JP4947301B2 - Dimension measuring apparatus and dimension measuring method - Google Patents

Description

  The present invention relates to a dimension measuring apparatus and a dimension measuring method, and more particularly to a dimension measuring apparatus and a dimension measuring method using white interference.

  Conventionally, a method using the principle of white interference has been proposed as a method for accurately measuring the dimension or surface roughness of a processed part in a non-contact manner. For example, a measuring apparatus that measures the flange back of a digital camera using white light interference is known (see Patent Document 1). In the measuring apparatus described in Patent Document 1, light emitted from a white light source is divided into a first optical path and a second optical path by a beam splitter. And the light which went to the 1st optical path is reflected by the reference mirror for length measurement which can move along a 1st optical path. On the other hand, the light traveling toward the second optical path is reflected by an image sensor of the camera fixedly attached to a reference plane that can come into contact with the flange of the camera. The light reflected by the reference mirror and the image sensor is united by a beam splitter and detected by a detector. Here, by moving the reference mirror along the first optical path, the position of the reference mirror that detects the maximum amount of white interference fringes of the light passing through the first optical path and the light passing through the second optical path is detected. To do. Based on the position of the reference mirror, the length from the flange to the image sensor is detected.

  In addition, in order to detect weak reflected light from the object to be measured with high sensitivity, a measurement method in which an interferometer that scans interference fringes and an interferometer for measurement are separately provided has been developed (see Patent Document 2). .

JP 2005-115149 A JP 2000-65530 A

  In the measurement method using white interference as described above, in order to perform accurate measurement, it is necessary to detect the position of the white interference fringe with the maximum light amount, that is, the peak position of the white interference fringe with high accuracy. . However, in actual measurement, the peak position fluctuates due to different conditions such as the surface state of the object to be measured that reflects the light beam, for example, the surface roughness, phase penetration due to the amount of moisture present on the surface, and the like. . Therefore, in order to obtain the dimension of the measurement object with high accuracy, it is necessary to consider the surface state of the measurement object.

  In view of the above problems, an object of the present invention is to provide a dimension measuring apparatus and a dimension measuring method capable of accurately measuring a dimension to be measured regardless of the surface state of an object to be measured in dimension measurement using white interference. There is.

According to one embodiment of the present invention, a dimension measuring device for measuring a dimension of an object to be measured is provided. Such a dimension measuring apparatus is configured to measure a white light source unit capable of setting a central wavelength of emitted light to at least one of a first central wavelength and a second central wavelength, and light emitted from the white light source unit. A first optical path that branches into a first light beam and a second light beam that are directed toward the object, reflects the first light beam on the object to be measured, and corresponds to a measurement target dimension of the object to be measured between the second light beam and the second light beam A first interferometer that generates a difference and emits the first and second light beams in accordance with one light beam, a reference mirror having a fixed position, and a movable mirror that is movable along the optical path A second interferometer having the first interferometer splitting the light beam emitted from the first interferometer into a third light beam directed toward the reference mirror and a fourth light beam directed toward the movable mirror; A second interferometer that produces a second optical path difference with the four light fluxes, and receives the third and fourth light fluxes. , Detecting an interference signal generated when the first optical path difference and the second optical path difference are substantially equal, outputting a signal corresponding to the interference signal, and obtaining a measurement target dimension of the object to be measured from the interference signal Has a controller.
The controller includes a peak position measuring unit that measures the position of the movable mirror corresponding to the maximum value of the interference signal for the first center wavelength or the second center wavelength, and the first center measured by the peak position measuring unit. Wavelength dependent dimension determination for obtaining the first measurement value or the second measurement value of the measurement target dimension of the object to be measured by calculating the second optical path difference from the position of the movable mirror with respect to the wavelength or the second center wavelength And the true value of the measurement target dimension of the object to be measured in accordance with the wavelength-dependent characteristics of the measurement target dimension of the object to be measured from the first measurement value or the second measurement value obtained by the wavelength dependent dimension determination unit. A size estimation unit for estimation.
The true value of the measurement target dimension of the object to be measured refers to the value of the measurement target dimension when it does not depend on the center wavelength of the measurement light and therefore there is no light penetration.

  The dimension measuring apparatus further includes an optical fiber disposed between the first interferometer and the second interferometer, and the light beam emitted from the first interferometer is transmitted through the optical fiber through the second optical fiber. It is preferably incident on the interferometer.

According to another embodiment of the present invention, a dimension measuring device for measuring a dimension of an object to be measured is provided. Such a dimension measuring device includes a white light source unit capable of setting the central wavelength of emitted light to at least one of the first central wavelength and the second central wavelength, a reference mirror having a fixed position, and an optical path. A first movable interferometer having a movable mirror, wherein the light emitted from the white light source is branched into a first light beam directed toward the reference mirror and a second light beam directed toward the movable mirror, A first interferometer that generates a first optical path difference between the first light flux and the second light flux, and the first light flux and the second light flux emitted from the first interferometer are measured. A second optical path that branches into a third light beam and a fourth light beam that are directed toward the object, reflects the third light beam on the object to be measured, and corresponds to the measurement target dimension of the object to be measured between the fourth light beam and the fourth light beam A second interferometer that produces a difference so that the third and fourth light beams are emitted in accordance with one light beam; A detector that receives the fourth light flux, detects an interference signal that is generated when the first optical path difference and the second optical path difference are substantially equal, and outputs a signal corresponding to the interference signal; A controller for obtaining a measurement target dimension of the object to be measured;
The controller includes a peak position measuring unit that measures the position of the movable mirror corresponding to the maximum value of the interference signal for the first center wavelength or the second center wavelength, and the first center measured by the peak position measuring unit. Wavelength-dependent dimension determination for obtaining the first measurement value or the second measurement value of the measurement target dimension of the object to be measured by calculating the first optical path difference from the position of the movable mirror with respect to the wavelength or the second center wavelength And the true value of the measurement target dimension of the object to be measured in accordance with the wavelength-dependent characteristics of the measurement target dimension of the object to be measured from the first measurement value or the second measurement value obtained by the wavelength dependent dimension determination unit. A size estimation unit for estimation.

