JPH11230726A - Projecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To freely change a pattern and quickly perform the change work using an optical device such as a DMD(digital micromirror device: a light deflector). SOLUTION: A light source 11 and a DMD 20 are placed on the optical axis of an incident optical system 12. A projection optical system 13 is placed on the opposite of the incident optical system 12 with a straight line A located between these systems on the surface of the DMD 20. The DMD 20 can be selectively set an on-condition that deflects an incident light from the light source 11 to a predetermined direction or an off-condition that does not deflect, providing a plurality of micromirrors two-dimensionally arranged. An exiting light from the projection optical system 13 is emitted to a measured object S. The on-off condition of each micromirror is respectively controlled by a DMD driving circuit 31 and, a pattern projected on the measured object S is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for projecting a predetermined pattern on an object to be measured in order to measure a three-dimensional surface shape of the object.

[0002]

2. Description of the Related Art Conventionally, as a projection device of this type, a transparent film on which a predetermined pattern is drawn is provided, and the pattern is projected on the surface of an object by irradiating light from the back side of the transparent film. Things are known. The pattern projected on the surface of the measured object is photographed from, for example, two directions, and two images obtained thereby are processed to obtain three-dimensional coordinates of each point of the surface shape of the measured object.

On the other hand, in recent years, DMD (trade name; digital
Abbreviation for micromirror device. ) Has been developed. The DMD is configured by two-dimensionally arranging a large number of micromirrors each having a side of about 16 μm in a lattice shape. Each micromirror can be tilted in two directions, and the tilt direction is changed by an electrostatic field effect of a memory element provided immediately below each micromirror. That is, assuming that the micromirror receiving the electrostatic force is tilted in the first tilt direction, the micromirror not receiving the electrostatic force tilts in the second tilt direction.

[0004]

As described above, in the conventional projection apparatus, it is necessary to prepare a transparent film on which a pattern is drawn, and when it is necessary to change the pattern, it is necessary to prepare a transparent film. The film must be replaced accordingly. For this reason, there has been a problem that it takes time to change the pattern.

An object of the present invention is to provide a projection apparatus which can change a pattern freely using an optical element such as a DMD, and can perform the change operation quickly.

[0006]

A projection apparatus according to the present invention can selectively set a light source and an on state in which incident light from the light source is deflected in a predetermined direction and an off state in which light is not deflected, A light deflecting unit having a plurality of two-dimensionally arranged light deflecting elements, an incident optical system provided between the light source and the light deflecting unit, and provided in a predetermined direction to irradiate the object with the incident light And a deflection control unit that controls the on / off state of the plurality of light deflection elements to form a pattern projected on the object to be measured.

[0007] The projection apparatus may include storage means for storing a plurality of patterns. In this case, the deflection control means selects one of the plurality of patterns, and based on the selected pattern, a plurality of light deflectors. Controls the on / off state of the element.

The light deflecting element is, for example, a mirror element which is set to an on state or an off state by changing a tilt angle by an electrostatic force, or the light deflecting element is set to an on state or an off state by a diffraction effect of light. It is a diffractive light modulation element.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a projection device according to a first embodiment of the present invention.

A light source 11 and an incident optical system 12 are provided on a main body 10 of the projection apparatus, and a DMD 20 serving as a light deflecting unit is provided on the optical axis. A projection optical system 13 is provided on the opposite side of the incident optical system 12 with respect to a straight line A perpendicular to the surface of the DMD 20. DMD 20 is light source 1
The light emitted from 1 and incident via the incident optical system 12 can be reflected to the projection optical system 13 side. An opening 14 is formed in the main body 10 at a position facing the projection optical system 13, and the light reflected by the DMD 20 is applied to the outside of the main body 10 via the projection optical system 13 and the opening 14.

A large number of micromirrors (not shown) are provided on the surface of the DMD 20, and these micromirrors are arranged in a lattice, that is, two-dimensionally. The tilt angle of each micromirror is changed by the control of the DMD drive circuit 31, whereby light forming a predetermined pattern is emitted from the opening 14. This light is applied to the device under test S arranged to face the opening 14 to form a pattern on the surface of the device under test S. The incident optical system 12 and the projection optical system 1
At least one of the three is position-adjustable along the optical axis so that the image of the pattern is focused on the measured object S.

The DMD drive circuit 31 has a microcomputer and is connected to a memory 32. The memory 32 stores data corresponding to a plurality of patterns that can be formed on the surface of the device under test S.

