JP3554268B2 - Light beam irradiation measurement device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention emits a light beam from a light beam radiator to an object to form an irradiation spot on the surface of the object, receives reflected light from the object, and receives an object from the light beam radiator. The present invention relates to a light beam irradiation measurement device for measuring a distance to an irradiation spot on a surface of a target or a three-dimensional shape of a surface of an object.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as shown in Japanese Patent Application Laid-Open No. H10-38511, this type of apparatus has a reflectivity difference due to a difference in the reflectance of the surface of a different object and a difference in the position of the same object. In order to prevent the measurement accuracy from being deteriorated due to the difference in the amount of reflected light due to the difference, the following measures have been adopted. A first measure is to take out a part of the reflected light guided to a light receiver for measuring the distance or the three-dimensional shape by a beam splitter, and to guide the light to a photosensor for detecting the amount of received light. The light amount of the light beam emitted from the light beam radiator to the object is corrected based on the detected light reception amount. The second measure is to derive the amount of reflected light separately from the measurement of the distance or the three-dimensional shape using the reflected light received by the light receiver for measuring the distance or the three-dimensional shape. The light quantity of the light beam emitted from the light beam radiator to the object is corrected by the derived light quantity.
[0003]
[Problems to be solved by the invention]
However, in the first conventional measure described above, the amount of reflected light received by the light receiver for measuring the distance or the three-dimensional shape is reduced, so that the accuracy of the distance or three-dimensional shape measurement is reduced. There was a problem of getting worse. Further, since the beam splitter requires a certain size and is not inexpensive, there are problems that the whole apparatus becomes large and the manufacturing cost increases. In the second countermeasure, since the light receiver for measuring the distance or the three-dimensional shape is usually composed of a plurality of independent light receiving elements, a detection signal is extracted from each of these light receiving elements. Requires a certain amount of time, and also requires time to derive the amount of reflected light from the extracted detection signal, so the amount of light beam emitted from the light beam radiator to the target in real time is corrected There is a problem that you can not.
[0004]
Summary of the Invention
The present invention has been made to address the above problems, and has as its object to correct in real time the light quantity of a light beam emitted from a light beam radiator to an object without increasing the size of the apparatus at low cost. Accordingly, it is an object of the present invention to provide a light beam irradiation measurement device with improved distance or three-dimensional shape measurement accuracy.
[0005]
The present inventors have made various attempts to achieve the above-mentioned object, and while performing various attempts to measure the distance or the three-dimensional shape, a photodetector that receives reflected light from an object is also partially used. I discovered that the light was reflecting. Then, paying attention to the reflected light from the light receiver, the amount of the reflected light from the light receiver is detected, and the light amount of the light beam emitted from the light beam radiator to the object is corrected using the detected light amount. Thought about doing.
[0006]
The present invention configured using this idea provides a light beam radiator that emits a light beam toward an object to form an irradiation spot on the surface of the object, and a light beam that reflects light reflected from the surface of the object. A light receiver that receives light at a position corresponding to the distance from the radiator to the irradiation spot on the surface of the object, and a light beam radiator that receives light from the light beam radiator in accordance with the position of the reflected light received by the light receiver. In a light beam irradiation measuring device for measuring a distance to an irradiation spot or a three-dimensional shape of a surface of an object, a photo sensor for receiving reflected light reflected from a light receiving surface of a light receiver and detecting an amount of the reflected light. And a light amount correcting means for correcting the light amount of the light beam emitted from the light beam radiator to the object in accordance with the amount of light received by the photo sensor.
[0007]
In this case, for example, the light receiver is constituted by a line sensor in which a plurality of light receiving elements are arranged in a line, and the photo sensor is elongated in a direction corresponding to the arrangement direction of the plurality of light receiving elements constituting the line sensor. It is good to form it.
[0008]
According to this, it is not necessary to use a relatively large and expensive beam splitter, and since the reflected light is not divided unlike the beam splitter, the amount of reflected light received by the light receiver is reduced. Without doing so, the accuracy of distance or three-dimensional shape measurement is improved, and the entire device can be manufactured compactly and inexpensively. In addition, since the amount of reflected light from the light receiver can be easily and quickly extracted by the photosensor, the amount of light emitted from the light beam radiator to the object can be corrected in real time.