  According to still another embodiment of the present invention, a dimension measuring device for measuring a dimension of an object to be measured is provided. Such a dimension measuring apparatus has a white light source unit capable of setting the center wavelength of emitted light to at least one of the first center wavelength and the second center wavelength, and a movable mirror movable along the optical path. An interferometer that splits the light emitted from the white light source unit into a first light beam directed to the object to be measured and a second light beam directed to the moving mirror, and reflects the first light beam by the object to be measured. An interferometer that generates an optical path difference between the first light flux and the second light flux, and the first light flux and the second light flux emitted from the interferometer, and the optical path length of the first light flux, A detector for detecting an interference signal generated when the optical path lengths of the second light flux are substantially equal, and outputting a signal corresponding to the interference signal; and a controller for obtaining a measurement target dimension of the object to be measured from the award signal . The controller includes a peak position measuring unit that measures the position of the movable mirror corresponding to the maximum value of the interference signal for the first center wavelength or the second center wavelength, and the first center measured by the peak position measuring unit. By calculating the difference between the position of the movable mirror with respect to the wavelength or the second central wavelength and the reference position of the predetermined movable mirror, the first measurement value or the second measurement of the measurement target dimension of the object to be measured The wavelength-dependent dimension determining unit for obtaining the value, and the first measured value or the second measured value obtained by the wavelength-dependent dimension determining unit according to the wavelength-dependent characteristics of the measurement target dimension of the measured object. A dimension estimation unit that estimates the true value of the measurement target dimension.

  Further, according to the present invention, the controller uses the reference measurement object as the measurement object, and the reference measurement object includes a true value of the measurement target dimension of the reference measurement object and a plurality of white lights having different center wavelengths. A memory that stores a reference table that represents the wavelength-dependent characteristics of the measurement target dimensions of the reference measurement object by associating and recording the respective wavelength-dependent dimensions obtained by measuring the measurement target dimensions of the measurement object and the center wavelength. The dimension estimating unit refers to the reference table stored in the storage unit to obtain a first wavelength-dependent dimension of the measurement target dimension of the reference measurement object with respect to the first center wavelength; The difference between the measured value of 1 and the first wavelength-dependent dimension is calculated, and the value obtained by adding the difference to the true value of the measurement target dimension of the reference measurement object is the true value of the measurement target dimension of the measurement object. It is preferable.

  Alternatively, the controller uses the reference measurement object as the measurement object, and the measurement target dimension of the reference measurement object with a plurality of white lights having different center wavelengths from the true value of the measurement target dimension of the reference measurement object By recording the wavelength-dependent dimensions obtained by measuring the wavelength and the center wavelength in association with each other, the wavelength-dependent characteristics of the measurement target dimensions of the reference measurement object are represented, and the reference measurement object reflected by the first light flux is displayed. The apparatus further includes a storage unit that stores a plurality of reference tables created according to the state of the surface of the object, and the size estimation unit uses a difference between the first measurement value and the second measurement value as a first change amount. The difference between the first wavelength-dependent dimension and the second wavelength-dependent dimension of the measurement target dimension of the reference object to be measured for each of the first center wavelength and the second center wavelength is calculated for each of the plurality of reference tables. Is calculated as the second change amount Among the second change amounts calculated for each of the plurality of reference tables, a reference table corresponding to the one having the smallest difference from the first change amount is selected, and the first measurement value and the selected reference table are selected. The difference from the first wavelength-dependent dimension obtained with respect to is calculated, and a value obtained by adding the difference to the true value of the measurement target dimension of the reference measurement object is the true value of the measurement target dimension of the measurement object. preferable.

According to still another embodiment of the present invention, the light emitted from the white light source unit capable of setting the central wavelength of the emitted light to at least either the first central wavelength or the second central wavelength is used. The first light beam and the second light beam that are directed to the object to be measured are branched into the first light beam, the first light beam is reflected by the object to be measured, and the second light beam corresponds to the measurement target dimension of the object to be measured. A first interferometer that generates an optical path difference of 1 and emits a first light beam and a second light beam in accordance with one light beam, a reference mirror having a fixed position, and a movable movement along the optical path A second interferometer having a mirror, wherein the light beam emitted from the first interferometer is branched into a third light beam directed toward the reference mirror and a fourth light beam directed toward the movable mirror, A second interferometer that produces a second optical path difference between the luminous flux and the fourth luminous flux; and the third interferometer and the fourth luminous flux. Then, there is provided an object to be measured in a measurement system having a detector that detects an interference signal generated when the first optical path difference and the second optical path difference are substantially equal and outputs a signal corresponding to the interference signal. The
The dimension measuring method includes a step of measuring the position of the movable mirror corresponding to the maximum value of the interference signal for each of the first center wavelength and the second center wavelength, and the first position measured by the peak position measuring unit. Obtaining a first measurement value and a second measurement value of the measurement target dimension of the object to be measured by calculating a second optical path difference from the position of the movable mirror with respect to the center wavelength and the second center wavelength, respectively. The true value of the measurement target dimension of the object to be measured is estimated from the first measurement value and the second measurement value obtained by the wavelength dependent dimension determination unit according to the wavelength dependency characteristic of the measurement object dimension of the measurement object. And a step.
In each of the above embodiments, the white light source is not limited to a light source that emits light in a broad band in the visible light range, but a light source that emits light in a certain wavelength band with a predetermined wavelength as a center wavelength.

  ADVANTAGE OF THE INVENTION According to this invention, it became possible to provide the dimension measuring apparatus and dimension measuring method which can measure a measuring object dimension correctly irrespective of the surface state of a to-be-measured object in the dimension measurement using white interference.

Hereinafter, embodiments in which the present invention is applied to an inner diameter measuring device that measures the inner diameter of a cylindrical object to be measured, such as a ring gauge and a cylinder, will be described with reference to the drawings.
An inner diameter measuring apparatus to which the present invention is applied causes light from a white light source unit to enter a first interferometer, and the first interferometer generates two light beams having an optical path difference corresponding to the inner diameter of the object to be measured. To do. The two light beams are incident on the second interferometer, and the light beams are divided and interfered with each other in two optical paths that generate an optical path difference substantially equal to the optical path difference, thereby generating white interference fringes. Then, the inner diameter of the object to be measured is obtained by detecting the maximum signal value of the white interference fringe with a detector and measuring the optical path difference between the two optical paths of the second interferometer. At that time, the inner diameter measuring device changes the center wavelength of the light emitted from the white light source unit, obtains the position of the movable mirror where the interference fringe becomes the maximum signal value for each center wavelength, and determines the inner diameter depending on the center wavelength. Calculate the measured value. Then, the true value of the inner diameter of the object to be measured is estimated from the calculated measurement values according to the wavelength dependence characteristics.

  FIG. 1 is a diagram showing a schematic configuration of an inner diameter measuring apparatus 1 to which the present invention is applied. The inner diameter measuring device 1 includes a white light source unit 2 that can change the center wavelength of emitted light, a first interferometer 3 that generates an optical path difference corresponding to twice the inner diameter of the object to be measured, and a first interference. A second interferometer 4 for generating a white interference fringe by generating an optical path difference similar to the optical path difference generated by the total 3, a detector 5 for detecting the interference fringe generated by the second interferometer 4, A controller 6 is provided for determining the inner diameter of the object to be measured from the control of each part and the detected interference fringes. Furthermore, the inner diameter measuring device 1 includes an optical fiber 7 that transmits light from the white light source 2 to the first interferometer 3 and an optical fiber 8 that transmits light emitted from the first interferometer 3 to the second interferometer. Have.

