JP2007263904A - Device and method for measuring three-dimensional shape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three dimensionally measuring apparatus which detects wide band light and coherent light and can perform abnormality self-diagnosis. <P>SOLUTION: In an optical system, which combines white light and a laser beam, and makes the result incident on a reference optical path and a measurement path and they are irradiated by a beam splitter 5, carries out a wave combining of returning light from a reference mirror, measures the returning light from an object of measurement, and outputs them; an optical path length of the measurement path is changed by a variable optical path means 8, a camera 10 images output from the beam splitter 5, and acquires data of an interference pattern. In a constitution which seeks the optical path length of the measurement path which interference pattern by the white light produces with the variations in the interference pattern by the laser beam to the variation of the optical path length to be a scale with the data, a self-diagnosis provides a laser photodetection means 31 and a wide-band photodetection means 32, and decides on the abnormalities of an He-Ne laser 11 and an optical source 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a three-dimensional shape measurement apparatus and measurement 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 spectra (hereinafter, described by wavelengths). Regarding the method. 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. In the interferometer (interferometer) that causes interference due to each return light, the optical path length generated by the interference fringe obtained by changing the optical path length of either the reference optical path or the measurement optical path is scaled based on the coherent light (value) Is a three-dimensional shape measuring apparatus for measuring the shape of the interference fringe light source object to be measured based on the scaled optical path length, and performs self-diagnosis relating to failure of each light source of coherent light and broadband light Regarding technology.

  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. And the optical path length of the measurement optical path at that time is detected by detecting the electric quantity called the piezo drive voltage at the point where the maximum brightness of the interference fringes is detected from the imaging data.

  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

  In order to solve the above problem, in the previous application (Japanese Patent Application No. 2006-006729), the present applicant has determined that the interference fringes of coherent light having a substantially single wavelength are uniquely determined by the wavelength of the coherent light. Focus on and capture the interference pattern of broadband light including multiple wavelengths and the interference pattern of coherent light of almost single wavelength when the optical path length of the measurement optical path is changed. The optical path length in which features such as peaks of interference fringes 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 can 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.

  However, according to this configuration, measurement is performed by processing data of interference fringes by broadband light and coherent light after optically processed imaging, and the bands of coherent light and broadband light overlap. For example, an erroneous measurement value may be output even if any one of the light sources is abnormal. Further, when the light source is inside, there is a possibility that the abnormal part cannot be grasped unless the internal structure is disassembled.

  It is an object of the present invention to provide a three-dimensional measuring apparatus capable of performing self-diagnosis of whether or not an abnormality is detected by detecting broadband light and coherent light.

To achieve the above object, according to the present invention, a broadband light source (1) that outputs broadband light, a coherent light source (11) that outputs coherent light, and a reference mirror are arranged at the far ends, respectively. An optical path forming unit (5) that is incident on both the reference optical path and the measurement optical path in which the object to be measured is arranged, and combines and outputs the reflected light from the reference mirror and the reflected light from the object to be measured; Based on the optical path length varying means (8) for changing the optical path length of either the reference optical path or the measurement optical path, and the reflected wave output from the optical path forming unit, interference fringes due to the broadband light are generated. An optical path length detecting means (14) for determining an optical path length based on a change in interference fringes due to the coherent light, and a three-dimensional shape measuring apparatus for measuring a three-dimensional shape from the determined optical path length,
Broadband light detection means (32) for detecting at least a part of the broadband light, coherent light detection means (31) for detecting at least a part of the coherent light, an output of the coherent light detection means, and the broadband light detection And a control unit (30) that receives the outputs of the means and determines the quality of each output.

  The invention according to claim 2 is the invention according to claim 1, wherein the control unit outputs at least an alarm when it is determined as one of the respective outputs as a result of the quality determination, Alternatively, the broadband light source and the coherent light source are turned off.

  According to the third aspect of the present invention, the controller (30) sets the self-diagnosis mode, at least part of the broadband light output from the broadband light source (1), and the coherent light output from the coherent light source (11). Detecting at least a part of each, and determining the quality of each light quantity based on a part of the broadband light and a part of coherent light detected in the detection stage, and at least one of them If it is determined as NO, at least the alarm is output, or the control unit sets the measurement mode after it is determined that the broadband light source and the coherent light source are turned off, and the determination step determines good. A broad band from the broadband light source in both the stage and the optical path forming unit (5) at each of the reference optical path where the reference mirror is arranged and the measurement optical path where the object to be measured is arranged at the far end An interference stage for making light and coherent light from the coherent light source incident, combining the reflected light from the reference mirror and each reflected light from the object to be measured, and an optical path length varying means (8); The step of changing the optical path length of either the reference optical path or the measurement optical path, and the optical path length detection means (14) is based on the broadband light based on the combined wave of the reflected waves output in the interference stage. And determining the optical path length in which the interference fringes occur based on the change of the interference fringes due to the coherent light, and measuring the three-dimensional shape from the obtained optical path length.

