JP2007187585A - Three-dimensional shape measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of reducing optical processing and reliably performing three-dimensional measurements by a simple size. <P>SOLUTION: In an optical system, a beam splitter 5 multiplexes wide-band light and coherent light, branches them into a reference optical path having a reference mirror and a measuring optical path in which an object to be measured is arranged, makes them incident and irradiated, multiplexes reflected light from the reference mirror and each reflected light from an irradiation location within an irradiation range of the object to be measured, and outputs them. An optical path length changing means 8 changes the optical path length of the measuring optical path, and a camera 10 images output from an optical path formation part according to the changes to acquire data on interference fringes. An optical path length detection means 14 uses changes in the interference fringes due to the coherence light to changes in the optical path length as a scale to determine the optical length of the measuring optical path generated by the interference fringes due to the wide-band light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a three-dimensional shape measuring apparatus that three-dimensionally measures the shape of an object to be measured using an interference phenomenon caused by broadband light (for example, white light) having a plurality of spectrums (hereinafter, described in terms of wavelengths). In particular, one of the broadband light is incident on a reference optical path having a reference mirror at the far end, and the other of the broadband light is incident on a measurement optical path having an object to be measured at the far end, from the reference mirror (reflecting mirror) and the object to be measured. The shape of the object to be measured based on the optical path length in which the interference fringes obtained by changing the optical path length of either the reference optical path or the measurement optical path in the interference section (interferometer) that causes interference due to each return light It is related with the technique which calculates | requires reliably the optical path length which the interference fringe produces.

  In general, the shape measuring apparatus using the above interference phenomenon utilizes the fact that interference fringes exhibit the maximum luminance when the optical path lengths of both the reference optical path and the measurement optical path are equal. That is, the optical path length of either the reference optical path or the measurement optical path is changed (hereinafter, the optical path length of the reference optical path is fixed and the optical path length of the measurement optical path is changed), and the interference fringes generated at that time are the largest. The optical path length (change amount of the optical path length) at the position indicating the luminance is measured as the displacement of the object to be measured in the optical path length change direction (Patent Documents 1 and 2).

  In Patent Document 1, the optical path length of the measurement optical path is changed by piezo actuators (by driving the piezo voltage), and the interference fringes corresponding to the change in the optical path length at a certain measurement point of the object to be measured are imaged by the imaging means. To do. Then, by detecting an electrical quantity called a piezo driving voltage at a point where the maximum luminance of the interference fringes is detected from the imaged data, the optical path length of the measurement optical path at that time is detected.

  According to the method of Patent Document 1, although it is simple, there is a fear that the reliability is poor. That is, the characteristics of elements such as piezos may directly affect the measurement accuracy. Therefore, it is easily affected by the surrounding environment, secular change and the like. In order to prevent this influence, a calibration means (method) is required.

  According to the method of Patent Document 2, white light is branched and input to a reference optical path and a measurement optical path, and light of a predetermined wavelength is extracted from the return light from the reference mirror in the reference optical path by an optical narrowband filter. The optical path length of the measurement optical path in which the peak of the interference fringe appears is obtained by repeating the extracted light. In this case, the accuracy is improved, but there is a problem that it becomes large in scale because it is extracted by a narrow band filter in the light region.

JP 2000-310518 A USP 662894

  The present invention provides a technique for reducing the optical processing and performing the three-dimensional measurement with a simple scale and with high reliability.

  In order to achieve the above object, the present inventors have focused on the fact that the wavelength (period) of interference fringes of coherent light having a substantially single wavelength coincides with the coherent light. In other words, when the optical path length of the measurement optical path is changed, the interference fringes of the broadband light including a plurality of wavelengths and the interference fringes of the coherent light having a substantially single wavelength are imaged, and the optical path length in which the interference fringes of the broadband light are generated (for example, The optical path length in which features such as interference fringe peaks occur is scaled (valued) using the interference fringes of coherent light as a scale. The optical path length in which the interference fringes due to the broadband light are generated may be expressed by a change amount (movement amount) when the optical path length of the measurement optical path is changed from a certain reference position. In addition, scaling is performed on the basis of interference fringes of broadband light including a plurality of wavelengths and interference fringes of partial wavelengths extracted from the plurality of wavelengths.