  The white light source unit 2 is a light source that has a short coherence length and can emit light having a broad wavelength. Further, the white light source unit 2 is configured such that the center wavelength of the emitted light can be selected from a plurality of wavelengths. Therefore, the white light source unit 2 includes a plurality of white light sources having different center wavelengths and a control circuit that emits only the light source selected based on the control signal from the controller 6 among the white light sources. As the white light source constituting the white light source unit 2, for example, an LED, an SLD (super luminescent diode), an SOA (Semiconductor Optical Amplifier) light source, an ASE (Amplified Spontaneous Emission) light source, or the like can be used. In the present embodiment, two types of infrared LEDs having a center wavelength of 1550 nm and 1200 nm are used as the white light source constituting the white light source unit 2.

  FIG. 2 shows a schematic configuration diagram of the first interferometer 3. In the first interferometer 3, two light beams B 1 and B 2 having an optical path difference corresponding to twice the inner diameter of the DUT 10 arranged on the XYZ stage 36 are generated. For this purpose, in the first interferometer 3, the light incident from the white light source 2 through the first optical fiber 7 is converted into parallel light by the collimator lens 31, and the first position for adjusting the output position with respect to the incident parallel light is adjusted. To the wedge prism 32. Then, the light emitted from the wedge prism 32 is incident on a beam splitter 33 disposed substantially at the center of the inner diameter of the DUT 10. The incident light is reflected by the beam splitter 33 and branched into a light beam traveling toward the inner surface S1 of the DUT 10 and a light beam B2 that passes through the beam splitter 33 and travels straight. The light beam traveling toward the inner surface S1 of the device under test 10 returns to the beam splitter 33 after being reflected by the inner surface S1 of the device under test 10. A part of the light beam returned to the beam splitter 33 passes through the beam splitter 33 and travels to the inner surface S2 opposite to the inner surface S1 of the DUT 10. Then, the light beam directed toward S2 is reflected by the inner surface S2 and returns to the beam splitter 33 again. A part of the light beam returned to the beam splitter 33 is reflected by the beam splitter 33. This light beam is called B1. The light beam B1 and the light beam B2 are emitted together when emitted from the beam splitter 33. The light beam B1 and the light beam B1 exit from the beam splitter 33, enter the second wedge prism 34 for position adjustment, and are adjusted in position so as to enter the condenser lens 35. Then, the light beam B 1 and the light beam B 2 are collected through the condensing lens 35, exit from the first interferometer, and enter the optical fiber 8.

  At this time, since the light beam B1 emitted from the first interferometer 3 reciprocates between the inner surfaces S1 and S2 of the object to be measured 10, if the inner diameter of the object to be measured 10 is D, the light beam B1 and the light beam B2 2D, a 2D optical path difference occurs. Then, the light beam B 1 and the light beam B 2 having a 2D optical path difference are incident on the second interferometer 4 through the optical fiber 8.

  The XYZ stage 36 has three directions: an axial direction of the device under test 10 (that is, a direction parallel to the light beam B2), a direction parallel to the light beam B1 and a direction perpendicular to the light beam B1 within the cylindrical surface of the device under test 10. And is driven by the stage controller 37. The stage controller 37 is electrically connected to the controller 6 and is controlled by the controller 6.

  FIG. 3 shows a schematic configuration diagram of the second interferometer 4. The light beams B1 and B2 emitted from the optical fiber 8 pass through the collimator lens 41 of the second interferometer 4 and become parallel light. Then, the light enters the beam splitter 42. The light beams B1 and B2 are reflected by the beam splitter 42 and branched into light beams B11 and B21 that travel toward the first optical path, and light beams B12 and B22 that pass through the beam splitter 42 and travel toward the second optical path. A light beam B11 represents a light beam that travels toward the first optical path of the second interferometer 4 among the light beams B1 emitted from the first interferometer 3, and a light beam B21 emitted from the first interferometer 3. Of the light beam B2, the light beam traveling toward the first optical path of the second interferometer 4 is represented. Similarly, a light beam B12 represents a light beam that travels to the second optical path of the second interferometer 4 out of the light beam B1 emitted from the first interferometer 3, and a light beam B22 exits the first interferometer 3. Of the measured light beams B2, the light beams traveling toward the second optical path of the second interferometer 4 are represented.

  A reference mirror 43 whose position is fixed is installed in the first optical path. The light beams B <b> 11 and B <b> 21 going to the first optical path are reflected by the reference mirror 43 and return to the beam splitter 42, and part of the light passes through the beam splitter 42 and goes to the detector 5. On the other hand, a movable mirror 44 that is movable along the optical path is provided in the second optical path. Then, the light beams B12 and B22 traveling toward the second optical path are reflected by the moving mirror 44 and returned to the beam splitter 42. A part of the light beams B12 and B22 are reflected by the beam splitter 42 and travel to the detector 5 together with B11 and B21.

The movable mirror 44 is attached to the support member 45. The movable mirror 44 and the support member 45 are installed on a piezo fine movement stage 46 that can finely adjust the position of the movable mirror 44 although the movement range is narrow. The movable mirror 44 and the support member 45 are installed on a coarse movement stage 47 that, together with the piezo fine movement stage 46, has a relatively large movement range and roughly determines the position of the movement mirror 44. The piezo fine movement stage 46 and the coarse movement stage 47 are electrically connected to the piezo controller 51 and the stage controller 52, respectively. Then, the piezo fine movement stage 46 and the coarse movement stage 47 move the movable mirror 44 along the second optical path based on control signals from the piezo controller 51 and the stage controller 52.
If the interference signal is continuously measured during the movement while moving the movable mirror 44, the piezo fine movement stage 46 and the piezo controller 51 may be omitted.

  A corner cube 48 is attached to the back surface of the support member 45. Further, an interferometer 49 for measuring the position of the movable mirror 44 is installed behind the support member 45 (that is, on the opposite side of the beam splitter 42 with the support member 45 as the center). The position measurement interferometer 49 is irradiated to the corner cube 48, reflected by the corner cube 48 and returned to the position measurement interferometer 49, and interference observed between the reference light and the reference light. The amount of movement of the movable mirror 44 can be measured by counting the number of moving stripes.

The detector 5 outputs the detected light quantity as an electrical signal. As the detector 5, for example, a semiconductor detection element such as a photodiode, CCD, or C-MOS can be used. In this embodiment, a detector in which CCD elements are arranged in a two-dimensional array is used as the detector 5.
The detector 5 is electrically connected to the controller 6 and transmits an electrical signal corresponding to the detected light amount to the controller 6.

