JPH11183126A - False image preventive optical detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a false image preventive optical detector with no erroneous measurement and detection by, related to an optical detecting device for measuring 3D shape and position of an object to be measured,, eliminating a false image caused by multiple reflection occurring between a lens and a filter. SOLUTION: A case window glass, a filter, a lens, and an imaging element are provided. Further, a first means (imaging element) 22 for imaging light from an object to be measured, a second means (colored glass filter) 19 which prevents a reflection light occurring among the case window glass, the filter 21, and the lens 20 from entering an imaging view-field, and a third means which prevents the reflection light between the lens 20 and the filter 21 from entering the imaging view-field for generating a false image by providing an interference filter 21 having incident angle characteristics between the lens 20 and the imaging element 22 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a false image preventing light detecting device in a three-dimensional shape measuring device using a laser beam, or a false image preventing light detecting device when a self-luminous light source is captured by an imaging device.

[0002]

2. Description of the Related Art Conventionally, for example, in a three-dimensional shape measuring apparatus using a laser beam as shown in FIG. 1, a laser beam 2 is projected from a laser projector 1 to an object 3 to be measured. The laser projection angle θ and the reflected light position of the laser light hitting the measurement target 3 are detected by the light detection device 4, and the three-dimensional shape of the measurement target is measured using the principle of triangulation.

Further, when measuring the position and displacement of a moving measurement object, a light source that emits light of a specific wavelength by itself is attached to the measurement object, and a light source of a specific wavelength is detected by a photodetector. , And the position and displacement of the measurement target are measured.

[0004] In such a photodetector, since it is affected by disturbance light such as sunlight and background light, in order to cut off such influence, a band that passes only laser light or light of a specific wavelength of a light source is used. CC with pass filter
An imaging device such as a D camera detects light from a measurement target without being affected by disturbance light.

[0005] As a bandpass filter, an interference film deposition filter utilizing light interference is generally used in order to pass only light of a specific wavelength. The transmission characteristic of the interference film deposition filter at the wavelength λ depends on the incident angle and the optical thickness of the filter, and the transmission of light of a specific wavelength becomes maximum when represented by the following equation. At this time, almost all of the light of other wavelengths is reflected by the light source without passing through the filter.

Mλ = 2t cos θ where t is the optical thickness of the filter, θ is the incident angle, and m is an integer. The transmission peak occurs at a position of an integral multiple of the wavelength λ. For this reason, in the band-pass filter, by combining the interference film deposition filter and the color glass filter, the transmission of light in the sub-transmission wavelength region occurring on the short wavelength / long wavelength side of the main transmission wavelength of the interference film deposition filter is prevented. doing. Also, as can be seen from the above equation, the interference film deposition filter has an incident angle characteristic, and when the filter is tilted, the case of the incident angle of 0 ° in FIG.
As shown by dotted lines, the case where the incident angle is 10 ° has a characteristic that the main transmission wavelength shifts to the shorter wavelength side (that is, from right to left in FIG. 2) as the incident angle increases. .

[0007]

The above-described conventional photodetector 4 generally has a structure as shown in FIG. As shown by arrows in FIG. 3, light from the measurement object (not shown) includes a case window glass 7, a band-pass filter (consisting of a color glass filter 8, an interference film deposition filter 9), and a lens. The image is formed on the image sensor 10 in the camera body 12 through the camera body 11. At this time, part of the light from the object to be measured is, as shown by another arrow in FIG. 3, the surface of the bandpass filter (color glass filter).
8) The light is reflected on the surface of the lens 11 respectively. The light thus reflected is further reflected by the window glass 7 of the case and the band-pass filter (the interference film deposition filter 9) as shown by the dotted line in FIG.
By being incident on the light 1, the light to be measured is imaged on the image sensor 10 by the lens as if it were there.

