JP2000241134A - Apparatus and method for measuring shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measuring apparatus capable of measuring the distance from an object at a high precision. SOLUTION: A semiconductor laser 3 emits an illuminating light 4a intensity- modulated by a modulating signal S0, a half-mirror 11 reflects a part of the illuminating light 4a while the remaining part transmits through the half-mirror 11 to irradiate an object 6. A transmittance control circuit 13 controls the transmittance of a second liq. crystal shutter 12B so that the intensity of a reflected light 4c from the object 6 and the intensity of a reference light 4c reflected on the half-mirror 11 are approximately equal. On a plane sensor 9, a resultant light is incident from the reflected light 4c and the reference light 4c both having approximately equal intensities. A distance calculator 10 computes a precise distance from the plane sensor 9 to each of points two-dimensionally on the surface of the object 6, based on an output signal from the plane sensor 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating an object with intensity-modulated light to detect reflected light of the object, detecting an intensity-modulated reference light, and converting the reflected light and reference light into a combined light. More particularly, the present invention relates to a shape measuring apparatus and a shape measuring method capable of measuring a distance to an object with high accuracy.

[0002]

2. Description of the Related Art A target object is irradiated with intensity-modulated light,
A conventional shape measuring device that measures the distance to an object by detecting the phase of the reflected light is disclosed, for example, in Japanese Patent Publication No. 59-30233.

FIG. 9 shows this shape measuring apparatus. The shape measuring apparatus 100 includes a light emitting element 123 that emits light whose intensity is modulated at a predetermined frequency by a driving signal from a driving circuit 121 based on a signal from an oscillator 120, and a light emitting element 1
A beam splitter 125 that transmits and reflects light that has entered from 23 through a projection lens 124; a beam that passes through the beam splitter 125, is reflected by the object 6, is reflected by the beam splitter 125 again, and is reflected by the beam splitter 125 again. The light receiving element 127 receives the light reflected by the reflecting mirror 122 and transmitted again through the beam splitter 125 via the condenser lens 126, the amplifier 128 amplifies the output signal of the light receiving element 127, and the output signal of the amplifier 128. It has a detector 129 for detecting, and a level meter 130 for reading the amplitude from the output signal of the detector 129.

In such a configuration, when light whose intensity is modulated at a predetermined frequency by the driving signal from the driving circuit 121 based on the signal of the oscillator 120 is emitted from the light emitting element 123, the light is transmitted through the projection lens 124. Incident on the beam splitter 125. Beam splitter 12
One light (illumination light) that has passed through 5 is reflected by the object 6,
The light is reflected again by the beam splitter 125, and the reflected light is incident on the light receiving element 127 via the condenser lens 126.
The other light (reference light) reflected by the beam splitter 125 is reflected by a reflecting mirror 122 installed at a known distance, transmitted by the beam splitter 125, and also incident on the light receiving element 127. The two reflected lights and the reference light are optically combined on the light receiving element 127, the waveforms of which are converted into electric signals, and sent to the amplifier 128. The amplitude of this waveform changes depending on the difference between the distance from the light receiving element 127 to the object 6 and the distance from the light receiving element 127 to the reflecting mirror 122. The amplified waveform signal is detected by the detector 129, and the amplitude is read by the level meter 130.
Can be calculated.

[0005]

However, according to the conventional shape measuring apparatus, when the distance from the light receiving element 127 to the object 6 is different from the distance to the reflecting mirror 122, or when the reflectance between the object 6 and the reflecting mirror 122 is different. If different, or both, the light intensity of the reflected light from the object 6 and the light intensity of the reference light from the reflecting mirror 122 are different. In such a case, according to the simulation results by the present inventors, It has been found that the change in the output signal of the light receiving element is small with respect to the change in the phase of the combined light of the reflected light and the reference light, and it is not possible to perform highly accurate distance measurement.

Accordingly, it is an object of the present invention to provide a shape measuring device and a shape measuring method capable of measuring a distance to an object with high accuracy.

