice lines of the two element lattices can be linear lattice lines.

In addition, a projection optical system that projects the image of the first reference grating onto the measured object, and the image of the fringe pattern formed on the measured object by this projection are connected onto the second reference grating. And an observation optical system for observing moire fringes formed by the image formation.
In this case, it is preferable that the second reference grating is configured such that a light transmittance distribution is a sine wave shape between the pair of the opaque grating lines and the transparent grating lines. .

  Note that the above "parallel state" means that when one grid line is moved in a laterally shifted direction (in the case where the grid line is a straight line, the direction is generally perpendicular to the grid line), the other grid lines are almost completely overlapped. When a state, that is, a group of straight lines extending in the moving direction is set, it means a state in which the slopes of the boundary portions of the lattice lines intersecting with the straight lines of the straight line group are equal to each other between the lattice lines.

  In addition, the direction of the above-mentioned “lateral shift” is the direction in which such a group of straight lines extends, that is, when the two element lattices are laterally shifted in this direction, each straight line is connected to each opaque lattice line and each transparent lattice line, respectively. It means a direction in which the length of the intersecting portion changes approximately equally between the straight lines.

  The “lateral shifting direction” is not limited to one direction. For example, when the grid line is a straight line, the horizontal shift direction can be taken in an arbitrary direction obliquely intersecting the grid line.

  The "binary lattice" is a lattice line formed by etching a metal thin film formed on a glass plate, and a light-transmitting lattice line from which the metal thin film has been removed and a light-transmitting lattice line from which the metal thin film remains. In addition to the one in which light transmission is strictly turned on and off at the boundary, the light-transmitting lattice line and the light-transmitting lattice line are formed, for example, a light-transmitting lattice line and a light-transmitting lattice line are formed by photographic emulsion. Since slight blur occurs at the boundary, the light is not strictly turned on / off at the boundary.

  Further, the first and second reference gratings are not limited to linear gratings in which the grating lines are straight lines. As described above, a curved grid in which the grid lines are curved may be used as long as the grid lines are arranged in parallel (so-called parallel grid). Each grid line of such a curved grid is different from a “parallel curve” defined in the field of mathematics.

  In general, when the projection light to be used is white light, a reference grating in which the transparent grating line is colorless and transparent is used. However, the first and second reference gratings are used for the projection light to be used. The light-transmitting grid lines need only be transparent and the light-transmitting grid lines opaque with respect to the wavelength, and the light-transmitting grid lines need not be colorless and transparent.

  According to the lattice pattern projection shape measuring apparatus according to the present invention, the lattice pitch of the first reference lattice is changed even when measuring a measurement object having translucency with respect to the wavelength of the light source to be used. Without changing the measurement sensitivity, it is possible to increase the fringe contrast on the projected object by changing the ratio of the line width between the light-transmitting and non-light-transmitting lattice lines. A highly accurate measurement result with little measurement error can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing the overall configuration of a lattice pattern projection shape measuring apparatus according to an embodiment of the present invention. As shown in FIG. 1, the lattice pattern projection shape measuring apparatus 10 (hereinafter sometimes simply referred to as “measuring apparatus 10”) according to this embodiment includes a measuring head 12, a power supply device driving unit 14, a control unit 16, And the monitor 18, the measuring head 12 takes in the three-dimensional shape information and pattern (texture) information of the measurement object 2, and these three-dimensional shape information and pattern information are supplied to the control unit 16 via the power supply device driving unit 14. The three-dimensional shape information and the pattern information are synthesized by the control unit 16 to generate a three-dimensional image of the measurement object 2 and displayed on the monitor 18. A keyboard 20 and a mouse 22 are connected to the control unit 16, and by operating these, it is possible to change the display contents such as changing the display angle of the three-dimensional image on the monitor 18. ing.

  Further, the three-dimensional shape information is taken in by the measurement head 12 by using a lattice projection type moire topography. In FIG. 1, a lattice plane Pg indicated by a two-dot chain line in front of the measurement head 12 is a virtual reference lattice plane in the lattice projection type moire topography. The basic configuration and function of the measurement head 12 as a lattice projection type moire device will be described with reference to FIG. FIG. 2 is a plan view showing the basic configuration and function of the measurement head 12 as a grating projection type moire device.