  According to the present invention, since the configuration is such that the abnormality of each light source can be grasped and measured, a reliable measurement can be performed. In addition, it is possible to easily know whether there is a failure due to the light source.

  Embodiments according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a functional configuration of an embodiment according to the present invention. FIG. 2 shows a modification thereof. FIG. 3 is a diagram for explaining the optical path length detection means of FIG. FIG. 4 is a diagram for explaining the branching means of FIG.

  In the following description of the present invention, [1. Light source and its self-diagnosis configuration], [2. Measurement Configuration of Embodiment] [3. A series of operations from self-diagnosis to measurement will be described in this order.

[1. Light source and its self-diagnosis configuration]
The target of self-diagnosis in this embodiment is the two light sources of the light source 1 and the He—Ne laser 11 in FIG. For each light source, “1.1 Configuration of optical system for generating interference fringes by broadband light (white light)” [1.2 Configuration of optical system for generating interference fringes by laser light (coherent light)] “1.3 Self-diagnosis” will be explained.

"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 1 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 DUT 7 is simultaneously irradiated with white light.

  The light source 1 can use a halogen lamp or the like as a white light source. The broadband light detecting means 32 receives a part of the light from the halogen lamp, converts it into electricity, and outputs it. The output of the broadband light detecting means 32 is used by the control unit 30 for self-diagnosis. Further, since the light source 1 is driven by a power source, the output of white light is turned on and off by turning the power source on and off. Further, in FIG. 1, the optical path may be constituted by a fiber between the light source 1 and the collimator lens 2 immediately before.

[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.

  Further, on the opposite side to which the laser beam from the He-Ne laser 11 is incident, there is provided a laser beam detecting means 31 that receives a part of the laser beam, converts it into electricity, and outputs it. The output of the laser light detecting means 31 is used by the control unit 30 for self-diagnosis. Further, since the He-Ne laser 11 is driven by a power source, the output of the laser beam is turned on and off by turning on and off the power source. In the configuration of FIG. 1, it is desirable that the laser light is detected by the laser light detection means 31 when the light source 1 is turned off. In FIG. 1, the optical path may be constituted by a fiber between the He—Ne laser 11 and the beam splitter 12.

“1.3 Self-diagnosis”
The control unit 30 in FIG. 1 performs control that is unified with the whole, and performs self-diagnosis by receiving the output of the broadband light detection means 32 as described above. The timing for performing the self-diagnosis is when the measurement is not performed first. For example, (a) a stage before the entire power source is turned on and measurement is performed, and (b) a measurement object replacement time from the end of the measurement to the measurement of the next measurement object. That is, the control unit 30 controls each unit as the self-diagnosis mode in the cases (a) and (b) and as the measurement mode at other measurement periods. The self-diagnosis mode may be specified by the user interface 18, or may be configured to be automatically set first after the entire apparatus is turned on, or may be set when the object to be measured is replaced.

  For the replacement of the object to be measured, the next object to be measured is directly transported and replaced with the measured object to be measured, or each component (beam splitters 3, 5, 12,. There is any method in which the stage 40 on which the camera 10 and the like are mounted is moved to the place where the next object to be measured is set and replaced. The stage 40 is movable by a drive unit (not shown). Regardless of the method, the control unit 30 detects the measurement end of the current object to be measured, issues the measurement end, and stops the measurement for each component until receiving the next measurement start command. Enter diagnostic mode.

  The control unit 30 includes a determination unit 30a. During the self-diagnosis mode, the determination unit 30a compares the output (the magnitude or intensity of the light amount) of the broadband light detection unit 32 with the first threshold value. If the former is equal to or less than the first threshold value, the light source 1 If it is abnormal or greater than the first threshold, it is determined that the light source 1 is normal. In addition, the control unit 30 turns off the light source 1 during the self-diagnosis mode, and at that time, the determination unit 30a compares the output (the magnitude or intensity of the light amount) of the laser light detection unit 31 with the second threshold value, If the former is equal to or less than the second threshold value, the He-Ne laser 11 is determined to be abnormal, and if it is equal to or greater than the second threshold value, the He-Ne laser 11 is determined to be normal. The determination unit 30a determines that a failure occurs when either one of the light source 1 or the He—Ne laser 11 or both are abnormal, and determines that it is normal only when both are normal. In response to the abnormality determination result, the control unit 30 outputs an alarm indicating “failure” with a buzzer or / and by voice on a display on the display unit of the user interface 18. In addition to outputting these alarms or independently, the light source 1 and the He—Ne laser 11 are turned off.