[0007]

In order to achieve the above object, the present invention has an illumination light source for emitting illumination light whose intensity is modulated at a predetermined frequency. Reflected light generating means for generating reflected light from an object; reference light emitting means for emitting reference light intensity-modulated by the predetermined frequency; and receiving and detecting a combined light of the reflected light and the reference light. Detection means for outputting a signal; and control for controlling the reflected light generation means and the reference light emission means such that the light intensity of the reflected light and the light intensity of the reference light are substantially equal on the detection surface of the detection means. Means, and calculating means for calculating a distance from the detection surface to the object based on a detection signal from the detection means that has received the combined light of the reflected light and the reference light having substantially the same light intensity. Specially equipped Providing a shape measuring device according to. According to the above configuration, by setting the light intensities of the reflected light and the reference light to be substantially equal on the detection surface, the change of the detection signal becomes largest with respect to the phase change of the combined light due to the reflected light and the reference light. .

In order to achieve the above object, the present invention irradiates an object with illumination light whose intensity is modulated at a predetermined frequency, detects reflected light from the object, and detects the intensity of light modulated at the predetermined frequency. In the shape measuring method for detecting the reference light and measuring the distance from the detection surface to the object based on the combined light of the reflected light and the reference light, the light intensity of the reflected light and the light intensity of the reference light Are set to be substantially equal on the detection surface, and the distance is measured based on the detection of the combined light of the reflected light and the reference light having the same light intensity. I do.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a three-dimensional shape measuring apparatus according to a first embodiment of the present invention. The device 1 includes a modulation signal generator 2 for generating a modulation signal S _m, a semiconductor laser 3 which emits illumination light 4a made of laser light intensity-modulated by a modulation signal S _m from the modulation signal generator 2,
A planar lens via a projection lens 5 for irradiating illumination light 4a from the semiconductor laser 3 toward the target object 6 and an optical filter 8 for selectively transmitting the reflected light 4b reflected by the target object 6 through only the laser light Imaging lens 7 for imaging on 9
A distance calculator 10 that two-dimensionally calculates distance data on the surface shape of the target object 6 based on the output signal of the plane sensor 9, and transmits and reflects the illumination light 4 a from the semiconductor laser 3. A half mirror 11 for guiding the reflected laser light as reference light 4c onto the flat sensor 9 via the optical filter 8 and a two-dimensional first liquid crystal shutter disposed between the target object 6 and the optical filter 8 1
2A, a two-dimensional second liquid crystal shutter 12B disposed between the half mirror 10 and the optical filter 8, and a second liquid crystal shutter 12 based on the output signal of the flat sensor 9.
The apparatus 1 includes a transmittance control circuit 13 for controlling transmittance for each pixel constituting B, a CPU, a ROM, a RAM, and the like.
And a computer 14 for controlling each of the components and displaying the calculation result of the distance calculation unit 10.

[0010] The semiconductor laser 3, together with the illumination light 4a emitted consisting of intensity-modulated laser light based on a modulation signal S _m from the modulation signal generator 2, the modulation signal generator 2
The illumination light 4a is composed of stationary light that has not been intensity-modulated based on the stationary signal _Sco from the controller. The stationary light has a light intensity that matches the average intensity of the intensity-modulated illumination light 4a.

First and second liquid crystal shutters 12A, 1
2B can control the transmittance in the range of 0 to 100% by controlling the applied voltage for each pixel.

FIG. 2 shows the modulation signal generator 2. The modulation signal generator 2 includes a modulation current source 20 that outputs a modulation signal,
A direct current source 21 for outputting a stationary signal;
And a current signal mixer 22 for synthesizing the output signal of the DC current source 21 and outputting the combined signal to the semiconductor laser 3.