  As shown in FIG. 2, the measurement head 12 includes a projection optical system 26 and an observation optical system 28. The projection optical system 26 includes a grating illumination system (not shown) including a projection lamp, a heat ray cut filter, and a condenser lens, a projection grating 40 as a first reference grating, and a projection lens 42. The observation optical system 28 includes an imaging lens 44, an observation reference grating (imaging grating) 46 as a second reference grating, and a television optical system (not shown) including a field lens, a folding mirror, and a CCD camera. Become.

  The projection lens 42 and the photographic lens 44 are mounted so that their optical axes Ax1 and Ax2 are parallel to each other, and the grating illumination system (not shown) is obliquely left rearward with respect to the optical axis Ax1. The projection grating 40 is arranged so as to irradiate the projection grating 40, and the image of the projection lamp is substantially formed at the entrance pupil position of the projection lens 42.

  On the other hand, the observation reference grating 46 is disposed on the optical axis Ax2 together with a field lens and a folding mirror (not shown) of the television optical system, and the CCD camera is perpendicular to the optical axis Ax2 by the folding mirror. It is arranged on the folded optical axis.

  Both the projection grating 40 and the observation reference grating 46 have lattice lines extending in the vertical direction (direction perpendicular to the paper surface) at equal pitches, and are provided in the same plane orthogonal to the optical axes Ax1 and Ax2. ing. The projection grating 40 is arranged in a positional relationship conjugate with the virtual reference grating plane Pg so that an image of the projection grating 40 is formed on the virtual reference grating plane Pg. The virtual reference grating plane Pg is arranged in a conjugate positional relationship with the virtual reference grating plane Pg so that the image on the observation reference grating 46 is formed.

  Then, the measuring head 12 projects an image of the projection grating 40 onto the measurement object 2 by the projection optical system 26 and uses the observation optical system 28 to observe the deformed grating image formed on the measurement object 2 by this projection. An image is formed on the reference grating 46, and moiré fringes generated by the image formation are observed.

  In FIG. 2, a virtual reference lattice plane Pg indicated by a one-dot chain line and a plurality of surfaces indicated by solid lines parallel to the virtual reference lattice plane Pg form equal order moire surfaces (hereinafter referred to as “moire surfaces”) having different orders. Then, moire fringes are formed along a curve where each of these moire surfaces and the measured object 2 intersect. In FIG. 2, the moire surface is indicated by a solid line only on the front side (lower side in the figure) of the virtual reference grid surface Pg, but a plurality of moire surfaces are also provided on the back side (upper side in the figure) of the virtual reference grid surface Pg. Is formed. Accordingly, moire fringes are formed even when the DUT 2 is arranged so as to straddle the virtual reference lattice plane Pg.

  A measured body 2 shown in FIG. 2 schematically represents a human body (face part). As described above, it is semi-transparent to the wavelength of projection light, such as a living body such as a human body, ceramics made of fine particles such as alumina, foamed plastic such as expanded polystyrene, diffused glass such as foamed glass and opal glass. Therefore, when measuring with a moire device that tends to cause internal scattering, the contrast of moire fringes is large even though good contrast is obtained when measuring those that do not have such characteristics. A decreasing phenomenon is observed.

  The lattice pattern projection shape measuring apparatus 10 according to the present embodiment can adjust the fringe contrast and obtain high measurement accuracy even when the measured object 2 is semi-transparent to the wavelength of the projection light. In order to be able to do so, it has the following features.

  That is, the projection grating 40 shown in FIG. 2 is a binary grating in which the transmittance of the projection light changes approximately in a binary manner between the non-transparent grid line and the translucent grid line. It is configured so that the ratio of the line width with the optical lattice line can be continuously changed.

  In addition, the projection grating 40 is formed by superimposing a plurality of element gratings having substantially the same lattice line pitch so that the lattice lines are parallel to each other. The line width ratio is changed by laterally shifting each other.

Hereinafter, these feature points will be described in more detail with reference to FIGS.
First, a schematic configuration of the projection grating 40 and a moving mechanism thereof will be described with reference to FIG. FIG. 3 is a diagram schematically showing the configuration of the projection grating 40 and its moving mechanism, in which FIG. 3 (a) is a front view thereof, FIG. 3 (b) is a sectional view showing a part of the projection grating 40 in an enlarged manner, FIG. 3C is a front view showing a part of the projection grating 40 in an enlarged manner.

