JP2005098833A - Displacement meter and displacement measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement meter for stably measuring a measured object regardless of its surface state, and a displacement measuring method. <P>SOLUTION: The displacement meter is provided with an objective lens scanning part 52 for moving the objective lens 15 in a plane orthogonal to the optical axis direction, an objective lens movement detecting part 53 for detecting positions to which the objective lens 15 is moved in the orthogonal plane by the objective lens scanning part 52, a memory 72 for a peak of the quantity of a received light which obtains and stores position information of the objective lens 15 at a plurality of measurement points included in a measured region detected by the objective lens movement detecting part 53 and designated by a measured region designating part 51, the local maximal value of the quantity of the received light received by a light receiving part at a plurality of the measurement points and an oscillation position in a position detecting part, and a processor 73 for processing the quantity of the received light which accumulates the quantity of the received light stored in the memory 72 and calculating a displacement on the basis of the accumulated quantity of the received light. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a displacement meter and a displacement measuring method for measuring the displacement of the surface of the object to be measured by projecting light onto the surface of the object to be measured such as metal, resin, glass, ceramic, paper, and the like.

  Conventionally, for example, an in-focus detection type non-contact displacement meter is used as an apparatus for measuring the displacement of the surface of an object to be measured such as metal or resin. Moreover, the present inventors developed the displacement meter shown in patent document 1 previously. A configuration example of the displacement meter according to Patent Document 1 is shown in FIG. In the displacement meter shown in this figure, the light emitted from the laser diode 12 driven by the laser power control unit 11 sequentially passes through the beam splitter 13, the collimator lens 14, and the objective lens 15, and is projected onto the object 16 to be measured. It is configured to be. The reflected light from the object to be measured 16 passes through the objective lens 15 and the collimating lens 14 and is reflected by the beam splitter 13, and passes through the pinhole 17 a of the optical aperture portion 17 forming the pinhole 17 a to the photodiode 18. Incident. The signal photoelectrically converted by the photodiode 18 is input to the amplifier 19, and the output signal X is input to the arithmetic unit 20.

  A peripheral portion of the objective lens 15 is attached to the tip of one long portion of the U-shaped tuning fork 21. The objective lens 15 is vibrated with a predetermined amplitude in the optical axis direction of the light emitted from the laser diode 12 by the vibration of the tuning fork 21. A tuning fork amplitude detection unit 22 serving as a position detection unit, which includes a sensor using, for example, magnetism, light, or capacitance, is disposed on the side of the long side of one side of the tuning fork 21. That is, the position of the objective lens 15 can be detected. The detected amplitude signal detected by the tuning fork amplitude detector 22 is input to the amplifier 23, and the output signal Y is input to the calculator 20. A solenoid 24 for vibrating the tuning fork 21 is disposed on the side of the leading end side of the other long portion of the tuning fork 21. The solenoid 24 is supplied with a control current from the tuning fork amplitude control unit 25, and the tuning fork amplitude control unit 25 is supplied with an output signal of the amplifier 23 to control the tuning fork 21 to have a constant amplitude.

  Hereinafter, the operation of the displacement meter will be described. When a control current is supplied from the tuning fork amplitude controller 25 to the solenoid 24, a magnetic field corresponding to the control current is generated by the solenoid 24. This generated magnetic field causes the tuning fork 21 to vibrate with a predetermined amplitude, causing the objective lens 15 to vibrate in the direction of the optical axis of the light passing therethrough. The tuning fork amplitude detector 22 detects the amplitude of the tuning fork 21, that is, the amplitude of the objective lens 15, and outputs a sine wave signal as the amplitude of the objective lens 15. The sine wave signal is amplified by the amplifier 23, and the output signal Y output from the amplifier 23 is input to the arithmetic unit 20.

  On the other hand, when a drive current is supplied from the laser power control unit 11 to the laser diode 12, the laser diode 12 emits laser light. The emitted light passes through the beam splitter 13, the collimating lens 14, and the objective lens 15 and is projected onto the object 16 to be measured. The reflected light reflected by the DUT 16 passes through the objective lens 15 and the collimating lens 14 and is reflected by the beam splitter 13 and projected to the optical diaphragm 17 side, and only the light transmitted through the pinhole 17a is incident on the photodiode 18. . For this reason, in the photodiode 18, the diverging light generated by the object 16 to be measured and the reflected light due to the stray light generated by the laser diode 12 are blocked by the pinhole 17a and do not pass through the pinhole 17a. Only the in-focus light generated in 16 enters.

