JP2011013104A - Three-dimensional shape measurement apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional shape measurement apparatus for extending a measurement range without reducing a spatial resolution in the depth direction of a to-be-measured object.SOLUTION: The three-dimensional shape measurement apparatus has: a first pulse light source 30 for generating chirp light pulses whose colors are regularly changed with time; a second pulse light source 32 for generating a single wavelength light pulse having a predetermined wavelength; a reflection light image obtaining section 78 for obtaining a first reflection light image of the chirp light pulses 110a, 110b reflected by a workpiece 24; a reflection light image obtaining section 78 for referring to two-dimensional information on a second reflection light image, and obtaining the second reflection light image of the single wavelength light pulse 112 reflected by the workpiece 24; a three-dimensional information obtaining section 80 for obtaining three-dimensional information on the workpiece 24 by using the two-dimensional information and the color information on the first reflection light image; and a timing control section 70 for adjusting timing when the workpiece 24 is irradiated with the chirp light pulses, and timing when the workpiece 24 is irradiated with the single wavelength light pulse.

Description

  The present invention relates to a three-dimensional shape measuring apparatus for measuring a three-dimensional shape of an object to be measured.

  One of the methods for measuring the three-dimensional shape of an object to be measured, for example, a surface defect such as a painted surface of a workpiece and its smoothness, is a TOF (Time of Flight) method using pulsed light.

  The TOF method using pulsed light is based on the time of flight (TOF) until the pulsed light emitted from the pulsed light source is reflected by the irradiation area on the surface of the object to be measured and detected by the detector, and the speed of light. It is converted as a distance difference in the depth direction, and the three-dimensional shape of the object to be measured is measured.

  For example, Patent Document 1 discloses a technique for detecting by converting three-dimensional information into a colored contour map, which is a two-dimensional image, using pulsed light whose wavelength changes regularly with time (so-called chirped light pulse). Yes. If comprised in this way, the three-dimensional shape of a to-be-measured object can be measured with high precision and high speed.

Japanese Patent No. 2500379

  However, while using the apparatus disclosed in Patent Document 1, the three-dimensional shape of the object to be measured can be measured with high accuracy, but in order to ensure the measurement accuracy, the irradiation area (depth) of the pulsed light is a narrow space. Must be set in.

  Hereinafter, the relationship between the step ΔH in the depth direction and the length L of the chirped light pulse will be specifically described. There is a step of height ΔH in the depth direction of two measurement positions on the surface of the object to be measured, and two chirped light pulses are simultaneously directed to the two measurement positions and parallel to the depth direction. Consider the case of incidence (reflection). At this time, the optical path difference caused by the step (height ΔH) between the two measurement positions is 2ΔH.

If Δt is a time for extracting reflected light detected by the detector (so-called shutter opening / closing time) and c is a light velocity, a part of the two chirped light pulses are simultaneously extracted by one shutter opening / closing operation. Must satisfy the relationship shown in the following formula (1).
L ≧ 2ΔH + cΔt (1)

  Considering measurement at high resolution, 2ΔH >> cΔt, so the measurable range (height difference) in the depth direction is at most L / 2, in other words, half the chirp pulse length. That is, even if the length of the chirped light pulse is 20 mm, it is only possible to measure a height difference of about 10 mm at most.

  Even if the total length of the chirped light pulse is increased, the wavelength resolution of the chirped light pulse per unit length may be reduced because the wavelength resolution of the chirp introducing device or the detector is limited.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a three-dimensional shape measuring apparatus that can expand the measurement range without reducing the spatial resolution in the depth direction of the object to be measured.

  In this section, for ease of understanding, reference numerals in the attached drawings are used for explanation. Therefore, the contents described in this section should not be construed as being limited to those having the reference numerals.

  The three-dimensional shape measuring apparatus (12) according to the first aspect of the present invention, for example, as shown in FIGS. 2 and 3, generates a chirped light pulse whose color regularly changes over time. The generation means (30, 82), the single wavelength optical pulse generation means (32) for generating a single wavelength optical pulse of a predetermined wavelength, and the chirped light pulse generated by the chirped light pulse generation means are measured (( 24), a first reflected light image acquiring means (78) for acquiring a first reflected light image of the chirped light pulse reflected from the object to be measured (24), and the single wavelength light pulse generating means. Irradiating the object to be measured (24) with the single-wavelength light pulse generated in (32) to obtain a second reflected light image of the single-wavelength light pulse reflected from the object to be measured (24). 2 reflected light image acquisition means (78 And the two-dimensional information of the second reflected light image acquired by the second reflected light image acquiring means (78), and the second reflected light image acquiring means (78) acquired by the first reflected light image acquiring means (78). Three-dimensional information acquisition means (80) for acquiring three-dimensional information of the object to be measured using two-dimensional information and color information of one reflected light image, and directing the chirped light pulse to the object to be measured (24) An irradiation timing adjusting means (70) for adjusting the irradiation timing and the timing of irradiating the single wavelength light pulse toward the object to be measured (24) is provided.

  According to invention of Claim 1, the single wavelength optical pulse production | generation means which produces | generates a single wavelength optical pulse, the 2nd reflected light image acquisition means which acquires a single wavelength optical pulse (2nd reflected light image), The irradiation timing adjustment means for irradiating short-wavelength light pulses according to the irradiation timing of the chirped light pulses is provided, so that the short-wavelength light pulses perform the marking function, so that multiple chirped light pulses can be combined into one long chirped light pulse. It can be used as a light pulse in a pseudo manner, and the measurement range can be expanded without reducing the spatial resolution in the depth direction of the object to be measured.

  The three-dimensional shape measuring apparatus (12) according to the invention described in claim 2 is the three-dimensional shape measuring apparatus (12) according to claim 1, for example, as shown in FIGS. Optical combining means (84, 96, 98, 102) for generating a combined optical pulse by combining the single wavelength optical pulses, and the combined optical pulse by the first reflected light image acquisition means (78). Optical demultiplexing means (50) for demultiplexing the first reflected light image acquired and the second reflected light image acquired by the second reflected light image acquisition means (78). And

  According to the second aspect of the present invention, since the optical multiplexing means and the optical demultiplexing means are provided, it is possible to share the light guide path of the combined optical pulse, and the manufacturing cost of the apparatus can be reduced.