  As shown in FIG. 3B, the projection grating 40 includes an element grating 41 arranged on the projection lamp side (not shown) and an element grating 43 arranged on the measured object 2 (see FIG. 2) side. The grid lines (both straight) are overlapped so as to be in parallel. The two element gratings 41 and 43 transmit projection light between the opaque area B that forms opaque grating lines 45 and 47 and the transparent area W that forms transparent grating lines 61 and 63, respectively. It is a binary lattice in which the rate changes in a substantially binary manner. The lattice line width, the lattice pitch P, and the light-transmitting region B, that is, the light-transmitting lattice lines 45 and 47, and the light-transmitting region W, that is, the light-transmitting lattice lines 61 and 63. The line width ratio (1: 1) is substantially equal to each other.

  Further, the projection grating 40 is configured so that the two element gratings 41 and 43 can be laterally shifted from each other in a moving direction (indicated by an arrow in the figure) perpendicular to the grating lines. Specifically, this lateral displacement is performed by a uniaxial moving stage 49 shown in FIG. That is, the uniaxial moving stage 49 supports an upper plate 51 that supports one element lattice 43 attached to the support frame 48, and supports the upper plate 51 so as to be movable in the moving direction, and the other element lattice 41. The upper plate 51 that supports one element lattice 43 is supported by the other element lattice 41 by the operator operating the adjustment screw 54. It is configured to move in the moving direction relative to the middle plate 53, thereby adjusting the lateral shift.

  By this lateral shift adjustment, the projection grating 40 causes the ratio of the line widths of the opaque area B and the transparent area W to completely overlap the opaque grating lines 45 and 47 of the two element gratings 41 and 43. The state is arbitrarily changed from a closed state (line width ratio 1: 1) to a state in which a part of each of the opaque lattice lines 45 and 47 overlaps (for example, the line width ratio 1.8: 1, see FIG. 3C). Is possible. An electric actuator is provided in place of the adjustment screw 54, and a control signal is output from the control unit 16 via the power supply device driving unit 14 by an input operation from the keyboard 20 shown in FIG. The lateral displacement adjustment may be performed by driving an actuator.

  As shown in FIG. 3A, the projection grating 40 is supported by a pulse stage 55. The pulse stage 55 includes a middle plate 53, a lower plate 57 that supports the middle plate 53 so as to be movable in the moving direction, and a pulse motor 59. By driving the pulse motor 59, two element lattices 41 are provided. 43, the intermediate plate 53 is moved along the moving direction with respect to the lower plate 57, thereby causing the projection grating 40 to reciprocate finely (fringe scan) over the length of one phase. Note that a fringe scan may be performed using a piezoelectric element or the like instead of the pulse stage.

  Due to the movement of the projection grating 40, the phase between the projection grating 40 and the observation reference grating 46 changes, and the moire fringes move accordingly. In the measurement apparatus 10 shown in FIG. 1, the moire fringe image is obtained for each ¼ phase, so that the control unit 16 performs highly accurate shape measurement and unevenness determination of the measured object 2 (see FIG. 2). It is like that.

  Next, the operation of the line width ratio adjustment in the projection grating 40 will be described with reference to FIG. 4A and 4B are diagrams showing the effect of adjusting the line width ratio in the projection grating 40. FIGS. 4A to 4E are before the line width ratio adjustment, and FIGS. 4A to 4E are the line width ratio adjustment. Shows the back. 2A and 2A are enlarged sectional views showing a part of the projection grating 40, and FIGS. 2B and 2B are front views showing an enlarged part of the projection grating 40. FIG. FIGS. 3C and 3C show the transmittance distribution of the projection grating 40 with respect to the projection light, and FIGS. 2D and 2D show one of the fringe patterns formed on the measurement object 2. FIG. The figure which shows a part, The figure (e), (e ') is the figure which shows the light intensity distribution.