Specifically, the invention described in claim 1 includes a broadband light source (1) that outputs broadband light having a plurality of spectra,
A coherent light source (11) that outputs coherent light having a substantially single wavelength component;
The broadband light and the coherent light are combined and branched into a reference optical path having a reference mirror and a measurement optical path in which the object to be measured is arranged, and the reflected light from the reference mirror and the irradiated object to be measured An optical path forming unit (5) for combining and outputting each reflected light from the irradiation position of the irradiation range;
Optical path length varying means (8) for changing the optical path length of either the reference optical path or the measurement optical path;
In response to the change in the optical path length by the optical path length varying means, the imaging means (10) for acquiring interference fringe data by imaging the output from the optical path forming unit;
Based on the data output from the imaging means, the optical path length of either the reference optical path or the measurement optical path in which the interference fringe due to the broadband light is generated is based on the change in the interference fringe due to the coherent light with respect to the change in the optical path length. And a desired optical path length detection means (14).

According to a second aspect of the present invention, in the first aspect of the present invention, the image pickup unit picks up an image in accordance with a change in time with respect to the change in the optical path length changed by the optical path length variable unit,
The optical path length detection means, based on the data output by the imaging means, contrasts the characteristic points of the interference fringes due to the broadband light with respect to the time change and the changes in interference fringes due to the coherent light with respect to the time change, The feature point of the interference fringes due to the broadband light is obtained by converting it to the optical path length based on the wavelength of the coherent light.

  The invention according to claim 3 is the invention according to claim 2, wherein the optical path length detection means includes a demultiplexing means (14a) for demultiplexing at least a component of the coherent light from data output by the imaging means. White light interference fringe optical path length detection means (14c) for obtaining feature points of interference fringes by the broadband light with respect to the time change based on data output from the imaging means, and the time by the demultiplexed component of the coherent light A coherent optical path length obtained by converting an interference fringe due to the coherent light with respect to a change and comparing the characteristic point with a change in the interference fringe due to the coherent light and converting the characteristic point into an optical path length based on the wavelength of the coherent light. Reference means (14b).

  The invention according to claim 4 is the invention according to claim 2, wherein the change in interference fringe due to the coherent light is a periodic change in amplitude or phase of the interference fringe. The three-dimensional shape measuring apparatus according to 2 or 3.

  The invention according to claim 5 is the invention according to claim 2, wherein the optical path length detection means is either the reference optical path or the measurement optical path at each irradiation position in the irradiation range of the irradiated object to be measured. Based on the result of obtaining one optical path length, based on the difference between the optical path length at one irradiation position and the optical path length at the other irradiation position, a displacement calculation means (15) for obtaining a relative displacement at each irradiation position; Equipped with.

  According to a sixth aspect of the present invention, in the second aspect of the present invention, the feature point of the interference fringe due to the broadband light is an amplitude peak point of the interference fringe or at least two or more spectra included in the broadband light. It was set as the structure which is the intersection of the phase of a component.

The invention according to claim 7 is a broadband light source (1) for outputting broadband light having a plurality of spectra;
The broadband light is branched and incident on a reference optical path having a reference mirror and a measurement optical path on which the object to be measured is placed, and the reflected light from the reference mirror and the irradiation position of the irradiation range irradiated by the object to be measured are incident. An optical path forming section (5) for combining and outputting each reflected light;
Optical path length varying means (8) for changing the optical path length of either the reference optical path or the measurement optical path;
An imaging means (10) for acquiring interference fringe data by imaging an output from the optical path forming unit in accordance with a change in the optical path length by the optical path length varying means;
From the data output by the imaging means, coherent light of almost a single spectral component is extracted, and the optical path length of either the reference optical path or the measurement optical path in which interference fringes due to the broadband light are generated is changed in the optical path length. And an optical path length detection means (14) obtained based on a change in interference fringes due to the coherent light.

The invention according to claim 8 is a broadband light source (1) that outputs broadband light having a plurality of wavelength components;
The broadband light is branched and incident on a reference optical path having a reference mirror and a measurement optical path on which the object to be measured is placed, and the reflected light from the reference mirror and the irradiation range irradiated by the object to be measured are irradiated. An optical path forming section (5) for combining and outputting each reflected light from the position;
Optical path length varying means (8) for changing the optical path length of either the reference optical path or the measurement optical path;
An imaging means (10) for acquiring interference fringe data by imaging an output from the optical path forming unit in accordance with a change in the optical path length by the optical path length varying means;
Demultiplexing means (14d) for extracting at least two or more spectral components from the data output by the imaging means, and interference fringe optical path length detection for obtaining the intersection of the phase changes of each interference fringe of the two or more spectral components. The optical path length of either the reference optical path or the measurement optical path at the intersection of the means (14f) and the phase change is referred to the interference fringe change due to any one of the two or more spectral components. And a coherent optical path length reference means (14e) to be obtained.

