JP7379096B2 - Measuring device and light amount control method - Google Patents

Description

The present invention relates to a measuring device that specifies the shape and properties of a target object using a laser probe that irradiates the target object with laser light and receives the laser light reflected by the target object, and This invention relates to a light amount control method.

2. Description of the Related Art Measuring devices equipped with a laser probe are conventionally known (see, for example, Patent Document 1).
The measuring device described in Patent Document 1 is a device that uses a flying spot method to scan the surface of the measuring object with a laser beam to measure the shape of the measuring object. In other words, in this measurement device, a laser beam (spot light) from a laser light source (spot light source section) is guided to a scanning section composed of a galvanometer mirror, etc., and the scanning section changes the direction of reflection of the spot light to create a spot. The light is oscillated and the spot light is scanned over the surface of the measurement target. Then, the spot light reflected by the measurement target is imaged by an imaging unit (CMOS sensor), and the position of the spot light image in the captured image is detected, thereby detecting the position of the measurement target.

Furthermore, in a measuring device that uses a flying spot method to scan a spot light over the surface of a measurement target, diffused light from the measurement target is captured to measure the shape of the measurement target. Therefore, measurement accuracy depends on the amount of diffused light that is diffused on the surface of the measurement target, and it is necessary to adjust the amount of spot light so that the amount of diffused light above a certain value is received by the imaging unit. be. Therefore, many flying spot measuring devices are equipped with an automatic power control function (APC) that automatically adjusts the light intensity of the spot light.

Japanese Patent Application Publication No. 2014-509730

However, the output upper limit of the amount of spot light emitted by the laser light source is determined depending on the laser class. For this reason, depending on the reflectance of the measurement object, etc., the amount of diffused light may be insufficient, making measurement difficult for some measurement objects. For example, a measurement object with a black surface has a low reflectance, so the amount of diffused light reflected by the measurement object is insufficient, resulting in a decrease in measurement accuracy. Another problem is that increasing the power of the laser light source shortens the life of the laser light source.

SUMMARY OF THE INVENTION An object of the present invention is to provide a measuring device that can measure the shape of a measurement target with high measurement accuracy, and a method of controlling the amount of light in the measuring device.

A measuring device according to a first aspect of the present invention includes a spot light source that emits a spot light, a spot light source that reflects the spot light toward a measuring object, and a direction in which the spot light is reflected within a predetermined plane. a scanning unit that scans the spot light on the surface of the measurement target; a light receiving unit that receives the spot light reflected by the measurement target and detects the amount of the received spot light; a scan control section that controls a scanning speed, the scan control section controlling the scanning speed at which the light amount of the spot light is equal to or higher than a threshold value based on the light amount of the spot light received by the light receiving section. Scan the spot light.

In this aspect, the scanning speed of the spot light in the scanning section is changed so that the light amount of the spot light received by the light receiving section is equal to or greater than a threshold value. For example, when the amount of light received by the light receiving section is small, reducing the scanning speed increases the apparent amount of light received by the light receiving section. Therefore, even if the light reflectance of the surface of the measurement target is low or the upper limit of the power of the spot light source is low, the light receiving section can detect light with an amount of light above the threshold, allowing the measurement device to perform high measurements. The shape of the object to be measured can be measured with precision.

The measuring device according to the first aspect further includes an exposure control section that changes an exposure time for detecting the light amount of the spot light at the light receiving section, and the exposure control section is configured to control the light amount of the spot light received at the light receiving section. Based on this, it is preferable that the light receiving section receives the spotlight at the exposure time during which the amount of the spotlight becomes equal to or greater than a threshold value.

In this aspect, the amount of light received by the light receiving section is further increased by changing the exposure time at the light receiving section. Thereby, the amount of spot light received by the light receiving section can be increased more reliably. Further, when increasing the amount of spot light received by the light receiving section only by slowing down the scanning speed of the scanning section, the measurement time for measuring the shape of the object to be measured also becomes longer due to the reduction in the scanning speed. On the other hand, by controlling the scanning speed and controlling the exposure time in combination, it is possible to increase the amount of spot light received by the light receiving section while suppressing a decrease in the scanning speed.

A measuring device according to a second aspect of the present invention includes a spot light source that emits a spot light, a spot light source that reflects the spot light toward a measurement object, and a reflection direction of the spot light that is swung within a predetermined plane. a scanning section that scans the spot light on the surface of the measuring object; a light receiving section that receives the spot light reflected by the measurement target and detects the amount of the received spot light; an exposure control section that changes an exposure time for detecting a light amount, and the exposure control section is configured to detect the light amount of the spot light at a threshold value or more based on the light amount of the spot light received by the light receiving section. The light receiving section receives the spot light during an exposure time.

In this aspect, the amount of light received by the light receiving section is increased by changing the exposure time at the light receiving section.
As a result, even if the light reflectance of the surface of the measurement target is low or the power upper limit of the spot light source is low, the light receiving section can detect light with an amount of light above the threshold, and the measurement device can The shape of the object to be measured can be measured with high measurement accuracy. Furthermore, the amount of spot light received by the light receiving section can be increased without changing the scanning speed at the scanning section.

