JPH09145321A - Projection apparatus and imaging apparatus for three-dimensional measurement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small projection apparatus in which a slit width can be adjusted and by which slit light with a small deformation can be radiated by a method wherein a laser beam which is radiated from a variator optical system used to adjust a beam diameter is spread to one direction and the slit light is generated. SOLUTION: In an optical system 40, a laser beam which is radiated by a semiconductor laser 41 is passed through a projection lens system 42, and it is changed into slit light U so as to be deflected by a galvanomirror 43. In the projection lens system 42, the laser beam is first made parallel by a collimating lens 241. Then, the diameter of the laser beam is adjusted by a variator lens 422. Lastly, the beam is expanded to a slit length direction M1 by an expander lens 423. Since a slit length is expanded before the beam is deflected by the galvanomirror 43, the deformation of the slit light can be reduced as compared with a case in which it ia expanded before the deflection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light projecting device and an image pickup device for three-dimensional measurement in which an object is irradiated with slit light to measure the shape of the object in a non-contact manner.

[0002]

2. Description of the Related Art A non-contact type three-dimensional measuring device called a range finder can perform higher-speed measurement than a contact type. Therefore, data input to a CG system or CAD system, body measurement, robot It is used for visual recognition.

[0003] As a measurement method suitable for a range finder, a slit light projection method (also called a light cutting method) is known. This method is a method of obtaining a three-dimensional image (distance image) by optically scanning an object, and is a kind of an active measurement method of irradiating specific detection light and photographing the object. The three-dimensional image is a set of pixels indicating the three-dimensional positions of a plurality of parts on the object. In the slit light projection method, a slit light having a linear cross section is used as detection light.

FIG. 15 is a diagram showing an outline of the slit light projection method, and FIG. 16 is a diagram for explaining the principle of measurement by the slit light projection method. An object Q to be measured is irradiated with slit light U having a narrow cross section, and the reflected light is incident on, for example, the image pickup surface S2 of the two-dimensional image sensor [FIG. 15].
(A)]. If the irradiated portion of the object Q is flat, the photographed image (slit image) becomes a straight line [FIG. 15 (b)]. If the irradiated portion has irregularities, the straight line may be curved or stepped [Fig. 15 (c)]. That is, the size of the distance between the measuring device and the object Q is reflected on the incident position of the reflected light on the imaging surface S2 [FIG. 15 (d)]. By deflecting the slit light U in the width direction, a three-dimensional position can be sampled by scanning the object surface in a range visible from the light receiving side. The number of sampling points depends on the number of pixels of the image sensor.

In FIG. 16, the light projecting system and the light receiving system are arranged so that the base line AO connecting the light projecting origin A and the principal point O of the lens of the light receiving system is perpendicular to the light receiving axis. The light receiving axis is perpendicular to the image pickup surface S2. Note that the principal point of the lens is defined as an image distance S by a so-called image distance (image distance) b when an image of a subject at a finite distance is formed on the imaging surface S2.
It is a point on the light receiving axis away from 2. The image distance b is the sum of the focal length f of the light receiving system and the lens extension for focus adjustment.

The principal point O is defined as the origin of a three-dimensional rectangular coordinate system.
The light receiving axis is the Z axis, the base line AO is the Y axis, and the length direction of the slit light is the X axis. When the slit light U reaches a point P (X, Y,
When the angle between the light projecting axis and the light projecting reference plane (the light projecting surface parallel to the light receiving axis) when irradiating Z) is θa and the light receiving angle is θp,
The coordinate Z of the point P is represented by the equation (1).

Base line length L = L1 + L2 = Ztan θa + Ztan θp∴Z = L / (tan θa + tan θp) (1) The light receiving angle θp is a straight line connecting the point P and the principal point O.
This is an angle formed with a plane including the light receiving axis (light receiving axis plane).

Since the image pickup magnification β = b / Z, assuming that the distance in the X direction between the center of the image pickup surface S2 and the light receiving pixel is xp and the distance in the Y direction is yp [see FIG. 16 (a)], point P Coordinates X and Y are expressed by equations (2) and (3).

X = xp / β (2) Y = yp / β (3) The angle θa is uniquely determined by the angular velocity of the deflection of the slit light U. The light receiving angle θp can be calculated from the relationship tan θp = b / yp. In other words, the position (xp,
By measuring yp), the three-dimensional position of the point P can be obtained based on the angle θa at that time.