FIG. 4 shows a functional block diagram of the controller 6.
The controller 6 is configured by a so-called PC, and is in accordance with a storage unit 61 including an electrically rewritable nonvolatile memory, a magnetic disk, an optical disk, and a reading device thereof, and communication standards such as RS232C and Ethernet (registered trademark). The communication unit 62 includes software such as the configured electronic circuit and device driver.
Further, the controller 6 is a functional module realized by a CPU, ROM, RAM and its peripheral circuits (not shown) and a computer program executed on the CPU, based on the detected light amount and the position of the movable mirror 44. The peak position measurement unit 63 that measures the position of the movable mirror 44 corresponding to the maximum value of the interference signal, and the measurement of the inner diameter D of the DUT 10 corresponding to the center wavelength of the measurement light from the measured position of the movable mirror 44. A wavelength-dependent dimension measuring unit 64 for obtaining a value, a size estimating unit 65 for estimating a true value of the inner diameter D from the measured value, each part of the controller, a position measuring interferometer 49, a piezo controller 51, a stage controller 52, and a detection And a control unit 66 for controlling devices connected to the controller 6 such as the device 5.

Hereinafter, an operation for measuring the inner diameter of the DUT 10 by the inner diameter measuring apparatus 1 will be described.
Since the light from the white light source 2 has a short coherence length, interference fringes are generated only when the optical path differences are substantially equal. Here, the distance from the beam splitter 42 to the reference mirror 43 in the first optical path of the second interferometer 4 is L1, and the distance from the beam splitter 42 to the moving mirror 44 in the second optical path is L2. If there is, an optical path difference of 2 (L2−L1) is generated between the third light flux and the fourth light flux (where L2> L1). At this time, if (L2−L1) and D are equal, the first interferometer 3 uses the first interferometer 4 out of the light beams B1 reflected by the inner surfaces S1 and S2 of the DUT 10. The optical path difference between the light beam B11 passing through the optical path and the light beam B2 passing through the beam splitter 33 in the first interferometer 3 and the light beam B22 passing through the second optical path in the second interferometer 4 is 0. It becomes. Therefore, the maximum interference signal can be observed. Then, as the difference between (L2−L1) and D increases, the magnitude of the interference signal decreases rapidly. Therefore, the inner diameter D of the DUT 10 can be obtained by measuring (L2-L1) when the interference signal is maximum.

  Further, when the moving mirror 44 is brought closer to the beam splitter 42, the optical path difference 2 (L1-L2) generated between the third light flux and the fourth light flux is twice the inner diameter D of the DUT 10. Interference fringes can be observed even at equal points (however, L1> L2). In this case, among the light beams B1 reflected by the inner surfaces S1 and S2 of the object to be measured 10 in the first interferometer 3, the light beams B12 that have passed through the second optical path in the second interferometer 4 and the first This is because, in the second interferometer 4, the optical path difference between the light beam B 2 that has passed through the beam splitter 33 in the interferometer 3 and the light beam B 21 that has passed through the first optical path becomes zero. Therefore, the difference between the position of the moving mirror 44 at which the interference signal generated between the light beams B11 and B22 is maximized and the position of the moving mirror 44 at which the interference signal generated between the light beams B12 and B21 is maximized. By dividing by 2, the inner diameter D of the DUT 10 can be obtained.

Here, on the surfaces of the inner surfaces S1 and S2 of the DUT 10, light penetration occurs when the light beam B1 is reflected. The optical path difference between the light beams B1 and B2, that is, the measured value of the inner diameter D varies depending on the degree of penetration.
A graph 501 illustrated in FIG. 5 represents an outline of the wavelength dependence characteristics with respect to the center wavelength of the light emitted from the white light source unit 2 with respect to the measured value of the inner diameter D. In FIG. 5, the horizontal axis represents the center wavelength, and the vertical axis represents the measured value of the inner diameter D. As shown in FIG. 5, since the penetration amount decreases as the center wavelength increases, the measured value of the inner diameter D decreases as the center wavelength increases. When the length of the central wavelength is greater than or equal to a certain value, light hardly permeates the inner surfaces S1 and S2 of the object to be measured 10, and the measured value of the inner diameter D converges to a constant value. This converged value is considered to be the true value of the inner diameter D. The wavelength-dependent characteristics vary depending on the surface roughness of the inner surfaces S1 and S2, the amount of moisture contained on the surface, and the like.

Therefore, in order to correct the measurement error of the inner diameter D due to such light penetration, the inner diameter D is measured in advance using white light having various center wavelengths with respect to the master which is the reference product of the device under test 10. The relationship between the center wavelength and the inner diameter D is measured. Then, the reference table representing the measurement result and the true value of the inner diameter D of the master are stored in the storage unit 61.
When measuring the device under test 10, the inner diameter measuring apparatus 1 measures the inner diameter D of the device under test 10 using light having different center wavelengths in the white light source unit 2. Then, the measurement result is compared with the measured value of the inner diameter of the master recorded in the reference table. Based on the comparison result, the inner diameter measuring device 1 estimates the measured value of the inner diameter D of the object to be measured 10 when there is no light penetration, that is, the true value of the inner diameter D.

Note that a plurality of reference tables are created in accordance with the state in which the surface roughness of the inner surfaces S1 and S2 and the amount of moisture contained on the surface are variously changed. For example, with respect to the surface roughness, three types of masters of the DUT 10 are prepared in which the inner surfaces S1 and S2 are processed in different states within a range that satisfies the product specifications. Then, the humidity of the measurement environment is set to three levels of 40%, 60%, and 80%, the inner diameter is measured for each of the three types of masters for each level, and a total of nine types of reference tables are created. At the time of creating this reference table, in order to obtain a true value of the inner diameter D without light penetration, only a light source having a center wavelength equivalent to the light source used in the inner diameter measuring device 1 is used as a white light source used for measurement. In addition, it is preferable to use one having a longer center wavelength. In addition, in order to use such a long wavelength light source, the first interferometer 3 and the second interferometer 4 are not connected by an optical fiber when the reference table is created. The light beam emitted from the interferometer 3 may be directly incident on the second interferometer 4. In the created reference table, the center wavelength of the measurement light and the measured value of the inner diameter corresponding to the center wavelength are expressed as a pair of data using, for example, a two-dimensional array.
Further, as described above, by measuring each master at a plurality of center wavelengths, it is possible to evaluate including measurement errors due to wavelengths of the measurement optical system. For example, the beam splitter 34 is a cube with a side of 10 mm and is made of BK7, which is a kind of optical glass, and includes a measurement light having a center wavelength of 1.5 μm and a measurement light having a center wavelength of 1.3 μm. Consider the case of measuring the master. The refractive index of BK7 is about 0.0004 greater for light with a wavelength of 1.3 μm than for light with a wavelength of 1.5 μm. Here, the light beam B1 passes through the beam splitter 34 twice more than the light beam B2. Therefore, when measuring the inner diameter of the master with measurement light having a center wavelength of 1.5 μm and measurement light having a center wavelength of 1.3 μm, it is better to perform measurement with the measurement light having a center wavelength of 1.3 μm. About 8 μm measured value becomes large.
An error in the measurement optical system that occurs according to the difference in the center wavelength of the measurement light also occurs during measurement of the DUT 10. Therefore, if the reference table including the error generated in the measurement optical system as described above is created, the influence of the error in the measurement optical system can be eliminated.

