JP2002323404A - Surface inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface inspection device detectable of reflection light with sufficient sensitivity in measuring reflectivity by irradiating light to a reflection mirror formed with a part of a rotary ellipse surface being a surface to be measured and detecting the reflection light. SOLUTION: The end surface of a light guide means 16 for irradiation on the surface to be measured is placed at the more distant focus of the two from the surface to be measured and a light guide means 17 for detection on the surface to be measured is formed around the end surface of the light guide means 16 for irradiation on the surface to be measured. By this, the reflection light can be sufficiently introduced in the detector 14 and this can detect the reflection light detected with sufficient detection sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface inspection apparatus for inspecting the degree of convergence of a reflector formed from a part of a spheroid in a light source with a reflector.

[0002]

2. Description of the Related Art Light sources used in data projectors and projection televisions have an arc length of 1.0 to 1.0.
A high pressure discharge lamp of a short arc type such as 1.5 mm is used. In these lamps, an arc light-emitting portion is provided at a focal position of a reflecting mirror formed from a part of a paraboloid of revolution or a part of a spheroid, and irradiates light in a desired direction for use. FIG. 7 shows an outline of an irradiation optical system in the data projector. The reflecting mirror 1 in FIG. 7 is a reflecting mirror 1 in which a concave portion of a concave mirror formed from a part of a shape obtained by rotating an ellipse around a straight line connecting two focal points of the ellipse is used as a reflecting surface. The lamp 2 installed on the reflecting mirror 1 includes an arc tube 3 and an electrode 4, and the lamp 2 is installed such that an arc emitting portion generated between the electrodes 4 is located at a position including the first focal point 5 of the reflecting mirror 1. . The light emitted from the arc light emitting portion is reflected by the reflecting surface of the reflecting mirror 1, and the reflected light is condensed at the second focal point 6, is converted into parallel light by the convex lens 7, and is converted through the projection lens 8 into the screen. Projected on Here, the first focus 5 is a focus closer to the surface to be measured, and the second focus 6
Is a focus far from the surface to be measured.

In order to effectively project the light emitted from the lamp 2 onto the screen without any loss, it is necessary to reduce the loss in optical components that transmit and reflect the light until it reaches the screen. In particular, if minute irregularities on the reflecting surface of the reflecting mirror 1 are inadvertently generated, the light is reflected on the reflecting surface and then scattered without traveling on the designed ray trajectory, so that the light is not used effectively. For this reason, the finished condition of the irregularities on the reflecting surface of the reflecting mirror 1 is very important in condensing the light emitted from the lamp 2.

An apparatus for irradiating an inspection object with light and inspecting the surface state of the inspection object from the intensity of the reflected light is disclosed in, for example, JP-A-08-110964. In this configuration, the optical path of the reflected light reflected from the inspection object is branched from the irradiation light by a beam splitter or the like, and the light receiving unit is obliquely disposed.

[0005]

When the object to be inspected is the reflecting mirror 1 having a shape obtained by rotating an ellipse as shown in FIG. An apparatus for inspecting the finish of unevenness on the reflection surface has a configuration as shown in FIG. 8, for example. Light emitted from the light source 9 is converted into parallel light by the convex lens 10, passes through the beam splitter 11, and is emitted to the convex lens 7. The light applied to the convex lens 7 is converged by the convex lens 7 so as to pass through the aperture of the aperture 12 arranged so that the aperture is located at the position of the second focal point 6 of the reflecting mirror 1. The light is applied to the reflecting surface. The light reflected on the surface to be measured of the reflecting mirror 1 returns to the stop 12
, And is converted into parallel light by the convex lens 7 and returns to the beam splitter 11. The returned light has its traveling direction changed in the beam splitter 11 and enters the convex lens 13. The parallel light that has entered the convex lens 13 enters a detection unit 14 connected to a photodetector by the convex lens 13 and is measured by the detector. FIG.
1 ′ indicates a lamp insertion hole.

In the case of FIG. 8, the convex lens 7 and the stop 12 are required as optical elements, and the aperture surface of the reflecting mirror 1 and the stop 1
Accuracy of positioning the distance L1 to the lens 2 and the distance L2 to the stop 12 and the convex lens 7 is required.