FIG. 3 shows one pixel circuit constituting the flat sensor 9. The plane sensor 9 has a plurality of pixels arranged two-dimensionally, and one pixel is, as shown in FIG.
A photodiode 90, a first bypass circuit switching unit 91A, and a high pass filter (HPF: High Pass Filtration).
ter) 92, a peak hold circuit 93 including a comparator 93a, a diode 93b, and a capacitor 93c, a current conversion circuit 94, and a second bypass circuit switching unit 91B.
And a bypass line 9 connected to the first bypass circuit switching unit 91A and the second bypass circuit switching unit 91B to bypass the HPF 92 and the peak hold circuit 93.
5, a switch 96, and a charge storage circuit 97.
The flat sensor 9 has an amplitude detection mode and a light amount detection mode.

FIGS. 4A to 4D show the operation of the flat sensor 9. FIG. First and second bypass circuit switching unit 9
When 1A and 91B are set to the A side under the control of the computer 14, a signal Sa is output from the photodiode 90, and the output signal Sa of the photodiode 90 is output by the HPF 92 as shown in FIG. The DC component V ₀ is cut to become a high-frequency signal Sb shown in FIG.
The signal is input to the peak hold circuit 93. The peak hold circuit 93 outputs a peak value signal Sc holding the peak value of the amplitude as shown in FIG. Since this peak value signal Sc has a very low voltage and is difficult to detect, it is converted into a current by the current conversion circuit 94 and then stored in the charge storage circuit 97 for a certain period of time. Charge storage circuit 9
7 accumulation voltage Sd of, as shown in FIG. 2 (d), increases linearly, when compared with the modulation frequency omega / 2 [pi of laser light period the integral of a sufficiently large time T _1, a readily detectable The voltage value becomes V. It is clear that this voltage value V is proportional to the amplitude of the combined light. Voltage value to the data transfer period T ₂ V
Is transferred to the distance calculation unit 13. From the charge storage circuit 97, the amplitude of the intensity-modulated light from the target object 6 is detected, and an image signal including phase data corresponding to the distance to the target object 6 is obtained. Charge storage circuit 97 in the discharge period T ₃ is grounded by the switch 96, the accumulated charge is released, subsequently accumulation begins again. With these circuits, the amplitude of the high frequency component of the output signal Sa of the photodiode 90 can be detected in the form of a voltage. Meanwhile, the first
And second bypass circuit switching units 91A and 91B
Is set to the B side under the control of the computer 14, the output signal Sa of the photodiode 90 is directly input to the charge storage circuit 97, and the average luminance of the reflected light 4b from the target object 6 is detected. Is obtained.

Next, the operation of the device 1 according to the first embodiment will be described.

(1) Transmittance Adjustment Mode of Second Liquid Crystal Shutter 12B The CPU of the computer 14 executes the transmittance adjustment mode according to a program in the ROM. The CPU generates a stationary signal S _co from the modulation signal generator 2 according to a control signal to the modulation signal generator 2. That is, the current signal mixer 22 of the modulation signal generator 2 outputs a steady signal S _{co of} only the DC current source 21 to the semiconductor laser 3 under the control of the CPU. The semiconductor laser 3 emits illumination light 4a composed of stationary light according to the stationary signal _Sco from the modulation signal generator 2. The CPU includes first and second liquid crystal shutters 12A,
12B, the first liquid crystal shutter 12A
Is opened, the second liquid crystal shutter 12B is closed, the reflected light 4b from the target object 6 is transmitted, and the reference
c is shielded from light. Only the reflected light 4b enters the flat sensor 9. At this time, the CPU sets the light detection mode of the flat sensor 9 to the light amount detection mode according to a control signal to the flat sensor 9. Thereby, the light amount of only the reflected light 4b is 1
Detected for each pixel. This light amount data is stored in a memory (not shown) in the transmittance control circuit 13.

The CPU closes the first liquid crystal shutter 12A by a control signal to the first and second liquid crystal shutters 12A and 12B while the modulation signal generator 2 generates the steady signal _Sco. Then, the second liquid crystal shutter 12B is opened to shield the reflected light 4b from the target object 6 and transmit the reference light 4c. The plane sensor 9 has a reference light 4c
Only incident. Thus, the light amount of only the reference light 4c is detected for each pixel. The transmittance control circuit 13 sets the second light amount for each pixel such that the light amount data of the reflected light 4b and the light amount data of the reference light 4c already stored in the memory coincide with each other.
Is set for the liquid crystal shutter 12B. Reflected light 4b
By matching the light amount data of the reference light 4c with the light amount data of the reference light 4c, the light intensity of the reflected light 4b and the light intensity of the reference light 4c on the flat sensor 9 match in the distance measurement mode described later.