[0009]
Embodiment
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a light beam irradiation measurement apparatus according to the embodiment.
[0010]
This light beam irradiation measurement device includes a light beam radiator 10 including a laser light source 11, a condenser lens 12, a light amount control circuit 13, and the like. The laser light source 11 is configured by a semiconductor laser or the like, and emits laser light toward the condenser lens 12. The condenser lens 12 condenses the laser light emitted from the laser light source 11 to form a small irradiation spot on the surface of the object OB. The light amount control circuit 13 controls the laser light source 11 to control the light amount of the laser light emitted from the laser light source 11.
[0011]
A scanning optical system 20 for changing the position of the irradiation spot on the surface of the object OB and scanning the surface of the object OB with the irradiation spot is provided on the path of the laser light condensed by the condenser lens 12. Is provided. The scanning optical system 20 includes a plurality of mirrors that reflect laser light, an electric motor that rotates one of the plurality of mirrors, a rotation angle sensor that detects a rotation angle of the electric motor, and the like. The detection signal from the rotation angle sensor is supplied to a controller 40 described later, and the rotation of the electric motor is controlled by the controller 40 using the detection signal. The spot scans the surface of the object OB two-dimensionally (X-axis direction and Y-axis direction).
[0012]
The light beam irradiation measurement device also includes an imaging lens 31 and a line sensor (light receiver) 32. The imaging lens 31 forms an image of the reflected light from the object OB on the line sensor 32. The line sensor 32 is configured in a long shape by arranging a plurality of light receiving elements such as CCDs in a line, and measures the distance from the laser light source 11 to the irradiation spot of the object OB via the scanning optical system 20. The detection is performed based on the position of the light receiving element that has received the reflected light from the object OB among the plurality of light receiving elements. Specifically, as shown in FIG. 2, when the distance is long (see the solid line of the object OB in the figure), the light receiving element located above the line sensor 32 in the figure receives the reflected light. When the distance is short (see the figure, see the two-dot chain line of the object), the light receiving element located below the line sensor 32 in the figure receives the reflected light.
[0013]
The optical axis L1 of the imaging lens 31 may be set so as to pass through the center of the line sensor 32. Further, as the reflection position of the laser light from the laser light source 11 on the surface of the object OB becomes closer to the laser light source 11, the focal position of the reflected light becomes farther from the imaging lens 31, so that the light receiving surface of the line sensor 32 is extended. The direction (that is, the elongate direction) is set to be inclined at a predetermined angle from 90 degrees with respect to the optical axis L1. Due to the structure of the apparatus itself, the illustrated angle θ between the optical axis L1 and the direction in which the light receiving surface of the line sensor 32 extends is set to an angle determined between 42.5 degrees and 60.0 degrees. Also, due to this inclination, the direction of reflection of the light reflected by the line sensor 32 does not overlap with the direction of the light reflected from the object incident on the line sensor 32 from the imaging lens 31. Guide to the photosensor 61 to be performed.
[0014]
A sensor signal extracting circuit 33 is connected to the line sensor 32. The sensor signal extracting circuit 33 sequentially extracts signals indicating the amount of reflected light received from each light receiving element of the line sensor 32 and supplies the signals to the controller 40.
[0015]
As described above, the controller 40 receives the detection signal from the rotation angle sensor and rotates the electric motor to rotate the mirror, thereby two-dimensionally irradiating the surface of the object OB with the irradiation spot (in the X-axis direction and the X-axis direction). It has a function of scanning in the Y-axis direction). Further, the controller 40 has a function of outputting a light amount command signal, which is set automatically or manually, and indicates a light amount of the laser light emitted from the laser light source 11 to the light amount control circuit 13, and an output from the sensor signal extracting circuit 33. It has a function of measuring the distance from the laser light source 11 to the surface of the object OB by inputting a signal and measuring the three-dimensional shape of the surface of the object OB based on the distance. The measurement of the distance and the three-dimensional shape is based on the position of the light receiving element that receives the reflected light at the line sensor 32, that is, the principle of the triangulation method based on the light receiving position of the reflected light at the line sensor 32. It is performed using. The controller 40 is usually configured by a microcomputer or the like and is program-controlled, but may be configured by a hardware circuit.