Further, in order to inspect whether or not the reflecting surface of the reflecting mirror 1 can collect the reflected light at the position of the second focal point 6 without scattering the light, the light to be irradiated on the reflecting mirror 1 needs to be close to a point light source. There is. Therefore, it is effective to reduce the aperture 12 as much as possible. However, if the reflected light is slightly scattered when the aperture 12 is too narrow, the amount of light passing through the aperture 12 is reduced, and the detection sensitivity is lowered.

On the other hand, as another configuration of the apparatus for inspecting the finish of the reflecting surface of the reflecting mirror 1, for example, as shown in FIG.
A method of installing the light source 9 at the second focal point 6 is also conceivable. In this case, the distance between the second focal point 6 and the opening surface of the reflecting mirror 1 becomes short, and when the diameter of the opening portion is large, the irradiation light and the It becomes spatially difficult to install the beam splitter 11 having a size capable of transmitting the reflected light. FIG. 9 shows a case where the distance between the opening surface of the reflecting mirror 1 and the second focal point 6 cannot be sufficiently set, only the beam splitter 11 having a small size can be installed, and reflected light only from a part of the reflecting surface of the reflecting mirror. This shows a state in which only detection can be performed.

The present invention irradiates a reflecting surface (hereinafter referred to as a measured surface) of a reflecting mirror 1 formed from a part of a spheroid with irradiation light, detects reflected light, and detects reflected light. It is an object of the present invention to provide a surface inspection device that measures the degree of light collection on a measurement surface and that can detect reflected light with sufficient detection sensitivity.

[0010]

According to a first aspect of the present invention, there is provided a light source, a detector, and a light guiding means for illuminating light for guiding light output from the light source to a surface to be measured. When,
Light detection means for guiding light reflected on the surface to be measured to the detector, wherein the surface to be measured has a part of a shape obtained by rotating the ellipse about a straight line connecting two focal points of the ellipse as a rotation axis. The concave surface of the concave mirror used, the end face of the light guide means for irradiation light on the side of the surface to be measured is installed at a focal point farthest from the surface to be measured among two focal points on the surface to be measured,
This is a surface inspection apparatus in which the end face of the light guide means for detection light on the side of the measured surface is formed around the end face of the light guide means for irradiation light on the side of the measured face.

The end face of the irradiation light guiding means is disposed at a focal point farthest from the measured surface among the two focal points on the measured surface, and the detection light guiding means is provided around the end face of the irradiation light guiding means. By providing the end face of the means, the distant focus position conventionally required for reducing the irradiation light is eliminated. By eliminating the stop, the light reflected from the surface to be measured is not cut at the stop, and sufficient light can be incident on the detector, and the detection sensitivity can be improved.

According to a second aspect of the present invention, in the first aspect, the end face of the irradiation light guiding means on the side of the measured surface is the same as the end face of the detection light guiding means on the measured surface side. This is a surface inspection device formed on a flat surface.

According to a third aspect of the present invention, in the first aspect of the present invention, the end face of the light guide means for irradiation light on the side of the surface to be measured is curved and the detection light on the side of the surface to be measured is detected. It is a surface inspection device which is raised with respect to the end face of the light guide means for use. By bulging the end surface of the irradiation light guide means into a curved shape, the spread angle of the irradiation light can be increased, and the entire surface to be measured can be irradiated with the irradiation light.

According to a fourth aspect of the present invention, there is provided any one of the first to third aspects of the present invention, further comprising a light shielding means for adjusting a light distribution of light emitted from the irradiation light guiding means. Surface inspection device. By providing the light shielding means, reflected light at a partial position of the measured surface can be detected, and a partial surface inspection of the measured surface can be performed.

A fifth aspect of the present invention is the surface inspection apparatus according to the fourth aspect, wherein the light shielding means is movable.