  At this time, since the objective lens 15 is vibrated, the distance between the objective lens 15 and the DUT 16 changes. When the focal point of the light projected onto the object 16 to be measured is generated at the object 16 at a predetermined distance, the light receiving output of the photodiode 18 is instantaneously maximized, and a signal corresponding to this light receiving output is input to the amplifier 19. An output signal X is output from the amplifier 19 and input to the arithmetic unit 20. By measuring the position where the amount of received light is maximum, that is, the position of the objective lens 15 obtained on the measured object 16 by the focal point of the light projected on the measured object 16, the displacement of the surface of the measured object 16 is measured. By doing so, the displacement can be measured with high accuracy. Further, since the optical diaphragm is used, even if the reflected light due to the submerged light or stray light generated in the object to be measured 16 is generated, it is possible to provide a displacement meter that hardly causes an error in the measured value of displacement.

  However, since the spot size of the light projected on the object to be measured is small in this displacement meter, there is a problem that measurement may become impossible depending on the surface state of the object to be measured. For example, as shown in FIG. 2, when there is a region where light is not normally reflected due to a concave portion or a hole on the surface of the object 16 to be measured, light is projected from the displacement meter to the object to be measured. The measured light is not correctly reflected by the displacement meter, and measurement cannot be performed. Also, if the surface of the object to be measured has fine irregularities on the order of the spot size, the measurement position will change even slightly, and the amount of light will change greatly if the object to be measured moves, making accurate measurement difficult. There was also a problem.

  In order to solve such a problem, the present inventor moves the measurement point in a linear manner, and even if there is a point where the displacement cannot be measured, it is supplemented by using the displacement of the measurable point before and after the point. (Patent Document 2). In this method, the amount of light received by the photodiode is monitored while moving the measurement point linearly, the displacement at the position where the amount of received light reaches a peak is calculated, and the displacement at each position is averaged. The displacement can be obtained even if possible points are included.

  However, when consecutive points that cannot be measured are consecutive, it is difficult to supplement the displacement from the front and rear points. For example, as shown in FIG. 2C, when trying to measure the displacement of a surface shape with continuous irregularities, since there are a number of sites that cannot be measured, it is difficult to complement using nearby points. In addition, if only points where the displacement can be measured are extracted and the displacement at each point is averaged, the number of samples of the points that can be measured is small, or the accuracy of the displacement obtained at each point varies. Since there is a possibility that data with a lot of errors may be included, highly accurate displacement measurement cannot be expected. Particularly in a displacement meter, in general, the larger the amount of light detected by a photodiode, the more accurate displacement can be measured, and conversely, the smaller the amount of light, the lower the accuracy. In other words, when the displacement is calculated with the peak value of the light amount, the greater the absolute value of the peak, the higher the reliability of the data, and the lower the peak, the lower the reliability. However, an irregular surface shape as shown in FIG. 2 (c) contains a lot of data with a low light quantity stochastically, resulting in poor measurement accuracy. For this reason, if the average obtained by simply adding the displacements at which the peaks are detected is not considered, the reliability of each data is not considered, and the reliability of the calculated displacement cannot be expected.

On the other hand, as another problem, there is a problem that accurate displacement measurement becomes difficult when there are portions having different reflectivities on the surface of the object to be measured. For example, when a part with a high reflectance and a part with a low reflectance are mixed on the surface of the object to be measured, an error occurs in a measurement value at a part with a high reflectance when measurement is performed in accordance with a condition with a part with a low reflectance. Conversely, when conditions are set in accordance with a part having a high reflectance, there is a problem that a part having a low reflectance cannot be measured.
Patent 3300803 Japanese Patent Application No. 2003-079122

  As described above, the conventional displacement meter has a problem that appropriate displacement measurement cannot be performed depending on the object to be measured. The present invention has been made to solve such problems, and the main object of the present invention is to provide a displacement meter and a displacement capable of stable and accurate displacement measurement regardless of the surface state of the object to be measured. It is to provide a measurement method.