  When the reference table is created, the relationship between the center wavelength of the measurement light and the measured value of the inner diameter corresponding to the center wavelength is extrapolated using a method such as least squares or spline interpolation, and the master of the object to be measured 10 is A value (convergence value) at which the measured value for the inner diameter D does not change even when the center wavelength changes is obtained. Then, the convergence value is stored in the storage unit 10 in association with the reference table as the true value of the inner diameter D of the master of the DUT 10. Note that the true value of the inner diameter D of the master of the object to be measured 10 may be obtained using another method, for example, a contact type dimension measuring device.

6 and 7 show operation flowcharts of the inner diameter measuring apparatus 1 when measuring the inner diameter D of the DUT 10.
First, as an initialization procedure, the reference position of the movable mirror 44, that is, the position of the movable mirror 44 at which the optical path difference between the first optical path and the second optical path of the second interferometer 4 becomes 0 is determined ( Step S101). Therefore, the position where the object to be measured 10 is not installed in the first interferometer 3 of the inner diameter measuring device 1 and the interference fringe is detected by the second interferometer 4 is obtained. At this time, since there is no light beam reflected by the inner surface of the DUT 10, all the light beams emitted from the first interferometer 3 are B2. Therefore, in the second interferometer 4, the difference between the distance L1 from the beam splitter 42 to the reference mirror 43 in the first optical path and the distance L2 from the beam splitter 42 to the movable mirror 44 in the second optical path is zero. When the interference signal is maximized. Therefore, the controller 66 of the controller 6 drives the piezo fine movement stage 46 through the piezo controller 51 to move the movable mirror 44. Then, the peak position measurement unit 63 of the controller 6 observes the light amount detected by the detector 5 at a plurality of measurement points, and finds the position where the detected light amount is maximum, that is, the interference signal is maximum. At that time, the peak position measurement unit 63 may obtain a time average value or a moving average value for the output signal from the detector 5 at each measurement point, and use it as the output signal at that measurement point. Then, the maximum value of the output signal value, that is, the maximum value of the interference signal is obtained. The peak position measurement unit 63 receives the position of the movable mirror 44 when the interference signal reaches the maximum value from the position measurement interferometer 49 and stores it in the storage unit 61 of the controller 6 as a position P1 where L1 = L2. Remember.

  Next, the DUT 10 is installed on the first interferometer 3 of the inner diameter measuring device 1. And the control part 66 of the controller 6 selects the light source which radiates | emits the light of the 1st center wavelength (this embodiment 1550 nm) among the light sources which the white light source unit 2 has (step S102). Then, the white light source unit 2 is caused to emit light by supplying current to the selected light source. At this time, as described above, the white interference fringes are observed only at a position where the inner diameter D of the DUT 10 and (L2−L1) are substantially equal. Therefore, the control unit 66 of the controller 6 drives the coarse movement stage 47 through the stage controller 52 to retract the movable mirror 44 of the second interferometer 4 by a distance substantially equal to the inner diameter D of the object to be measured 10. Then, similarly to the above, the control unit 66 of the controller 6 drives the piezo fine movement stage 46 through the piezo controller 51 and moves the movable mirror 44 to increase or decrease the amount of light detected by the detector 5 at a plurality of measurement points. Check out. At that time, the controller 66 of the controller 6 obtains a time average value or a moving average value for the output signal from the detector 5 at each measurement point, and sets it as the output signal at that measurement point (step S103). Then, the peak position measurement unit 63 of the controller 6 obtains the maximum value of the output signal value, that is, the maximum value of the interference signal (step S104). The position P2 of the movable mirror 44 when the output signal becomes maximum is received from the position measurement interferometer 49 (step S105). Then, the wavelength dependent dimension determining unit 64 of the controller 6 reads the position P1 of the movable mirror 44 when L1 = L2 from the storage unit, calculates the value of P2-P1, and measures the object 10 to be measured with respect to the first central wavelength. A measured value of the inner diameter D (hereinafter referred to as a first measured value) is obtained (step S106).

  Next, the controller 66 of the controller 6 determines whether or not the measured value of the inner diameter of the DUT 10 has been obtained for all the light sources of the white light source unit 2 (step S107). If there is a light source that has not yet been measured, the light source is switched to an unmeasured light source, that is, a light source that emits light of the second center wavelength (1200 nm in this embodiment), and the above steps S102 to S106 are performed. Repeat the process. And the measured value (henceforth a 2nd measured value) of the internal diameter D of the to-be-measured object 10 with respect to a 2nd center wavelength is obtained. On the other hand, when the measured values of the inner diameter D of the DUT 10 are obtained for all light sources in step S107, the control unit 66 of the controller 6 shifts the control to step S108.

  Here, the operation of the controller 6 when detecting the position where the interference signal has the maximum value will be described. As described above, in actual measurement, noise is added due to the influence of air turbulence, mechanical vibration of the measurement system, and the amount of light detected by the detector 5 varies with time. Therefore, in this embodiment, the measurement signal acquired while moving the movable mirror 44 within the range in which the interference signal is observed is acquired a plurality of times, and the time average of these is obtained to obtain the interference signal. Since the noise component becomes almost zero by averaging over time, the position where the interference signal is maximized can be accurately detected by obtaining the interference signal as described above.

Next, the controller 6 corrects the obtained measurement result in consideration of the state of the inner surfaces S1 and S2 of the device under test 10, and the surface condition (surface roughness) of the inner surfaces S1 and S2 of the device under test 10 is corrected. For the master having the surface state of the inner surface that is assumed to be closest to the (water content), a reference table that represents the relationship with the inner diameter D of the center wavelength is selected.
As shown in FIG. 7, when the first and second measured values of the inner diameter D of the DUT 10 with respect to the first center wavelength (1550 nm) and the second center wavelength (1200 nm) are obtained, the dimensions of the controller 6 are obtained. The estimation unit 65 reads each of the above reference tables from the storage unit 61 (step S108). Next, the dimension estimation part 65 calculates | requires the difference (henceforth a to-be-measured object variation | change_quantity) between a 1st measured value and a 2nd measured value (step S109). Similarly, for each reference table, the dimension estimating unit 65 also measures the measured value of the inner diameter D of the master of the device under test 10 with respect to the first center wavelength and the inner diameter D of the master of the device under test 10 with respect to the second center wavelength. A difference from the measured value (hereinafter referred to as master change amount) is obtained (step S110). The dimension estimation unit 65 detects a master change amount obtained for each reference table that has the smallest difference from the measured object change amount (step S111). Then, the reference table corresponding to the master change amount with the smallest difference from the measured object change amount is selected (step S112).

