JP2002090681A - Optical scanner and three-dimensional measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a small-sized and low-priced scanner whose actual scanning characteristics can be grasped. SOLUTION: This optical scanner 10, provided with a light source 11 which emits a light beam U and a scanning mechanism 13 deflecting or moving the light beam in parallel, is provided with an optical detector 18, optical devices 161 and 162 which form monitor light guides 16 that the light beam passes through from positions differing in passage time to the optical detector 18, and a means 31, which detect the relation between the time of scanning and the beam positions, based on signals indicating the passage time of the light beam at the positions obtained by the optical detector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device for sequentially irradiating different parts on an object and a three-dimensional measuring device using the same.

[0002]

2. Description of the Related Art An optical scanning type three-dimensional digitizer for performing distance measurement in many directions to convert a three-dimensional shape of an object into data has been developed.
It is used for data input to G system and CAD system, body measurement, visual recognition of robots, and the like. As the distance measurement method, the method using the principle of triangulation and the time from transmission to reception of a pulse (TOF: Time Of Flight)
There is something to measure. In any method, in order to obtain accurate shape data, it is necessary to understand the relationship between the elapsed time in optical scanning and the position of the optical axis, that is, the scanning characteristics.

Conventionally, in optical scanning in which a light beam is deflected by using a galvano scanner, feedback control for detecting a mirror angle position and adjusting rotational driving has been performed. Regarding the detection of the angular position, see Japanese Patent Application Laid-Open No. 7-3359.
No. 62 and Japanese Patent Application Laid-Open No. H11-144273 disclose a technique for performing angle detection using a dedicated light source and a light receiving element. In the optical detection in which the detection beam is reflected by the scanning mirror and made incident on the light receiving element, the influence of the change in the environmental temperature is smaller than the detection by the capacitance type angle sensor.

[0004]

By detecting the state of the scanning mechanism, errors due to variations in the characteristics of the scanning mechanism and changes in the characteristics due to changes in the environmental temperature (shifts between the control target and actual scanning). Can be corrected.

However, conventional optical detection using a light source dedicated to detection does not directly detect a light beam (main beam) irradiating an object to be scanned, so that the influence of errors caused by factors other than the operation of the scanning mechanism. There was a problem of receiving.
For example, if there is a displacement between the main light source that emits the main beam and the scanning mirror, the deflection angle indicated by the detected mirror angle and the actual deflection angle will be different. In addition, there is a problem that providing a light source dedicated to detection increases power consumption and complicates a control system.

An object of the present invention is to realize a small-sized and low-cost optical scanning device capable of grasping actual scanning characteristics.

[0007]

According to the present invention, there is provided an optical scanning apparatus comprising a light source for emitting an optical beam and a scanning mechanism for deflecting or translating the optical beam.
A photodetector, an optical device forming a monitor light guide path from a plurality of positions through which the light beam passes and at different passage times to the photodetector, and a plurality of positions obtained by the photodetector. Means for detecting the relationship between the scanning time and the beam position based on a signal indicating the passage time of the light beam in each case.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a block diagram of a three-dimensional digitizer according to a first embodiment.

The three-dimensional digitizer 1 includes a scanning device 10 for emitting slit light, and measures the shape of the object Q by a light cutting method. In the scanning device 10, the light source 11 includes a laser diode 111 and a lens group (collimator lens and cylindrical lens) 112. The laser diode 111 receives a power supply from the light emitting circuit 14 and emits a laser beam. The laser light passes through the lens group 112 and becomes the slit light U, and the mirror light of the galvano scanner 13 is
The light is reflected at 31 toward the object Q. The beam cross section of the slit light U has a linear band shape extending in a direction perpendicular to the plane of FIG. The slit light U is deflected by the galvano scanner 13, whereby the object Q is optically scanned.
In the scanning device 10, the monitor light guide path 16, the light receiving element 18, and the beam detection circuit 19 are provided so that the controller 31 can grasp the scanning characteristics. Monitor light guide 1
6 is composed of two optical fibers 161, 162,
The light is guided from different positions in the space through which the slit light U passes to the light receiving element 18. Optical fibers 161, 162
Is sufficiently smaller than the beam cross section of the slit light U at that position, and only a part of the slit light U is used as monitor light. The beam detection circuit 19 includes the light receiving element 18
The controller 31 sends a signal to the controller 31 indicating the passage of the slit light U, which is deflected at the input ends of the optical fibers 161 and 162, based on the output of the optical fibers 161 and 162.