In FIG. 4, the original position of the light to be measured formed on the imaging screen 17 is indicated by ●, and the noise generated by the reflection is indicated by ○. As shown in FIG. 4, when the light formed by the above-described reflected light detects the position of the original light, a false image is generated. In particular, when the light from the measurement target is weakened due to a measurement target having a large variation in reflectance, a measurement target having many curves, or a large change in the distance between the measurement targets, the above-described phenomenon is remarkably exhibited. If the threshold value for light detection is lowered in order to solve the above-described problem and accurately detect weak light, there is a problem that false detection of the shape and position is caused by a false image.

As a method of mounting the interference filter,
A method disclosed in JP-A-8-75427 is known. This method consists of mounting the filter at an angle so that the light quantity can be sufficiently secured when the object to be measured is farthest.However, the interference filter has an incident angle characteristic. There is a problem that the transmission wavelength shifts to a shorter wavelength side, the transmittance of the light to be detected decreases, and the power level of the laser beam or the self-luminous light source applied to the measurement target must be increased to a level sufficient for measurement. Was.

The present invention provides a photodetector for measuring a three-dimensional shape and position of a measurement object, which eliminates false images due to multiple reflections generated between a lens and a filter, thereby eliminating false measurements and false detections. It is an object to provide an image prevention light detection device.

[0011]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems of the prior art. As a result, a window glass and a color glass filter arranged on the front surface of the lens in accordance with the angle of view of the imaging apparatus are attached alternately and obliquely at a predetermined angle, and an interference film deposition filter having an incident characteristic is attached to the lens and the imaging device. It has been found that the attachment between the two prevents the reflected light from forming an image on the image pickup device by the lens and causing a false image.

[0012] The present invention has been made based on the above findings, and an anti-aliased image detection device according to the present invention is a anti-aliased light detection device having a case window glass, a filter, a lens, and an image sensor. First means for imaging light from the object to be measured, second means for preventing reflected light generated between the case window glass, the filter and the lens from entering the imaging field of view, and the lens and the imaging means Third means for preventing reflected light between the lens and the filter from entering the imaging field of view and causing a false image by disposing an interference filter having an incident angle characteristic between the device and the element. It is characterized by the following.

Further, in the false image preventing light detecting device according to the present invention, the second means is configured to detect at least one of the glass and at least one of the glasses disposed at the front of the lens when detecting light from the object to be measured. A false image due to reflected light generated between one of the filters and between the filter and the lens is prevented by alternately arranging the filters and the glass at a predetermined angle. Things.

[0014]

Next, the present invention will be described in detail. The false image prevention light detection device of the present invention includes first means, second means, and third means. The first to third means will be specifically described below.

FIG. 5 is a diagram showing an outline of the photodetector of the present invention. In FIG. 5, an image sensor 22 (first means) is disposed in a camera body 23, and an interference film deposition filter 21 and a lens 20 are sequentially disposed on the front surface thereof. On the front surface of the lens 20, a color glass filter 19 is attached obliquely at an attachment angle θ, and further on the front surface, a window glass 18 of the case is attached alternately with the color glass filter 19 at an attachment angle θ. ing.

As described above, the window glass 1 is provided on the front of the apparatus.
8. A color glass filter 19 for cutting off sub-transmission light generated on the short wavelength side and the long wavelength side of the main transmission wavelength of the interference film deposition filter 21 is obliquely attached. The window glass 18 and the color glass filter 19 are staggered at an angle θ.
As shown by the arrow, the light reflected by the color glass filter 19 travels out of the field of view without being reflected by the window glass 18 and is reflected by the window glass 18 and enters the field of view of the apparatus. Preventing.

Further, by attaching the color glass filter 19 obliquely, the light reflected between the lens and the filter is prevented from entering the field of view of the camera as shown by the arrow in the figure (second). Means).

Further, as shown in FIG. 5, an interference film deposition filter 21 having an incident angle characteristic is
2, the light reflected by the interference film deposition filter 21 is prevented from being formed on the image sensor to cause a false image, and furthermore, a reduction in the amount of transmitted light at the wavelength to be detected is prevented. I have. By the above means, only a specific wavelength from the measurement object is imaged on the image sensor without being affected by the reflected light from the window glass 18, the lens 20, and the interference film deposition filter 21 of the case (second means). ).