  Each of the first threshold value or the second threshold value is equal to or higher than the noise level and corresponds to a single standard value of the light source 1 or the He—Ne laser 11, or an accuracy or accuracy required for measurement. Based on the value to satisfy, it is set or stored in the control unit 30 in advance. Further, the first threshold value or the second threshold value is compared with each of the output of the light source 1 or the output of the laser light detection means 31 if the corresponding relationship with all of them is known. It may be.

  Only when it is determined to be normal in the above self-diagnosis mode, the control unit 30 can shift to a measurement mode as described below, so that the reliability of the measurement value can be ensured.

"1.5 Modifications"
FIG. 2 is a modification of FIG. 1, in which the He-Ne laser 11 is partially reflected by the half mirror 33 and incident on the beam splitter 12, and another part of the output from the half mirror is shown. The laser light detecting means 31 can detect the laser light. In this case, detection is always possible without turning off the light source 1. Other configurations and operations in FIG. 2 are the same as those in FIG. However, in FIG. 2, the optical path may be configured with a fiber between the He—Ne laser 11 and the half mirror 33. Since FIG. 1 gives priority to the optical path configuration for measurement, the half mirror 33 is unnecessary and the loss of laser light entering the beam splitter 3 of the interference system can be reduced compared to FIG. A beam splitter may be used instead of the half mirror 33.

[2. Measurement Configuration of Embodiment]
[2.1. Overview of measurement configuration]
In the embodiment, as described above, the interference fringes due to both white light (broadband light) and laser light (coherent light) are imaged by the imaging means 10, and the data of the respective interference fringes obtained from the imaging means 10. Based on the above, the optical path length in which interference fringes due to white light are generated (the optical path length may be the amount of change when the optical path length is changed before the interference fringes are generated) is obtained with reference to the change in interference fringes due to laser light. It is a configuration.
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 embodiment is broadly divided into a case where an interference fringe due to laser light is imaged by the camera 10 (imaging means), and a scale is generated from repetition of the interference fringe, and an optical path length (specific optical path) in which the interference fringe due to white light occurs There are two cases in which the length) is obtained with reference to the change (scale) of interference fringes caused by laser 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.

[2.2 Common optical system and processing configuration until interference fringe detection by white light and laser light]
The configuration and operation of the interference system will be described based on the description of the light source 1 and the He—Ne laser 11 in the above [1.1] and [1.2].

  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 will be described as being continuously variable and having a constant variable speed. However, as will be described later, the variable method may be changed stepwise. 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. 3A 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 14a 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 the data 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 detecting means 14c by white light (the interference fringes by the separated color lights are shown in FIG. A).).

  FIG. 3A is 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 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 due to the white light in FIG. 3A 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. 3B is a diagram showing changes in interference fringes due to laser light in terms of luminance (amplitude) and phase on the same time axis as white light interference fringes. The horizontal axis in FIG. 3B is time, but is 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. 4A shows a waveform of interference fringes caused by white light, FIG. 4B shows a waveform of interference fringes caused by laser light, and FIG. 4C shows a waveform of interference fringes caused by white light and laser light. As shown in FIG. 4C, if the size of the interference fringe of the laser beam is an appropriate size, the peak position of the interference fringe 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. 3A 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 interference fringe period (interval between fringe amplitudes) in FIG. 3A, 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 for obtaining the peak of interference fringes from discrete imaging data, the optical path length is changed stepwise, and the next processing is performed based on the discrete imaging data taken for each of the changed predetermined optical path lengths. There is technology to do. 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.

[2.3 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. 3B 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.

  Among the above-described configurations, the control unit 30, the signal processing unit 20, and the optical path length control unit 16 can be configured by a CPU and a memory.