  The three-dimensional shape measuring apparatus (12) according to the invention described in claim 3 is the three-dimensional shape measuring apparatus (12) according to claim 1 or 2, as shown in FIGS. The wavelength light pulse generating means (32) is characterized by alternately generating single wavelength light pulses having different wavelengths.

  According to the invention described in claim 3, since the single wavelength optical pulse generating means alternately generates single wavelength optical pulses having different wavelengths, the single wavelength optical pulses having different wavelengths perform a marking function. The sequence of chirped light pulses can be specified, and multiple chirped light pulses can be used as a single chirped light pulse with a long length, without reducing the spatial resolution in the depth direction of the measurement object. The measurement range can be expanded.

  The three-dimensional shape measuring apparatus (12) according to the invention described in claim 4 is the three-dimensional shape measuring apparatus (12) according to claim 1 or 2, wherein, for example, as shown in FIGS. An optical distribution unit (84) for distributing optical pulses, and the chirped optical pulses distributed so that the chirped optical pulses distributed by the optical distributing unit (84) have optical path lengths that do not overlap each other on the same optical path. And an optical path length adjusting means (76, 92) for adjusting the optical path length.

  According to the invention described in claim 4, the optical distribution means for distributing the chirped light pulses and the optical path length adjusting means for adjusting the chirped light pulses so that the optical path lengths do not overlap each other on the same optical path are provided. Therefore, the chirped light pulse that can be used for measurement in the depth direction of the object to be measured can be maximized, and the erroneous detection of the imaging signal due to the separation and duplication of each chirped light pulse can be prevented.

  According to the three-dimensional shape measuring apparatus of the present invention, a chirped light pulse generating means for generating a chirped light pulse whose color changes regularly with time, and a single wavelength light pulse generating for generating a single wavelength light pulse of a predetermined wavelength A first reflected light image acquisition means for irradiating the measured object with the generated chirped light pulse and acquiring a first reflected light image of the chirped light pulse reflected from the measured object; A second reflected light image acquisition means for irradiating the measured object with the single wavelength light pulse and acquiring a second reflected light image of the single wavelength light pulse reflected from the measured object; 3D information acquisition means for referring to the 2D information of the second reflected light image and acquiring the 3D information of the object to be measured using the acquired 2D information and color information of the first reflected light image And the chirped light pulse to be measured Since the irradiation timing adjusting means for adjusting the timing of irradiating toward the object to be measured and the timing of irradiating the single wavelength light pulse toward the object to be measured are provided, the short wavelength light pulse performs a marking function. This chirped light pulse can be used in a pseudo manner as one long chirped light pulse, and the measurement range can be expanded without reducing the spatial resolution in the depth direction of the object to be measured.

It is a schematic side view of the three-dimensional shape measurement system according to the present embodiment. It is a block diagram of the configuration of the three-dimensional shape measuring apparatus according to the present embodiment. It is a block diagram of the configuration of the pulsed light adjustment optical system according to the present embodiment. FIG. 4A is a schematic diagram showing the relationship between the flight positions of the chirped light pulse and the single wavelength light pulse immediately before passing through the shutter. FIG. 4B is a schematic diagram illustrating the relationship between the flight positions of the chirped light pulse and the single wavelength light pulse immediately before passing through the shutter. FIG. 4C is a schematic diagram illustrating the relationship between the flight positions of the combined optical pulses supplied to the magnification optical system side. FIG. 5A is a graph showing the relationship between the wavelength of the first imaging signal and the gradation level of the combined imaging signal. FIG. 5B is a graph showing the relationship between the detected light intensity of the second imaging signal and the gradation level of the combined imaging signal. It is a block diagram of the configuration of a three-dimensional shape measuring apparatus according to a first modification of the present embodiment. FIG. 7A is a schematic diagram illustrating a relationship between flight positions immediately before the combined optical pulse according to the second modification reaches the magnifying optical system. FIG. 7B is a graph showing the relationship between the wavelength of the first imaging signal and the gradation level of the combined imaging signal. FIG. 7C is a graph showing the relationship between the detected light intensity of the second imaging signal and the gradation level of the combined imaging signal. FIG. 8A is a schematic diagram illustrating a relationship between flight positions immediately before the combined optical pulse according to the third modification reaches the magnifying optical system. FIG. 8B is a graph showing the relationship between the wavelength of the first imaging signal and the gradation level of the combined imaging signal. FIG. 8C is a graph showing the relationship between the detected light intensity of the second imaging signal and the gradation level of the combined imaging signal.

  Hereinafter, preferred embodiments of the three-dimensional shape measuring apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  First, a three-dimensional shape measurement system incorporating a three-dimensional shape measurement apparatus according to the present embodiment will be described with reference to FIG. The three-dimensional shape measurement system 10 includes a three-dimensional shape measurement device 12, an image processing device 14, a monitor 16, a host control device 18, and a robot control device 20.

  The imaging surface 22 of the three-dimensional shape measuring apparatus 12 is directed to the surface 26 side of the workpiece 24 as the object to be measured. Further, since the three-dimensional shape measuring device 12 is mounted on a robot arm (not shown), the robot arm 20 can be moved in the vertical and horizontal directions by driving the robot arm under the control of the robot control device 20. is there.

  The image processing device 14 is electrically connected to the three-dimensional shape measuring device 12, and performs various image processing on the imaging signal supplied from the three-dimensional shape measuring device 12.

  The monitor 16 is connected to the image processing device 14 and displays an image processed by the image processing device 14, measurement information, and the like.

  The host control device 18 is composed of, for example, a PLC (Programmable Logic Controller), and transmits various commands to the image processing device 14 and a robot control device 20 that performs drive control of a robot (not shown). Various measurement conditions can be set from an operation unit (not shown) included in the host control device 18.

  FIG. 2 is a schematic configuration diagram of the three-dimensional shape measuring apparatus 12 according to the present embodiment.