When a zoom lens group is provided in the light receiving system as shown in FIG. 16C, the principal point O becomes the rear principal point H '.
Assuming that the distance between the rear principal point H ′ and the front principal point H is M, the point P
Is represented by equation (1B).

L = L1 + L2 = Ztan θa + (Z−M) tan θp ∴Z = (L + Mtan θp) / (tan θa + tan θp) ... When using an image pickup means composed of a finite number of pixels, the resolution of measurement depends on the pixel pitch of the image pickup means. However, the resolution can be increased by setting the slit light U so that the width of the slit light U in the Y direction (scanning direction) on the imaging surface S2 is a plurality of pixels.

FIG. 17 is a diagram for explaining an example of a method for improving the resolution. Assuming that the reflectance of the illuminated portion on the object is uniform, the received light intensity has a normal distribution that spreads in the Y direction. If the effective intensity range of this normal distribution is for a plurality of pixels, the maximum intensity position (called the center of gravity) can be measured in units of the pixel pitch or less by performing interpolation calculation on the amount of received light of each pixel g. The interpolation calculation is to fit a normal distribution to the amount of light received by each pixel. The coordinates Z, X, Y are calculated based on the calculated center of gravity. According to this method, the actual resolution is about 1/8 to 1/10 pixels.

In order to make the width of the slit light U on the image pickup surface S2 equal to a plurality of pixels, the width (length in the scanning direction) of the slit light U may be expanded at the stage of light projection. However, in this case, since the width of the slit light U in the Y direction also spreads on the object Q, when the irradiation portion (point P) is, for example, the boundary of the object color, the distribution of the received light intensity is not a normal distribution, and a measurement error occurs. growing. As a method for solving this problem, the object Q
There is a method in which the light projecting condition is set so that the slit width is as narrow as possible, and the width of the slit light U is expanded by a filter or the like in the light receiving system so as to be incident on the imaging surface S2 (Japanese Patent Laid-Open No. 174536/1995).

[0014]

By providing the range finder with a zooming function, the degree of freedom of framing for determining the scanning range of the object Q is increased. When zooming is performed on the light receiving side, the angle of view for imaging changes. Therefore, in order to make the slit light U having the optimum width incident on the imaging surface S2, it is necessary to adjust the width of the slit light U on the light projecting side according to the zooming state on the light receiving side.

An object of the present invention is to realize a light projecting device which can adjust the slit width, emit slit light with little distortion, and is small in size. Another object is to provide a compact imaging device for three-dimensional measurement having a zooming function.

[0016]

According to a first aspect of the present invention, there is provided a light projecting apparatus which emits a laser beam, a variator optical system for adjusting the beam diameter of the laser beam, and a variator optical system. Expander optical system that expands the laser beam in one direction to generate slit light,
And an optical scanning unit that deflects the slit light.

An image pickup apparatus according to a second aspect of the present invention includes the light projecting apparatus according to the first aspect of the present invention, a photoelectric conversion unit that outputs a signal according to the amount of light incident on the image pickup surface, and a zooming mechanism. A light receiving optical system configured to form an optical image of a subject on the imaging surface, and a slit width for controlling movement of the variator optical system in the optical axis direction according to an angle of view set by the zooming mechanism. And control means.

In the image pickup device of the invention of claim 3, the image pickup surface comprises light-receiving pixels arranged in a matrix, and the slit width control means has a width of the slit light on the image pickup surface of the light-receiving pixels. The movement control of the variator optical system is performed so that the number is three or more.

[0019]

FIG. 1 is a configuration diagram of a measurement system 1 according to the present invention. The measurement system 1 includes a three-dimensional camera (range finder) 2 that performs three-dimensional measurement by the slit light projection method, and a host 3 that processes output data of the three-dimensional camera 2.

The three-dimensional camera 2 shows color information of the object Q together with measurement data (slit image data) for specifying the three-dimensional positions of a plurality of sampling points on the object Q.
Outputs a dimensional image and data necessary for calibration. The host 3 is responsible for the arithmetic processing for obtaining the coordinates of the sampling points using the triangulation method.

The host 3 includes a CPU 3a and a display 3
This is a computer system including a keyboard b, a keyboard 3c, a mouse 3d, and the like. Software for processing measurement data is incorporated in the CPU 3a. Between the host 3 and the three-dimensional camera 2, both online and offline data transfer by the portable recording medium 4 is possible. As the recording medium 4,
There are magneto-optical disks (MO), mini disks (MD), memory cards and the like.