  In order to achieve the above object, a displacement meter according to claim 1 of the present invention receives a light emitting unit that generates light to be projected onto the measurement object 16, and light emitted from the light emitting unit. An objective lens 15 that projects onto the measurement object 16, a vibration unit that vibrates the objective lens 15 along a first direction with a predetermined amplitude, and a position where the objective lens 15 is moved in the first direction. A position detection unit that detects light, a light diaphragm unit through which reflected light from the object to be measured 16 passes, a light receiving unit that receives light that has passed through the light diaphragm unit, and the objective lens 15 orthogonal to the first direction. The objective lens scanning unit 52 that moves along the second direction, and the objective lens scanning unit 52 moves the objective lens 15 along the second direction by a predetermined amount of movement. At each of a plurality of measurement points, The received light amount peak memory unit 72 that stores the maximum value of the received light amount and the vibration position detected by the position detection unit at this time, and the received light amount maximum stored in the received light amount peak memory unit 72 A light reception data processing unit 73 that integrates the values for each vibration position in the first direction of the objective lens 15 and calculates a displacement based on the integrated light reception amount is provided.

  Further, the displacement meter of claim 2 includes a light emitting unit that generates light to be projected onto the measurement object 16, an objective lens 15 that receives the light emitted from the light emission unit and projects the light onto the measurement object 16, and the A vibration unit that vibrates the objective lens 15 along a direction of an optical axis of light passing through the objective lens 15 with a predetermined amplitude, and a position detection unit that detects a position where the objective lens 15 is moved in the optical axis direction. And an optical aperture section through which reflected light from the object to be measured 16 passes, a light receiving section for receiving the light that has passed through the optical aperture section, and a measurement area designation for designating an area to be measured on the object to be measured 16 51, an objective lens scanning unit 52 for moving the objective lens 15 along a plane orthogonal to the optical axis direction, and the objective lens scanning unit 52 by the objective lens scanning unit 52 along the plane orthogonal to the optical axis direction. Measured when moving with the amount of movement A received light amount peak memory unit 72 that stores the maximum value of the received light amount received by the light receiving unit at a plurality of measurement points on the image 16 and the vibration position detected by the position detecting unit at this time; A light reception data processing unit 73 that integrates the maximum value of the received light amount stored in the amount peak memory unit 72 for each vibration position in the optical axis direction of the objective lens 15 and calculates a displacement based on the integrated received light amount; Is provided.

  Further, the displacement meter according to claim 3 is the displacement meter according to claim 1 or 2, wherein the light reception data processing unit 73 is based on the maximum value of the amount of received light received by the light receiving unit. A light reception waveform indicating a change in the amount of received light at the vibration position of the lens 15 is created, and the displacement is obtained by integrating the created light reception waveforms.

  Furthermore, the displacement meter according to claim 4 is the displacement meter according to claim 3, wherein when the light reception data processing unit 73 calculates the displacement based on the integrated light reception waveform, the center of gravity of the light reception waveform is calculated. The displacement is calculated.

  Furthermore, the displacement meter according to claim 5 is the displacement meter according to claim 3 or 4, wherein the light reception waveform generated by the light reception data processing unit 73 is a triangular wave having a maximum value of the amount of received light. is there.

  Furthermore, the displacement meter according to claim 6 is the displacement meter according to claim 3 or 4, wherein the light reception waveform generated by the light reception data processing unit 73 has a normal distribution in which the maximum value of the light reception amount is a height. It is a waveform.

Furthermore, the displacement meter according to claim 7 includes a light emitting unit that generates light to be projected onto the measurement object 16, an objective lens 15 that receives the light emitted from the light emission unit and projects the light onto the measurement object 16, and A vibration unit that vibrates the objective lens 15 along a direction of an optical axis of light passing through the objective lens 15 with a predetermined amplitude, and a position detection that detects a position where the objective lens 15 is moved in the optical axis direction. A light-reducing unit through which reflected light from the object to be measured 16 passes, a light-receiving unit that receives light that has passed through the light-reducing unit, and an amount of light received by the light-receiving unit for A / D conversion The A / D conversion unit 75, the objective lens scanning unit 52 that moves the objective lens 15 along a plane orthogonal to the optical axis direction, and the objective lens 15 is moved on the orthogonal plane by the objective lens scanning unit 52. Objective lens movement detection A plurality of measurement points detected by the objective lens movement detection unit 53 when the objective lens 15 is moved by a predetermined amount of movement along a plane orthogonal to the optical axis direction by the unit 53 and the objective lens scanning unit 52. The position information of the objective lens 15 at the position, and the value obtained by A / D converting the received light amount received by the light receiving unit at the plurality of measurement points by the A / D conversion unit 75 for each predetermined vibration position of the objective lens 15 The received light amount peak memory unit 72 that stores the associated vibration position in the position detecting unit in association with the received light amount stored in the received light amount peak memory unit 72 in the optical axis direction of the objective lens 15. Is generated for each vibration position, and a light reception waveform indicating a change in the amount of light received at the vibration position of the objective lens 15 is generated, and a displacement is calculated based on the generated light reception waveform. And a data processing unit 73.
Displacement meter characterized by that.