  The three-dimensional shape measuring apparatus 12 includes a first pulse light source 30 that emits first pulse light, a second pulse light source 32 that emits second pulse light, and a first pulse emitted by the first pulse light source 30. A chirped light pulse is generated by chirping light, and a pulsed light adjusting optical system 34 that generates a combined light pulse by adjusting the optical path of the chirped light pulse or the second pulsed light emitted by the second pulsed light source 32. And an expansion optical system 36 for expanding the beam diameter of the combined light pulse generated by the pulse light adjusting optical system 34, and the combined light pulse whose beam diameter is expanded by the expansion optical system 36 is divided according to the polarization direction. Polarizing beam splitter 38, collimating lens 40 for collimating the combined light pulse transmitted by polarizing beam splitter 38, and collimating lens 40 A λ / 4 wavelength plate 42 that tilts the polarization direction of the paralleled combined optical pulse in a predetermined direction, and the light beam of the combined optical pulse polarized by the λ / 4 wavelength plate 42 is collected to collect the surface of the work 24. And an objective lens 46 that forms a focus image (hereinafter referred to as an irradiation region 44) on 26 and is movable along the A direction (vertical direction with respect to the workpiece 24) by a drive mechanism (not shown).

Further, on the optical path L ₁ , a shutter 48 (not shown) capable of opening and closing a light-shielding shutter curtain can be freely opened and cut out of the combined light pulse reflected by the polarization beam splitter 38, and the combined light extracted by the shutter 48. Of the pulses, only the optical pulse of the predetermined wavelength (hereinafter referred to as “single wavelength optical pulse component”) is reflected to the optical path L ₂ side, and the optical pulse of other wavelengths (hereinafter referred to as “chirped optical pulse component”). .), A reflection mirror 52 that reflects the chirped light pulse component transmitted by the dichroic mirror 50 in a predetermined angle direction, and a chirped light pulse component reflected from the reflecting mirror 52 An imaging optical system 54 that forms a reflected light image (first reflected light image), and a reflected light image generated by the imaging optical system 54 is a first imaging signal. A color two-dimensional detector 56 to be converted into a signal, an image synthesis unit 57 for synthesizing the first imaging signal converted by the color two-dimensional detector 56 with a second imaging signal to be described later, and synthesis by the image synthesis unit 57 And an I / F 58 that transmits the captured image signal to the image processing apparatus 14.

Furthermore, an imaging optical system 60 that forms an appropriate reflected light image (second reflected light image) from the single-wavelength light pulse component reflected by the dichroic mirror 50 on the optical path L ₂ , and the imaging optical system 60 A two-dimensional detector 62 that converts the generated second reflected light image into a second imaging signal, and an image synthesis unit 57 that combines the second imaging signal converted by the two-dimensional detector 62 with the first imaging signal. And an I / F 58 that transmits the image signal synthesized by the image synthesis unit 57 to the image processing device 14.

  Further, the three-dimensional shape measuring apparatus 12 includes a first pulsed light emission control unit 64 that controls the emission operation of the first pulsed light by the first pulsed light source 30, and an emission operation of the second pulsed light by the second pulsed light source 32. A second pulse light emission control unit 66 for controlling the shutter, a shutter opening / closing control unit 68 for controlling the opening / closing operation of a shutter curtain (not shown) by the shutter 48, the emission operation of the first pulse light source 30 and the second pulse light source 32, and the shutter 48. And a timing control unit 70 that controls the timing of the opening / closing operation.

  Further, the three-dimensional shape measuring apparatus 12 is an I / F 74 that is electrically connected to an external device PC 72 and can acquire optical path adjustment parameters set by the PC 72, and an optical path acquired by the I / F 74. And an optical system control unit 76 that controls the optical path length of the pulsed light adjustment optical system 34 based on the adjustment parameters.

The single-wavelength light pulse generating means for generating a single-wavelength light pulse having a predetermined wavelength is composed of the second pulse light source 32. The reflected light image acquisition unit 78 as a first reflected light image acquisition means for acquiring a first reflected light image of the chirped light pulse reflected on the optical path L ₁ reflected from the work 24 includes a polarization beam splitter 38, a collimator The lens 40, the λ / 4 wavelength plate 42, the objective lens 46, the shutter 48, and the shutter opening / closing control unit 68 are configured. Furthermore, the second reflected light image acquisition means for acquiring the second reflected light image of the single wavelength light pulse on the optical path L ₁ reflected from the work 24 is the first reflected light image acquisition means. The unit 78 is provided in common. Further, while referring to the two-dimensional information of the second reflected light image of the single wavelength light pulse, the three-dimensional information of the object to be measured is obtained using the two-dimensional information and the color information of the first reflected light image of the chirped light pulse. The three-dimensional information acquisition unit 80 that is a three-dimensional information acquisition unit to be acquired includes a color two-dimensional detector 56, an image composition unit 57, and a two-dimensional detector 62. Further, the optical demultiplexing means for demultiplexing the multiplexed light pulse into the first reflected light image and the second reflected light image is constituted by the dichroic mirror 50.

  FIG. 3 is a schematic configuration diagram of the pulsed light adjustment optical system 34 according to the present embodiment.

The three-dimensional shape measuring apparatus 12 includes a chirp introducing device 82 that generates a chirped light pulse by chirping the first pulsed light emitted from the first pulse light source 30, and the chirped light generated by the chirped introducing device 82. A beam splitter 84 for dividing the pulse, a beam splitter 86 for further dividing the chirped light pulse transmitted by the beam splitter 84, and a reflecting mirror for reflecting the chirped light pulse transmitted by the beam splitter 86 in a predetermined angle direction 88, a beam splitter 90 that reflects a part of the chirped light pulse reflected by the reflecting mirror 88 toward the optical path L ₃ , and a chirped light pulse reflected by the beam splitter 90 is reflected in the opposite direction, and optical The C direction is controlled by a drive mechanism (not shown) under the control of the system controller 76. And a movable reflective mirror 92 along the (direction parallel to the optical path L _3).