According to the ninth aspect of the present invention, a broadband light source (1) that outputs broadband light having a plurality of spectral components, and the broadband light is branched into a reference optical path having a reference mirror and a measurement optical path in which an object to be measured is arranged. An optical path forming unit (5) that combines the reflected light from the reference mirror and the reflected light from each irradiation position of the irradiated range of the object to be measured, and the reference optical path or The optical path length varying means (8) for changing the optical path length of any one of the measurement optical paths, and imaging the output from the optical path forming section at a predetermined time interval on the time axis when the optical path length changes. Based on the imaging means (10) for acquiring the interference fringe data by the broadband light and the data output from the imaging means based on the time position with respect to the predetermined time interval at which the characteristic point of the interference fringe by the broadband light is generated Of each irradiation position The optical path length detecting means for determining the path length (14), in the three-dimensional shape measurement device equipped with,
A coherent light source (11) for outputting a reference light having a substantially single wavelength component;
A combining unit (12) that combines the coherent light with the broadband light and enters the optical path forming unit;
The optical path length detecting means indicates a time position with respect to the predetermined time interval at which a characteristic point of the interference fringe due to the broadband light occurs, and an amplitude change or a phase change with respect to the time interval of the interference fringe due to the coherent light output from the imaging means. Is represented as a reference.

  In the first, second, third, and ninth aspects, each interference fringe by both the broadband light and the coherent light is simultaneously imaged by the imaging means, and data of each interference fringe obtained from the imaging means (data as an electrical signal) Based on this, the optical path length in which the interference fringes due to the broadband light are generated is obtained with reference to the change of the interference fringes due to the coherent light. Therefore, although a coherent light source is required, measurement can be performed with high reliability by electrical processing, that is, with a simple configuration and with a repetition interval of interference fringes of coherent light (equal to the wavelength of coherent light).

  In the sixth and eighth aspects of the present invention, when obtaining the peak position representing the characteristic of the interference fringe as the position of the interference fringe by the broadband light (both positions are positions on the optical path length), two different fringes of the interference fringe by the broadband light are used. Since it calculates | requires based on the phase of two interference fringes by a wavelength component, it can measure more accurately.

  In the seventh and eighth aspects, instead of using the coherent light source, instead of extracting a part of the wavelength of the broadband light and using the interference fringes, the configuration is further simplified.

  Embodiments according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a functional configuration of the first embodiment. FIG. 2 is a diagram for explaining the optical path length detection means 14 of FIG. FIG. 3 is a diagram for explaining the demultiplexing unit 14a of FIG. FIG. 4 shows an example of an optical path length varying means that replaces the piezo 8. FIG. 5 is a diagram illustrating a functional configuration of the second embodiment. FIG. 6 is a diagram illustrating a functional configuration of the third embodiment.

[1. Overall Configuration of First Embodiment]
In the first embodiment, as described above, the interference fringes due to both the broadband light and the coherent light are imaged by the imaging means 10, and the broadband is obtained based on the data of the interference fringes obtained from the imaging means 10. In this configuration, an optical path length in which an interference fringe due to light occurs (the optical path length may be a change amount when the optical path length is changed before the interference fringe is generated) is obtained with reference to a change in interference fringe due to coherent light.
In the following description, when the optical path length of the measurement optical path is changed, the optical path length in which the interference fringe is generated (the change amount when the optical path length is changed before the interference fringe is generated) is referred to as “specific optical path length”. There are times.

  The first embodiment is broadly divided into a case where an interference fringe due to coherent light is imaged by the camera 10 (imaging means), and a scale is generated from the repetition of the interference fringe, and an optical path length in which the interference fringe due to broadband light occurs. There are two cases where the (specific optical path length) is obtained with reference to a change (scale) of interference fringes due to coherent light. These operations may be performed almost simultaneously, or may be an operation in which a scale is generated first and an optical path length is obtained thereafter. Since the former simultaneous operation has almost no time difference in operation, it is less affected by environmental changes and differences in measurement conditions. Even in the latter time-series operation, since the time difference is a short time, a reliable result can be obtained in the same manner as in the former if the measurement is performed under the same conditions in a room or the like.

"1.1 Configuration of optical system for generating interference fringes by broadband light (white light)"
The light source 1 in FIG. 1 is a light source that emits broadband light having a large number of wavelength components over a wide band and low coherency. Here, for example, a white light source is used. The collimator lens 2 collects the white light (broadband light) from the light source 2 and sends it to the beam splitter 3. The beam splitter 3 converts the direction of white light and sends it to the objective lens 4. The objective lens 4 converts white light into parallel light and sends it to the beam splitter 5 (optical path forming unit). The beam splitter 5 branches the white light received from the objective lens 4 in two directions, and one is sent as measurement light to the measurement object 7 (the optical path from the beam splitter 5 to the measurement object 7 is used as a measurement optical path). The other one is sent to the reference mirror 6 as reference light (the optical path from the beam splitter 5 to the reference mirror 6 is taken as the reference optical path). In this example, the distance between the beam splitter 5 and the reference mirror 6 is fixed, that is, the optical path length of the reference optical path is fixed.
Instead of the beam splitter 5, a half mirror may be used.