In the measuring device of the first aspect or the second aspect, the light receiving section is an imaging section that has a plurality of pixels and outputs a detection signal for each pixel according to the amount of light of the spot light received by the pixel. It is preferable.
In this aspect, the light receiving section is an image sensor configured with a plurality of pixels, and can capture a captured image based on a detection signal from each pixel. As a result, the measurement device detects the position of the spot light in the captured image, uses triangulation, etc., to calculate the position of the spot light irradiated on the measurement target, and measures the shape of the measurement target. be able to. In addition, as described above, the scanning speed of the scanning section or the exposure time of the light receiving section is controlled so that the light intensity of the spot light is equal to or higher than the threshold value, thereby accurately detecting the pixel position that received the spot light. can do.

The measuring device of the first aspect or the second aspect includes a light source driving section that controls turning on and off of the spot light source, and the light source driving section has a constant speed such that the scanning speed of the spot light by the scanning section is constant. Preferably, the spot light source is turned on during a period, and the spot light source is turned off during an acceleration/deceleration period in which the scanning speed is accelerated or decelerated.
In this aspect, the spot light source is turned on during a constant speed period in which the scanning speed of the scanning unit is constant, and is turned off during an acceleration/deceleration period. Generally, when using the flying spot method to scan the surface of a measurement target with a spot light, there will be unevenness in the scanning speed of the spot light at both ends of the scanning range where the scanning speed of the spot light is accelerated or decelerated, which will affect measurement accuracy. coming out. Therefore, the results of light reception by the light receiving section during the acceleration/deceleration period are usually not used to measure the shape of the object to be measured. If the spot light source continues to be turned on during such acceleration/deceleration periods, power will be wasted. On the other hand, in this aspect, the spot light source is turned off during the acceleration/deceleration period, and is turned on only during the constant velocity period, so power saving can be achieved.

A light amount control method according to a third aspect of the present invention includes a spot light source that emits a spot light, a spot light source that reflects the spot light toward a measurement object, and a direction in which the spot light is reflected within a predetermined plane. A light amount of a measuring device comprising: a scanning section that scans the spot light on the surface of the object; and a light receiving section that receives the spot light reflected by the measurement object and detects the amount of the received spot light. In the control method, the scanning section scans the spot light at a scanning speed such that the light amount of the spot light is equal to or higher than a threshold value based on the light amount of the spot light received by the light receiving section.
In this aspect, the same effect as the first aspect described above can be obtained, and even if the light reflectance of the surface of the measurement target is low or the upper limit of the power of the spot light source is low, the light receiving part will exceed the threshold value. The measuring device can measure the shape of the object with high measurement accuracy.

A light amount control method according to a fourth aspect of the present invention includes a spot light source that emits a spot light, a spot light source that reflects the spot light toward a measurement object, and a direction in which the spot light is reflected within a predetermined plane. A light amount of a measuring device comprising: a scanning section that scans the spot light on the surface of the object; and a light receiving section that receives the spot light reflected by the measurement object and detects the amount of the received spot light. In the control method, the light receiving section is caused to receive the spot light for an exposure time such that the light amount of the spot light is equal to or greater than a threshold value based on the light amount of the spot light received by the light receiving section.
In this aspect, the same effect as in the second aspect described above can be obtained, and even if the light reflectance of the surface of the measurement target is low or the power upper limit of the spot light source is low, the light receiving part will exceed the threshold value. The measuring device can measure the shape of the object with high measurement accuracy. Furthermore, the amount of spot light received by the light receiving section can be increased without changing the scanning speed at the scanning section.

1 is a schematic diagram showing a schematic configuration of a measuring device according to an embodiment of the present invention. FIG. 3 is a diagram showing the scanning speed in the scanning section of the present embodiment. FIG. 3 is a diagram showing the timing of turning on and turning off the laser light source of the present embodiment. 1 is a flowchart showing a measurement method using the measurement device of this embodiment. FIG. 3 is a diagram showing an example of the light amount of a spot light image detected by the imaging unit of the present embodiment. FIG. 3 is a diagram showing an example of the scanning speed of the scanning section of the present embodiment. FIG. 3 is a diagram showing the relationship between exposure time and exposure amount for one pixel of the imaging unit of the present embodiment.

An embodiment according to the present invention will be described below.
FIG. 1 is a schematic diagram showing a schematic configuration of a measuring device 1 including a laser probe 10 of this embodiment.
The measuring device 1 is a three-dimensional measuring device that non-contactly measures the shape of a target object (measurement target W) using a laser beam, and includes a laser probe 10 and a laser probe 10 that can be moved to an arbitrary position in three-dimensional space. and a control unit 30 that measures the shape of the measurement target W based on a signal from the laser probe 10.
Each configuration will be described in detail below.

[Configuration of laser probe 10]
As shown in FIG. 1, the laser probe 10 includes a laser irradiation optical system 110 (light source section) and a light receiving optical system 120.
The laser irradiation optical system 110 includes a laser light source 111, a reflection mirror 112, a scanning section 113, a scanning drive circuit 114, and a light source drive circuit 115.