FIG. 2 is a view showing the outer appearance of the three-dimensional camera 2. A light projecting window 20a and a light receiving window 2 are provided on the front surface of the housing 20.
0b is provided. The light projecting window 20a is located above the light receiving window 20b. Slit light (band-shaped laser beam with a predetermined width w) U emitted from the internal optical unit OU
Goes to the object (subject) to be measured through the light projecting window 20a. The emission angle φ of the slit light U in the length direction M1 is fixed. A part of the slit light U reflected on the surface of the object enters the optical unit OU through the light receiving window 20b. The optical unit OU includes a biaxial adjustment mechanism for optimizing the relative relationship between the light projecting axis and the light receiving axis.

On the top surface of the housing 20, there are zooming buttons 25a, 25b and a manual focusing button 26.
a, 26b, and a shutter button 27 are provided. As shown in FIG. 2B, on the back surface of the housing 20,
A liquid crystal display 21, a cursor button 22, a select button 23, a cancel button 24, analog output terminals 31, 32, a digital output terminal 33, and an attachment / detachment port 30a for the recording medium 4 are provided.

The liquid crystal display 21 (LCD) is used as an operation screen display means and an electronic finder.
The photographer can set the photographing mode by using the buttons 21 to 24 on the rear surface. Measurement data is output from the analog output terminal 31, and a two-dimensional image signal is output from the analog output terminal 31 in the NTSC format, for example. The digital output terminal 33 is, for example, a SCSI terminal.

FIG. 3 is a block diagram showing the functional arrangement of the three-dimensional camera 2. In the figure, solid arrows indicate the flow of electric signals, and broken arrows indicate the flow of light. 3D camera 2
Has two optical systems 40 and 50 on the light-projecting side and the light-receiving side that constitute the above-mentioned optical unit OU. Optical system 40
At the wavelength 6 emitted by the semiconductor laser (LD) 41
The 70 nm laser beam becomes slit light U by passing through the light projecting lens system 42 and is deflected by the galvanomirror (scanning means) 43. Semiconductor laser 4
The No. 1 driver 44, the drive system 45 of the projection lens system 42, and the drive system 46 of the galvanometer mirror 43 are controlled by the system controller 61.

In the optical system 50, the zoom unit 51
The light condensed by the beam splitter 52 is split by the beam splitter 52. The light in the oscillation wavelength band of the semiconductor laser 41 is
The light enters the sensor 53 for measurement. Light in the visible band enters the monitor color sensor 54. The sensor 53 and the color sensor 54 are both CCD area sensors. The zoom unit 51 is of an in-focus type, and a part of the incident light is used for auto focusing (AF). The AF function is realized by an AF sensor 57, a lens controller 58, and a focusing drive system 59. The zooming drive system 60 is provided for electric zooming.

Information on the image picked up by the sensor 53 is obtained by the driver 5
The data is transferred to the output processing circuit 62 in synchronization with the clock from 5. The output processing circuit 62 generates measurement data corresponding to each pixel of the sensor 53 and stores it in the memories 63 and 64. After that, when the operator instructs the data output, the measured data is displayed by the SCSI controller 66 or N.
The TSC conversion circuit 65 outputs the data online in a predetermined format or stores it in the recording medium 4. The analog output terminal 31 or the digital output terminal 33 is used for online output of the measurement data. Image information from the color sensor 54 is transferred to the color processing circuit 67 in synchronization with a clock from the driver 56. The color-processed imaging information is output online via the NTSC conversion circuit 70 and the analog output terminal 32, or quantized by the digital image generation unit 68 and stored in the color image memory 69. After that, the color image data is transferred from the color image memory 69 to the SCSI controller 66, online output from the digital output terminal 33, or stored in the recording medium 4 in association with the measurement data. In addition,
The color image is an image having the same angle of view as the distance image obtained by the sensor 53, and is used as reference information during application processing on the host 3 side. The processing using color information includes, for example, processing of generating a three-dimensional shape model by combining a plurality of sets of measurement data having different camera viewpoints, and processing of thinning out unnecessary vertices of the three-dimensional shape model. The system controller 61 gives an instruction to the character generator 71 to display appropriate characters and symbols on the screen of the LCD 21.