Further, on the optical path L ₄ , the reflected light from the beam splitter 86 is received, and a light-blocking shutter curtain (not shown) can be freely opened and closed by using the received light as a trigger, and a shutter 94 constituted by an ultrafast nonlinear optical shutter or the like. Is provided.

Further, on the optical path L ₅ , a reflection mirror 96 that reflects the chirped light pulse from the beam splitter 84 in a predetermined angle direction, and only a single wavelength light pulse having a specific wavelength among the reflected light from the reflection mirror 96 is provided. A dichroic mirror 98 that reflects and transmits light pulses of other wavelengths (including chirped light pulses), a shutter 94 that can cut out chirped light pulses that have passed through the dichroic mirror 98, and is cut out by the shutter 94. A reflecting mirror 100 that reflects the chirped light pulse in a predetermined angle direction, and a beam splitter 90 that reflects a part of the chirped light pulse reflected by the reflecting mirror 100 toward the magnifying optical system 36 are provided.

Furthermore, a reflection mirror 102 that reflects the second pulse light emitted from the second pulse light source 32 in a predetermined angular direction, that is, in the direction toward the dichroic mirror 98 is provided. This second pulse light has a wavelength (λ <λ _P or λ> λ _R ) that is outside the range of the wavelength (for example, λ _P ≦ λ ≦ λ _R ) of the chirped light pulse generated by the chirp introducing device 82. Is a single wavelength light.

  The light pulse generating means for generating a chirped light pulse whose color regularly changes with time is composed of a first pulse light source 30 and a chirp introducing device 82. The optical multiplexing means for generating a combined optical pulse by combining the chirped optical pulse and the single wavelength optical pulse includes a beam splitter 84, a reflective mirror 96, a dichroic mirror 98, and a reflective mirror 102. The light distribution means for distributing the chirped light pulse is constituted by a beam splitter 84. Furthermore, the optical path length adjusting means for adjusting the optical path length of each chirped light pulse so that each chirped light pulse has an optical path length that does not overlap with each other on the same optical path includes an optical system control unit 76 and a reflection mirror 92. The

  The three-dimensional shape measuring apparatus 12 according to this embodiment is basically configured as described above, and the operation thereof will be described next.

  First, an operator who is a user prepares for the three-dimensional shape measurement of the surface 26 of the workpiece 24 by the three-dimensional shape measurement system 10.

  Subsequently, when the operator gives a measurement start instruction from an operation unit (not shown) of the host controller 18, the three-dimensional shape measurement on the surface 26 of the workpiece 24 is started.

  As shown in FIG. 2, pulse light is emitted from the first pulse light source 30 that has received the pulse emission instruction from the first pulse light emission control unit 64, and the pulse light is supplied to the pulse light adjustment optical system 34. Similarly, pulse light is emitted from the second pulse light source 32 that has received the pulse emission instruction from the second pulse light emission control unit 66, and the pulse light as a single wavelength light pulse is supplied to the pulse light adjustment optical system 34. .

As shown in FIG. 3, the pulsed light emitted from the first pulsed light source 30 is chirped by the chirp introducing device 82 to generate a chirped light pulse. The chirped light pulse is reflected by the reflecting mirror 88 via the beam splitter 84 and the beam splitter 86, and a part of the chirped light pulse is further reflected by the beam splitter 90. The chirped light pulse (hereinafter, referred to. Chirped light pulses 110b) is on the optical path L _3, is reflected in the opposite direction by the reflecting mirror 92, is transmitted by the beam splitter 90, it is supplied to the magnifying optical system 36 side.

A part of the chirped light pulse transmitted by the beam splitter 84 is reflected in the direction of the optical path L ₄ by the beam splitter 86 and is applied to the shutter 94. At this time, the shutter 94 composed of an ultrafast nonlinear optical shutter or the like is opened only when a chirped light pulse as excitation light arrives, and can achieve a response time of about picoseconds to femtoseconds. In addition, by appropriately setting the optical path length of the optical path L ₅ , the opening / closing operation of the shutter 94 is controlled at an appropriate timing.

Some of the chirped optical pulses generated by the chirped introduction device 82 (hereinafter, referred to as chirped light pulse 110a.) Is reflected in the optical path L ₅ direction by the beam splitter 84, it is reflected by the reflecting mirror 96, transmitted by the dichroic mirror 98 Then, it is cut out at a predetermined timing by the shutter 94, reflected by the reflecting mirror 100, reflected by the beam splitter 90, and supplied to the magnifying optical system 36 side.

  The single-wavelength light pulse 112 emitted from the second pulse light source 32 is reflected by the reflection mirror 102, reflected by the dichroic mirror 98, extracted by the shutter 94 at a predetermined timing, reflected by the reflection mirror 100, and beam splitter 90. And is supplied to the magnifying optical system 36 side.

  Here, based on the optical path length control of the chirped light pulse 110a by the optical system control unit 76 and the emission timing control of the single wavelength optical pulse 112 by the timing control unit 70 (see FIG. 2), the chirped light pulses 110a, 110b, And the flight position of the single wavelength light pulse 112 is adjusted appropriately. The adjustment of the flight position of each light pulse will be described in detail with reference to FIGS. 4A to 4C.

Figure 4A is a schematic view showing the relationship of the flight position of the chirped optical pulses 110a and monochromatic light pulse 112 immediately before the passage of the shutter 94 (the position of P ₁ illustrated in FIG. 3).

  Here, the chirped light pulse 110a and the single-wavelength light pulse 112 fly in the direction of the arrow, and the chirped light pulse 110a is from the long wavelength side (red side, which is represented as R in FIG. 4A), which is the leading edge. It is assumed that the color continuously changes up to the short wavelength side (purple side, which is represented as P in FIG. 4A) which is the trailing edge. Further, it is assumed that the single wavelength light pulse 112 having a predetermined wavelength (denoted as S1 in FIG. 4A, which corresponds to a wavelength in the ultraviolet region, for example) is longer than the chirped light pulse 110a.