  Furthermore, the displacement meter according to claim 8 includes a light emitting unit that generates light to be projected onto the measurement target 16, an objective lens 15 that receives the light emitted from the light emission unit and projects the light onto the measurement target 16, and A vibration unit that vibrates the objective lens 15 along a direction of an optical axis of light passing through the objective lens 15 with a predetermined amplitude, and a position detection that detects a position where the objective lens 15 is moved in the optical axis direction. An optical diaphragm section through which reflected light from the object to be measured 16 passes, a light receiving section that receives light that has passed through the optical diaphragm section, and the objective lens 15 is moved along a plane orthogonal to the optical axis direction. An objective lens scanning unit 52, an objective lens movement detecting unit 53 for detecting a position where the objective lens 15 is moved on an orthogonal plane by the objective lens scanning unit 52, and an objective lens 15 by the objective lens scanning unit 52. With optical axis direction When the object lens 15 is moved along the intersecting plane by a predetermined amount of movement, the position information of the objective lens 15 at the plurality of measurement points detected by the object lens movement detection unit 53 and the light receiving unit at the plurality of measurement points. The received light amount peak memory unit 72 that stores the maximum value of the received light amount and the vibration position detected by the position detector at this time, and the data of each received light amount stored in the received light amount peak memory unit 72 On the other hand, an average value of received light amount is calculated from a plurality of received light amount data located in the vicinity thereof, a received light amount threshold value is set, and a received light data processing unit that calculates a displacement based on the received light amount data exceeding the received light amount threshold value 73.

  Furthermore, the displacement meter according to claim 9 includes a light emitting unit that generates light to be projected onto the measurement object 16, an objective lens 15 that receives the light emitted from the light emission unit and projects the light onto the measurement object 16, and A vibration unit that vibrates the objective lens 15 along a direction of an optical axis of light passing through the objective lens 15 with a predetermined amplitude, and a position detection that detects a position where the objective lens 15 is moved in the optical axis direction. , A light diaphragm part through which reflected light from the object to be measured 16 passes, a light receiving part for receiving light that has passed through the light diaphragm part, and a direction orthogonal to the optical axis direction while the object to be measured is placed on the upper surface A stage 76 that can move along a plane, a stage movement detector 78 that detects a position where the stage 76 has moved on an orthogonal plane, and a stage movement detector 78 that moves the stage 76 along an orthogonal plane. Move by the amount of movement The position information of the objective lens 15 at a plurality of measurement points detected by the stage movement detector 78, the maximum value of the amount of light received by the light receiver at the plurality of measurement points, and the position detector at this time The received light amount peak memory unit 72 that stores the detected vibration position in association with each other, and the received light amount maximum value stored in the received light amount peak memory unit 72 for each vibration position in the optical axis direction of the objective lens 15. And a received light data processing unit 73 that calculates the displacement based on the integrated received light amount.

  Furthermore, the displacement meter according to claim 10 is the displacement meter according to any one of claims 1 to 9, wherein the excitation unit uses the tuning fork 21, and the position detection unit uses the amplitude of the tuning fork 21. The tuning fork amplitude detection unit 22 detects.