The slit light U emitted from the scanning device 10
Is reflected on the surface of the object Q, and a part of the light returns to the three-dimensional digitizer 1 as reflected light U ′. The reflected light U ′ enters the area sensor 22 via the light receiving lens 21. The area sensor 22 outputs a signal corresponding to the amount of light received by each pixel during the exposure period according to a control signal from the drive circuit 23. The imaging information by the area sensor 22 is A / D-converted by the image processing circuit 32.
The data is converted and written into the memory 33 as image data. The triangulation calculation based on the image data in the memory 33 is performed by the controller 31. Controller 31
Takes into account the scanning characteristics in the triangulation calculation. That is, necessary correction is performed according to the difference between the angle command value given to the driver 15 of the galvano scanner 13 and the actual mirror angle. The distances (three-dimensional data) to each of the plurality of positions on the object Q are calculated by the triangulation. The calculated three-dimensional data is displayed on the display of the user interface 35. When the user instructs data storage, the three-dimensional data is recorded on the portable recording medium 34. As the recording medium 34, a smart media, a compact flash (registered trademark) card, or another memory card is suitable.

FIG. 2 is a diagram showing a beam detection method, and FIG. 3 is a graph showing scanning characteristics. The incident ends of the optical fibers 161 and 162 of the monitor light guide path 16 are arranged at angles θ1 and θ2 with respect to the reference direction about the rotation axis of the galvano scanner. It is preferable that the incident end face is directly opposed to the rotation center of the galvano scanner.

The slit light U is transmitted through optical fibers 161, 162
Is deflected to pass through the entrance end of As time elapses from the start of deflection (scanning) of the slit light U, the light receiving element 1
The output (light receiving signal) of No. 8 changes as shown in FIG.
Time points t1 and t2 when the deflection angles of the slit light U with respect to the reference direction become θ1 and θ2 from the light receiving signal are detected.

In FIG. 3, the command angle characteristic is an angle command value given to the driver 15 by the controller 31. In the figure, the transition of the angle command value is linear, and rotation at a constant angular velocity is commanded.

The time points t1, t1 detected by the light receiving element 18
Linear interpolation is performed based on t2, and the obtained characteristics are used as actual angle characteristics. From the actual angle characteristics, the actual scanning speed and scanning range can be known (strictly estimated). If the triangulation is performed using the deflection angle at the time during the scanning period indicated by the actual angle characteristic, the triangulation is more accurate than the calculation based on the commanded angle characteristic.
Dimension data can be calculated.

FIG. 4 is a diagram showing the principle of three-dimensional measurement. At a certain time, a case where reflected light from an object enters a pixel at an address m in the area sensor 22 is considered. If the arrangement relationship between the area sensor 22 and the light receiving lens 21 and the lens characteristics are known, the incident angle φm of the reflected light from the object with respect to the reference direction is obtained. The deflection angle θm at the time is obtained from the actual angle characteristics described above. Based on the base line length L (known), the incident angle φm, and the deflection angle θm from the starting point of the projection of the slit light to the principal point position of the light receiving lens 21, the distance Dm to the object is obtained by applying a triangulation calculation formula. Ask for.
Once the distance Dm is determined, the coordinates of the object surface in the direction in which the pixel of interest m of the area sensor 22 gazes can be calculated.

FIG. 5 is a flowchart of the schematic operation of the three-dimensional digitizer. The scanning conditions (scanning angular velocity, scanning angle range, exposure timing of imaging) according to the measurement range designated by the user are set (# 1). At this time, the scanning angle range always includes the positions of the angles θ1 and θ2.

The scanning is performed by driving the galvano scanner 13 and the area sensor 22 (# 2 to # 6). The three-dimensional data is calculated based on the image data obtained by the scanning and the actual angle characteristics (# 7), and the three-dimensional data is displayed (# 8). When the user performs a predetermined running operation, three-dimensional data is recorded (# 9, # 10).

FIGS. 6 and 7 show another example of the beam detection method. In the example of FIG. 6A, the monitor light guide path 1
One light receiving element 18a, 18b is provided for each of the optical fibers 161, 162 constituting 6A. This configuration is useful when the signals representing the time points t1 and t2 overlap as shown in FIG. The light receiving element 18a,
Since the signals 18b are independent, signals representing the time points t1 and t2 can be individually detected.

In the example of FIG. 7A, the monitor light guide path 16B
Are four optical fibers 161a, 162a, 161b, 1
Each of the two light receiving elements 18a and 18b detects the passage of the slit light U at the first and second positions. Output signal of light receiving element 18a and light receiving element 1
8b, it is possible to perform high-precision detection with the cross point with the output signal of time 8b as time points t1 and t2.
a, 18b can be eliminated.