When the reference table is selected, the controller 6 obtains a correction value for the measured value of the inner diameter D using the reference table, and corrects the measured value using the correction value, thereby obtaining the true value of the inner diameter D. presume.
Therefore, the size estimation unit 65 of the controller 6 calculates the difference between the first measurement value and the measurement value of the inner diameter D of the master of the DUT 10 with respect to the first center wavelength extracted from the selected reference table. A correction value is obtained (step S113). Finally, the dimension estimation unit 65 adds the obtained correction value to the true value of the master inner diameter D stored in association with the selected reference table to obtain the true value of the inner diameter D of the DUT 10 ( Step S114).

  In addition, when the information regarding the surface roughness and water content of the inner surfaces S1 and S2 of the DUT 10 can be acquired by another method, the reference table may be selected based on the information. In that case, the above steps S108 to S112 can be omitted.

  Further, in the first interferometer 3, when the position of the beam splitter 33 does not exactly coincide with the center of the inner diameter of the device under test 10, the light beam B 1 is shifted from the diameter of the inner diameter of the device under test 10. The measured value is not accurate. In order to solve the problem, the measurement of the inner diameter is repeated by shifting the positional relationship between the beam splitter 33 and the DUT 10 in the direction perpendicular to the light beam B1 within the cylindrical surface of the DUT 10. Then, the value at which the obtained measurement value is maximum is taken as the inner diameter of the DUT 10.

  Therefore, once the controller 6 obtains the measured value of the inner diameter by the above procedure, it stores it in the storage unit 61. Next, the controller 6 transmits a control signal to the stage controller 37 of the first interferometer 3 to drive the XYZ stage 36, and the measured object 10 is changed to the light beam B1 by a predetermined amount (for example, 0.1 μm). It is moved in a direction perpendicular to the direction. Then, the inner diameter is measured again to obtain a measured value. The obtained measurement value is compared with the measurement value stored in the storage unit 61 of the controller 6. If the newly obtained measurement value is larger than the stored measurement value, the measurement value stored in the storage unit 61 is updated with the newly obtained measurement value. Thereafter, the DUT 10 is moved again in the same direction, and the measurement of the inner diameter is repeated. And when the measured value memorize | stored in the memory | storage part 61 becomes more than the newly measured value, let the measured value memorize | stored in the memory | storage part 61 be the internal diameter D of the to-be-measured object 10. FIG.

On the other hand, when the measured value of the inner diameter measured first is equal to or larger than the measured value measured next, the controller 6 moves the DUT 10 in the direction opposite to the direction in which the measured object 10 is first moved. Then, the measurement is repeated in the same manner as described above, and when the measured value stored in the storage unit 61 becomes equal to or greater than the newly measured value, the measured value stored in the storage unit 61 is used as the measured object 10. The inner diameter D of
In this way, by searching for the maximum measured value of the inner diameter D while changing the positional relationship between the object to be measured 10 and the beam splitter 33, the inner diameter measuring apparatus 1 accurately sets the beam splitter 33 to the center of the object to be measured 10. Since the inner diameter measurement result in the state of being placed in the position can be obtained, the inner diameter of the DUT 10 can be measured with high accuracy. Note that once the beam splitter 33 is positioned at the center of the device under test 10, in the subsequent measurement, the positioning procedure of the beam splitter 33 can be omitted unless the device under test 10 is replaced.

  Instead of measuring the reference position P1 of the movable mirror 44 in step S101, as described above, the movable mirror 44 is moved closer to the beam splitter 42 than the reference mirror 43 for each central wavelength, and the light beam B12 and the light beam You may obtain | require the position P3 of the movable mirror 44 from which the interference signal produced between B21 becomes the maximum. And the value of (P2-P3) / 2 is calculated, respectively, and the value may be a measured value of the inner diameter of the DUT 10 for each central wavelength. The intensity of the interference signal observed at the reference position P1 is greatly different from the intensity of the interference signal observed at the position P2. On the other hand, the interference signal observed at the position P2 and the interference signal observed at the position P3 have substantially the same intensity. Therefore, when the measured value of the inner diameter of the DUT 10 is obtained based on the difference between the position P2 and the position P3, the detector 5 can be obtained more than when the measured value of the inner diameter is obtained based on the difference between the reference position P1 and the position P2. Since the change in the output signal with respect to the change in the amount of received light can be increased, the position of the movable mirror 44 where the interference signal becomes the maximum value can be specified more accurately.

  As described above, the inner diameter measuring apparatus 1 to which the present invention is applied measures the inner diameter D of the DUT 10 depending on the center wavelength by changing the center wavelength of the light emitted from the white light source unit 2. Calculate the value. Then, a correction value is obtained from a reference table representing the wavelength-dependent characteristics of the measured values calculated and the measured value of the inner diameter D of the master of the measured object 10, and the measured value is corrected by correcting the measured value. The true value of the inner diameter can be estimated with high accuracy. Furthermore, the inner diameter measuring apparatus 1 changes the surface state of the reflecting surface of the master in various ways, and stores the above-described reference table corresponding to each state in advance. In actual measurement, the wavelength dependence characteristic of the measured value of the inner diameter of the master shown in each reference table is compared with the wavelength dependence characteristic of the measured value of the inner diameter D of the object 10 to be measured. Select a look-up table with close wavelength dependence. Therefore, the inner diameter measuring apparatus 1 can accurately estimate the true value of the inner diameter D of the device under test 10 regardless of the surface state of the inner surface of the device under test 10. In actual measurement, the true value of the inner diameter D can be estimated based on the measurement result with a small number of wavelengths by using a reference table, so that the time required for one measurement is shortened. Can do. Further, as in the above-described embodiment, a light source that emits light in a wavelength region that is less attenuated by the optical fiber can be selected as the white light source, so that the first interferometer 3 and the second interferometer 4 can be remotely located. Can be arranged. Therefore, the inner diameter measuring device 1 can be configured flexibly according to its operation.

  In addition, this invention is not limited to said embodiment. For example, the device under test is not limited to a cylindrical one. The measuring apparatus of the above embodiment can be applied as it is when measuring the distance between two opposing surfaces of an object to be measured. In the measurement apparatus of the above embodiment, the second interferometer may be a Fizeau interferometer. Furthermore, the number of light sources used in the white light source unit 2 is not limited to two types, and three or more types may be used. Furthermore, the controller 6 uses the least square method to calculate the measured value obtained by measuring the inner diameter D by changing the center wavelength in various ways, instead of using the reference table representing the wavelength dependence characteristics of the measured value of the inner diameter D of the DUT 10. The wavelength dependence characteristics of the measured value may be obtained by extrapolation using spline interpolation or the like. In this case, the true value is the value of the inner diameter D that does not change even if the center wavelength changes due to extrapolation. In order to increase the accuracy of extrapolation, it is preferable to measure the inner diameter D of the DUT 10 using three or more types of measurement light having different center wavelengths.