FIG. 4 is a schematic diagram showing the structure of the projection lens system 42. FIG. 4A is a front view and FIG. 4B is a side view. The projection lens system 42 includes the collimator lens 4
21, a variator lens 422, and an expander lens 423. The laser beam emitted from the semiconductor laser 41 is subjected to an optical process for obtaining an appropriate slit light U in the following order. First, the collimator lens 421 collimates the beam. Next, the beam diameter of the laser beam is adjusted by the variator lens 422. Finally, the beam is expanded in the slit length direction M1 by the expander lens 423.

The variator lens 422 is provided to allow the slit light U having a width of three or more pixels to enter the sensor 53 regardless of the shooting distance and the angle of view for shooting. The drive system 45 moves the variator lens 422 according to an instruction from the system controller 61 so as to keep the width w of the slit light U on the sensor 53 constant. The variator lens 422 and the zoom unit 51 on the light receiving side work together.

By expanding the slit length before the deflection by the galvanometer mirror 43, the distortion of the slit light U can be reduced as compared with the case where the slit light U is deflected. By disposing the expander lens 423 at the final stage of the projection lens system 42, that is, by bringing the expander lens 423 close to the galvanometer mirror 43, the galvanometer mirror 43 can be downsized.

FIG. 5 is a schematic diagram of the zoom unit 51 for receiving light. The zoom unit 51 includes a front imaging unit 51.
5, a variator unit 514, a compensator unit 513, a focusing unit 512, a rear imaging unit 511, and a beam splitter 516 that guides a part of incident light to the AF sensor 57.
It is composed of The front imaging unit 515 and the rear imaging unit 511 are fixed with respect to the optical axis.

The focusing drive system 59 is responsible for the movement of the focusing unit 512, and the zooming drive system 60 is responsible for the movement of the variator unit 514. Focusing drive system 5
Reference numeral 9 includes a focusing encoder 59A that indicates the moving distance (extending amount) of the focusing unit 512. The zooming drive system 60 includes a variator unit 514.
The zooming encoder 60A for indicating the moving distance (zoom increment value) of the.

FIG. 6 is a schematic diagram of the beam splitter 52, FIG. 7 is a graph showing the light receiving wavelength of the sensor 53 for measurement, and FIG.
4 is a graph showing the light receiving wavelength of the monitor color sensor 54.

The beam splitter 52 includes a color separation film (dich lock mirror) 521, two prisms 522 and 523 sandwiching the color separation film 521, and an exit surface 52 of the prism 522.
2b, an infrared cut filter 524, a visible cut filter 525 provided on the front side of the sensor 53,
The infrared cut filter 526 and the low pass filters 527, 5 provided on the exit surface 523b of the prism 523.
28.

Light UC incident from the zoom unit 51
Enter the color separation film 521 through the low-pass filter 527 and the prism 522. Light U0 in the oscillation band of the semiconductor laser 41 is reflected by the color separation film 521, and is reflected by the prism 522.
After being reflected by the incident surface 522a of the light emitting element 522, the light is emitted from the emitting surface 522b toward the sensor 53. Of the light U0 emitted from the prism 522, the light that has passed through the infrared cut filter 524 and the visible cut filter 525 is received by the sensor 53. On the other hand, the light C0 transmitted through the color separation film 521
Exits from the exit surface 523b toward the color sensor 54 through the prism 523. Of the light C0 emitted from the prism 523, the light transmitted through the infrared cut filter 526 and the low-pass filter 528 is the color sensor 54.
Is received by the

In FIG. 7, the color separation film 521 reflects light in a relatively wide wavelength band including the slit light wavelength (λ: 670 nm) as shown by the broken line. That is, the wavelength selectivity of the color separation film 521 is insufficient for selectively allowing only the slit light to enter the sensor 53. However, since the beam splitter 52 is provided with the infrared cut filter 524 having the characteristic indicated by the chain line and the visible cut filter 525 having the characteristic indicated by the solid line,
The light that finally enters the sensor 53 has a narrow range of wavelengths indicated by the diagonal lines in FIG. 7. As a result, measurement with a small influence of ambient light, that is, a large optical SN ratio can be realized.

On the other hand, in the color sensor 54, since the infrared cut filter 528 having the characteristic shown by the solid line in FIG. 8 blocks the light in the infrared band transmitted through the color separation film 521 having the characteristic shown by the broken line, Only visible light is incident.
Thereby, the color reproducibility of the monitor image is improved.