  As shown in FIG. 4A, when the lattice lines 45 and 47 of the two element lattices 41 and 43 constituting the projection lattice 40 are substantially overlapped with each other, as shown in FIG. The line width ratio between the 40 opaque regions B and the transparent regions W is 1: 1. Since the projection grating 40 functions as a binary grating for the projection light, the transmittance distribution of the projection light is approximately 2 at the boundary between the opaque region B and the transparent region W, as shown in FIG. It changes to value (0, 1).

  When the projection grating 40 having a line width ratio of 1: 1 is projected onto the measurement object 2 shown in FIG. 2, that is, the face of the human body, the fringe pattern formed on the measurement object 2 by this projection is shown in FIG. As shown in (d), by being affected by the internal scattering of the DUT 2, the part that originally appears dark appears to be entirely light and the width of the part that appears dark decreases. That is, at this time, the light intensity distribution of the fringe pattern is different from the sinusoidal shape as the bias intensity β increases as shown in FIG. In the light intensity distribution of the fringe pattern, the contrast of the projected fringe pattern is lowered due to the increase of the bias intensity β, thereby reducing the contrast of the moire fringes observed in the observation optical system 28 shown in FIG. Further, since the light intensity distribution of the fringe pattern does not become sinusoidal, the light intensity distribution of the observed moire fringe also does not become sinusoidal, which adversely affects the measurement accuracy when performing fringe scan measurement.

  On the other hand, as shown in FIG. 4 (a ′), when the two element lattices 41 and 43 constituting the projection lattice 40 are laterally shifted so that the lattice lines 45 and 47 partially overlap each other, As shown in the diagram (b ′), the line width ratio between the opaque region B and the transparent region W of the projection grating 40 changes (for example, 1.3: 1). Note that the grating pitch P of the projection grating 40 does not change even when shifted laterally, and the projection grating 40 functions as a binary grating with respect to the projection light, so the transmittance distribution of the projection light is shown in FIG. As shown in the figure, the boundary portion between the light-impermeable region B and the light-transmissive region W has a shape that changes in a substantially binary manner (0, 1).

  When the image of the projection grating 40 with the line width ratio changed in this way is projected onto the measurement object 2 shown in FIG. 2, the fringe pattern formed on the measurement object 2 by this projection is shown in FIG. 4 (d ′). As described above, the influence of the internal scattering of the DUT 2 decreases the width of the portion that originally looks dark but improves the contrast. That is, looking at the light intensity distribution of the fringe pattern at this time, as shown in FIG. 4 (e ′), the bias intensity β ′ does not become so large, and the overall shape is close to a sine wave shape. At this time, the contrast of moire fringes observed in the observation optical system 28 shown in FIG. 2 is also improved, and the light intensity distribution is also sinusoidal.

  Note that the adjustment of the line width ratio in the present embodiment is performed by operating the adjustment screw 54 shown in FIG. 3 so as to improve the contrast while observing the moire fringes displayed on the monitor 18 shown in FIG. Done. Further, the fringe pattern formed on the measurement object 2 by projecting the image of the projection grating 40 onto the measurement object 2 shown in FIG. 2 is deformed reflecting the uneven shape of the measurement object 2. However, in FIGS. 4D and 4D, the fact that the fringe pattern is deformed is ignored for the sake of convenience.

  Next, the observation reference grating 46 will be described with reference to FIG. FIG. 5 is a diagram showing the configuration and function of the observation reference grid 46. FIG. 5 (a) is a front view showing the observation reference grid 46 together with its support frame 48, and FIG. FIG. 6C is a diagram showing the transmittance distribution of the observation reference grating 46 with respect to the projection light.

  As shown in FIG. 5 (a), the observation reference grating 46 macroscopically appears as if the non-transmissive region B and the transparent region W are formed in vertical stripes at equal intervals. As shown in b), it is microscopically constituted by a repetitive pattern in which the left and right widths and intervals of the non-light-transmitting region B and the light-transmitting region W are gradually changed. The left and right widths and intervals of the opaque region B and the transparent region W are set so that the transmittance distribution of the projection light is substantially sinusoidal as shown in FIG. It is set to be equal to the grating pitch P of the projection grating 40.

  The observation reference grating 46 shown in FIG. 5 is based on the technique described in Patent Document 5, but a sine wave grating based on the technique described in Patent Document 3 is used as the observation reference grating 46. It can also be used.