  The timing at which the single wavelength light pulse 112 from the second pulse light source 32 is emitted by the timing control unit 70 (see FIG. 2) is adjusted. Therefore, the single-wavelength light pulse 112 is multiplexed at the position of the dichroic mirror 98 with the chirped light pulse 110a emitted from the first pulse light source 30, and then flies on the same optical path.

Figure 4B is a schematic view showing the passage immediately relationship flight position of the chirped optical pulse 110a and the single-wavelength optical pulse 112 in the (position of P ₂ shown in FIG. 3) of the shutter 94.

  The combined chirped light pulse 110a and single wavelength light pulse 112 are cut out by an appropriate opening / closing operation of the shutter 94. Therefore, the trailing edge portion 114 of the single wavelength light pulse 112 is cut out so that the flight positions of the trailing edges of the chirp light pulse 110a and the single wavelength light pulse 112 are aligned.

  Thereafter, the chirped light pulse 110a and the single wavelength light pulse 112 from which the trailing edge portion 114 has been cut off are reflected by the reflecting mirror 100, reflected by the beam splitter 90, and expanded as a combined light pulse 116 together with the other chirped light pulse 110b. It is supplied to the optical system 36 side.

FIG. 4C is a schematic diagram showing the relationship of the flight position of the combined light pulse 116 immediately before reaching the magnifying optical system 36 (position P ₃ shown in FIG. 3).

Of chirped light pulses from the first pulse light source 30, chirped light pulses 110b supplied to the beam splitter 90 is transmitted through the beam splitter 84 is suitably adjusted optical path length of the light path L ₃ is the position movement of the reflecting mirror 92 Has been. Therefore, the flight positions of the trailing edge P of the chirped light pulse 110a and the leading edge R of the chirped light pulse 110b substantially coincide, that is, the chirped light pulses 110a and 110b are not spaced apart from each other, in other words, the chirped light pulse 110a. The trailing edge P and the leading edge R of the chirped light pulse 110b are combined so as to be arranged in series.

  In the present embodiment, optical path adjustment parameters set in advance by the PC 72 can be acquired via the I / F 74 and stored in a storage unit (not shown). Then, the optical system control unit 76 appropriately reads the optical path adjustment parameter stored in the storage unit, determines the movement amount of the reflection mirror 92 based on the optical path adjustment parameter, and moves the reflection mirror 92 along the C direction. Can be moved to an appropriate position.

  As shown in FIG. 2, when the combined light pulse 116 is supplied from the pulsed light adjusting optical system 34, the combined light pulse 116 has its beam diameter expanded by the expanding optical system 36, transmitted through the polarization beam splitter 38, The light is collimated by the collimator lens 40, converted from linearly polarized light to circularly polarized light by the λ / 4 wavelength plate 42, and the light flux of the combined light pulse is condensed by the objective lens 46, and irradiated on the irradiation region 44 on the surface 26 of the workpiece 24. Is done.

  The objective lens 46 is moved by a predetermined displacement amount along the A direction (Z-axis direction) by a driving mechanism (not shown), and the irradiation area 44 is set in advance to have a desired size.

The combined light pulse 116 reflected by the irradiation region 44 on the surface 26 of the work 24 is collected by the objective lens 46, converted from circularly polarized light to linearly polarized light by the λ / 4 wavelength plate 42, and collimated by the collimator lens 40. The light beam is reflected in the direction of the optical path L ₁ by the polarization beam splitter 38, and is cut out by a predetermined amount of light at a predetermined timing by the shutter 48. Is reflected in a predetermined angle direction by the reflecting mirror 52, a first reflected light image is formed by the imaging optical system 54, converted into a first imaging signal by the color two-dimensional detector 56, and an image synthesis unit 57. To be supplied.

  The gradation characteristics of the first captured image relating to the three-dimensional shape acquired in this way will be described. A difference in depth in the Z-axis direction at each position on the XY axis plane defined in FIG. 1 is converted as a difference in flight time of the combined optical pulse 116 that reaches the shutter 48. This difference in flight time is detected by the difference in light color (wavelength) cut out simultaneously by the opening / closing operation of the shutter 48, and is expressed as the gradation characteristic (signal value) of the captured image. Specifically, the time for the combined light pulse 116 to reach the shutter 48 is delayed at a position on the XY axis plane where the depth in the Z direction is large. Therefore, the color two-dimensional detector 56 tends to detect the light color on the leading edge side (long wavelength side) of the chirped light pulse 110a, which is the leading edge of the combined light pulse 116 (see FIG. 4C).

Further, the multiplexed light pulses 116 which is cut out by the shutter 48, dichroic monochromatic light pulse component of the multiplexed light pulses by dichroic mirror 50 only (single-wavelength light pulse 112) is reflected in the optical path L ₂ direction, the optical system 60 Thus, a second reflected light image is formed, converted into a second imaging signal by the two-dimensional detector 62, and supplied to the image composition unit 57.

The single-wavelength light pulse 112 has a wavelength that is outside the range of the wavelengths (λ _P ≦ λ ≦ λ _R ) of the chirped light pulses 110a and 110b. Therefore, the multiplexed light pulse 116 is completely demultiplexed into a chirped light pulse component and a single wavelength light component by the dichroic mirror 50.

  Thereafter, the first and second imaging signals are synthesized by the image synthesis unit 57. A specific example of image processing in the image composition unit 57 will be described in detail with reference to FIGS. 4C, 5A, and 5B.

  First, appropriate image processing is performed so that the two-dimensional positions (XY coordinates) of the pixels of the first and second captured images correspond to each other. For example, known image processing methods such as affine transformation, image enlargement / reduction processing, and region-based matching can be used. Note that it is preferable that the imaging regions of the color two-dimensional detector 56 and the two-dimensional detector 62 coincide. Furthermore, the resolution and the number of pixels of the color two-dimensional detector 56 preferably match the resolution and the number of pixels of the two-dimensional detector 62. If it does so, since the two-dimensional position (XY coordinate) of each pixel of the 1st and 2nd captured images is matched beforehand, the above-mentioned image processing becomes unnecessary.