Instead of using two filters, the infrared cut filter 524 and the visible cut filter 525, one filter having a characteristic of blocking infrared light and visible light may be used. Both the infrared cut filter 524 and the visible cut filter 525 may be provided on the prism 522 side, or conversely, both filters may be provided on the sensor 53.
May be provided on the side of. Contrary to the example of FIG. 6, the visible cut filter 525 may be provided on the prism 522 side, and the infrared cut filter 524 may be provided on the sensor 53 side.

FIG. 9 is a principle diagram of calculation of a three-dimensional position in the measurement system 1. In the same figure, the elements corresponding to those in FIGS. 15 and 16 are designated by the same reference numerals for easy understanding.

On the image pickup surface S2 of the sensor 53, the object Q is irradiated with slit light U having a relatively wide width corresponding to a plurality of pixels. Specifically, the width of the slit light U is set to 5 pixels. The slit light U is generated on the imaging surface S2 by one every sampling cycle.
It is deflected from the top to the bottom of FIG. 9 so that it moves by the pixel pitch pv, so that the object Q is scanned.
The photoelectric conversion information for one frame is output from the sensor 53 for each sampling cycle.

Focusing on one pixel g on the image pickup surface S2,
Effective light reception data can be obtained in 5 out of N samplings performed during scanning. The timing at which the optical axis of the slit light U passes through the object surface ag in the range in which the pixel of interest g gazes (time centroid Npeak: the time at which the amount of light received by the pixel of interest g becomes maximum) is obtained by interpolation calculation on these five times of received light data. . In the example of FIG. 9B, the amount of received light is maximum at the timing between the nth time and the (n-1) th time immediately before the nth time. The position (coordinates) of the object Q based on the relationship between the irradiation direction of the slit light at the determined timing and the incident direction of the slit light with respect to the pixel of interest.
Is calculated. This enables measurement with a higher resolution than the resolution defined by the pixel pitch pv of the imaging surface.

The amount of light received by the target pixel g depends on the reflectance of the object Q. However, the relative ratio of each received light amount of the five samplings is constant regardless of the absolute amount of received light. That is, the shading of the object color does not affect the measurement accuracy.

In the measurement system 1 of this embodiment, the three-dimensional camera 2 outputs the received light data for five times for each pixel g of the sensor 53 to the host 3 as the measurement data, and the host 3 outputs the object Q of the object Q based on the measurement data. Calculate the coordinates. The output processing circuit 62 (see FIG. 3) of the three-dimensional camera 2 is responsible for generating measurement data corresponding to each pixel g.

FIG. 10 is a block diagram of the output processing circuit 62,
FIG. 11 is a diagram showing a read range of the sensor 53. The output processing circuit 62 includes an AD conversion unit 620 that converts the photoelectric conversion signal of each pixel g output from the sensor 53 into 8-bit received light data, four frame delay memories 621 to 624 connected in series, and effective five times. Five memory banks 625A to 625E for storing received light data, a memory bank 625F for storing a frame number (sampling number) FN that maximizes received light data, and a comparator 62
6, a generator 627 pointing to the frame number FN,
And a memory control unit (not shown) for addressing the memory banks 625A-F. Each of the memory banks 625A to 625E has a capacity capable of storing the same number of received light data as the number of measurement sampling points (that is, the number of effective pixels of the sensor 53).

Four frame delay memories 621-6
By delaying the data at 24, the received light data of 5 frames for each pixel g is simultaneously stored in the memory bank 6.
25A to 25E can be stored. In addition,
The reading of one frame by the sensor 53 is performed by the imaging surface S2.
In order to increase the speed, not only the whole of the above, but only the effective light-receiving area (belt-shaped image) Ae of a part of the imaging surface S2 as shown in FIG. The effective light receiving area Ae is shifted by one pixel for each frame as the slit light U is deflected. In the present embodiment, the number of pixels of the effective light receiving area Ae in the shift direction is fixed to 32. A method of reading out only a part of the captured image of the CCD area sensor is disclosed in Japanese Patent Application Laid-Open No. 7-174536.

The AD converter 620 sets 32 for each frame.
The received light data D620 for a line is serially output in the arrangement order of the pixels g. Each frame delay memory 621-6
24 is an FI having a capacity of 31 (= 32-1) lines
It is FO.