[3. A series of operations from self-diagnosis to measurement]
The control unit 30 sets the self-diagnosis mode and the measurement mode, and causes each unit to execute the following steps. The following part overlaps with the above description.
Step 1: The control unit 30 sets a self-diagnosis mode.
Step 2: The light source 1 is turned on by the control unit 30, and at least a part of the white light to be output is detected by the broadband light detection means 32. Further, the He-Ne laser 11 is turned on and at least the laser light to be output is output. A part is detected by the laser light detection means 31.
Step 3: The determination means 30a compares the detected white light part and part of the laser light with the first and second threshold values, determines the quality of each, and determines the broadband light source. 1 and the He-Ne laser 11 are turned off, and an alarm is given to the operator to prompt repair.
Step 4: The control means 30 switches from the self-diagnosis mode to the measurement mode when it is determined to be good, or when it is determined to be good after completion, and controls each part to execute measurement.
Step 5: The optical path forming unit 5 causes the white light from the broadband light source 1 and the laser light from the He-Ne laser 11 to enter both the reference optical path and the measurement optical path as described above, and the reflected light from the reference mirror 6 And the reflected light from the object to be measured 7 are combined and output to the camera 10 side to be imaged.
Step 6: On the other hand, the optical path length varying means 8 changes the optical path length of either the reference optical path or the measurement optical path.
Step 7: Based on the output of the camera 10 in which the optical path length detection means 14 images the combined reflected waves to be output, the optical path length in which the interference fringes due to white light are generated is determined based on the change in the interference fringes due to the laser light. Ask.
Then, the three-dimensional shape of the DUT 7 is measured from the obtained optical path length.

  A program corresponding to the flow of these operations can be stored and executed by the CPU.

It is a figure which shows the function structure of embodiment which concerns on this invention. It is a figure which shows the modification of FIG. It is a figure for demonstrating the optical path length detection means of FIG. It is a figure for demonstrating the branching means of FIG.

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 Demultiplexing means 14b Coherent Optical path length reference means 14c White light interference fringe optical path length detection means 15 Displacement calculation means 16 Optical path length control means 18 User interface 20 Signal processing means 30 Control unit 30a Determination means 31 Laser light detection means 32 Broadband light detection means 33 Half mirror 40 Stage

Claims (3)

The broadband light source (1) that outputs broadband light, the coherent light source (11) that outputs coherent light, and the broadband light source both on the reference optical path in which the reference mirror is arranged on the far end and on the measurement optical path on which the object to be measured is arranged. An optical path forming unit (5) that makes light and coherent light incident, combines the reflected light from the reference mirror and the reflected light from the object to be measured, and outputs either the reference light path or the measurement light path Based on the optical path length varying means (8) for changing one optical path length and the reflected wave output from the optical path forming section, the optical path length in which the interference fringes due to the broadband light are generated is set as the interference fringes due to the coherent light. An optical path length detecting means (14) to be obtained based on the change of the three-dimensional shape measuring device for measuring a three-dimensional shape from the obtained optical path length,
Broadband light detection means (32) for detecting at least a part of the broadband light, coherent light detection means (31) for detecting at least a part of the coherent light, an output of the coherent light detection means, and the broadband light detection A three-dimensional shape measuring apparatus comprising: a control unit (30) that receives the output of the means and determines whether each output is good or bad.   The control unit outputs at least an alarm, or turns off the broadband light source and the coherent light source when it determines that any of the respective outputs is negative as a result of the quality determination. Item 3. The three-dimensional shape measuring apparatus according to Item 1. The control unit (30) sets the self-diagnosis mode;
A detection stage for detecting at least part of the broadband light output from the broadband light source (1) and at least part of the coherent light output from the coherent light source (11), respectively;
Based on a part of the broadband light and a part of the coherent light detected in the detection step, the quality of each light quantity is judged to be good, and if at least one of them is judged to be negative, at least an alarm is output Or determining to turn off the broadband light source and the coherent light source;
After the determination in the determination step is good, the control unit sets a measurement mode;
The optical path forming unit (5) causes the broadband light from the broadband light source and the coherent light from the coherent light source to enter both the reference optical path in which the reference mirror is disposed and the measurement optical path in which the object to be measured is disposed at the far ends. An interference stage for combining and outputting the reflected light from the reference mirror and the reflected light from the object to be measured;
An optical path length varying means (8) changing the optical path length of either the reference optical path or the measurement optical path;
A step in which an optical path length detecting means (14) obtains an optical path length in which an interference fringe caused by the broadband light is generated based on a change in the interference fringe caused by the coherent light, based on a combination of reflected waves output in the interference step; And comprising
A three-dimensional shape measuring method for measuring a three-dimensional shape from the obtained optical path length.

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