The present invention can also be applied to a configuration in which only one Michelson interferometer is used as in the measurement apparatus described in Patent Document 1.
FIG. 8 shows a schematic configuration diagram of a configuration of the dimension measuring apparatus 11 using only one Michelson interferometer. In this configuration, the measurement light emitted from the white light source 12 is converted into a first light beam directed to the object to be measured 10 ′ by the beam splitter 13 and a second light beam directed to the movable mirror 14 movable along the optical path. To divide. Then, the first light beam reflected by the object to be measured 10 ′ and the second light reflected by the moving mirror 14 are converted into one light beam again by the beam splitter 13, and the interference signal is detected by the detector 15. . The signal output from the detector 15 is transmitted to the controller 16. Then, the controller 16 obtains the position where the interference signal has a peak, and obtains the position of the movable mirror 14 where the optical path difference between the first light flux and the second light flux is zero. Then, by calculating the difference between the reference position of the movable mirror 14 predetermined in relation to the measured object 10 ′ and the obtained position of the movable mirror 14, the dimension of the measured object 10 ′ (for example, the surface Height).

  The controller 16 has the same configuration as the controller 6 in the above embodiment. Then, the true value of the dimension of the DUT 10 ′ is estimated by the same procedure as in the above embodiment. That is, for the master of the object to be measured 10 ′, the center wavelength of the measurement light from the white light source unit 12 and the state of the reflecting surface that reflects the measurement light are changed in advance, and the wavelength of the dimension of the master of the object to be measured 10 ′. A reference table representing dependency characteristics and the true value of the master dimension are stored. In actual measurement, the controller 16 determines the amount of change of the dimension according to the wavelength obtained from the wavelength-dependent dimension of the DUT 10 ′ measured by changing the center wavelength of the measurement light from the white light source unit 12. Then, the change amount of the dimension of the master shown in each reference table is compared. Then, a reference table is selected that has the closest change amount to the change amount of the dimension of the DUT 10 '. Finally, the controller 16 measures the dimension value of the object to be measured 10 ′ by the measurement light having a predetermined center wavelength and the dimension measurement value of the master by the measurement light having the predetermined center wavelength extracted from the selected reference table. Is obtained as a correction value and added to the true value of the master dimension stored in association with the reference table, thereby obtaining the true value of the dimension of the object to be measured 10 '.

Further, in the embodiment using two interferometers, the white light source unit arranged on the first interferometer 3 side and the detector arranged on the second interferometer 4 side may be interchanged. Good. In this case, two light beams having an optical path difference corresponding to the measurement target dimension of the object to be measured are generated in advance on the second interferometer 4 side, and these light beams are sent to the first interferometer 3 side through the optical fiber. In the first interferometer 3, the received two light beams are further divided into a light beam reflected by the inner surfaces S 1 and S 2 of the object to be measured 10 and two light beams traveling straight through the beam splitter 33, and one of them. The white interference fringes are observed by detecting with a detector. Also in this case, the measured value of the inner diameter D of the DUT 10 can be obtained by measuring the optical path difference generated on the second interferometer 4 side.
As described above, various modifications can be made within the scope of the present invention according to the embodiment to be implemented.

It is a schematic block diagram of the internal diameter measuring apparatus to which this invention is applied. It is a schematic block diagram of the 1st interferometer which comprises an internal diameter measuring apparatus. It is a schematic block diagram of the 2nd interferometer which comprises an internal diameter measuring apparatus. It is a functional block diagram of the controller of an internal diameter measuring device. It is a graph which shows the relationship between the center wavelength of measurement light, and the dimension measurement value of to-be-measured object. It is an operation | movement flowchart of an internal diameter measuring apparatus. It is an operation | movement flowchart of an internal diameter measuring apparatus. It is a schematic block diagram of the dimension measuring apparatus by other embodiment to which this invention is applied.

Explanation of symbols

1 Inner Diameter Measuring Device (Dimension Measuring Device)
DESCRIPTION OF SYMBOLS 11 Dimension measuring apparatus 10, 10 'Measured object 2, 12 White light source unit 3, 4 Interferometer 5, 15 Detector 6, 16 Controller 31, 41 Collimator lens 32, 34 Wedge prism 33, 42, 13 Beam splitter 35 Collection Optical lens 36 XYZ stage 37 Stage controller 43 Reference mirror 44, 14 Moving mirror 45 Support member 46, 17 Piezo fine movement stage 47 Coarse movement stage 48 Corner cube 49 Position measurement interferometer 51 Piezo controller 52 Stage controller 61 Storage unit 62 Communication unit 63 Peak Position Measurement Unit 64 Wavelength Dependent Dimension Determination Unit 65 Dimension Estimation Unit 66 Control Unit 7, 8 Optical Fiber

Claims (7)