The light reception data D620 of the target pixel g output from the AD conversion unit 620 is delayed by two frames, and the past light reception data D620 for the target pixel g stored in the memory bank 625C is stored by the comparator 626. Is compared to the maximum value of. Delayed received light data D620 (output of frame delay memory 622)
Is larger than the maximum value in the past, the output of the AD converter 620 at that time and each frame delay memory 621 to
The outputs of 624 are stored in the memory banks 625A-E, respectively, and the stored contents of the memory banks 625A-E are rewritten. At the same time, the frame number FN corresponding to the received light data D620 stored in the memory bank 625C is stored in the memory bank 625F.

That is, when the amount of light received by the target pixel g is maximized in the nth (n <N) frame, the data of the (n + 2) th frame is stored in the memory bank 625A and the memory bank 625B is stored. The data of the (n + 1) th frame is stored, and the data of the nth frame is stored in the memory bank 625C.
Data of the (n-1) th frame is stored in D, data of the (n-2) th frame is stored in the memory bank 625E, and n is stored in the memory bank 625F.

Next, the operations of the three-dimensional camera 2 and the host 3 will be described together with the measurement procedure. Below, the number of sampling points for measurement is set to 200 × 231. That is, the number of pixels in the slit length direction on the imaging surface S2 is 231 and the substantial number of frames N is 200.

The user (photographer) determines the camera position and direction and sets the angle of view while looking at the color monitor image displayed on the LCD 21. At that time, zooming operation is performed as necessary. The three-dimensional camera 2 does not adjust the aperture of the color sensor 54, and displays a color monitor image whose exposure is controlled by the electronic shutter function. This is because the amount of light incident on the sensor 53 is increased as much as possible by opening the diaphragm.

FIG. 12 is a diagram showing the data flow in the three-dimensional camera 2, FIG. 13 is a diagram showing the data flow in the host 3, and FIG. 14 is a diagram showing the relationship between each point of the optical system and the object Q. .

The variator unit 51 of the zoom unit 51 is operated in response to a user's operation of selecting an angle of view (zooming).
4 moves are made. Further, manual or automatic focusing is performed by moving the focusing unit 512.
An approximate object distance d ₀ is measured during the focusing process.

In response to such lens driving of the light receiving system, the amount of movement of the variator lens 422 on the light projecting side is calculated by an arithmetic circuit (not shown), and movement control of the variator lens 422 is performed based on the calculation result.

The system controller 61 receives the focusing encoder 59 via the lens controller 58.
The output of A (extending amount Ed) and the output of the zooming encoder 60A (zoom increment value fp) are read. Inside the system controller 61, the distortion aberration table T1, the principal point position table T2, and the image distance table T3.
Is referred to, and shooting condition data corresponding to the extension amount Ed and the zoom step value fp is output to the host 2. The shooting condition data here is a distortion aberration parameter (lens distortion correction coefficients d1, d2), a front principal point position FH, and an image distance b. The front principal point position FH is represented by the distance between the front end point F of the zoom unit 51 and the front principal point H. Since the front end point F is fixed, the front main point H can be specified by the front main point position FH.

The system controller 61 calculates the output (laser intensity) of the semiconductor laser 41 and the deflection conditions (scan start angle, scan end angle, deflection angular velocity) of the slit light U. This calculation method will be described in detail. First, assuming that a plane object exists at an approximate object distance d ₀ , the projection angle is set so that the reflected light is received at the center of the sensor 53. The pulse lighting for calculating the laser intensity described below is performed at this set projection angle.

Next, the laser intensity is calculated. Since the human body may be measured when calculating the laser intensity, it is essential to consider safety. First, the minimum strength LDm
The pulse light is turned on at in, and the output of the sensor 53 is captured. Captured signal [Son (LDmin)] and appropriate level S
The ratio with typ is calculated, and the temporary laser intensity LD1 is set.