According to a sixth aspect of the present invention, there are provided a plurality of light guiding means for detecting light, and the plurality of light guiding means for detecting light are formed circumferentially around the light guiding means for irradiation light. This is a surface inspection device in which at least one detector for measuring the intensity of the light is installed in each light guide means for detection light. By forming a plurality of light guide means for detection light in a circumferential shape around the light guide means for irradiation light, it is possible to grasp the intensity distribution of light from the light guide means for irradiation light toward the surrounding side, It is possible to evaluate the degree of local light focusing on the surface to be measured from the state of distribution.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, at least one of the irradiation light guiding means and the detection light guiding means is an optical fiber. It is a surface inspection device.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a surface inspection apparatus according to the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 shows a configuration diagram of a surface inspection apparatus according to the present invention. Irradiation light supplied from the light source 9 whose output is stabilized is irradiated to the reflection mirror 1 which is a surface to be measured through an optical fiber (hereinafter, referred to as an irradiation light optical fiber 16) used as a light guiding means for illumination light. Here, the reflecting mirror 1 is a concave mirror having a shape obtained by rotating an open ellipse around a straight line connecting two focal points of the open ellipse as a rotation axis, and the surface to be measured is a concave surface of the concave mirror. The reflected light reflected on the surface to be measured is guided to an optical fiber (hereinafter, referred to as an optical fiber 17 for detection light) used as a light guiding means for detection light, and the detector 14 measures the intensity of the reflected light. In addition, 1 'of FIG. 8 has shown the insertion hole of a lamp.

In this configuration, the optical fiber for irradiation light 1
6 and the end face of the optical fiber 17 for detection light, the end face of the optical fiber 16 for irradiation light is on the center side, and the end face of the optical fiber
7 form a concentric coplanar surface with the end face on the periphery side,
The end face of the irradiation light optical fiber 16 on the plane is set at a position including the second focus of the measured surface (the one of the two focuses on the measured surface that is farthest from the measured surface). Here, the irradiation light optical fiber 16 and the detection light optical fiber 17 are formed by bundling optical fibers,
Each bundle of optical fibers is bundled and connected to the light source 9 and the detector 14.

FIG. 2A shows the state of the end face of the optical fiber 16 for irradiation light and the optical fiber 17 for detection light. The concentric center side is the end face of the irradiation light optical fiber 16 and the surrounding side is the end face 17 of the detection light optical fiber. The diameter D1 of the end face of the optical fiber 16 for irradiation light is φ3 mm, and the diameter D2 of the end face of the optical fiber 17 for detection light is φ7 mm.

FIG. 2B shows the difference in the optical path due to the unevenness of the surface to be measured. The dimension L3 of the opening of the reflecting mirror 1 is φ68 mm. The distance L4 from the starting position O to the first focal point 5 of the reflecting mirror 1 is 12 mm, the distance L5 from the starting position O to the second focal point 6 is 92 mm, and the distance between the opening surface of the reflecting mirror 1 and the end surface of the optical fiber 16 for irradiation light. Is 38 mm. here,
The first focus 5 is a focus closer to the measured surface among the two focuses on the measured surface.

In FIG. 2B, the irradiation light emitted from the end face of the irradiation light optical fiber 16 will be traced. Irradiation light emitted from the second focal point 6 returns to the basically same second focal point 6 if there is no scattering on the surface to be measured. However, in practice, such examples are few and some scattering occurs. The emitted light a is ideally reflected at the measured surface portion A without scattering, reflected at the measured surface portion B without scattering, and returns to the second focal position 6 (indicated by a solid line). However, in the case where the light a is scattered due to minute irregularities on the surface of the surface B to be measured, the emitted light a becomes light a ′ at the surface B of the measurement surface and does not return to the second focal point 5. When such scattering occurs in each part in the surface to be measured, by installing the end face of the optical fiber for detection light 17 on the concentric peripheral side, it is possible to detect the detection light that has been scattered and reflected. . In other words, in the case of a mirror surface in which scattering does not occur in any part of the surface to be measured, all the reflected light is emitted from the irradiation optical fiber 16.
And the detection light is ideally zero. On the other hand, if any scattering occurs, strong reflected light is detected at the end face of the detection light optical fiber 17 on the concentric peripheral side, and as the degree of scattering on the surface to be measured increases, the amount of detection light limited. The amount of detection light returning within the area of the end face of the fiber 17 decreases. That is, a schematic diagram of the relationship between the relative value of the linear reflectance and the illuminance of the inspection apparatus is as shown in FIG. Here, the relative value of the linear reflectance refers to the irradiation light optical fiber 1.
This is a relative value indicating the rate at which the light emitted from 6 returns to the second focal point 6, and becomes zero when all of the irradiation light returns to the optical fiber 16 for irradiation light. As shown in FIGS. 3A and 3B, there are a case where the relative value of the linear reflectance is good and a case where the relative value of the linear reflectivity is bad at the same inspection device illuminance. In this case, by adopting a structure in which the position of the optical fiber 16 for irradiation light can be slightly moved, the illuminance of the inspection device changes abruptly in the case of a, whereas it changes gently in the case of b. a and b can be distinguished.