A dimension measuring device for measuring a dimension of an object to be measured,
A white light source unit capable of setting the central wavelength of the emitted light to at least one of the first central wavelength and the second central wavelength;
The light emitted from the white light source unit is branched into a first light beam and a second light beam that are directed toward the object to be measured, and the first light beam is reflected by the object to be measured to generate the second light beam. A first interferometer that causes a first optical path difference corresponding to a measurement target dimension of the object to be measured between the first and second light beams to emit in accordance with one light beam;
A second interferometer having a reference mirror having a fixed position and a movable mirror movable along the optical path, wherein the light beam emitted from the first interferometer is directed to the reference mirror. A second interferometer for branching into a light beam and a fourth light beam directed to the movable mirror to produce a second optical path difference between the third light beam and the fourth light beam;
The third light beam and the fourth light beam are received, an interference signal generated when the first optical path difference and the second optical path difference are substantially equal is detected, and a signal corresponding to the interference signal is output. A detector to
A controller for obtaining a measurement target dimension of the object to be measured,
A peak position measuring unit that measures the position of the movable mirror corresponding to the maximum value of the interference signal for the first center wavelength or the second center wavelength;
By calculating the second optical path difference from the position of the movable mirror with respect to the first center wavelength or the second center wavelength measured by the peak position measurement unit, the measurement target dimension of the object to be measured is calculated. A wavelength-dependent dimension determining unit for obtaining a first measurement value or a second measurement value;
From the first measurement value or the second measurement value obtained by the wavelength-dependent dimension determining unit, the true dimension of the measurement target dimension of the measurement object is determined according to the wavelength-dependent characteristic of the measurement target dimension of the measurement object. A size estimator for estimating the value;
A controller having
A dimension measuring apparatus comprising:   The optical system further includes an optical fiber arranged between the first interferometer and the second interferometer, and a light beam emitted from the first interferometer is transmitted to the second interferometer through the optical fiber. The dimension measuring apparatus according to claim 1, which is incident. A dimension measuring device for measuring a dimension of an object to be measured,
A white light source unit capable of setting the central wavelength of the emitted light to at least one of the first central wavelength and the second central wavelength;
A first interferometer having a reference mirror having a fixed position and a movable mirror movable along an optical path, wherein the light emitted from the white light source is directed to the reference mirror; A first interferometer for branching into a second light beam directed toward the movable mirror and causing a first optical path difference between the first light beam and the second light beam;
The first light beam and the second light beam emitted from the first interferometer are branched into a third light beam and a fourth light beam that are directed toward the object to be measured, and the third light beam is divided into the measured light. A second optical path difference corresponding to the measurement object size of the object to be measured is generated between the fourth light flux and the fourth light flux, and the third light flux and the fourth light flux are combined into one light flux. A second interferometer that emits together,
The third light beam and the fourth light beam are received, an interference signal generated when the first optical path difference and the second optical path difference are substantially equal is detected, and a signal corresponding to the interference signal is output. A detector to
A controller for obtaining a measurement target dimension of the object to be measured,
A peak position measuring unit that measures the position of the movable mirror corresponding to the maximum value of the interference signal for the first center wavelength or the second center wavelength;
By calculating the first optical path difference from the position of the movable mirror with respect to the first center wavelength or the second center wavelength measured by the peak position measuring unit, the measurement target dimension of the object to be measured is calculated. A wavelength-dependent dimension determining unit for obtaining a first measurement value or a second measurement value;
From the first measurement value or the second measurement value obtained by the wavelength-dependent dimension determining unit, the true dimension of the measurement target dimension of the measurement object is determined according to the wavelength-dependent characteristic of the measurement target dimension of the measurement object. A size estimator for estimating the value;
A controller having
A dimension measuring apparatus comprising: A dimension measuring device for measuring a dimension of an object to be measured,
A white light source unit capable of setting the central wavelength of the emitted light to at least one of the first central wavelength and the second central wavelength;
An interferometer having a movable mirror movable along an optical path, wherein the light emitted from the white light source unit is converted into a first luminous flux directed toward the object to be measured and a second luminous flux directed toward the movable mirror. An interferometer that branches and reflects the first light beam by the object to be measured to generate an optical path difference between the first light beam and the second light beam;
An interference signal generated when the first light flux and the second light flux emitted from the interferometer are received, and an optical path length for the first light flux is substantially equal to an optical path length for the second light flux. A detector for detecting and outputting a signal corresponding to the interference signal;
A controller for obtaining a measurement target dimension of the object to be measured,
A peak position measuring unit that measures the position of the movable mirror corresponding to the maximum value of the interference signal for the first center wavelength or the second center wavelength;
By calculating a difference between the position of the movable mirror with respect to the first center wavelength or the second center wavelength measured by the peak position measurement unit and a predetermined reference position of the movable mirror, A wavelength-dependent dimension determining unit for obtaining a first measurement value or a second measurement value of a measurement target dimension of the measurement object;
From the first measurement value or the second measurement value obtained by the wavelength-dependent dimension determining unit, the true dimension of the measurement target dimension of the measurement object is determined according to the wavelength-dependent characteristic of the measurement target dimension of the measurement object. A size estimator for estimating the value;
A controller having
A dimension measuring apparatus comprising: The controller uses a reference measurement object as the measurement object, and measures the reference measurement object with a plurality of white lights having different center wavelengths from the true value of the measurement target dimension of the reference measurement object. A storage unit storing a reference table that represents the wavelength-dependent characteristics of the measurement target dimensions of the reference measurement object by associating and recording the respective wavelength-dependent dimensions obtained by measuring the target dimensions and the center wavelength. In addition,
The dimension estimation unit refers to the reference table stored in the storage unit to obtain a first wavelength-dependent dimension of a measurement target dimension of the reference measurement object with respect to the first center wavelength, and The difference between the measurement value of 1 and the first wavelength-dependent dimension is calculated, and the value obtained by adding the difference to the true value of the measurement object dimension of the reference measurement object is the measurement object dimension of the measurement object. The dimension measuring apparatus according to any one of claims 1 to 4, which is a true value. The controller uses a reference measurement object as the measurement object, and measures the reference measurement object with a plurality of white lights having different center wavelengths from the true value of the measurement target dimension of the reference measurement object. Each wavelength-dependent dimension obtained by measuring the target dimension and the center wavelength are recorded in association with each other to represent the wavelength-dependent characteristics of the measurement target dimension of the reference measurement object, and the first light beam is reflected. A storage unit that stores a plurality of reference tables created according to the state of the surface of the reference measurement object;
The size estimation unit calculates a difference between the first measurement value and the second measurement value as a first change amount, and for each of the plurality of reference tables, the first center wavelength and the second measurement value are calculated. A difference between the first wavelength-dependent dimension and the second wavelength-dependent dimension of the measurement target dimension of the reference measurement object with respect to each of the center wavelengths is calculated as a second change amount, and is calculated for each of the plurality of reference tables. The reference table corresponding to the difference between the second change amount and the first change amount that is the smallest is selected, and the first measurement value and the selected reference table are obtained. A difference from the wavelength-dependent dimension of 1 is calculated, and a value obtained by adding the difference to a true value of the measurement target dimension of the reference measurement object is a true value of the measurement target dimension of the measurement object. The dimension measuring apparatus as described in any one of 1-4. The light emitted from the white light source unit capable of setting the center wavelength of the emitted light to at least one of the first center wavelength and the second center wavelength is converted into the first light flux and the second light beam directed to the object to be measured. Branching into a light beam, reflecting the first light beam by the object to be measured, and generating a first optical path difference corresponding to the measurement object size of the object to be measured between the second light beam and the second light beam. A second interferometer having a first interferometer that emits one light beam and the second light beam in accordance with one light beam, a reference mirror having a fixed position, and a movable mirror movable along the optical path A light beam emitted from the first interferometer is split into a third light beam directed toward the reference mirror and a fourth light beam directed toward the movable mirror, and the third light beam and the first light beam A second interferometer that generates a second optical path difference with the four luminous fluxes, and receives the third luminous flux and the fourth luminous flux, A method for measuring a dimension of an object to be measured in a measurement system, comprising: a detector that detects an interference signal generated when an optical path difference of 1 and the second optical path difference are substantially equal, and outputs a signal corresponding to the interference signal. There,
Measuring the position of the movable mirror corresponding to the maximum value of the interference signal for each of the first center wavelength and the second center wavelength;
By measuring the second optical path difference from the position of the movable mirror with respect to the first center wavelength and the second center wavelength measured by the peak position measurement unit, the measurement target dimension of the object to be measured Determining a first measurement value and a second measurement value of
From the first measurement value and the second measurement value obtained by the wavelength-dependent dimension determination unit, the true value of the measurement target dimension of the measurement object according to the wavelength-dependent characteristic of the measurement target dimension of the measurement object Estimating
A dimension measuring method characterized by comprising:

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