The laser light source 111 is a spot light source that emits a point laser (hereinafter referred to as spot light).
The reflecting mirror 112 reflects the spot light emitted from the laser light source 111 toward the scanning section 113.
The scanning unit 113 is configured by, for example, a galvano mirror, and includes a mirror unit 113A, a drive shaft 113B, a drive motor 113C, and an encoder 113D.
The mirror unit 113A reflects the spot light reflected by the reflection mirror 112 toward the measurement target W.
The drive shaft 113B is a shaft that supports the mirror portion 113A, and is rotatable about the axis of the drive shaft 113B by the drive motor 113C.
The drive motor 113C is a drive source that rotates the drive shaft 113B about its axis. The drive motor 113C repeats rotation and reversal within a predetermined angular range. As a result, the direction of reflection of the spot light reflected by the mirror portion 113A changes within the same plane, and the spot light oscillates. That is, the spot light is scanned within the scanning range W0 of the surface of the measurement object W.
Encoder 113D detects the rotation angle of drive shaft 113B.
Note that here, an example is shown in which the spot light reflected by the reflecting mirror 112 is incident on the scanning unit 113, but a configuration in which the light emitted from the laser light source 111 is incident on the scanning unit 113 without passing through the reflecting mirror 112 is also possible. You can also use it as

The scan drive circuit 114 is configured by, for example, a driver circuit that controls the drive of the scan unit 113, and is connected to the control unit 30 and the light source drive circuit 115.
The scan drive circuit 114 calculates the angular velocity of the scan unit 113 based on the rotation angle of the drive shaft 113B detected by the encoder 113D of the scan unit 113.
Further, the scan drive circuit 114 drives the scan unit 113 based on a scan command from the control unit 30. This scanning command includes a swinging speed when swinging the spot light in the scanning unit 113, that is, a scanning speed of the spot light scanned on the measurement target W. Therefore, the scan drive circuit 114 controls the drive of the drive motor 113C of the scanning unit 113 so that the angular velocity calculated based on the encoder 113D becomes the scanning velocity included in the scan command.

FIG. 2 is a diagram showing the scanning speed of the scanning section 113 (galvano mirror).
The scan drive circuit 114 changes the direction in which the spot light is reflected by the scanning unit 113 so that the spot light moves back and forth in one direction on the surface of the measurement target W. Therefore, the scanning speed of the spot light is accelerated or decelerated at both ends of the spot light scanning range W0.
That is, when moving the spotlight in one direction from one end of the scanning range W0, the scanning drive circuit 114 accelerates the scanning speed of the scanning unit 113 at a predetermined acceleration during the predetermined acceleration period T1. Then, when the scanning speed reaches the scanning speed included in the scanning command from the control unit 30, the scanning drive circuit 114 maintains the scanning speed for a predetermined constant speed period T2 and directs the spot light in the one direction. move it to Thereafter, the scan drive circuit 114 decelerates the scanning speed of the scanning unit by a predetermined acceleration during a predetermined deceleration period T3, and reverses the scanning direction of the spot light. After the scanning direction of the spot light is reversed, the scan drive circuit 114 again accelerates the scanning speed of the scanning section during the acceleration period T1, and then scans the spot at a constant speed during the constant speed period T2 in which the scanning speed reaches a predetermined scanning speed. The light is scanned and the spot light is decelerated in a deceleration period T3. Thereafter, by scanning the spot light through the same process, the scanning speed is accelerated or decelerated at both ends of the scanning range W0 as described above, and the spot is scanned at a constant scanning speed in the area excluding both ends. Light scanning is performed. The acceleration period T1 and the deceleration period T3 correspond to the acceleration/deceleration period of the present invention.
Then, the scan drive circuit 114 outputs a timing signal to the light source drive circuit 115 at the timing of switching from the acceleration period T1 to the constant velocity period T2 and at the timing of switching from the constant velocity period T2 to the deceleration period T3.

The light source drive circuit 115 constitutes a light source drive section. The light source drive circuit 115 includes a driver circuit that controls driving of the laser light source 111 and the like, and is connected to the control section 30 and the scan drive circuit 114. When the light source drive command from the control section 30 is input, the light source drive circuit 115 controls turning on and off of the laser light source 111 in synchronization with the driving of the scanning section 113.
FIG. 3 is a diagram showing the timing of turning on and turning off the laser light source 111 by the light source drive circuit 115.
As shown in FIG. 3, the light source drive circuit 115 turns on the laser light source 111 during a constant velocity period T2 during which the scanning unit 113 scans the spot light at a constant scanning speed, and turns on the laser light source 111 during an acceleration period T1 and a deceleration period T3. The light source 111 is turned off. That is, when the light source drive circuit 115 receives a timing signal outputted from the scan drive circuit 114 at the timing of switching from the acceleration period T1 to the constant velocity period T2, the light source drive circuit 115 turns on the laser light source 111. When the light source drive circuit 115 receives a timing signal output at the timing of switching from the constant velocity period T2 to the deceleration period T3, the light source drive circuit 115 turns off the laser light source 111.