  The measurement optical path is configured so that a desired irradiation range to be measured on the surface of the object to be measured 7 is simultaneously irradiated with white light.

[1.2 Configuration of optical system for generating interference fringes by laser light (coherent light)]
In FIG. 1, a He—Ne laser 11 is a light source having a substantially single wavelength. That is, “substantially single wavelength” means a wavelength component (spectrum) that can ensure coherency in the range of the optical path length changed by the piezo 8. The laser light from the He—Ne laser 11 is introduced into the same optical path as the white light by the beam splitter 12. Then, like the white light, the light enters the reference optical path and the measurement optical path. The laser beam is condensed toward the object 7 to be measured. In FIG. 1, the laser beam (indicated by a rough dotted line) is at a position shifted from the center of the measurement range of the object 7 to be measured. It may be the center.

[1.3 Common optical system and processing configuration until interference fringe detection by white light and laser light]
In the following description, when the expressions “return light”, “interference fringes”, etc. are simply used without distinguishing between white light and laser light, they are common to white light and laser light.

  The DUT 7 is mounted on the piezo 8. The piezo 8 is composed of a piezoelectric element, and in accordance with an instruction from the optical path length control means 16, the object to be measured 7 is continuously moved in the Z-axis direction (FIG. 1) with respect to the XY plane (surface orthogonal to the paper surface of FIG. 1). The optical path length of the measurement optical path is variably controlled at a predetermined speed by being displaced (moved) in the vertical direction of the paper surface.

  Here, the variable method for changing the optical path length in the present invention is described as being continuously variable and having a constant variable speed. However, as will be described later, the variable method can be varied on a step basis. The variable speed may be changed to a predetermined function such as a sine function.

  The piezo 8 is means (optical path length variable means) that changes the optical path length of the measurement optical path with respect to the fixed position of the beam splitter 5 under the control of the optical path length control means 16. Here, the description will be given by fixing the optical path length of the reference optical path and changing the optical path length of the measurement optical path. However, in order to generate interference fringes, the piezo 8 is attached to the reference mirror 6, the measurement optical path is fixed, A configuration in which the optical path length of the reference optical path is variable is also possible.

  Each white light and each laser light reflected from the reference mirror 6 and the object 7 to be measured (hereinafter referred to as “return white light” and “return laser light” when distinguished, and collectively referred to as “return light”). Are combined (combined) by the beam splitter 5 and further condensed by the objective lens 4. The returned white light passes through the beam splitter 3, is converted into parallel light by the imaging lens 9, and is input to the camera 10. The return laser light passes through the beam splitter 3, is condensed by the imaging lens 9, and is input to the camera 10.

  At this time, in response to an instruction from the optical path length control means 16, the camera 10 captures the return light according to the distance (or the time interval at which the piezo 8 changes the optical path length of the measurement optical path). Interference fringes due to light (including return white light and return laser light) are imaged (actually, the imaging is merely imaging the return white light and the return laser light, but when the image data is developed later (Including interference fringes due to return white light and return laser light appearing, and therefore, "interference fringes are imaged"). The captured interference fringes are stored in the memory 13. At this time, since the measurement optical path is configured to simultaneously irradiate the desired irradiation range of the DUT 7 with white light as described above, each irradiation position of the irradiation range, that is, a position to be measured (hereinafter referred to as “measurement”). An interference fringe corresponding to the returning white light from the “position” is imaged.

  As a modification of the optical system of FIG. 1, an optical system in which an objective lens is arranged in each of the measurement optical path and the reference optical path instead of the objective lens 4 can be configured. Not limited to. The following description will be given with reference to FIG.

  In the memory 13, since the optical path length control means 16 generates a timing signal at a predetermined time interval and instructs the piezo 8 to variably specify the optical path length according to the time interval, imaging data (return light) of the return light at the timing of the timing signal. Is acquired and stored. For example, if the optical path length is continuously variable linearly in time, the imaging data is stored using the time interval of the timing signal as an address. These timing advance directions (that is, address directions) represent the Z-axis direction. At that time, the imaging data is stored together with the measurement position (Xm, Yp). The information on the measurement position (Xm, Yp) is the position of the pixel in the XY direction corresponding to the position of the image sensor of the camera 10. Since the data is stored in the memory 13 as described above, for example, if the imaging data is extracted from the memory 13 in the order of the addresses and reproduced as described later, the interference fringe data as shown in FIG. 2A is obtained. .