FIG. 8 is a diagram showing a modification of the beam detection position. It is sufficient that the number of beam detection positions is two or more. The more the number is, the more accurate the actual angle characteristic can be obtained.

In FIG. 8A, the monitor light guide path 16C
Is composed of five optical fibers 161 to 165, and guides light to one light receiving element 18 from each of five positions separated from each other. In FIG. 8B, the monitor light guide path 16D is 5
Optical fibers 161 to 165,
One light receiving element 18 for each of 61 to 165
a, 18b, 18c, 18d, and 18e. In FIG. 8C, the monitor light guide path 16E is composed of five optical fibers 161 to 165, and guides light from each of five positions separated from each other to different pixels of one line sensor 18A. Line sensor 18A is CCD
Or a position detection type detector (PSD).

FIG. 9 is a view showing another embodiment of the monitor light guide path. 9A, the monitor light guide path 17 includes two fixed mirrors 171 and 172, and the slit light U
Is reflected to return to the line sensor 18A. The incident position of the slit light U in the line sensor 18A moves with the deflection of the slit light U. FIG. 9 (B)
In the example of FIG. 9, the line sensor 18A in the example of FIG.
, Two light receiving elements 18a and 18b are provided. The function of the monitor light guide path 17A is the same as that of the monitor light guide path 17.

In FIG. 9C, the monitor light guide path 17B
Is composed of one curved fixed mirror 173, and the first
Is guided to the light receiving element 18a, and the slit light U having the second deflection angle is guided to the light receiving element 18b.
In FIG. 9D, the monitor light guide path 17C is composed of one curved fixed mirror 174, and receives both the slit light having the first deflection angle and the slit light U having the second deflection angle as one light receiving element. Lead to 18. The slit light U having another deflection angle does not enter the light receiving element 18.

FIG. 10 is a diagram showing another example of the beam detection mode. FIG. 10A is a front view showing a beam detection position,
FIG. 10B is a side view showing a beam detection position.
(C) is a graph showing scanning characteristics.

As shown in FIGS. 10A and 10B, the monitor light guide path 16F includes a total of six optical fibers 161a, 162a, 16F.
1b, 162b, 161c and 162c. Two optical fibers are allocated to one end, the center and the other end in the length direction of the slit light U, and the incident end of the optical fiber is located at a position separated along the moving direction of the slit light U in each part. Are located. Such a configuration is useful when the relationship between the moving direction of the slit light U and the length direction of the slit light U changes. In the example, the actual angle characteristics can be obtained for three places in the length direction of the slit light U. In the case where the resolution of the beam detection and the resolution of the three-dimensional measurement area sensor 22 are different in the length direction of the slit light U (this is referred to as the horizontal direction), the actual angle characteristics obtained by the beam detection are used. First, an actual angle characteristic of each line along the vertical direction of the area sensor 22 is obtained by interpolation processing or thinning processing.

FIG. 11 is a diagram showing another example of beam detection by a fixed mirror. In FIG. 11, the monitor light guide path 1
7D includes a fixed mirror 175 and another fixed mirror (not shown). In the fixed mirror 175, only the vicinity of the periphery is a reflecting portion 1751, and the inside of the reflecting portion 1751 is a light transmitting portion 1752. The monitor light guide path 17D is also shown in FIG.
This is useful when the relationship between the moving direction of the slit light U and the length direction of the slit light U changes like the monitor light guide path 16F. [Second Embodiment] FIG. 12 is a configuration diagram of a three-dimensional digitizer according to a second embodiment. 12, elements having the same functions as those in the configuration example of FIG. 1 are denoted by the same reference numerals as in FIG. 1, and description thereof will be omitted.

The three-dimensional digitizer 2 measures the shape of the object Q by a light section method. In the three-dimensional digitizer 2, an area sensor 2 that receives reflected light U 'is used as a light receiving unit for detecting characteristics of scanning by the galvano scanner 13.
Use 2. Monitor light guide path 1 in scanning device 10G
6G guides light from a position apart from each other where the slit light U passes to a specific pixel of the area sensor 22. The configuration of the monitor light guide path 16G may be any of the above-described configurations using an optical fiber or a fixed mirror.

FIG. 13 is a flowchart showing another example of the operation of the three-dimensional digitizer. In response to the measurement start operation, preliminary scanning is performed under conditions (scanning angular velocity, scanning angle range) according to the measurement range specified by the user before that, and scanning characteristics are detected (# 20).