By the way, the size of the end face of the irradiation light optical fiber 16 is determined by a light take-in angle desired by the projection optical system until it is projected on the screen. The judgment of the intensity of the obtained light is
An object to be measured as a reference of the reflection performance is prepared, and the measurement is performed by relative comparison. FIG. 4 is a graph showing the illuminance at the time of actual screen projection with respect to the illuminance measured by the surface inspection apparatus in the configuration according to the first embodiment. It can be confirmed that the measured value of the present inspection apparatus and the illuminance at the time of projection have a substantially proportional correlation, and the use of the present inspection apparatus can predict the quality of the screen projection on the reflecting mirror 1.

The concentric arrangement is used because the surface to be measured is a rotating surface, and is to make it easier to uniformly receive light reflected from each part on the surface to be measured. Further, the diameter of the end face of the optical fiber for detection light 17 is appropriately determined so that the light that has been diffused and reflected cannot be selectively detected, or the light that has been diffused and reflected less can be detected. By appropriately reducing the diameter of the end surface of the irradiation light optical fiber 16, the surface inspection of the surface to be measured according to various conditions becomes possible.

In the present embodiment, the end face of the irradiation light optical fiber 16 is arranged at the one of the two focal points on the measured surface that is farther from the measured surface. In this configuration, the end face of the optical fiber 17 for detection light is installed. This configuration eliminates the need for the stop required in FIG. 8 of the conventional example at the position of the second focal point 6 to stop the irradiation light. By eliminating the stop, the light reflected from the surface to be measured is not cut at the stop, and sufficient light can be made incident on the detector 14, and the detection sensitivity can be improved. Further, by arranging the optical fibers 17 for detection light in a concentric manner, the spatial narrowness which has been a problem in FIG. 9 does not matter.

(Embodiment 2) Optical fiber 16 for irradiation light
There is a case where the light distribution of the light emitted from the end face of the light source becomes a problem. FIG. 5 shows a range in which the measured surface is irradiated when the irradiation light distribution angle of the prepared optical fiber is 40 ° in the configuration of FIG. In this case, when it is desired to inspect the degree of convergence on the entire surface to be measured, a surface that is not irradiated occurs. In such a case, as shown in FIG. 6, the end face of the irradiation light optical fiber 16 is connected to the detection light optical fiber 1.
A raised bowl-shaped curved surface may be formed with respect to the end face 7. Even if the light distribution angle of each fiber is a narrow angle, arranging the directions of the ends of the fibers in a bowl shape makes it possible to irradiate the entire surface to be measured with irradiation light. Further, when it is desired to precisely control the irradiation angle, a light shielding means 18 for controlling the opening diameter may be attached to the opening surface of the reflecting mirror 1 as shown in FIG. With the configuration as shown in FIG. 6, it is also possible to specify a part to be inspected on the surface to be measured and perform the inspection.

The light shielding means 18 shown in FIG. 6 is provided so as to be in contact with the opening surface of the reflecting mirror 1. By providing the light-shielding means 18 that can irradiate only the surface, the surface inspection of a partial position of the surface to be measured can be performed. Also,
By making the opening diameter and position of the light shielding means movable,
Further, the distribution inspection of the surface state on the surface to be measured can be performed in detail.

In the first embodiment, the end face of the optical fiber 16 for illumination light and the end face of the optical fiber 17 for detection light are coplanar and coplanar, but are not necessarily limited to the same plane. .

When an illuminometer is used as the detector 14, the light intensity can be detected as a visual physical quantity, which is suitable for evaluation of video equipment such as a projector.