The signal processing means 20 includes an optical path length detection means 14 and a displacement calculation means 15.
As shown in FIG. 1, the optical path length detection means 14 includes a demultiplexing means 14a, a laser optical path length reference means 14b, and a white light interference fringe optical path detection means 14c. The demultiplexing unit 14a receives imaging data from the memory 13, for example, data of measurement positions (Xm, Yp), and separates and extracts interference fringes due to laser light. The interference fringes due to the white light may be separated and taken out. In this case, the interference fringes due to the coherent light may remain overlapped (the reason will be described later). The demultiplexing unit 14c converts the imaging data for a predetermined time interval from the memory 13 into data in the frequency (wavelength) domain by Fourier transform or the like, and separates and extracts it by a frequency (wavelength) filter. The converted laser beam data is converted again into time domain data and input to the coherent optical path length reference means 14b. The reconverted waveform is shown in FIG. On the other hand, the interference fringes of white light and the interference fringes of laser light are not separated or separated and sent to the white light interference fringe optical path length detection means 14c by white light (the interference fringes by the separated color lights are shown in FIG. A).).

  FIG. 2A shows a waveform of interference fringes due to white light developed on coordinates where the horizontal axis represents the time when the optical path length changes and the vertical axis represents the luminance (amplitude). The peak position at the approximate center of the interference fringes due to white light is when the optical path length of the reference optical path is the same as the optical path length of the measurement optical path. Further, the wavelength of the interference fringes due to the white light is made by synthesizing each wavelength which is an element of almost white light (broadband light), and becomes half of the wavelength λ at the center of those bands. Further, the spread of the interference fringes in the optical path length direction by the white light in FIG. 2A depends on the degree of coherency of the white light. The lower the coherency, the narrower the spread.

  The “peak position” (or “peak position”) is a position on the horizontal axis where the luminance (amplitude) of interference fringes due to white light is maximum (hereinafter referred to as “peak”). The horizontal axis is the optical path length direction of the measurement optical path (Z-axis direction: the vertical direction of the paper in FIG. 1), and the time axis direction when the optical path length is variable (time when images are taken at predetermined time intervals by the camera 10) Axial direction).

  FIG. 2B is a diagram showing changes in interference fringes due to laser light on the same time axis as the interference fringes of white light in terms of luminance (amplitude) and phase. The horizontal axis in FIG. 2B is also the time, but also the amount of change in the optical path length of the measurement optical path from the reference position (position before changing the optical path length, for example, this is zero). The repetition of the interference fringe change by the laser light is the same as the half of the wavelength of the laser light. The change (amount) of the phase is a change (amount) with respect to the phase at the reference position (a relative change amount). Therefore, the change of the interference fringes due to the laser beam can be used as a scale carved with the wavelength of the laser beam.

  Here, separation of interference fringes by laser light from interference fringes by white light by the demultiplexing unit 14a will be described. The white light interference fringe optical path length detection means 14c obtains a peak (characteristic point) for specifying the position of the white light interference fringe. On the other hand, FIG. 3A shows a waveform of interference fringes caused by white light, FIG. 3B shows a waveform of interference fringes caused by laser light, and FIG. 3C shows a waveform of interference fringes caused by white light and laser light. As shown in FIG. 3C, if the size of the interference fringes of the laser beam is an appropriate size, the peak position of the interference fringes of white light can be extracted even if they are not separated and overlapped. The size of the interference fringes of the laser beam can be made appropriate by adjusting the intensity of the laser beam from the He—Ne laser 11. In general, it is desirable that the size of the interference fringes of the laser light be less than the size of the interference fringes of the white light.

  In addition, since the imaging data stored in the memory 13 is stored at the above time interval (FIG. 2A is a continuous representation by connecting them), the imaging data is discretely obtained. Become. If this time interval (timing) is fine enough to be ignored with respect to the period of interference fringes (interval between fringe amplitudes) in FIG. 2A, the white light interference fringe optical path length detection means 14c The point indicating the maximum value among the maximum points of the imaging data (luminance data) may be obtained as a peak position, or the peak position of the envelope obtained by connecting the maximum points may be obtained by calculation. Since it is discrete, the maximum point and the peak position of the envelope do not match, and the envelope may not be connected. However, since it is a smooth characteristic, it may be obtained by interpolation calculation from the front and rear maximum points. Regardless of the time interval of the imaging data and the period of the interference fringes, the signal processing means 20 may be obtained by discrete processing as described in JP-A-9-318329.