The light receiving optical system 120 includes an imaging lens 121 and an imaging section 122.
The imaging lens 121 forms an image of the spot light reflected in the scanning range W0 of the measurement target W on the imaging unit 122.
The imaging unit 122 includes, for example, an image sensor such as a complementary metal-oxide-semiconductor (CMOS). The imaging unit 122 includes a plurality of pixels (photoelectric conversion elements) arranged in a two-dimensional array, and each pixel receives light and outputs a detection signal according to the amount of the received light. In this embodiment, the imaging unit 122 is an image sensor driven by a rolling shutter type electronic shutter, and detection signals from each pixel are delayed by a predetermined delay time and sequentially output.
Furthermore, in the imaging unit 122 of this embodiment, the shutter time (the exposure time during which each pixel receives light) by the electronic shutter can be changed. That is, in the present embodiment, the imaging unit 122 receives an imaging command including an exposure time from the control unit 30, and determines the exposure time (shutter time) from the start of exposure to the end of exposure of each pixel as included in the imaging command. Set the exposure time and perform imaging processing.

Note that the laser probe 10 of this embodiment constructs a Scheimpflug optical system. In other words, the plane including the irradiation surface (scanning range W0) of the spot light scanned by the scanning section 113, the main surface of the imaging lens 121, and the imaging surface of the imaging section 122 intersect on the same straight line. An optical system has been constructed.

[Configuration of moving mechanism 20]
The moving mechanism 20 is a device that moves the laser probe 10 to an arbitrary position. Further, the moving mechanism 20 is provided with a position detection sensor (not shown) for detecting the position of the laser probe 10.
The specific configuration of the moving mechanism 20 is not particularly limited, and for example, the laser probe 10 may be held at the tip of a multi-joint arm and the angle of each arm of the multi-joint arm can be changed. In this case, an angle detection sensor such as a rotary encoder is provided to detect the rotation angle of each arm. Thereby, the control unit 30 can calculate the position and orientation of the laser probe 10 based on the arm length of each arm and the angle between the arms.
Furthermore, the moving mechanism 20 may be configured to be held by a portal frame that moves the laser probe 10 in the XYZ directions. In other words, the moving mechanism 20 includes a column movable in the Y direction, a beam held by the column parallel to the X direction, a slider movable on the beam in the X direction, and a slider provided on the slider to move in the Z direction. A movable head holding member may be provided, and the laser probe 10 may be held by the head holding member. In such a configuration, the moving mechanism 20 includes a Y scale for detecting the position of the column in the Y direction, an X scale for detecting the position of the slider in the X direction, and a Z scale for detecting the position of the head holding member in the Z direction. It may be configured as follows. Thereby, the XYZ coordinates of the laser probe 10 can be detected. The head holding member may be provided with an angle changing part that changes the angle of the laser probe 10, and in this case, the attitude of the laser probe 10 can be detected by providing an angle detection sensor in the angle changing part.

[Configuration of control unit 30]
The control unit 30 is configured by a computer, and includes a memory (not shown), an arithmetic circuit that executes various programs recorded in the memory, and the like. The control section 30 is connected to the laser probe 10 and the moving mechanism 20, and receives the imaging results (captured images) of the imaging section 122 of the laser probe 10 and the position and orientation of the laser probe 10 output from the moving mechanism 20. The shape of the measurement target W is measured based on .
Further, the control unit 30 adjusts the light amount of the laser probe 10 based on the imaging result from the imaging unit 122. Specifically, the control unit 30 controls the scanning speed of the scanning unit 113 based on the amount of spot light captured by the imaging unit 122.

Specifically, the control section 30 functions as a probe control section 31, a probe position detection section 32, and a shape calculation section 33, as shown in FIG.
The probe control section 31 functions as a lighting control section 311, a scanning control section 312, an imaging control section 313, and a light amount evaluation section 314.
The lighting control unit 311 outputs a drive command to drive the laser light source 111 to the laser probe 10. Thereby, the light source drive circuit 115 that has received the drive command controls the lighting drive of the laser light source 111. That is, the light source drive circuit 115 turns on the laser light source 111 during the constant speed period T2 in which the spot light is scanned at a constant scanning speed by the scanning unit 113, and turns on the laser light source 111 during the acceleration period T1 and the deceleration period T3. Turn off the lights.

The scan control section 312 outputs a scan command to the scanning section 113 to drive the scanning section 113. At this time, the scanning control unit 312 performs feedback control on the scanning unit 113 based on the amount of light of the spot light image received by the imaging unit 122. That is, the scan control unit 312 slows down the scanning speed of the spot light in the scanning unit 113 so that the light intensity of the spot light image received by the imaging unit 122 is equal to or greater than the threshold value. As a result, the light reception time at the pixel on which the spot light image is formed becomes longer, and the amount of light received by the pixel within the exposure time increases accordingly.

The imaging control unit 313 corresponds to the exposure control unit of the present invention, and outputs an imaging command including an exposure time to the imaging unit 122, and causes the imaging unit 122 to perform imaging processing. Thereby, the imaging unit 122 sets the exposure time based on the imaging command and performs imaging processing.
Further, the imaging control unit 313 feedback-controls the exposure time in the imaging unit 122 based on the light amount of the spot light image received by the imaging unit 122. In other words, the imaging control unit 313 lengthens the exposure time in the imaging unit 122 so that the amount of light of the spot light image received by the imaging unit 122 is equal to or greater than the threshold value. This increases the amount of light received by the pixel on which the spot light image is formed within the exposure time.