  According to the measuring apparatus 10 configured as described above, the projection grating 40, which is a binary grating, is used even when measuring the measurement object 2 such as a human body that is semi-transmissive to the wavelength of the light source to be used. By changing the line width ratio between the opaque region B and the transparent region W, it becomes possible to perform high-precision fringe scan measurement with good moire fringe contrast, and use a sine wave grating as the projection grating 40 It is possible to obtain a good measurement result that cannot be obtained if

  Further, the projection grating 40 is constituted by two element gratings 41 and 43, and the line width ratio between the opaque region B and the transparent region W by the relative lateral displacement of the two element gratings 41 and 43. Therefore, it is possible to easily adjust the line width ratio by manual operation.

  A technique for creating a reference grating using a liquid crystal element as described in Patent Document 3 described above is used to create a binary grating in which the transmittance distribution of projection light changes in a binary manner, and the opaqueness thereof. A configuration in which the line width ratio between the light region and the light transmission region can be changed can be used as the first reference grating of the present invention.

  Moreover, although the said embodiment has shown the example which applied this invention to the grating | lattice projection type | mold moire apparatus, this invention is a grid irradiation type | mold moire apparatus as described in the said patent document 1, and the said patent document 3, The present invention can be similarly applied to other lattice pattern projection shape measuring apparatuses as described in FIG.

1 is an overall configuration diagram of a lattice pattern projection shape measuring apparatus according to an embodiment of the present invention. The figure which shows the basic composition and function as a lattice projection type moire device Diagram showing the configuration of the projection grating and its moving mechanism The figure which shows the effect | action of line width ratio adjustment in a projection grating | lattice Diagram showing the configuration and function of the reference grid for observation

Explanation of symbols

2 Measurement object 10 Lattice pattern projection shape measuring device 12 Measuring head 14 Power supply device drive unit 16 Control unit 18 Monitor 26 Projection optical system 28 Observation optical system 40 Projection lattice (first reference lattice)
41, 43 Element lattice 42 Projection lens 44 Imaging lens 45, 47 Non-transparent lattice line 46 Observation reference lattice (second reference lattice)
48 support frame 49 1-axis moving stage 51 upper plate 53 middle plate 54 adjusting screw 55 pulse stage 57 lower plate 59 pulse motor 61, 63 light-transmitting lattice line P lattice pitch B light-transmitting region W light-transmitting region Ax1, Ax2 optical axis Pg virtual reference lattice plane

Claims (5)

A pair of non-transparent grid lines and translucent grid lines that are adjacent to each other, and each of the pair has a substantially constant line width in at least one direction over the entire length, and is parallel to the above direction without a gap. The shape of the object to be measured is based on a fringe pattern generated by projecting a plurality of pairs of grid patterns of the first reference grating onto the object to be measured and subjecting the lattice pattern to deformation according to the shape of the object to be measured. In a lattice pattern projection shape measuring apparatus for measuring
The first reference grating is a binary grating in which the transmittance of the projection light changes approximately in a binary manner between the opaque grating line and the transparent grating line.
The pair of pitches is not changed, and the ratio of the line width of the light-transmitting grid lines and the light-transmitting grid lines constituting the pitch is configured to be variable in the direction. apparatus.   The first reference grating is configured by superimposing the two element gratings having the same pair of pitches so that the grating lines are parallel to each other, and the two element gratings are arranged in the direction. 2. The lattice pattern projected shape measuring apparatus according to claim 1, wherein the ratio of the line width is changed by laterally shifting the line width.   3. The lattice pattern projection shape measuring apparatus according to claim 2, wherein the lattice lines of the two element lattices are linear lattice lines. A projection optical system that projects an image of the first reference grating onto the measurement object;
An observation optical system that forms an image of the fringe pattern formed on the object to be measured by the projection on a second reference grating and observes the moire fringes formed by the image formation; The lattice pattern projected shape measuring apparatus according to any one of claims 1 to 3, wherein:   The second reference grating is characterized in that a light transmittance distribution is a sine wave between the pair of the opaque grating lines and the transparent grating lines. The lattice pattern projection shape measuring apparatus according to any one of 1 to 4.

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