[0016]
A light amount command correction circuit 50 is connected between the controller 40 and the light amount control circuit 13. The light quantity command correction circuit 50 corrects the light quantity command signal from the controller 40 according to a correction signal from a correction signal generation circuit 62 described later, and supplies the corrected light quantity command signal to the light quantity control circuit 13.
[0017]
Further, the light beam irradiation measuring device includes a photo sensor 61 for receiving the reflected light reflected from the line sensor 32 and detecting the amount of the received reflected light. As shown in FIGS. 1 to 3, the photosensor 61 is formed in a long rectangular shape on a long rectangular parallelepiped substrate 61a, and is made of any one of a photodiode, a phototransistor, and a photoresistance. The optical sensor element 61b is fixed. The optical sensor element 61b is configured so as to face the light receiving surface of the line sensor 32 and receive reflected light from all the light receiving elements constituting the line sensor 32. It corresponds to the arrangement direction of the plurality of light receiving elements to be configured.
[0018]
A correction signal generation circuit 62 is connected to the photo sensor 61. The correction signal generation circuit 62 outputs a correction signal corresponding to the amount of light received by the line sensor 32 detected by the photo sensor 61 to the light amount command correction circuit 50. That is, if the received light amount of the reflected light is smaller than the predetermined reference amount, the correction signal generation circuit 62 outputs a correction signal for correcting the light amount command signal from the controller 40 in a direction indicating an increase in the light amount. Output to the circuit 50. If the received light amount of the reflected light is larger than a predetermined reference amount, a correction signal for correcting the light amount command signal from the controller 40 in a direction indicating a decrease in the light amount is output to the light amount command correction circuit 50.
[0019]
Next, the operation of the embodiment configured as described above will be described. The controller 40 outputs a light amount command signal, which is set automatically or manually and indicates the light amount of the laser light emitted from the laser light source 11, to the light amount control circuit 13 via the light amount command correction circuit 50. Accordingly, the laser light source 11 is controlled by the light amount control circuit 13 and emits the laser light of the light amount corresponding to the light amount command signal toward the condenser lens 12. The condenser lens 12 condenses the laser light from the laser light source 11 and forms a small irradiation spot at a predetermined position on the surface of the object OB in cooperation with the scanning optical system 20.
[0020]
Due to the formation of the irradiation spot on the surface of the object OB, the laser light is reflected from the surface, and the reflected light is imaged on the line sensor 32 by the imaging lens 31. This image formation is performed on one or a small number of light receiving elements of the plurality of light receiving elements constituting the line sensor 32 and corresponding to the distance from the laser light source 11 to the irradiation spot. Then, the sensor signal extracting circuit 33 supplies the controller 40 with a signal indicating the image formation, that is, the light receiving element that has received the reflected light. The controller 40 calculates the distance from the laser light source 11 to the irradiation spot on the surface of the object OB based on the triangulation principle based on the supplied signal.
[0021]
On the other hand, the controller 40 receives a detection signal from the rotation angle sensor in the scanning optical system 20 and rotates the electric motor in the optical system 20 using the detection signal, thereby controlling the rotation in the optical system 20. By rotating some mirrors, the irradiation spot is moved two-dimensionally (X-axis direction and Y-axis direction) on the surface of the object OB, and the surface of the object OB is sequentially scanned. Then, the controller 40 sequentially calculates each distance from the laser light source 11 to the irradiation spot on the surface of the object OB for each irradiation spot as described above. Therefore, after the scanning of the surface of the object OB is completed, each distance from the laser light source 11 to each of the division positions of the object OB is divided for each of the two-dimensionally divided positions of the surface of the object OB. Are all measured.
[0022]
Then, finally, the controller 40 generates a three-dimensional image of the surface of the target object OB by image processing using each of the measured distances at each of the divided positions.
[0023]
During the measurement of the distance at each of the division positions, the line sensor 32 receives light reflected from the surface of the target object OB and reflects a part of the reflected light. Experiments by the present inventors have shown that the amount of reflected light is about 10% of the amount of light received by the line sensor 32. FIG. 3 shows the light receiving portion of the reflected light by fine points. The reflected light is received by the photo sensor 61, and the sensor 61 outputs a detection signal indicating the amount of the received reflected light to the correction signal generation circuit 62.