FIG. 2 is a diagram conceptually showing a configuration for driving a micro mirror (light deflecting element) 21 provided in the DMD 20.

The micromirror 21 is a substantially rectangular plate-like member, and a mirror surface is formed by laminating an aluminum thin film on the surface of the micromirror 21. One side of the micro mirror 21 is, for example, about 16 μm. The two corners 21 a and 21 b on the diagonal line of the micro mirror 21 are
Torsion hinges 24 on a pair of support columns 23
Are connected via That is, the micro mirror 21
Is rotatable around the torsion hinge 24, and stably stops at a position where one of the two corners 21 c and 21 d different from the corners 21 a and 21 b is in contact with the silicon substrate 22.

(By the spring force of the torsion hinge ...
A plurality of electrodes 25 (memory elements) are formed on the surface of the silicon substrate 22 on the micromirror 21 side. By applying a voltage to a predetermined one of these electrodes 25,
An electrostatic force acts on the micromirror 21, and the micromirror 21 is inclined in the first inclination direction with the corner 21c abutting on the silicon substrate 22 (ON state). In contrast,
When no electrostatic force is applied, the micromirror 21 is inclined in the second inclination direction with the corner 21d abutting on the silicon substrate 22 (OFF state).

FIG. 3 is a diagram showing a state of reflection of light incident on the micro mirror 21. In this figure, when the micromirror 21 is in the ON state, as shown by the solid line L1, +1
It is displaced clockwise by 0 °, and when it is in the off state, it is displaced by -10 ° counterclockwise as shown by the broken line L2. In the ON state, light incident through the incident optical system 12 (see FIG. 1) is reflected by the micromirror 21 and enters the projection optical system 13 (see FIG. 1) (reference B).
1). On the other hand, in the off state, light guided from the incident optical system 12 and reflected by the micromirror 21 is:
The light does not enter the projection optical system 13 (reference B2). That is, the micromirror 21 can be selectively set between an on state in which the incident light is reflected to the projection optical system 13 side and an off state in which the incident light is not reflected to the projection optical system 13 side.

FIG. 4 is a front view of the DMD 20 as viewed from the side where the incident optical system 12 and the projection optical system 13 are provided. In each micromirror 21, the white micromirror 21 indicates the on state, and the hatched micromirror 21 indicates the off state.
In this figure, for the sake of explanation, the size of the micromirror 21 is shown larger than the overall size of the DMD 20.

According to the example shown in FIG. 4, a concentric pattern is formed depending on the inclined state of each micro mirror 21. That is, three concentric circles C1, C2, C3
Is set to the off state,
Micromirrors 21 other than these circles C1, C2, C3
Is set to the ON state. Therefore, in the DMD 20, light guided from the incident optical system 12 is reflected toward the projection optical system 13 in portions other than the concentric circles C1, C2, and C3. As a result, concentric circles C1, C
2. The image of C3 is formed as a black shadow.

The memory 32 stores such concentric circles C1,
Data corresponding to a plurality of patterns including the patterns C2 and C3 is stored in advance. By operating a predetermined operation switch, a predetermined pattern is selected by the control of the DMD drive circuit 31, and the on / off state of each micromirror 21 is controlled based on this pattern.

FIG. 5 is a top view of the object S on which the concentric pattern is projected, and FIGS. 6 and 7 are views of the object S obliquely from above. 8, 9, and 10 are views of the DUT S as viewed from the front, right side, and left side, respectively. As described above, even if the object S has a complicated shape, a concentric pattern is formed when viewed from directly above, and when viewed obliquely, a vertically extending stripe pattern is observed on the vertical wall S1, and the curved surface S2 is observed. In this case, a curved stripe pattern corresponding to the surface shape is observed.

By analyzing two images obtained from photographs taken from two different directions as shown in FIGS. 6 and 7 by a conventionally known method, three-dimensional coordinates of the surface of the object S can be obtained. Can be

As described above, in the present embodiment, the measured object S
Is formed by turning on and off the micro mirror 21 of the DMD 20. Therefore, it is not necessary to prepare a transparent film on which a pattern is drawn as in the related art, and even if it is necessary to change the pattern, data corresponding to the pattern to be changed can be read from the memory 32. The reading process is performed quickly.

FIGS. 11 to 14 show a diffractive light modulation element 40 provided in the second embodiment. In this embodiment, the light used for forming the pattern is monochromatic light, for example, infrared light. Diffractive light modulation element 4
0 is provided in place of the micro mirror 21 (see FIG. 2), and the other configuration is the same as that of the first embodiment.