The relationship between the detected scanning angular velocity and scanning angle range and the commanded scanning angular velocity and commanded scanning angle range in the preliminary scanning is determined, and based on this relationship, the commanded scanning angular velocity and the commanded scanning angular velocity are set so that the main scanning becomes a desired scan. The command scanning angle range is corrected (# 21).

Thereafter, the main scanning is performed by driving the galvano scanner 13 and the area sensor 22 (# 22 to # 2).
6). The three-dimensional data is calculated based on the image data obtained by the main scanning (# 27), and the three-dimensional data is displayed (# 28). When the user performs a predetermined operation, three-dimensional data is recorded (# 29, # 30).

In the above embodiment, three-dimensional data is calculated by performing a triangulation calculation based on the detection results of the scanning characteristics or correcting the command value of the main scanning.
The present invention is not limited to this. Data of the detected scanning characteristics (scanning angular velocity, scanning angle range) and image data (light receiving data of reflected light) obtained by the area sensor 22 are recorded on the recording medium 34, and other operations are performed. The apparatus may calculate three-dimensional data. When correcting the scanning command value based on the detected scanning characteristics, the deflection angle θm may be calculated from the command angle characteristics when calculating the three-dimensional data. The light beam projected onto the object Q is not limited to the slit light, but may be a spot light.

[0032]

According to the first to fifth aspects of the present invention,
It is possible to realize a small and low-cost scanning device or three-dimensional measuring device capable of grasping actual scanning characteristics.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a three-dimensional digitizer according to a first embodiment.

FIG. 2 is a diagram showing a beam detection method.

FIG. 3 is a graph showing scanning characteristics.

FIG. 4 is a principle diagram of three-dimensional measurement.

FIG. 5 is a flowchart of a schematic operation of the three-dimensional digitizer.

FIG. 6 is a diagram showing another example of the beam detection method.

FIG. 7 is a diagram showing another example of the beam detection method.

FIG. 8 is a diagram showing a modification of the beam detection position.

FIG. 9 is a diagram showing another form of the monitor light guide path.

FIG. 10 is a diagram showing another example of a beam detection mode.

FIG. 11 is a diagram showing another example of beam detection by a fixed mirror.

FIG. 12 is a configuration diagram of a three-dimensional digitizer according to a second embodiment.

FIG. 13 is a flowchart showing another example of the operation of the three-dimensional digitizer.

[Explanation of symbols]

 U Slit light (optical beam) 11 Light source 13 Galvano scanner (scanning mechanism) 10, 10G Scanning device (optical scanning device) 18, 18a, 18b Light receiving element (photodetector) 18A Line sensor (photodetector) 16, 16A to 16F Monitor light guide path 161 to 165 Optical fiber (optical device) 171 to 175 Fixed mirror (optical device) 31 Controller (data processing means) Q Object 1, 2 3D digitizer (3D measuring device)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA53 EE00 FF01 FF02 FF09 FF32 GG06 HH05 JJ01 JJ03 JJ05 JJ15 JJ26 LL02 LL04 LL13 LL62 MM16 QQ00 QQ03 QQ24 2H045 AB01 AC01 BA42 CA82 CA92 CB22

Claims (5)

[Claims] An optical scanning device comprising: a light source for emitting an optical beam; and a scanning mechanism for deflecting or translating the optical beam, comprising: a photodetector; An optical device forming a monitor light guide path from a plurality of positions through which light passes and passing times differing from each other to the photodetector; and a passing timing of the light beam at each of the plurality of positions obtained by the photodetector. Means for detecting the relationship between the time in scanning and the beam position based on a signal indicating the following. 2. The optical scanning device according to claim 1, wherein said photodetector comprises a plurality of independent light receiving elements for each of said plurality of positions. 3. The scanning mechanism according to claim 1, wherein the scanning mechanism is controlled based on the relationship between the time detected in the previous scanning and the beam position so that the beam position changes as set in the scanning. Optical scanning device. 4. A three-dimensional measuring device comprising the optical scanning device according to claim 1, and measuring the shape of the object by receiving light emitted from the optical scanning device and reflected by the object. A three-dimensional measuring apparatus comprising: a data processing unit that performs a triangulation calculation with reference to the relationship related to the scanning detected by the optical scanning device. 5. A three-dimensional measuring device comprising the optical scanning device according to claim 1, and measuring the shape of the object by receiving light emitted from the optical scanning device and reflected by the object. A three-dimensional measuring apparatus comprising: a data processing unit that records, as measurement data, data representing a shape of the object and data representing the relationship related to scanning detected by the optical scanning device.