The light amount evaluation section 314 evaluates whether the light amount of the image of the spot light that is diffusely reflected by the measurement target W and imaged on the imaging section 122 is appropriate. That is, based on the detection signal output from the imaging unit 122, it is determined whether the light amount of the spot light image is equal to or greater than a preset threshold.
Here, the light amount of the spot light image refers to the light amount at the peak position where the light amount is maximum in the light amount distribution of the spot light in the captured image. In this embodiment, the laser light source 111 is a point light source, and an image of the spot light is formed on one of a plurality of pixels that constitute the imaging section 122. Therefore, it is sufficient to detect the amount of light at the pixel where the image of the spot light is formed. At this time, in this embodiment, the imaging unit 122 is driven by a rolling shutter method and the detection signals from each pixel are output independently, so it is not necessary to perform processing to analyze the light amount distribution such as image analysis. Therefore, the light intensity of the spot light image can be easily detected.
Note that the light intensity of the spot light image is proportional to the signal voltage of the detection signal, so it is determined whether the detection signal from the pixel on which the spot light image is formed is equal to or higher than a predetermined voltage threshold. Good too.

The probe position detection unit 32 receives a position detection result input from a position detection sensor of the moving mechanism 20 (for example, a detection value of an angle detection sensor such as a rotary encoder or a detection value of an XYZ scale). Then, the probe position detection unit 32 calculates the position and orientation of the laser probe 10 in the three-dimensional space based on the position detection result.

The shape calculation unit 33 calculates the shape of the measurement target W based on the imaging result output from the imaging unit 122, the angle detected by the encoder 113D, and the position and orientation of the laser probe 10 detected by the probe position detection unit 32. Measure surface shape and surface texture.

[Optical control method]
Next, a measurement method including a method of controlling the light amount of the laser probe 10 in the measurement apparatus 1 as described above will be explained.
FIG. 4 is a flowchart showing a method for measuring the measurement target W using the measuring device 1 of this embodiment.
When measuring the shape of the object W to be measured using the measuring device 1, first, the laser probe 10 is moved to a position facing the measurement location of the object W to be measured (step S1).

Next, the lighting control unit 311 of the probe control unit 31 outputs a lighting command for the laser light source 111 (step S2).
Furthermore, the scan control section 312 outputs a scan command to drive the scanning section 113 at a predetermined scanning speed (step S3). Note that the scanning speed of the scanning command output in step S3 is a preset initial scanning speed.
Further, the imaging control unit 313 outputs an imaging command to cause the imaging unit 122 to perform imaging processing (step S4). As described above, this imaging command includes the exposure time for each pixel, and the exposure time included in the imaging command output in step S4 is a preset initial exposure time.

The laser probe 10 that has received each command from step S2 to step S4 performs measurement processing based on each command (step S5).
That is, the scan drive circuit 114 performs scan control of the scanning unit 113 based on a scan command, and the light source drive circuit 115 performs lighting control based on the scan control.
Specifically, the scan drive circuit 114 outputs a first timing signal to the light source drive circuit 115 at the timing of switching from the acceleration period T1 to the constant velocity period T2. The light source drive circuit 115 has received the lighting command in step S2, and upon receiving the first timing signal, lights the laser light source 111 as shown in FIG. 3.
Moreover, the scan drive circuit 114 maintains the scanning speed included in the scanning command and causes the spot light to scan during the constant velocity period T2.
Then, the scan drive circuit 114 outputs a second timing signal to the light source drive circuit 115 at the timing of switching from the constant velocity period T2 to the deceleration period T3. Upon receiving the second timing signal, the light source drive circuit 115 turns off the laser light source 111, as shown in FIG. Thereafter, until the measurement process by the laser probe 10 is completed, drive control of the scanning unit 113 and control of turning on and off the laser light source 111 in conjunction with the scanning unit 113 are repeatedly performed.

Further, in step S4, the imaging unit 122 that has received the imaging command captures an image of the spot light reflected on the surface of the measurement target W based on the imaging command. That is, the imaging unit 122 sets the exposure time for each pixel from the start of exposure to the end of exposure based on the imaging command, and outputs a detection signal from each pixel according to the amount of light received within the set exposure time.

Thereafter, the light amount evaluation unit 314 determines whether the light amount of the spot light image is equal to or greater than a threshold value based on the detection signal output from the imaging unit 122 in step S5 (step S6).
As described above, in this embodiment, the imaging unit 122 is an image sensor driven by a rolling shutter method, and detection signals from each pixel are sequentially output. Therefore, the light amount evaluation unit 314 identifies the pixel on which the image of the spot light (point light source) is formed based on the signal value of the detection signal, without forming a captured image based on the detection signals of all pixels. Based on the signal value, it can be determined whether the amount of light is equal to or greater than the threshold value.