LD1 = LDmin × Styp / MAX
[Son (LDmin)] Subsequently, the laser light intensity LD1 is turned on again for a pulse, and the sensor 5
Capture the output of 3. Captured signal [Son (LD
1)] is an appropriate level Styp or a value close thereto, LD1 is determined as the laser intensity LDs. In other cases, the laser intensity LD1 and MAX [Son (LD1)] are used to set the temporary laser intensity LD1 and the output of the sensor 53 is compared with the appropriate level Styp. The temporary setting of the laser intensity and the confirmation of suitability are repeated until the output of the sensor 53 becomes a value within the allowable range. Note that the output of the sensor 53 is captured for the entire image pickup surface S2. this is,
This is because it is difficult to accurately estimate the light receiving position of the slit light U in the passive distance calculation by AF. The integration time of the CCD in the sensor 53 is one field time (for example, 1/60 seconds), which is longer than the integration time in actual measurement. Therefore, by performing pulse lighting, a sensor output equivalent to that at the time of measurement is obtained.

Next, the distance d between the objectives is determined by triangulation from the projection angle and the light receiving position of the slit light U when the laser intensity is determined. Finally, the determined objective distance d
The deflection condition is calculated based on When the deflection condition is calculated, an offset doff in the Z direction (see FIG. 16) between the rear principal point H ′ of the light receiving system, which is the distance measurement reference point of the object distance d, and the projection origin point A is considered. In addition, in order to secure the same measurable distance range d ′ at the ends in the scanning direction as well, a predetermined amount (for example, 8 pixels) of overscan is performed. Scan start angle th1, scan end angle th
2. The deflection angular velocity ω is expressed by the following equation.

Th1 = tan ^-1 [β × pv (np / 2 +
8) + L) / (d + doff)] × 180 / π th2 = tan ⁻¹ [−β × pv (np / 2 + 8) + L)
/ (D + doff)] × 180 / π ω = (th1-th2) / np β: Imaging magnification (= d / effective focal length freal) pv: Pixel pitch np: Number of effective pixels in Y direction on imaging surface S2 L: Base line Length Under the conditions calculated in this way, the main light emission is next performed, the object Q is scanned (slit projection), and the measurement data (slits) for 5 frames per pixel obtained by the output processing circuit 52 is obtained. The image data) D62 is sent to the host 2. At the same time, the device information D10 indicating the deflection conditions (deflection control data) and the specifications of the sensor 53 is also stored in the host 3
Sent to Table 1 summarizes main data that the three-dimensional camera 2 sends to the host 3.

[0060]

[Table 1]

As shown in FIG. 13, in the host 3, the slit barycenter calculation # 31, the distortion aberration correction calculation # 32, the camera line-of-sight equation calculation # 33, the slit surface equation calculation # 34, and the three-dimensional position calculation #. 35 is executed, whereby the three-dimensional positions (coordinates X, Y, Z) of 200 × 231 sampling points are calculated. The sampling point is the intersection of the camera line of sight (the straight line connecting the sampling point and the rear principal point H ′) and the slit surface (the optical axis surface of the slit light U illuminating the sampling point).

The time center Npeak of the slit light U (FIG. 9)
(Reference) is given by the equation (3) using the received light data D (i) at each sampling. Npeak = n + Δn (3) Δn = [− 2 × D (n−2) −D (n−1) + D (n +)
1) + 2 × D (n + 2)] / ΣD (i) (i = n−2, n−1, n, n + 1, n + 2) or Δn = [− 2 × [D [n−2) −minD (i) ] −
[D (n-1) -minD (i)] + [D (n + 1)-
minD (i)] + 2 × [D (n + 2) -minD
(I)]] / ΣD (i) The influence of ambient light can be reduced by subtracting the minimum data minD (i) of the five received light data to obtain the weighted average.

The camera line-of-sight equations are equations (4) and (5). (U-u0) = (xp) = (b / pu) × [X / (Z-FH)] (4) (v−v0) = (yp) = (b / pv) × [Y / (Z -FH)] (5) b: Image distance FH: Front principal point position pu: Horizontal pixel pitch on the imaging surface pv: Vertical pixel pitch on the imaging surface u: Horizontal pixel position on the imaging surface u0: Center pixel position in the horizontal direction on the imaging surface v: Pixel position in the vertical direction on the imaging surface v0: Center pixel position in the vertical direction on the imaging surface The slit plane equation is given by equation (6).

[0064]

(Equation 1)

The geometrical aberration depends on the angle of view. Distortion occurs in the target substantially at the center pixel. Therefore, the amount of distortion is represented by a function of the distance from the center pixel. Here, the distance is approximated by a cubic function. The secondary correction coefficient is d1, and the tertiary correction coefficient is d2. The corrected pixel positions u ′ and v ′ are given by equations (7) and (8).