  Furthermore, as a method of obtaining the peak of interference fringes from discrete imaging data, the optical path length is changed stepwise, and the following is performed based on the discrete imaging data captured for each of the changed predetermined optical path lengths. There is a technology for processing. A direct current component is excluded from the interference fringe data obtained from the imaging data by a digital high-pass filter. The AC component is squared and rectified. Integration is performed through a digital low-pass filter that passes a repetitive component lower than the rectified repetitive component, and envelope data of interference fringes is calculated. At this time, according to a request for the fineness of the peak position, the rectified repetitive components are interpolated with, for example, a square characteristic, and the interpolated repetitive components are integrated to obtain envelope data. The position that becomes the peak of the envelope data is obtained. In these cases, since the imaging data is acquired at time intervals, the peak position is calculated on the time axis, but is finally scaled to the optical path length. The above calculation is performed by the white light interference fringe optical path length detection unit 14c, and can be scaled by the coherent path length reference unit 14b.

[1.4 Scaling and shape measurement]
As described above, the optical path length detection unit 14 reads out, for example, the imaging data at the measurement position (Xm, Yp) from the memory 13 in the order of addresses, and the interference fringes due to the laser light in FIG. 2B and FIG. To obtain white light interference fringes. The white light interference fringe optical path detection means 14c detects the peak position of the white light interference fringe. Then, the laser light path length reference means 14b sets the position where the peak appears as a scale in which the change of the interference fringe due to the laser light developed on the same time axis as that of the white light interference fringe is engraved with the wavelength of the laser light. The position is specified as Z1s. Similarly, the peak position Zss (amount of change in the optical path length) of the interference fringes of white light is also identified from the imaging data at the reference measurement position (Xs, Ys). That is, the optical path length (the amount of change) is valued and scaled. The image may be displayed on the user interface 18 as an image based on the scaled optical path length. Each numerical value and measurement position may be displayed in association with each other.

  And the displacement calculating means 15 calculates | requires those differences Zss-Z1s, and becomes the displacement with respect to the reference | standard measurement position (Xs, Ys) of a measurement position (Xm, YP), ie, height. Similarly, if processing is performed for each measurement position, the height (distance in the Z-axis direction) can be measured for the entire surface of the DUT 7. Since the relative displacement in the height direction is obtained by taking the difference between the specific optical path lengths between the measurement positions in this way, even if there is a response delay of the camera 10, it can be eliminated.

  Further, as described above, the change in the optical path length of the measurement optical path by the optical path length control means 16 and the acquisition of the photographing data by the camera 10 correspond to time, but the scaling is not related to time. is there. Therefore, even if the speed of change of the optical path length of the measurement optical path by the optical path length control means 16 changes and becomes non-constant, the distortion of interference fringes due to white light and the distortion of scales (that is, interference fringes due to laser light) are caused. Since the step of the scale (interference fringe spacing by the laser beam) is determined by the wavelength of the laser beam, the correspondence is clear and measurement can be performed while preventing the influence of the speed change.

"1.5 Modification of optical path length variable means 8"
FIG. 4 shows an optical path length variable means replacing the piezo 8. In place of the piezo 8, a reciprocating optical path length between the rotating element and the object to be measured is obtained by inserting a rotating element having a certain thickness in the measuring optical path and changing the incident angle to the rotating element. Is variable.

"Modification of 1.6 He-Ne laser 11"
In FIG. 1, the He-Ne laser 11 has been used as a coherent light source. However, a substantially single wavelength component is selected by a narrow band optical filter from a white light source or a light source having a plurality of wavelength components, and the beam is converted into a beam. You may make it the structure which injects into the splitter 12. FIG.

[2. Second Embodiment]
This will be described with reference to FIG. FIG. 5 differs from FIG. 1 in that it has a He—Ne laser light source 11 but does not have it. In FIG. 5, the optical path of the laser light from the He—Ne laser light source 11 is not formed, but the other is exactly the same as FIG. 1, and the operation is also the same. In this case, the demultiplexing unit 14a extracts interference fringes of a narrow band laser beam having the same wavelength as the laser beam from the He-Ne laser light source 11 from the imaging data of the memory 13 in the white light band. The coherent optical path length reference means 14b uses the interference fringes due to the laser light as a scale. Although the S / N may be deteriorated as compared with the interference fringes due to the laser beam of the He-Ne laser light source 11, it can be used depending on the required accuracy. There is also a technique for applying an S / N improvement measure.