  Next, an imaging signal representing the three-dimensional shape of the work 24 is acquired using the two-dimensional position and color information of the first imaging signal while referring to the two-dimensional position (address corresponding to each pixel) of the second imaging signal. .

  FIG. 5A is a graph showing the relationship between the wavelength of the first imaging signal and the gradation level of the combined imaging signal. Here, the larger the gradation level of the combined imaging signal, the larger the Z-axis coordinate (closer to the imaging surface 22), and the smaller the gradation level of the combined imaging signal, the smaller the Z-axis coordinate (imaging surface 22). It is far from).

When the chirped light pulses 110a and 110b shown in FIG. 4C can express 256 levels of gradation with respect to the spatial resolution in the depth direction (Z-axis direction), the combined light pulse 116 shown in FIG. A certain 512 gradation level can be expressed. In FIG. 4C, the gradation level 511 (highest value) corresponds to the wavelength λ _R at the leading edge R of the chirped light pulse 110a, and the gradation level 0 (lowest value) is the wavelength at the trailing edge P of the chirped light pulse 110b. The gradation level 255 (intermediate value) corresponds to λ _P and corresponds to the wavelength λ _P at the trailing edge P of the chirped light pulse 110a or the wavelength λ _R at the leading edge R of the chirped light pulse 110b. As described above, the wavelength of the first imaging signal and the gradation level of the combined imaging signal have a relationship that forms a saw-shaped graph.

  FIG. 5B is a graph showing the relationship between the detected light intensity of the second imaging signal and the gradation level of the combined imaging signal. The single-wavelength light pulse 112 is detected at the flight position corresponding to the chirped light pulse 110a, and thus has a predetermined value. On the other hand, the single-wavelength light pulse is not detected at the position corresponding to the chirped light pulse 110b, and the value is zero. (See FIG. 4C).

  Here, as shown in FIG. 4B, since the trailing edge portion 114 of the single wavelength light pulse 112 is cut off by the shutter 94, the single wavelength light is emitted when the chirped light pulse 110b is cut out by the shutter 48 (see FIG. 2). The pulse 112 is not cut out together. Therefore, the types of the extracted chirped light pulses 110a and 110b can be identified based on whether or not the single wavelength light pulse 112 is detected.

  Further, since the trailing edge of the chirped light pulse 110a and the tip of the chirped light pulse 110b are arranged without being separated or overlapped, there is no possibility of erroneous detection of the imaging signal.

  In this manner, by arranging the chirped light pulses 110a and 110b in series and generating the combined light pulse 116 accompanied by the single wavelength light pulse 112, it can be detected as a virtually long chirped light pulse. That is, when the single wavelength light pulse 112 exhibits the marking function, the arrangement order of the chirped light pulses 110a and 110b can be specified. Further, in the detected combined light pulse 116, a single chirped light is obtained by combining the wavelength of the first imaging signal (chirped light pulse component) and the detected light intensity of the second imaged signal (single wavelength light pulse component). A gradation level exceeding the gradation expression ability of a pulse can be expressed.

  The image signal thus synthesized is transmitted to the image processing apparatus 14 which is an external apparatus via the I / F 58, subjected to desired image processing by the image processing apparatus 14, and visible on the monitor 16 shown in FIG. Displayed as an image. With this visible image, the three-dimensional shape can be analyzed and grasped in the irradiation region 44 on the surface 26 of the workpiece 24.

  Next, a first modification of the three-dimensional shape measuring apparatus according to the present invention will be described with reference to FIG. FIG. 6 is a schematic configuration diagram of a first modification of the three-dimensional shape measuring apparatus 12 according to the present invention, and also shows the relationship between the flight positions of light pulses.

  The chirped light pulse 202 emitted from the chirped light source 200 is continuously colored in the order of red (R in FIG. 6), green (G in FIG. 6), and blue (B in FIG. 6) from the leading edge to the trailing edge. Is changing. The chirped light pulse 202 is divided by the beam splitter 204 into a first chirped light pulse 206 and a second chirped light pulse 208. The first chirped light pulse 206 reflected by the beam splitter 204 is further reflected by the reflecting mirror 210, combined with the single wavelength light pulse 214 emitted from the single wavelength light source 212 at an appropriate timing, and thereafter on the same optical path. To fly. The single wavelength light pulse 214 has a wavelength of purple (P in FIG. 6) that is outside the wavelength range of the chirped light pulse 202.

  The trailing edge of the single-wavelength light pulse 214 is cut off by an appropriate opening / closing operation of the shutter 216 so that the flight positions of the trailing edges of the first chirped light pulse 206 and the single-wavelength light pulse 214 on the same optical path are aligned. Thereafter, the first chirped light pulse 206 and the single-wavelength light pulse 214 are reflected by the reflecting mirror 218 in a predetermined angle direction and are irradiated toward the surface 26 side of the workpiece 24.

  On the other hand, the second chirped light pulse 208 transmitted through the beam splitter 204 is reflected by the reflecting mirror 220, reflected by the reflecting mirror 222 in a predetermined angle direction, and irradiated toward the surface 26 side of the workpiece 24.

  The separation distance between the reflection mirror 220 and the reflection mirror 222 is set appropriately, and the second chirped light pulse 208 is adjusted to an appropriate optical path length. Accordingly, the first chirped light pulse 206 and the second chirped light pulse 208 are combined so as to be arranged without a time interval, and form a combined light pulse 224 together with the single wavelength light pulse 214.

  The combined light pulse 224 applied to the work 24 is reflected on the surface 26 and is cut out by a predetermined amount of light at a predetermined timing by the shutter 226. Here, it is assumed that the green light component 228 of the first chirp light pulse 206 and the single wavelength component 230 that is a part of the single wavelength light pulse 214 are extracted. The extracted green light component 228 and single wavelength component 230 are divided by the beam splitter 232.

  The green light component 228a and the single wavelength component 230a that have been transmitted through the beam splitter 232 are blocked only by the single wavelength component 230a by the band pass filter 234 that transmits light having a wavelength higher than that of blue light. The green light component 228 a transmitted by the band transmission filter 234 is imaged by the depth measurement camera 236.