U ′ = u + d1 × t2 ² × (u−u0) / t2 + d2 × t2 ³ × (u−u0) / t2 (7) v ′ = v + d1 × t2 ² × (v−v0) / t2 + d2 × t2 ³ × (v−v0) / t2 (8) t2 = (t1) ⁻² t1 = (u−u0) ² + (v−v0) ^{2 In the} above formulas (4) and (5), u'instead of u
And substituting v ′ for v, a three-dimensional position taking distortion into account can be obtained. Regarding calibration, the Institute of Electronics, Information and Communication Engineers Study Group material PRU91-113 [Geometric correction of images without camera positioning] Onodera / Kanaya, IEICE Transactions D-II vol. J74-D-II No.9 pp.1227-1235, '91 / 9
[High-precision calibration method of range finder based on three-dimensional model of optical system] Ueshiba, Yoshimi, Oshima, etc. have detailed disclosure.

In the above embodiment, the host 3 carries out the calculation for calculating the three-dimensional position based on the measurement data D62, but the three-dimensional camera 2 may be provided with a calculation function for calculating the three-dimensional position. . It is also possible to calculate the three-dimensional position by a look-up table method. Optical system 5 on the light receiving side
In 0, the imaging magnification may be changed by an interchangeable lens instead of the zoom unit 51.

[0068]

According to the first aspect of the present invention, it is possible to realize a small-sized light projecting device capable of adjusting the slit width, emitting slit light with little distortion.

According to the second and third aspects of the present invention, it is possible to reduce the size of the image pickup device having a zooming function for three-dimensional measurement. According to the invention of claim 3, the resolution of the three-dimensional measurement can be set to a value determined by the pixel pitch of the photoelectric conversion means or more.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a measurement system according to the present invention.

FIG. 2 is a diagram showing an appearance of a three-dimensional camera.

FIG. 3 is a block diagram showing a functional configuration of a three-dimensional camera.

FIG. 4 is a schematic diagram showing a configuration of a light projecting lens system.

FIG. 5 is a schematic diagram of a zoom unit for receiving light.

FIG. 6 is a schematic diagram of a beam splitter.

FIG. 7 is a graph showing a light receiving wavelength of a sensor for measurement.

FIG. 8 is a graph showing a light receiving wavelength of a monitor color sensor.

FIG. 9 is a principle diagram of calculation of a three-dimensional position in the measurement system.

FIG. 10 is a block diagram of an output processing circuit.

FIG. 11 is a diagram showing a reading range of a sensor.

FIG. 12 is a diagram showing a data flow in a three-dimensional camera.

FIG. 13 is a diagram showing a data flow in a host.

FIG. 14 is a diagram showing a relationship between each point of the optical system and an object.

FIG. 15 is a diagram showing an outline of a slit light projection method.

FIG. 16 is a diagram for explaining the principle of measurement by the slit light projection method.

FIG. 17 is a diagram for explaining an example of a method for improving resolution.

[Explanation of symbols]

 2 Three-dimensional camera (imaging device) 40 Optical system on the projecting side (projecting device) 41 Semiconductor laser (light source) 43 Galvano mirror (optical scanning means) 51 Zooming unit (zooming mechanism) 53 Sensor for measurement (photoelectric conversion means) ) 61 system controller (slit width control means) 422 variator lens (variator optical system) 423 expander lens (expander optical system) U slit light g pixel (light receiving pixel) S2 imaging surface

Claims (3)

[Claims] 1. A light source for emitting a laser beam, a variator optical system for adjusting the beam diameter of the laser beam, and an extract for expanding the laser beam emitted from the variator optical system in one direction to generate slit light. A light projecting device for three-dimensional measurement, comprising: a panda optical system and an optical scanning means for deflecting the slit light. 2. A light projecting device according to claim 1, a photoelectric conversion means for outputting a signal according to the amount of light incident on the image pickup surface, and a zooming mechanism, wherein an optical image of a subject is displayed on the image pickup surface. According to the light receiving optical system configured to form an image, and the angle of view set by the zooming mechanism,
An image pickup apparatus comprising: a slit width control unit that controls movement of the variator optical system in an optical axis direction. 3. The image pickup surface comprises light receiving pixels arranged in a matrix, and the slit width control means sets the width of the slit light on the image pickup surface to be equal to or more than three of the light receiving pixels.
The image pickup apparatus according to claim 2, wherein movement control of the variator optical system is performed.