[3. Third Embodiment]
This will be described with reference to FIG. In the third embodiment, the signal processing means 20 having the configuration shown in FIG. 5 is replaced with the signal processing means 20a shown in FIG. 6A, and the camera 10 shown in FIG. 5 is replaced with a color camera. Therefore, the memory 13 in this case is configured to include color area data. Other constituent operations are the same as those in FIG.

  In FIG. 6A, the demultiplexing means 14d uses, for example, B component (blue band component), G component (green band component) and R component (red band component) from the image data stored in the memory 13. Are respectively transmitted to the white light interference fringe optical path length detecting means 14f. The B phase calculation unit 14f1, the G phase calculation unit 14f2, and the R phase calculation unit 14f3 respectively calculate the interference fringes due to the B component, the interference fringes due to the G component, and the interference fringes due to the R component. These changes in phase correspond to changes in the optical path length of the measurement optical path that is changed by the piezo 8 according to the control of the optical path length control means 16, and both of them are based on the phase before the optical path length is changed, for example. As a change in phase.

  Based on these phase changes, the optical path length determination unit 14f4 sets the phase coincidence point (interference fringe feature point) as the peak position of the interference fringe due to white light. Instead of providing the three phase calculation units (14f1, 14f2, 14f3) as described above, the phase difference zero is detected, and the optical path length determination unit 14f4 uses the point where the phase difference is zero as the peak position. It may be configured to do so.

  On the other hand, the coherent optical path length reference unit 14e generates an interference fringe of any one of the B component, the G component, or the R component, for example, the R component, and uses it as a scale, and the optical path length determination unit 14f determines it. The optical path length (change amount of the optical path length) of the measurement optical path at the peak position is specified. In addition, the displacement measurement can be performed similarly to the first embodiment.

  In addition, although demonstrated as B component, G component, or R component, it is not necessarily restricted to this, You may use the component of three wavelength bands which can identify a wavelength. In addition to the three wavelength bands, at least two wavelength bands are sufficient.

  Although the above description has been made by applying FIG. 6 to FIG. 5, it may be applied to FIG. In this case, the coherent optical path length calculation unit 14e in FIG. 6 performs scaling based on the interference fringes caused by the laser light from the He-Ne laser light source 11.

  Among the above configurations, the signal processing means 20 and 20a and the optical path length control means 16 can be constituted by a CPU and a memory.

It is a figure which shows the function structure of 1st Embodiment. It is a figure for demonstrating the optical path length detection means 14 of FIG. It is a figure for demonstrating the demultiplexing means 14a of FIG. This is an example of a variable optical path length means in place of the piezo 8. It is a figure which shows the function structure of 2nd Embodiment. It is a figure which shows the function structure of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Collimator lens 3 Beam splitter 4 Objective lens 5 Beam splitter 6 Reference mirror 7 Measured object 8 Piezo 9 Imaging lens 10 Camera 11 He-Ne laser 12 Beam splitter 13 Memory 14 Optical path length detection means 14a, 14d Demultiplexing means 14b, 14e Coherent optical path length reference means 14c, 14f White light interference fringe optical path length detection means 15 Displacement calculation means 16 Optical path length control means 18 User interface 20, 20a Signal processing means

Claims (9)