  On the other hand, the green light component 228b and the single wavelength component 230b reflected by the beam splitter 232 are blocked only by the green light component 228b by the band pass filter 238 that transmits light having a wavelength lower than that of the blue light. The single wavelength component 230 b transmitted by the band transmission filter 238 is imaged by the index determination camera 240.

  When the green light component 228 of the first chirped light pulse 206 is cut out by the shutter 226, the first image signal 242 captured by the depth measurement camera 236 and the index determination camera 240 are captured by the image composition unit 57. A second imaging signal 244 is supplied. On the other hand, when the green light component of the second chirped light pulse 208 is cut out by the shutter 226, the image synthesizing unit 57 captures the first image signal 246 captured by the depth measurement camera 236 and the index determination camera 240. The second imaging signal 248 is supplied.

  Then, the first imaging signal 242 and the first imaging signal 246 substantially match, but the second imaging signal 244 and the second imaging signal 248 are different. Therefore, the difference in depth position can be identified by referring to the second imaging signal as an index (arrangement order of chirped light pulses).

  Next, a second modification of the three-dimensional shape measuring apparatus according to the present invention will be described with reference to FIGS. 7A to 7C. This second modification is different from the present embodiment with respect to the configuration of the combined optical pulse generated by the pulsed light adjustment optical system 34 and the method for synthesizing the imaging signal by the image synthesizing unit 57.

  In the following modifications, the same components as those in the present embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and so forth.

FIG. 7A is a schematic diagram showing the relationship of the flight position immediately before the combined optical pulse 120 according to the second modification reaches the magnifying optical system 36 (position P ₃ shown in FIG. 3). The flight position of the trailing edge P of the chirped light pulse 110a and the leading edge R of the chirped light pulse 110b substantially match, and the flying position of the trailing edge P of the chirped light pulse 110b and the leading edge R of the chirped light pulse 110c approximately match. Yes. That is, the chirped light pulses 110a, 110b, and 110c are multiplexed so as to be arranged in series. Further, the single-wavelength light pulse 112 and the chirped light pulse 110a having a predetermined wavelength S1 (for example, corresponding to a wavelength in the ultraviolet region) are adjusted to have the same flight position and the same pulse length. Further, the single-wavelength light pulse 118 and the chirped light pulse 110b having a wavelength S2 different from S1 (for example, corresponding to the wavelength in the infrared region) are adjusted to have the same flight position and the same pulse length. Yes.

  The single wavelength light pulse 112 and the single wavelength light pulse 118 may be emitted from the same pulse light source (second pulse light source 32 shown in FIG. 2) or from different pulse light sources. May be.

FIG. 7B is a graph showing the relationship between the wavelength of the first imaging signal and the gradation level of the combined imaging signal. The combined optical pulse 120 shown in FIG. 7A can express a 768 gradation level that is three times 256. In FIG. 7A, the gradation level 767 (maximum value) corresponds to the wavelength λ _R at the leading edge R of the chirped light pulse 110a, and the gradation level 0 (lowest value) corresponds to the wavelength at the trailing edge P of the chirped light pulse 110c. Corresponds to λ _P.

  FIG. 7C is a graph showing the relationship between the detected light intensity of the second imaging signal and the gradation level of the combined imaging signal. Since the single wavelength light pulse 112 is detected at the flight position corresponding to the chirp light pulse 110a, it has a predetermined value (high level), and the single wavelength light pulse 118 is detected at the flight position corresponding to the chirp light pulse 110b. Therefore, while having a predetermined value (low level), no single-wavelength light pulse is detected at a position corresponding to the chirped light pulse 110c, so the value is zero.

  Next, a third modification of the three-dimensional shape measuring apparatus according to the present invention will be described with reference to FIGS. 8A to 8C. This third modified example is different from the present embodiment with respect to the configuration of the combined light pulse generated by the pulsed light adjustment optical system 34 and the image composition method by the image composition unit 57.

FIG. 8A is a schematic diagram showing the relationship of the flight positions immediately before the combined optical pulse 124 according to the third modification reaches the magnifying optical system 36 (position P ₃ shown in FIG. 3). The flight position of the trailing edge P of the chirped light pulse 110a and the leading edge R of the chirped light pulse 110b substantially match, and the flying position of the trailing edge P of the chirped light pulse 110b and the leading edge R of the chirped light pulse 110c approximately match. Yes. That is, the chirped light pulses 110a, 110b, and 110c are multiplexed so as to be arranged in series. Further, the single-wavelength light pulse 112a having a predetermined wavelength S1 (denoted as S1 in FIG. 8A, which corresponds to a wavelength in the ultraviolet region, for example) and having a high light intensity is the same as the chirped light pulse 110a. The single-wavelength light pulse 112b having the wavelength S1 and the light intensity at the medium level so as to be the flight position and the chirp light pulse 110b having the wavelength S1 and the light intensity at the low level so that the flight position is the same. Are adjusted so that the single-wavelength light pulse 112c and the chirped light pulse 110c are at the same flight position. Further, the chirp light pulse 110b overlaps in the range of the chirp light pulse 110a and OL1, and also overlaps in the range of the chirp light pulse 110c and OL2.

  The single-wavelength light pulses 112a, 112b, and 112c may be emitted from the same pulse light source (second pulse light source 32 shown in FIG. 2), respectively, or emitted using a plurality of light distributors. A single light pulse may be distributed.

  FIG. 8B is a graph showing the relationship between the wavelength of the first imaging signal and the gradation level of the combined imaging signal. The combined optical pulse 120 shown in FIG. 8A can express a 768 gradation level that is three times 256. Since this is the same as that of the second modification, detailed description thereof is omitted.

  FIG. 8C is a graph showing the relationship between the detected light intensity of the second imaging signal and the gradation level of the combined imaging signal. Since the single wavelength light pulse 112a is detected at the flight position corresponding to the chirp light pulse 110a, it has a predetermined value (high level = 8), and at the flight position corresponding to the chirp light pulse 110b, the single wavelength light pulse 112b is detected. Therefore, it has a predetermined value (medium level = 3), and has a predetermined value (low level = 1) because the single-wavelength light pulse 112c is detected at the flight position corresponding to the chirped light pulse 110b.