If the determination in step S6 is NO, the scanning control unit 312 and the imaging control unit 313 control the scanning unit 113 and the imaging unit 122 based on the light intensity of the image of the spot light so that the light intensity is equal to or greater than the threshold value. Feedback control.
Specifically, the scan control unit 312 calculates a difference value between the light amount of the spot light image detected in step S5 and the threshold value, and corrects the scanning speed based on the difference value (step S7). Similarly, the imaging control unit 313 corrects the exposure time based on the difference value between the light amount of the spot light image and the threshold value (step S8).
For example, a memory (not shown) provided in the control unit 30 stores speed correction data indicating a speed correction value for the difference value between the light amount of the spot light image and the threshold value, and speed correction data indicating the speed correction value for the difference value between the light amount of the spot light image and the threshold value. Time correction data indicating a time correction value for the difference value is stored in advance. Then, the scan control unit 312 reads a speed correction value corresponding to the difference value between the light intensity of the spot light image detected in step S5 and the threshold value from the speed correction data, and applies (for example, subtracts) the speed correction value to the current scanning speed. Then, calculate the new scanning speed. Similarly, the imaging control unit 313 reads a time correction value corresponding to the difference value between the light intensity of the spot light image detected in step S5 and the threshold value from the time correction data, and applies (for example, adds) the time correction value to the current exposure time. and calculate a new exposure time.
Thereafter, the scan control unit 312 outputs a scan command including the scan speed corrected in step S7 to the scan drive circuit 114, and the imaging control unit 313 outputs an imaging command including the exposure time corrected in step S8. The image is output to the imaging unit 122 (step S9), and the process returns to step S5.

FIG. 5 is a diagram illustrating an example of the light amount of the spot light image detected by the imaging unit 122. FIG. 6 is a diagram showing an example of the scanning speed in the scanning section 113. FIG. 7 is a diagram showing an example of the exposure time for one predetermined pixel of the imaging unit 122, and shows the relationship between the exposure time and the amount of exposure (amount of received light) in the imaging unit 122. The broken line in FIG. 6 indicates the initial scanning speed V ₀ , the broken line in FIG. 7 indicates the initial exposure time I ₀ , and the broken line in FIG. 5 indicates the initial scanning speed V ₀ and the initial exposure time. 7 is a diagram showing the light amount of a spot light image detected by the imaging unit 122 when the exposure time is _I0 . FIG. In addition, in FIG. 7, I _out indicates a period during which the charges accumulated in the pixel due to exposure are released, that is, a transfer period during which the detection signal is output to the control unit 30. As shown in FIG. Even if you change , the time of the transfer period does not change.
In steps S7 to _S9 described above, as _shown in FIG. As shown, the scanning speed of the scanning unit 113 is reduced. Furthermore, the imaging control unit 313 increases the exposure time of each pixel of the imaging unit 122, as shown in FIG. As a result, as shown in FIG. 5, the light amount of the spot light image detected by the imaging unit 122 increases and becomes equal to or greater than the threshold value S _th .

If the determination is YES in step S6, the shape calculation unit 33 performs shape measurement processing on the measurement target W based on the imaging result (captured image) obtained from the imaging unit 122 in step S5 ( Step S10). The shape measurement process by the shape calculation unit 33 can use a known technique, for example, triangulation. At this time, the position of the spot light image is specified based on the imaging result (captured image) by the imaging unit 122, but since the amount of light exceeding the threshold is detected from the pixel where the spot light image is formed, The shape calculation unit 33 can specify the position of the spotlight in the captured image with high accuracy. This makes it possible to improve the accuracy of shape measurement by the shape calculation unit 33.

[Actions and effects of this embodiment]
The measuring device 1 of this embodiment includes a laser probe 10 and a control section 30. The laser probe 10 includes a laser light source 111 (spot light source), a scanning section 113, and an imaging section 122. Laser light source 111 emits spot light. The scanning unit 113 reflects the spot light toward the measurement target W, swings the reflection direction of the spot light within a predetermined plane, and causes the spot light to scan the surface of the measurement target W. The imaging unit 122 receives the spot light reflected by the measurement target and detects the amount of the received spot light. The control unit 30 also includes a scan control unit 312 that controls the scanning speed at which the spot light is oscillated by the scanning unit 113. Based on this, the spot light is oscillated at a scanning speed at which the light amount of the image of the spot light is equal to or greater than the threshold value.

Therefore, for example, even if the reflectance of the surface of the measurement target W is low and the amount of light of the spot light image formed on the imaging unit 122 is small, the scanning speed of the scanning unit 113 can be reduced to reduce the image of the spot light. The time required for the spot light to pass over the pixel becomes longer, and the amount of light of the spot light image received by the pixel increases. Therefore, when identifying the pixel position where the spot light image is formed based on the imaging result of the imaging unit 122, it is possible to accurately identify the pixel position based on the light intensity of the spot light image. The measuring device 1 can measure the shape of the object W to be measured with high measurement accuracy.