(2) Distance measurement mode to the target object 6 The CPU of the computer 14 executes the distance measurement mode according to a program in the ROM. The CPU, the control signal to the modulation signal generator 2 generates a modulation signal S _m from the modulating signal generator 2. That is, the modulation signal generator 2
Current signal mixer 22 outputs a modulated signal S _m obtained by synthesizing the output signal of the output signal of the modulation current source 20 and the DC current source 21 to the semiconductor laser 3. The semiconductor laser 3 emits illumination light 4a, which is intensity-modulated by a modulation signal S _m from the modulation signal generator 2. The CPU operates the first liquid crystal shutter 12A in response to a control signal to the first liquid crystal shutter 12A.
Is opened, each pixel of the second liquid crystal shutter 12B is kept in the transmittance set in the transmittance adjustment mode, the reflected light 4b from the target object 6 is transmitted, and the reference light 4c is adjusted in transmittance. Transmit light with the transmittance set in the mode. The illumination light 4a emitted from the semiconductor laser 3 is incident on the half mirror 11, and is divided into two parts, a transmitted light and a reflected light. The illumination light 4a transmitted through the half mirror 11 is applied to the target object 6 and reflected light 4b reflected by the target object 6
Passes through the imaging lens 7 and the first liquid crystal shutter 12A and forms an image on the flat sensor 9 via the optical filter 8. The reference light 4c reflected by the half mirror 11 enters the flat sensor 9 via the second liquid crystal shutter 12B and the optical filter 8. Therefore, the combined light of the reflected light 4b and the reference light 4c having substantially the same light intensity enters the flat sensor 9. At this time, the CPU sets the light detection mode of the flat sensor 9 to the amplitude detection mode according to a control signal to the flat sensor 9. Thus, each pixel of the planar sensor 9 outputs a voltage V _n corresponding to the amplitude of the combined light of the reference light 4c and the reflected light 4b to the distance calculation unit 10. The distance calculation unit 10
The distance from the planar sensor 9 to each point on the surface of the object 6 is calculated two-dimensionally from Expression (9) described later.

Hereinafter, the calculation by the distance calculation unit 10 will be described in detail. The angular frequency of the intensity modulation of the illumination light 4a from the semiconductor laser 3 omega, if the amplitude and 2E, the light intensity I _o of the illumination light 4a emitted from the semiconductor laser 3, the table as in the following equation (1) Is done. I _o = E (sin ωt +1) (1)

If the distance to the target object 6 is 0 to 2.5 m, the required modulation frequency is 30 MHz. Assuming that the light transmittance of the half mirror 11 is a and the reflection coefficient at a certain point on the target object 6 is C _n , the light intensity of the reflected light 4 b incident on the point n where the point is imaged on the flat sensor 9 Is
It is expressed as the following equation (2). _{A n = C n · aE {} sin (ωt + φ n) +1} ... (2) Here, phi _n, is the phase delay caused by the flight distance from the semiconductor laser 3 of the light incident on the plane sensor 9 .
Assuming that the distance between (the semiconductor laser 3 to the target object 6) + (the target object 6 to the plane sensor 9) is L, the phase delay φ _n is expressed as follows. φ _n = ωL / C where C represents the speed of light.

On the other hand, assuming that the reflectance of the half mirror 11 is b and the optical path from the semiconductor laser 3 to the plane sensor 9 is sufficiently smaller than the wavelength of the modulated wave, a certain point n on the plane sensor 9 The light intensity _Bn of the reference light 4c is expressed by the following equation (3). B _n = bE (sin ωt +1) (3)

The light intensity P _n of the combined light at a certain point n of the plane sensor 9 is obtained by simply adding the reflected light 4b expressed by the equation (2) and the reference light 4c expressed by the equation (3). It is expressed as the following equation (4).