[0019]

Next, the apparatus of the present invention will be described with reference to embodiments. FIG. 6C is a diagram showing a coil position detecting device using laser light, using the light detecting device of the present invention. FIG. 6A shows the relationship between the camera, the angle of view, and the field of view of the camera, and FIG. 6B shows the mounting angle of the filter. As shown in FIG. 6C, the laser projector 31
, A laser beam 32 is projected onto the coil 33 to be measured, and the reflected light is captured by a camera (photodetector 34).

From the projection angle of the laser light and the position of the reflected light of the laser light at this time, the shape of the coil is calculated using the principle of triangulation to obtain the three-dimensional position and shape of the coil. The coil to be measured has a surface property ranging from a state close to a mirror surface to a rusted and rough state, and there are many variations in the curved surface due to the difference in coil size. It was necessary to detect even light.

As shown in FIG. 5, as a light detecting device for detecting a laser beam, a window glass 18 is provided on the front surface of the device.
And a color glass filter 19 for cutting off the sub-transmission light generated on the short wavelength side and the long wavelength side of the main transmission wavelength of the interference film deposition filter 21 are alternately and obliquely attached at a predetermined angle.

FIGS. 7 and 8 are views for explaining the mounting angle of the color glass filter on the front surface of the lens according to the present invention. 7 and 8, reference numeral 41 denotes incident light, 42 denotes a camera optical axis, 43 denotes a lens (position), 44 denotes a color glass filter (position), and 45 denotes a focal position.

The mounting angle of the color glass filter 44 is
7 and 8, the angle of view of the camera is 2θ, the distance l between the lens 43 and the color glass filter 44, the angle at which the color glass filter is mounted, as shown in FIGS. Assuming θ ₁ and a lens radius r, a part 41 of the light incident from the left end of the angle of view is reflected by the lens surface 43 and further reflected by the color glass filter surface 44 as shown in FIG. At this time, if θ ₁ is determined so as to satisfy Expression 1, the reflected light will not be reflected outside the lens and will not produce a false image.

R <l · tan (θ + 2θ ₁ ) Equation 1 Further, as shown in FIG. 8, if θ ₁ ≧ θ, the light incident from the right end of the angle of view is reflected rightward with respect to the optical axis 42 of the lens. Is done. At this time, θ ₁ may be determined so as to satisfy Expression 2.

R <l · tan (θ₁) Formula 2 From formulas 1 and 2, the lens and the color glass filter
For the reflection between ₁≧ θ and satisfies Equation 1
So that θ₁By determining the reflected light of the lens
Can be prevented. Note that θ₁When = θ, light
Is perpendicularly incident on the filter and θ₁When <θ, light
Comes within the camera angle of view.

FIGS. 9 and 10 show the window glass of the present invention,
It is a figure explaining the attachment angle of a color glass filter.
In the figure, 42 is a camera optical axis, 45 is a focal position, 46
Indicates a window glass, and 47 indicates a color glass filter.

As for the reflection between the color glass filter and the window glass of the case, as shown in FIG. 9, the color glass filter 47 and the window glass 46 are mounted at different angles. Mounting angle theta ₂ of the window glass 46, the mounting angle theta ₁ color glass filter 47, the distance l between the window glass and colored glass filters, camera angle 2 [Theta], and lens radius r.

Light incident from the left end of the camera angle of view is such that the incident angle of the color glass filter is θ ₁ −θ, and when θ ₁ ≧ θ, the incident angle to the window glass is θ ₁ + θ _2. Is reflected to the opposite side of the lens. Further, as shown in FIG. 10, the light incident from the right end of the camera angle of view light incident angle is reflected at theta + theta _1, and the filter of the filter is incident at an incident angle θ + 2θ ₁ + θ ₂ on the window glass. At this time, by determining θ ₁ and θ ₂ so that a + b + c> 2r, the reflected light is reflected out of the lens. By determining θ ₁ and θ ₂ so that θ ₁ ≧ θ and a + b + c> 2r, the reflected light is reflected out of the lens and does not cause a false image.