[0024]
The correction signal generation circuit 62 outputs a correction signal for correcting the light quantity command signal from the controller 40 in a direction indicating an increase in the light quantity when the received light quantity of the reflected light is smaller than a predetermined reference quantity. Output to Therefore, in this case, the light quantity command correction circuit 50 corrects the light quantity command signal from the controller 40 in a direction indicating an increase in light quantity, and outputs the signal to the light quantity control circuit 13. On the other hand, if the received light amount of the reflected light is larger than the predetermined reference amount, a correction signal for correcting the light amount command signal from the controller 40 in a direction indicating a decrease in the light amount is output to the light amount command correction circuit 50. Therefore, in this case, the light quantity command correction circuit 50 corrects the light quantity command signal from the controller 40 in a direction indicating a decrease in light quantity and outputs the signal to the light quantity control circuit 13.
[0025]
With such feedback control, the light amount control circuit 13 corrects and controls the light amount of the laser light emitted from the laser light source 11 so that the amount of reflected light received by the photosensor 61 becomes a predetermined reference amount. . The amount of light received by the photo sensor 61 and reflected from the line sensor 32 corresponds to the amount of light received by the line sensor 32 and reflected from the surface of the object OB. The correction of the light amount of the laser light according to the amount of light received by 61 is equivalent to the correction of the amount of light of the laser light according to the amount of light received by the line sensor 32.
[0026]
As a result, the amount of reflected light reflected by the surface of the object OB and received by the line sensor 32 is always kept at a substantially constant appropriate amount. Moreover, the light detected by the photo sensor 61 is reflected light from the line sensor 32, and the amount of reflected light received by the line sensor 32 does not decrease. Even if the amount is not so large, the line sensor 32 receives a sufficient amount of reflected light. Therefore, the accuracy of distance or three-dimensional shape measurement is improved without using a high-power laser light source 11.
[0027]
In addition, since the light amount of the reflected light from the line sensor 32 can be easily and quickly extracted by the photo sensor 61, the light amount of the laser light emitted from the laser light source 11 to the object OB can be corrected in real time. it can. Further, since the photosensor 61 is relatively small and inexpensive, the present measuring device does not become too large and is inexpensive.
[0028]
Further, the photo sensor 61, that is, the optical sensor element 61b is configured to be long along the arrangement direction of the light receiving elements so as to receive the reflected light from all the light receiving elements constituting the line sensor 32. Therefore, the reflected light from the line sensor 32 can be satisfactorily received, and the amount of laser light emitted from the laser light source 11 can be controlled with high accuracy.
[Brief description of the drawings]
FIG. 1 is an overall schematic diagram of a light beam irradiation measurement device according to an embodiment of the present invention.
FIG. 2 is an enlarged schematic diagram of an imaging lens, a line sensor, and a photo sensor unit of FIG.
FIG. 3 is an enlarged plan view of the photosensor of FIGS.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Light beam radiator, 11 ... Laser light source, 12 ... Condensing lens, 13 ... Light amount control circuit, 20 ... Scanning optical system, 31 ... Image forming lens, 32 ... Line sensor (receiver), 33 ... Sensor signal Take-out circuit, 40: controller, 50: light intensity command correction circuit, 61: photo sensor, 62: correction signal generation circuit.

Claims (2)

A light beam radiator that emits a light beam toward the object to form an irradiation spot on the surface of the object, and reflects light reflected from the surface of the object from the light beam radiator to the surface of the object. A light receiver for receiving light at a position corresponding to the distance to the irradiation spot, and a distance from the light beam radiator to the irradiation spot on the surface of the object according to the position of the reflected light received by the light receiver. Or in a light beam irradiation measurement device that measures the three-dimensional shape of the surface of the object,
A photosensor that receives the reflected light reflected from the light receiving surface of the light receiver and detects the amount of the received reflected light;
A light beam irradiation measuring device, comprising: light amount correcting means for correcting the light amount of a light beam emitted from the light beam radiator to the object according to the amount of light received by the photosensor. 2. The light beam irradiation measurement device according to claim 1, wherein the light receiver is constituted by a line sensor in which a plurality of light receiving elements are arranged in a line, and the photo sensor is formed by a plurality of light receiving elements constituting the line sensor. A light beam irradiation measuring device formed in a long shape corresponding to the arrangement direction.

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