(Equation 1) Equation (4) is, DC components _{(C n a + b) E} , and the high frequency component

(Equation 2) And the sum of

In the above equation, C _n appearing in the amplitude term
Since aE and bE are the components of the reflected light 4b and the reference light 4c when irradiating the light that is not intensity-modulated, it can be measured in advance. Therefore, in _order to obtain the phase delay φ _n due to the flight distance from the semiconductor laser 3,
It is sufficient that the amplitude of the high frequency component can be detected. Cut the DC component (C _n a + b) E by HPF92, the peak hold circuit 93 or later rectifying circuit, for detecting the amplitude of the high frequency components.

As can be seen from equation (4), the greater the amplitude of the high frequency component, the more advantageous in terms of measurement accuracy. The amplitude term of the equation (4) is extracted and expressed as in the following equation (5).

(Equation 3) Here, C _n aE and bE are reflected beam 4b and the reference light 4c component when irradiated with light which is not intensity-modulated,
Placing the ratio is k, the reflection coefficient C _n may then be expressed as Equation (6). C _n · aE = kbE (6) The voltage value V _n output from the plane sensor 9 is expressed as shown in the following equation (7).

(Equation 4) Differentiating this with θ yields the following equation (8).

(Equation 5)

FIG. 5 shows the relationship between the light intensity ratio of the reflected light 4b and the reference light 4c and the amplitude change rate (dV _n / dθ). k =
At 1, the amplitude change rate (dV _n / dθ) is the largest. Therefore, in the transmittance adjustment mode, the measurement accuracy is most improved by controlling the transmittance of the second liquid crystal shutter 12B so that the light intensity of the reflected light 4b and the light intensity of the reference light 4c are substantially equal. The light intensity ratio is
For example, a value between 0.8 and 1 is desirable, and in this embodiment, k = 1.

The distance L to be obtained can be obtained from Expression (5) as in the following Expression (9).

(Equation 6)

According to the above-described first embodiment, the following effects can be obtained. (A) Reflected light 4b and reference light 4c applied to flat sensor 9
Are almost equal, the amplitude change rate (dV
_n / dθ) is increased, and the measurement accuracy can be improved. (B) A phase distribution according to the distance to the object 6 can be obtained without the need for expensive and large-sized means such as a crystal light intensity demodulator and an image intensifier which have been conventionally used as a means for demodulating light. Therefore, an inexpensive and compact three-dimensional shape measuring apparatus can be provided. (C) Since the optical filter 8 that selectively transmits only the laser light is provided on the front surface of the flat sensor 9, it is possible to measure a highly accurate three-dimensional shape with a small error due to the influence of external light. (D) Since the phase distribution according to the distance to the target object 6 can be measured as a voltage value, a three-dimensional shape can be easily measured. (E) Both a distance image and a luminance image can be obtained by one plane sensor 9, and since these two images have one-to-one pixel correspondence, image processing of the luminance image using the distance image can be performed. It can be done easily.

FIG. 6 shows an example of a circuit using a rectifier circuit 98 including a resistor 98a and a diode 98b instead of the peak hold circuit 93 of FIG. The operation is the same as that of FIG. 4 except that the output signal of the rectifier circuit 98 becomes the rectified signal S as shown in FIG.