A, b, and c are obtained by the following equations. a = l · tan (θ + 2θ ₁ ) b = sin (θ + 2θ ₁ ) · sin θ ₂ · ltan (θ + 2θ ₁ ) / sin
(90-2θ ₁ -θ ₂ -θ) c = ｛l + cos (θ + 2θ ₁ ) · sin θ ₂ .ltan (θ + 2θ ₁ )
/ Sin (90−2θ ₁ −θ ₂ −θ)｝ tan (θ + 2θ ₁ + 2θ ₂ ) By mounting as described above, a false image due to reflected light could be prevented. In mounting the filter, the number of filters is not limited, and a filter can be provided on the glass part.

Further, when an interference film deposition filter having an incident angle characteristic is attached by the above-described method, the main transmission wavelength shifts to the short wavelength side, and the transmittance of light to be originally detected decreases. Therefore, the interference film deposition filter is disposed between the lens and the image sensor to prevent light reflected by the interference film filter from being imaged on the image sensor by the lens.

With the above-described apparatus, it is possible to detect even weak light without being affected by a false image generated by reflected light from a window glass, a lens, and a filter, and to measure a three-dimensional shape of a coil to be measured with high accuracy. It became possible.

[0032]

As described above, according to the apparatus of the present invention, it is possible to detect only light of a specific wavelength from the object to be measured, and erroneous measurement and position detection due to the generation of reflected light are eliminated. Thereby, weak light can be detected, and measurement accuracy and detection ability are improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a conventional three-dimensional shape measuring apparatus.

FIG. 2 is a diagram showing identification of an incident angle of a conventional interference filter.

FIG. 3 is a diagram showing an outline of a conventional photodetector.

FIG. 4 is a diagram illustrating noise due to reflection of a conventional photodetector.

FIG. 5 is a diagram showing an outline of a photodetector of the present invention.

FIG. 6 is a diagram illustrating an outline of a coil position detecting device according to an embodiment of the present invention.

FIG. 7 is a diagram illustrating a filter mounting angle on the front surface of the lens according to the present invention.

FIG. 8 is a diagram for explaining a filter mounting angle on the front surface of the lens according to the present invention.

FIG. 9 is a diagram illustrating a filter and a glass mounting angle of the present invention.

FIG. 10 is a diagram for explaining a filter and a glass mounting angle of the present invention.

[Explanation of reference numerals] 1. Laser projection device 2. Laser beam 3. Object to be measured 4. Photodetector 5. Image processing device 6. Shape calculation device 7. Case window glass 8. Colored glass filter 9. Interference film Filter 10. Image sensor 11. Lens 12. Camera body 13. Light to be measured originally 14. Light generated by reflection 15. Noise generated by reflection 16. Light to be measured 17. Image screen 18. Window glass of case 19. Color Glass filter 20. Lens 21. Filter of interference film 22. Image sensor 23. Camera body 24. Camera field of view 25. Camera 26. Filter mounting angle 31. Laser projection device 32. Laser beam 33. Coil 34. Photodetection device 35 Image processing unit 36. Shape calculation unit 41. Incident light 42. Camera optical axis 43. Lens position 44. Filter 45. Focus position 46. Glass 47. Filter

Claims (2)

[Claims] 1. A false image prevention light detecting device having a case window glass, a filter, a lens, and an image sensor, wherein the first means for capturing an image of light from an object to be measured is generated between the case window glass, the filter, and the lens. A second means for preventing reflected light from entering the imaging field of view, and an interference filter having an incident angle characteristic between the lens and the imaging element, whereby reflected light between the lens and the filter is provided. And a third means for preventing a false image from being generated in the imaging field of view. 2. The method according to claim 1, wherein the second unit is configured to detect light from an object to be measured, between the at least one glass and the at least one filter, which is disposed on a front surface of the lens, and The false image preventing light according to claim 1, wherein false images due to reflected light generated between the filter and the lens are prevented by alternately arranging the filter and the glass at a predetermined angle. Detection device.