The diffraction type light modulation element 40 includes a large number of beam members 41.
Having. The beam member 41 is made of, for example, silicon nitride, and is a thin plate-shaped member having a width of 1.0 to 1.5 μm and a length of 15 to 120 μm. The surface of the beam member 41 is coated with, for example, a thin film 42 of aluminum to form a mirror surface. Both ends of each beam member 41 are supported by spacers 44 fixed on a substrate 43. The spacer 44 is made of, for example, silicon dioxide. Each beam member 41 is disposed in parallel with each other, and the interval between adjacent beam members 41 is
It is substantially equal to the width of the beam member 41.

The distance between the front surface of the beam member 41 (ie, the back surface of the thin film 42) and the front surface of the substrate 43 is １ ／ of the wavelength (λ) of the light applied to the diffractive light modulation element 40. . The plate thickness of the beam member 41 is の of the wavelength.

When no voltage is applied between the beam member 41 and the substrate 43, as shown in FIGS. 11 and 12, the beam member 41 is parallel to the substrate 43, and the surface of the beam member 41 and the substrate 43 Are separated by λ / 2. In this state, the monochromatic light of wavelength λ applied to the substrate 43 is
Reflected by diffraction (ON state). On the other hand, when a voltage is applied between the beam member 41 and the substrate 43, as shown in FIGS.
1 is bent so that the back surface thereof is in close contact with the substrate 43, and the distance between the surface of the beam member 41 and the substrate 43 is λ / 4. In this state, the incident light and the reflected light on the substrate 43 cancel each other,
There is no reflected light (off state).

As described above, in the second embodiment, since the diffractive light modulating element 40 which is set to the ON state or the OFF state by the light diffraction action is used, the light incident from the incident optical system is monochromatic light. Except for the necessity, the operation is the same as that of the first embodiment, and an equivalent effect is obtained.

[0028]

As described above, according to the present invention, the projection pattern can be freely changed, and the change operation can be performed quickly.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a projection device according to a first embodiment of the present invention.

FIG. 2 is a diagram conceptually showing a configuration for driving a micro mirror.

FIG. 3 is a diagram illustrating a reflection state of light incident on a micromirror.

FIG. 4 is a front view of the DMD as viewed from an incident optical system and a projection optical system.

FIG. 5 is a top view of an object to be measured on which a pattern of concentric circles is projected.

FIG. 6 is a perspective view of an object to be measured as viewed obliquely from the upper right.

FIG. 7 is a perspective view of an object to be measured as viewed obliquely from the upper left.

FIG. 8 is a front view showing an object to be measured.

FIG. 9 is a right side view showing an object to be measured.

FIG. 10 is a left side view showing an object to be measured.

FIG. 11 is a cross-sectional view illustrating a diffractive light modulation element provided in the second embodiment and in an ON state, cut along a plane perpendicular to a beam member.

12 is a side view of the diffractive light modulation device shown in FIG.

FIG. 13 is a cross-sectional view showing the diffractive light modulation element in an off state by cutting along a plane perpendicular to a beam member.

14 is a side view of the diffractive light modulation device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Light source 12 Incident optical system 13 Projection optical system 20 DMD (optical deflecting means) 21 Micromirror (optical deflecting element) S DUT

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takaaki Yoshinari 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Gaku Kogyo Co., Ltd. (72) Inventor Kiyoshi Negishi 2-36-9 Maenocho, Itabashi-ku, Tokyo No. Asahi Gaku Kogyo Co., Ltd.

Claims (4)

[Claims] 1. A light source and an on state in which incident light from the light source is deflected in a predetermined direction and an off state in which light is not deflected can be selectively set, and a plurality of two-dimensionally arranged light deflection elements are provided. A light deflecting means having: an incident optical system provided between the light source and the light deflecting means; a projection optical system provided in the predetermined direction to irradiate the object with the incident light; A projection control device for controlling the on / off state of the light deflecting element to form a pattern projected on the object to be measured. 2. A storage means for storing a plurality of patterns, wherein the deflection control means selects one of the plurality of patterns and controls the on / off state of the plurality of light deflection elements based on the selected pattern. The projection device according to claim 1, wherein: 3. The projection apparatus according to claim 1, wherein the light deflecting element is a mirror element that is set to an on state or an off state by changing a tilt angle by electrostatic force. 4. The projection apparatus according to claim 1, wherein the light deflecting element is a diffractive light modulation element that is set to an on state or an off state by a diffraction effect of light.