FIG. 8 shows a shape measuring apparatus according to a second embodiment of the present invention. In the second embodiment, a semiconductor laser for emitting reference light is used without providing a half mirror. That is, the second embodiment, the modulation signal S and the first semiconductor laser 3A that emits illumination light 4a based on _m, see also based on a modulation signal S _m light 4
and a second semiconductor laser 3A for emitting c. The other configuration is the same as that of the first embodiment. According to the second embodiment, the second liquid crystal shutter 12B is set such that the light intensity of the reference light 4c emitted from the second semiconductor laser 3A is substantially equal to the light intensity of the reflected light 4b from the object 6.
By controlling the transmittance of each pixel, the light intensity of the reflected light 4b and the reference light 4c applied to the plane sensor 9 becomes substantially equal, and a high-precision distance measurement can be performed similarly to the first embodiment. Will be possible.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above-described embodiment, a semiconductor laser is used as a light source. However, since a coherent light is not required in principle, a general light source, for example, a xenon lamp or a strobe can be used. . Alternatively, an infrared filter or an ultraviolet ray may be used as a light source, and the optical filter 8 may be a filter that selectively transmits only light from the light source. Thus, a highly accurate three-dimensional shape with a small error due to the influence of external light can be measured. Further, in the first embodiment, the half mirror 11 is used, but a beam splitter that transmits and reflects incident light at a predetermined ratio may be used.
In addition, instead of the half mirror 11 of the first embodiment, a reflection mirror that reflects the illumination light 4a from the semiconductor laser 3 is arranged at a position off the optical path of the illumination light 4a applied to the target object 6. You may. As a result, the amount of the reflected light 4b incident on the flat sensor 9 is not reduced by half by the half mirror 11, so that the output signal of the flat sensor 9 increases and the S / N ratio improves.

[0031]

As described above, according to the shape measuring apparatus and the shape measuring method of the present invention, the light intensities of the reflected light and the reference light are made substantially equal on the detection surface. The change of the detection signal becomes the largest with respect to the change of the phase of the combined light with the above. As a result, it is possible to measure the distance to the object with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a three-dimensional shape measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a modulation signal generator according to the first embodiment.

FIG. 3 is a block diagram showing a pixel circuit constituting the flat sensor according to the first embodiment;

FIGS. 4A to 4D are timing charts for explaining the operation of the flat sensor according to the first embodiment;

FIG. 5 is a diagram showing a relationship between a light intensity ratio between reflected light and reference light and an amplitude change rate.

FIG. 6 is a block diagram of a flat sensor according to another embodiment of the present invention.

FIG. 7 is a timing chart for explaining the operation of the flat sensor shown in FIG. 6;

FIG. 8 is a configuration diagram of a three-dimensional shape measuring apparatus according to a second embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional shape measuring apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 3D shape measuring apparatus 2 Modulation signal generator 3, 3A, 3B Semiconductor laser 4a Illumination light 4b Reflected light 4c Reference light 5 Projection lens 6 Target object 7 Imaging lens 8 Optical filter 9 Flat sensor 10 Distance calculator 11 Half mirror 12A first liquid crystal shutter 12B first liquid crystal shutter 13 transmittance control circuit 14 computer 90 photodiode 91A, 91B bypass circuit switching section 92 high-pass filter (HPF) 93 peak hold circuit 93a comparator 93b diode 93c capacitor 94 current conversion circuit 95 bypass wire 96 switch 97 charge storage circuit 98 rectifying circuit 98a resistor 98b diodes S, Sa, Sb, Sc, Sd signal S _m-modulated signal S _{co-stationary} signals T ₁ integration period T ₂ data transfer period T ₃ discharge period V ₀ DC Ingredient _a high frequency component

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ken Tokai 430 Border, Nakai-cho, Ashigagami-gun, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. F-term (reference) 2F065 AA53 BB05 FF51 GG06 JJ03 JJ26 LL04 LL21 LL30 NN01 NN08 UU07

Claims (14)