The measuring device 1 of this embodiment further includes an imaging control section 313 (exposure control section) that controls the imaging process in the imaging section 122 by changing the exposure time of each pixel of the imaging section 122. Then, based on the light intensity of the spot light image received by the image capturing unit 122, the image capturing control unit 313 performs image capturing processing in the image capturing unit 122 at an exposure time such that the light intensity of the spot light image is equal to or greater than a threshold value. do.
As a result, even if, for example, the reflectance of the surface of the measurement target W is low and the amount of light of the spot light image formed on the imaging section 122 is small, the light can be received by increasing the exposure time of each pixel of the imaging section 122. In the pixel where the image of the spot light is formed, the amount of received light that is equal to or greater than the threshold value can be detected. Therefore, when identifying the pixel position where the spot light image is formed based on the imaging result of the imaging unit 122, it is possible to accurately identify the pixel position based on the light intensity of the spot light image. The measuring device 1 can measure the shape of the object W to be measured with high measurement accuracy.

Furthermore, if the light amount is adjusted only by feedback control of the scanning speed by the scanning section 113 by the scanning control section 312, the scanning speed of the scanning section will decrease, and the measurement time for shape measurement may become longer. Further, even if the scanning speed by the scanning unit 113 is slowed down, if the exposure time at each pixel by the imaging unit 122 is short, there is a limit to improving the amount of light received at each pixel. Conversely, even if the exposure time is lengthened, if the scanning speed by the scanning unit 113 is fast, the amount of light received by each pixel will be small.
In contrast, in this embodiment, by performing both feedback control of the scanning speed of the scanning unit 113 and feedback control of the exposure time of each pixel of the imaging unit 122, the scanning speed is excessively slowed down. The scanning speed of the scanning unit 113 and the exposure time of each pixel of the imaging unit 122 can be set to appropriate values in a well-balanced manner without the need to do so or make the exposure time excessively long. In other words, it is possible to suppress the lengthening of the measurement time for shape measurement by the measuring device 1 and to improve the measurement accuracy related to shape measurement.

In this embodiment, a plurality of pixels (photoelectric conversion elements) are arranged in an array as a light receiving unit that detects the amount of light of a spot light image, and a detection signal corresponding to the amount of light received by the pixel is output for each pixel. An imaging unit 122 is used.
Thereby, the measuring device 1 can easily identify the pixel position of the spot light based on the captured image that is the captured image obtained by the imaging unit 122. By calculating the position of the spot light, the shape of the measurement target W can be measured.

In this embodiment, the laser probe 10 includes a light source drive circuit 115 that controls turning on and off of the laser light source 111, and this light source drive circuit 115 operates during a constant velocity period during which the scanning speed of the spot light by the scanning unit 113 is constant. At T2, the laser light source 111 is turned on to emit a spot light, and during an acceleration period T1 and a deceleration period T3 in which the scanning speed is accelerated or decelerated, the laser light source 111 is turned off.
Generally, when the surface of the measurement target W is scanned with a spot light using the flying spot method, the scanning speed is not stable during the acceleration period T1 and the deceleration period T3 at both ends of the scanning range, resulting in variations in measurement results. Therefore, the imaging results during the acceleration period T1 and the deceleration period T3 are usually not used for shape measurement.
In the present embodiment, by turning off the laser light source 111 during the acceleration period T1 and the deceleration period T3, the power consumption of the laser light source 111 can be suppressed, and the decrease in the life of the laser light source 111 can also be suppressed.

[Modified example]
Note that the present invention is not limited to the above-described embodiments, and the present invention includes modifications, improvements, etc. within a range that can achieve the purpose of the present invention.
[Modification 1]
For example, in the embodiment described above, the imaging unit 122 is driven by a rolling shutter method, and the detection signals from each pixel are sequentially output with a predetermined delay time, but the present invention is not limited to this. The imaging unit 122 may be driven using a global shutter method, and detection signals from all pixels may be output simultaneously. Even in this case, since the laser light source 111 is a point light source, the number of pixels on which the spot light image is formed is one, and by detecting the light amount of each pixel, the pixel on which the spot light image is formed, and The amount of light can be easily detected.

Furthermore, in the embodiment described above, the image of the spot light is formed on one pixel, but the image of the spot light may be formed over a plurality of pixels. In this case, the light amount evaluation unit 314 may specify the imaging center of the spot light by image analysis or the like and detect the light amount at the imaging center.

[Modification 2]
In the embodiment described above, the control unit 30 of the measuring device 1 controls the scanning speed of the scanning unit 113 and each pixel of the imaging unit 122 so that the light intensity of the spot light image detected by the imaging unit 122 is equal to or higher than the threshold value. An example of feedback control of both the exposure time and the exposure time was shown. On the other hand, the measuring device 1 may be configured to feedback-control only the scanning speed of the scanning unit 113 so that the light intensity of the spot light image is equal to or greater than the threshold value. Alternatively, the measuring device 1 may be configured to perform feedback control only on the exposure time in each pixel of the imaging unit 122 so that the light amount of the spot light image is equal to or greater than a threshold value. In this case, the configuration related to light amount control of the laser probe 10 can be simplified.

The present invention can be applied to a measuring device that irradiates light onto a predetermined linear range of an object and receives the light reflected in the linear range with a line sensor.