A broadband light source (1) that outputs broadband light having multiple spectra;
A coherent light source (11) that outputs coherent light having a substantially single wavelength component;
The broadband light and the coherent light are combined and branched into a reference optical path having a reference mirror and a measurement optical path in which the object to be measured is arranged, and the reflected light from the reference mirror and the irradiated object to be measured An optical path forming unit (5) for combining and outputting each reflected light from the irradiation position of the irradiation range;
Optical path length varying means (8) for changing the optical path length of either the reference optical path or the measurement optical path;
In response to the change in the optical path length by the optical path length varying means, the imaging means (10) for acquiring interference fringe data by imaging the output from the optical path forming unit;
Based on the data output from the imaging means, the optical path length of either the reference optical path or the measurement optical path in which the interference fringe due to the broadband light is generated is based on the change in the interference fringe due to the coherent light with respect to the change in the optical path length. A three-dimensional shape measuring apparatus comprising: an optical path length detecting means (14) to be obtained. The image pickup means picks up an image according to a time change with respect to the change of the optical path length changed by the optical path length variable means,
The optical path length detection means, based on the data output by the imaging means, contrasts the characteristic points of the interference fringes due to the broadband light with respect to the time change and the changes in interference fringes due to the coherent light with respect to the time change, The three-dimensional shape measuring apparatus according to claim 1, wherein a feature point of the interference fringes due to the broadband light is obtained by converting into an optical path length based on a wavelength of the coherent light.   The optical path length detection means includes a demultiplexing means (14a) for demultiplexing at least the coherent light component from the data output from the imaging means, and the broadband light with respect to the time change based on the data output from the imaging means. A white light interference fringe optical path length detecting means (14c) for obtaining a feature point of the interference fringe, a change of the interference fringe due to the coherent light with respect to the time change by a component of the decohered coherent light, and the feature point; 3. A coherent optical path length reference means (14 b) that is obtained by converting the interference fringe due to the coherent light and converting it to an optical path length based on the wavelength of the coherent light. The three-dimensional shape measuring apparatus described.   4. The three-dimensional shape measuring apparatus according to claim 1, wherein the change in interference fringes due to the coherent light is a periodic change in amplitude or phase of the interference fringes.   Based on the result of the optical path length detection means obtaining the optical path length of either the reference optical path or the measurement optical path at each irradiation position in the irradiation range of the irradiated object to be measured, the optical path length of one irradiation position The displacement calculation means (15) which calculates | requires the relative displacement of each irradiation position based on the difference with the optical path length of other irradiation positions, and the three-dimensional shape of Claim 1, 2, 3 or 4 provided. measuring device.   The characteristic point of the interference fringes due to the broadband light is a peak point of the amplitude of the interference fringes or an intersection of the phases of at least two or more spectral components included in the broadband light. The three-dimensional shape measuring apparatus according to 3, 4, or 5. A broadband light source (1) that outputs broadband light having multiple spectra;
The broadband light is branched and incident on a reference optical path having a reference mirror and a measurement optical path on which the object to be measured is placed, and the reflected light from the reference mirror and the irradiation position of the irradiation range irradiated by the object to be measured are incident. An optical path forming section (5) for combining and outputting each reflected light;
Optical path length varying means (8) for changing the optical path length of either the reference optical path or the measurement optical path;
An imaging means (10) for acquiring interference fringe data by imaging an output from the optical path forming unit in accordance with a change in the optical path length by the optical path length varying means;
From the data output by the imaging means, coherent light of almost a single spectral component is extracted, and the optical path length of either the reference optical path or the measurement optical path in which interference fringes due to the broadband light are generated is changed in the optical path length. A three-dimensional shape measuring apparatus comprising: an optical path length detection means (14) obtained based on a change in interference fringes due to the coherent light. A broadband light source (1) for outputting broadband light having a plurality of wavelength components;
The broadband light is branched and incident on a reference optical path having a reference mirror and a measurement optical path on which the object to be measured is placed, and the reflected light from the reference mirror and the irradiation range irradiated by the object to be measured are irradiated. An optical path forming section (5) for combining and outputting each reflected light from the position;
Optical path length varying means (8) for changing the optical path length of either the reference optical path or the measurement optical path;
An imaging means (10) for acquiring interference fringe data by imaging an output from the optical path forming unit in accordance with a change in the optical path length by the optical path length varying means;
Demultiplexing means (14d) for extracting at least two or more spectral components from the data output by the imaging means, and interference fringe optical path length detection for obtaining the intersection of the phase changes of each interference fringe of the two or more spectral components. The optical path length of either the reference optical path or the measurement optical path at the intersection of the means (14f) and the phase change is referred to the interference fringe change due to any one of the two or more spectral components. A three-dimensional shape measuring apparatus comprising coherent optical path length reference means (14e) to be obtained. A broadband light source (1) that outputs broadband light having a plurality of spectral components, and the broadband light is branched and incident on a reference optical path having a reference mirror and a measurement optical path on which an object to be measured is placed, and from the reference mirror An optical path forming unit (5) for combining and outputting the reflected light from each irradiation position of the irradiation range of the object to be measured, and the optical path of either the reference optical path or the measurement optical path Interference fringe data by the broadband light by imaging the output from the optical path forming unit at a predetermined time interval on the time axis when the optical path length changes, and the optical path length varying means (8) for changing the length The optical path length of each irradiation position is determined based on the time position with respect to the predetermined time interval at which the characteristic point of the interference fringe due to the broadband light is generated based on the imaging means (10) that acquires the image and the data output by the imaging means. Optical path length detection A stage (14), in the three-dimensional shape measurement device equipped with,
A coherent light source (11) for outputting a reference light having a substantially single wavelength component;
A combining unit (12) that combines the coherent light with the broadband light and enters the optical path forming unit;
The optical path length detecting means indicates a time position with respect to the predetermined time interval at which a characteristic point of the interference fringe due to the broadband light occurs, and an amplitude change or a phase change with respect to the time interval of the interference fringe due to the coherent light output from the imaging means. A three-dimensional shape measuring apparatus, characterized in that it is expressed with reference to.

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