[Claims] An illumination light source for emitting illumination light intensity-modulated at a predetermined frequency; and a reflected light generating means for irradiating the object with the illumination light to generate reflected light from the object; A reference light emitting unit that emits reference light intensity-modulated by the frequency of, a detecting unit that receives a combined light of the reflected light and the reference light and outputs a detection signal thereof, and a light intensity of the reflected light. Control means for controlling the reflected light generating means and the reference light emitting means such that the light intensity of the reference light is substantially equal on the detection surface of the detection means; and the reflected light and the reference having substantially the same light intensity A shape measuring device comprising: a calculating unit that calculates a distance from the detection surface to the object based on a detection signal from the detecting unit that has received the combined light with light. 2. The shape measuring apparatus according to claim 1, wherein said reference light emitting means includes a reflecting member for guiding a part of said illumination light emitted from said illumination light source to said detecting means as said reference light. apparatus. 3. The shape measuring apparatus according to claim 2, wherein said reflecting member is a beam splitter for transmitting and reflecting said outgoing light at a predetermined ratio. 4. The shape measuring apparatus according to claim 2, wherein said reflection member is a reflection mirror provided at a position which does not hinder irradiation of said object with said illumination light. 5. The control device according to claim 1, wherein the reference light emitting means includes a light transmittance varying means provided on an optical path between the reflecting member and the detecting means, the light transmittance varying means being capable of varying the transmittance of the reference light. 3. The shape measurement device according to claim 2, wherein the means controls the transmittance of the light transmittance varying means so that the light intensity of the reflected light and the light intensity of the reference light become substantially equal on the detection surface. apparatus. 6. A first shutter means provided on an optical path of the illumination light or the reflected light for opening or blocking an optical path of the illumination light or the reflected light by an opening / closing operation. Wherein the reference light emitting means comprises a second shutter means provided on the optical path of the reference light, the shutter means opening or closing the optical path of the reference light by an opening / closing operation, and the control means comprises: The light intensity of the reflected light and the light intensity of the reflected light are controlled based on a detection signal from the detection means that controls the second shutter means and receives only the reflected light and a detection signal from the detection means that receives only the reference light. 2. The shape measuring apparatus according to claim 1, wherein control is performed such that the light intensity of the reference light is substantially equal on the detection surface. 7. A shape measuring apparatus according to claim 6, wherein said second shutter means also serves as a light transmittance changing means capable of changing the transmittance of said reference light. 8. The control means controls the illumination light source of the reflected light generation means to irradiate the object with the illumination light composed of stationary light whose intensity is not modulated, and controls only the reflected light. While irradiating the detection means, the control means controls the reference light emission means to emit the reference light consisting of stationary light that is not intensity-modulated, and irradiates the detection means only with the reference light, and only the reflected light. The light intensity of the reflected light and the light intensity of the reference light become substantially equal on the detection surface based on the detection signal from the detection means that has received the light and the detection signal from the detection means that has received only the reference light. The shape measuring apparatus according to claim 1, wherein the shape measuring apparatus is configured to perform the control as described above. 9. The detection means includes a plurality of detection elements arranged two-dimensionally and outputting the detection signal, and the calculation means includes a plurality of detection elements from the detection surface to a plurality of points on the surface of the object. The shape measuring device according to claim 1, wherein the shape measuring device is configured to calculate a distance. 10. The shape measuring apparatus according to claim 1, wherein said reference light emitting means includes a reference light source for irradiating said object with said reference light. 11. The reference light emitting means includes a light transmittance changing means provided on an optical path between the reference light source and the detection means, the light transmittance changing means being capable of changing the transmittance of the reference light. The shape according to claim 10, wherein the control means controls the transmittance of the light transmittance variable means so that the light intensity of the reflected light and the light intensity of the reference light become substantially equal on the detection surface. Measuring device. 12. The shape measuring apparatus according to claim 5, wherein said light transmittance changing means uses a liquid crystal. 13. A method for irradiating an object with illumination light intensity-modulated at a predetermined frequency to detect reflected light from the object, detecting reference light intensity-modulated at the predetermined frequency, and detecting the reflected light. A shape measurement method for measuring a distance from a detection surface to the object based on a combined light of the detection light and the reference light, wherein the light intensity of the reflected light and the light intensity of the reference light are substantially equal on the detection surface. And measuring the distance based on detection of the combined light of the reflected light and the reference light having the same light intensity. 14. The setting includes irradiating the object with the illumination light composed of stationary light that is not intensity-modulated, detecting only the reflected light, and setting the reference light composed of stationary light that is not intensity-modulated. The shape measuring method according to claim 13, wherein the shape measuring method is configured to detect only the reference light by emitting the light and perform the detection based on the detected reflected light and the reference light.