DESCRIPTION OF SYMBOLS 1... Measuring device, 10... Laser probe, 30... Control part, 31... Probe control part, 32... Probe position detection part, 33... Shape calculation part, 110... Laser irradiation optical system, 111... Laser light source, 112... Reflection mirror , 113...Scanning unit, 113A...Mirror unit, 113B...Drive shaft, 113C...Drive motor, 113D...Encoder, 114...Scanning drive circuit, 115...Light source drive circuit (light source drive unit), 120...Light receiving optical system, 121... Imaging lens, 122...imaging section (light receiving section), 311...lighting control section, 312...scanning control section, 313...imaging control section, 314...light amount evaluation section, W...measurement target.

Claims (6)

a spot light source that emits spot light;
a scanning unit that reflects the spot light toward the measurement target, swings the reflection direction of the spot light within a predetermined plane, and scans the spot light on the surface of the measurement target;
a light receiving unit that receives the spot light reflected by the measurement target and detects the amount of light of the received spot light;
a scanning control unit that controls the scanning speed of the spot light by the scanning unit;
an exposure control unit that changes an exposure time for detecting the light amount of the spot light in the light receiving unit;
Equipped with
The scanning control unit causes the spot light to scan at the scanning speed such that the light quantity of the spot light is equal to or higher than a threshold value based on the light quantity of the spot light received by the light receiving unit ,
The exposure control section causes the light receiving section to receive the spot light at the exposure time such that the light amount of the spot light is equal to or greater than a threshold value based on the light amount of the spot light received by the light receiving section.
A measuring device characterized by: a spot light source that emits spot light;
a scanning unit that reflects the spot light toward the measurement target, swings the reflection direction of the spot light within a predetermined plane, and scans the spot light on the surface of the measurement target;
a light receiving unit that receives the spot light reflected by the measurement target and detects the amount of light of the received spot light;
a scanning control unit that controls the scanning speed of the spot light by the scanning unit,
The light receiving unit is an imaging unit that has a plurality of pixels and outputs a detection signal for each pixel according to the amount of the spot light received by the pixel,
The scanning control section causes the spot light to scan at the scanning speed such that the light amount of the spot light is equal to or higher than a threshold value based on the light amount of the spot light received by the light receiving section.
A measuring device characterized by: a spot light source that emits spot light;
a scanning unit that reflects the spot light toward the measurement target, swings the reflection direction of the spot light within a predetermined plane, and scans the spot light on the surface of the measurement target;
a light receiving unit that receives the spot light reflected by the measurement target and detects the amount of light of the received spot light;
a scanning control unit that controls the scanning speed of the spot light by the scanning unit;
A light source drive unit that controls turning on and turning off the spot light source ,
The scanning control unit causes the spot light to scan at the scanning speed such that the light quantity of the spot light is equal to or higher than a threshold value based on the light quantity of the spot light received by the light receiving unit,
The light source driver turns on the spot light source during a constant velocity period in which the scanning speed of the spot light by the scanning section is constant, and turns off the spot light source in an acceleration/deceleration period in which the scanning speed is accelerated or decelerated. A measuring device characterized by: a spot light source that emits a spot light; a scanning unit that reflects the spot light toward the measurement target and swings the reflection direction of the spot light within a predetermined plane to scan the spot light on the surface of the measurement target ; a light receiving section that receives the spot light reflected by the measurement target and detects the amount of the received spot light ; and an exposure control that changes an exposure time for detecting the amount of the spot light with the light receiving section. 1. A light amount control method for a measuring device comprising :
Based on the amount of the spot light received by the light receiving section, the scanning section scans the spot light at a scanning speed such that the amount of the spot light is equal to or higher than a threshold value, and the spot light is received by the light receiving section. Based on the light amount of the spot light, the light receiving unit is caused to receive the spot light at the exposure time such that the light amount of the spot light is equal to or greater than a threshold value.
A light amount control method characterized by: a spot light source that emits a spot light; a scanning unit that reflects the spot light toward the measurement target and swings the reflection direction of the spot light within a predetermined plane to scan the spot light on the surface of the measurement target; and a light receiving unit configured to receive the spot light reflected by the measurement target and detect the amount of the received spot light, the light receiving unit having a plurality of pixels, and the light receiving unit configured to detect the amount of light received by the pixel. A light amount control method of a measuring device that is an imaging unit that outputs a detection signal corresponding to the light amount of the spot light for each pixel, the method comprising:
Based on the light amount of the spot light received by the light receiving section, the light amount of the spot light is determined to be a threshold value.
A light amount control method, characterized in that the spot light is scanned by the scanning unit at a scanning speed equal to or higher than a value . a spot light source that emits a spot light; a scanning unit that reflects the spot light toward the measurement target and swings the reflection direction of the spot light within a predetermined plane to scan the spot light on the surface of the measurement target; Light intensity control of a measuring device including a light receiving unit that receives the spot light reflected by the measurement target and detects the intensity of the received spot light, and a light source drive unit that controls turning on and off of the spot light source. A method,
Based on the light amount of the spot light received by the light receiving section, the light amount of the spot light is determined to be a threshold value.
The scanning section scans the spot light at a scanning speed equal to or higher than the scanning speed, and the spot light source is turned on during a constant speed period during which the scanning speed of the spot light by the scanning section is constant, and the scanning speed increases. The spot light source is turned off during the acceleration/deceleration period.
A light amount control method characterized by:

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