The end face of the detection light optical fiber 17 disposed on the peripheral side is a multi-branch fiber formed in a plurality of circumferential shapes, and a detector for measuring the intensity of each detection light is installed in each multi-branch fiber. You may. A plurality of detectors 14 for measuring the intensity of the detection light of each multi-branch fiber may be provided, or one detector 14 may be time-shared. With the configuration of each multi-branch fiber, it is possible to grasp the intensity distribution from the intensity of each detection light from the fiber end face formed closer to the center of the end face toward the surrounding fiber end face, and from the distribution state, the measured surface Can be evaluated locally.

If a monochromatic variable light source is prepared as the light source 9, a relative spectral reflection inspection can be performed.

[0033]

According to the surface inspection apparatus of the present invention, the end face of the irradiation light guiding means is disposed at the one of the two focal points on the surface to be measured which is farther from the surface to be measured. And the end face of the light guide means for detection light is set around the end face of the light guide means. This configuration eliminates the need for a conventionally required stop at the position of the second focal point to stop the irradiation light. By eliminating the stop, the light reflected from the surface to be measured is not cut at the stop, and sufficient light can be incident on the detector, and the detection sensitivity can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a surface inspection apparatus according to the present invention.

2A is a configuration diagram of an end face of an optical fiber for irradiation light and an optical fiber for detection light according to the present invention. FIG. 2B is a partially enlarged view showing an optical path of a surface inspection apparatus according to the present invention.

FIG. 3 is a diagram illustrating a relationship between a relative value of a linear reflectance and illuminance of an inspection device according to the first embodiment of the present invention.

FIG. 4 is a correlation graph between an inspection illuminance value and a screen illuminance value according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a light distribution angle of the surface inspection device according to the first embodiment of the present invention.

FIG. 6 is a partially enlarged view of a surface inspection apparatus in which light blocking means is provided on an opening surface according to the second embodiment of the present invention.

FIG. 7 is a schematic view of an irradiation optical system in the projection system.

FIG. 8 is a diagram showing a conventional example in which an aperture exists.

FIG. 9 is a diagram showing a conventional example without a stop.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reflecting mirror 2 Lamp 5 First focus 6 Second focus 9 Light source 14 Detector 16 Optical fiber for irradiation light 17 Optical fiber for detection light 18 Shielding means

Continuing on the front page (72) Inventor Tomoyuki Seki 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. 72) Inventor Shuji Tamaru 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (reference) 2G065 AB04 AB22 BB02 BB13 BB21 DA05 2G086 GG02

Claims (7)

[Claims] 1. A light source, a detector, irradiation light guiding means for guiding light output from the light source to a surface to be measured, and detection light for guiding light reflected on the surface to be measured to the detector A light guiding means, wherein the surface to be measured is a concave surface of a concave mirror using a part of a shape obtained by rotating the ellipse around a straight line connecting two focal points of the ellipse; An end surface of the irradiation light guiding means on a surface side is provided at a focal point farther from the measured surface out of two focal points on the measured surface, and the detection on the measured surface side is performed. A surface inspection apparatus wherein an end face of the light guiding means for light is formed around an end face of the light guiding means for irradiation light on the side of the surface to be measured. 2. An end face of the light guide means for irradiation light on the side of the measured surface is formed on the same plane as an end face of the light guide means for detection light on the side of the measured face.
A surface inspection apparatus according to item 1. 3. An end surface of the light guide means for irradiation light on the side of the surface to be measured has a curved surface, and the end surface of the light guide means for detection light on the side of the surface to be measured. The surface inspection device according to claim 1, wherein the surface inspection device is raised. 4. The surface inspection apparatus according to claim 1, further comprising a light shielding unit that adjusts a light distribution of the light emitted from the irradiation light guiding unit. 5. The surface inspection apparatus according to claim 4, wherein said light shielding means is movable. 6. A plurality of said light guide means for detecting light, wherein said plurality of light guide means for detecting light are formed circumferentially around said light guide means for irradiating light to measure light intensity. The surface inspection apparatus according to any one of claims 1 to 5, wherein at least one detector is provided for each light guide unit for detection light. 7. The surface inspection apparatus according to claim 1, wherein at least one of the irradiation light guide unit and the detection light guide unit is an optical fiber.