  In OL1, which is the overlapping range of the single-wavelength light pulse 112a and the single-wavelength light pulse 112b, the light intensity detected by the two-dimensional detector 62 can vary within the range indicated by the arrow depending on the optical interference. However, since it does not fall below 3 which is the middle level, it can be specified that the gradation level is around 511 and can be converted to an appropriate gradation level without erroneous detection.

  Further, in OL2, which is the overlapping range of the single wavelength light pulse 112b and the single wavelength light pulse 112c, the light intensity detected by the two-dimensional detector 62 can vary within the range indicated by the arrow depending on the optical interference. However, since it does not fall below 1, which is the low level, it can be specified that the gradation level is around 255 and can be converted to an appropriate gradation level without erroneous detection.

  This configuration is preferable because it is not necessary to adjust the flight positions (the leading edge and the trailing edge of the preceding and following light pulses) between the single wavelength light pulses 112a to 112c and the chirped light pulses 110a to 110c. Specifically, using the shutter 94 (see FIG. 3), the shutter 216 (see FIG. 6), etc., the rear edge portions 114 (or front edges) of the single-wavelength light pulses 112a to 112c as shown in FIG. The processing to do becomes unnecessary.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change freely in the range which does not deviate from the main point of this invention.

  For example, in the present embodiment, the first pulse light source 30 and the second pulse light source 32 as the light source unit, and the color two-dimensional detector 56 and the two-dimensional detector 62 as the detection unit are included in the three-dimensional shape measuring apparatus 12. Although the structure incorporated integrally is taken, you may comprise a light source part and a detection part as a separate apparatus.

  In this embodiment, the chirped light pulse and the single-wavelength light pulse are combined, but separate optical paths may be provided. This eliminates the concern about the effects of optical interference.

  Furthermore, in this embodiment, the image synthesis unit 57 that synthesizes the first and second imaging signals is configured to be incorporated in the three-dimensional shape measuring apparatus 12, but the image processing apparatus 14 performs the image processing. Also good.

  Further, the two-dimensional detector 62 can be configured by either a monochrome sensor (element having a single light receiving wavelength characteristic) or a color sensor (element having a plurality of kinds of light receiving wavelength characteristics).

  Furthermore, in this embodiment, although the structure which arrange | positions two or three chirp light pulses in series is taken, you may arrange | position four or more chirp light pulses. The chirped light pulse is not limited to the light wavelength in the visible region, and ultraviolet light, infrared light, or the like may be used.

DESCRIPTION OF SYMBOLS 10 ... Three-dimensional shape measuring system 12 ... Three-dimensional shape measuring device 14 ... Image processing device 22 ... Imaging surface 24 ... Work piece 26 ... Surface 30 ... First pulse light source 32 ... Second pulse light source 34 ... Pulse light adjustment optical system 38 ... Polarizing beam splitter 40 ... collimating lens 42 ... λ / 4 wavelength plate 44 ... irradiation area 46 ... objective lenses 48, 94, 216, 226 ... shutters 50, 98 ... dichroic mirrors 52, 88, 92, 96, 100, 102, 210 218, 220, 222 ... reflective mirrors 54, 60 ... imaging optical system 56 ... color two-dimensional detector 57 ... image synthesizer 58, 74 ... I / F
62 ... Two-dimensional detector 64 ... First pulse light emission control unit 66 ... Second pulse light emission control unit 68 ... Shutter opening / closing control unit 70 ... Timing control unit 76 ... Optical system control unit 78 ... Reflected light image acquisition unit 80 ... Three-dimensional information acquisition unit 82 ... chirp introduction devices 84, 86, 90, 204, 232 ... beam splitters 110a to 110c ... chirp light pulse 206 ... first chirp light pulse 208 ... second chirp light pulses 112, 112a to 112c, 118 214, single-wavelength optical pulses 116, 120, 124, 224, combined optical pulses

Claims (4)

Chirped light pulse generating means for generating a chirped light pulse whose color changes regularly with time;
Single-wavelength light pulse generating means for generating a single-wavelength light pulse of a predetermined wavelength;
First reflected light image acquisition for irradiating the object to be measured with the chirped light pulse generated by the chirped light pulse generating means and acquiring a first reflected light image of the chirped light pulse reflected from the measured object Means,
A second reflected light image of the single wavelength light pulse reflected from the object to be measured is obtained by irradiating the object to be measured with the single wavelength light pulse generated by the single wavelength light pulse generating means. Reflected light image acquisition means;
The two-dimensional information of the first reflected light image acquired by the first reflected light image acquisition means with reference to the two-dimensional information of the second reflected light image acquired by the second reflected light image acquisition means. And 3D information acquisition means for acquiring 3D information of the object to be measured using color information,
An irradiation timing adjusting unit that adjusts the timing of irradiating the measurement object with the chirped light pulse and the timing of irradiating the measurement object with the single wavelength light pulse;
A three-dimensional shape measuring apparatus comprising: The three-dimensional shape measuring apparatus according to claim 1,
Optical multiplexing means for generating a combined optical pulse by combining the chirped optical pulse and the single wavelength optical pulse;
The combined light pulse is demultiplexed into the first reflected light image acquired by the first reflected light image acquisition means and the second reflected light image acquired by the second reflected light image acquisition means. A three-dimensional shape measuring apparatus comprising: an optical demultiplexing unit; In the three-dimensional shape measuring apparatus according to claim 1 or 2,
The three-dimensional shape measuring apparatus, wherein the single-wavelength light pulse generating means alternately generates single-wavelength light pulses having different wavelengths. In the three-dimensional shape measuring apparatus according to claim 1 or 2,
Light distribution means for distributing the chirped light pulses;
Optical path length adjusting means for adjusting the optical path lengths of the distributed chirped light pulses so that the chirped optical pulses distributed by the optical distributing means have optical path lengths that do not overlap each other on the same optical path. Characteristic 3D shape measuring device.

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