  In the displacement measuring method according to claim 11, the light projected from the light emitting unit to the object to be measured 16 is reflected via the oscillating objective lens 15, and the light passing through the inner light aperture unit of the reflected light is received. In this method, the displacement of the surface of the object 16 to be measured is measured by detecting the light receiving unit. In this method, the objective lens 15 that allows light projected to the measurement object 16 to pass through at a plurality of measurement points in the region to be measured on the measurement object 16 is moved in the optical axis direction of the light by the excitation unit. While the light receiving unit measures the received light amount while vibrating, the received light amount at the time when the received light amount reaches a peak and the position of the objective lens 15 that has been vibrated at this time are associated and held in the received light amount peak memory unit 72. A step of integrating the maximum value of the received light amount stored in the received light amount peak memory unit 72 for each position in the vibration direction of the objective lens 15, and calculating a displacement based on the integrated received light amount; Is provided.

  According to the displacement meter and the displacement measuring method of the present invention, stable and highly accurate displacement measurement is realized regardless of the surface state of the object to be measured. The displacement meter and displacement measuring method of the present invention does not measure the displacement at a plurality of sites and use the average value, but instead determines the position of the objective lens based on the peak value of the received light amount detected at each measurement position. This is because the requested processing is performed. In the method in which the displacement is not obtained immediately after the amount of received light is obtained, and the average displacement is obtained by once integrating the amounts of received light at a plurality of sites, weighting is performed according to the size of the peak. The displacement can be calculated in the reflected form. Furthermore, in the method of restoring the received light amount waveform from the received light amount peak value, the original waveform is restored based on highly accurate data with the maximum peak value, and the accuracy is high. Since it is not necessary to measure the waveform by sequentially A / D converting the amount of received light, complicated calculation processing can be eliminated and simple processing can be realized at low cost. As described above, by calculating the amount of light received, a calculation result that emphasizes highly accurate data is obtained, and the object to be measured includes steps or irregularities or parts with different reflectivities. Even when the surface state of the object is bad and includes a portion that cannot be measured, accurate and reliable displacement measurement is realized.

  Further, according to the present invention, even when a part having a different reflectance is included on the surface of the object to be measured, the displacement can be measured with high accuracy. This is because the threshold value for eliminating data with a low light reception amount is dynamically changed according to the reflectance of the object to be measured. In particular, by setting a threshold value according to the amount of light received in the vicinity of the target region, a threshold value for the amount of received light is set for each of the regions with high and low reflectivity, thereby selecting an appropriate threshold value. Thus, only highly accurate data can be extracted, and as a result, highly accurate displacement measurement can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment shown below exemplifies a displacement meter and a displacement measuring method for embodying the technical idea of the present invention, and the present invention specifies the displacement meter and the displacement measuring method as follows. do not do.

  Further, in this specification, in order to facilitate understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as “claim column” and “means for solving the problems”. It is added to the members shown in the column. However, the members shown in the claims are not limited to the members in the embodiments. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

  In the present invention, the displacement meter is a displacement meter that measures the displacement of the surface of the object to be measured, and is a device that measures the height, depth, thickness, height difference, step, inclination, angle, etc. of the object to be measured. It is not limited, and is used in the meaning of including a device capable of measuring a surface shape and the like based on measurement results such as height and inclination. Similarly, the displacement measurement method is not limited to the method of measuring the height, depth, thickness, altitude difference, step, inclination, angle, etc. of these objects to be measured, and the surface shape and the like are measured based on these measurement results. It is used in the meaning which includes the method to do. Further, in this specification, the peak means a maximum value.

[Embodiment 1]
FIG. 3 shows a configuration diagram of the displacement meter according to the first embodiment of the present invention. The displacement meter shown in this figure includes a laser diode 12 as a light emitting unit, a collimating lens 14 that converts light emitted from the laser diode 12 into parallel light, an objective lens 15, and a tuning fork 21 that holds the objective lens 15, A solenoid 24 that is a vibration unit for vibrating the tuning fork 21 in the optical axis direction and a tuning fork amplitude detection unit 22 that is a position detection unit that detects the position of the tuning fork 21 that is vibrated by the solenoid 24 are provided. In addition, this displacement meter has a pinhole 17a formed in an optical aperture portion 17 through which reflected light from the object to be measured 16 passes. Further, at the position of the pinhole 17a of the optical diaphragm 17, a photodiode 18 is provided as a light receiving part.

  The light emitted from the laser diode 12 driven by the laser power control unit 11 sequentially passes through the beam splitter 13, the collimator lens 14, and the objective lens 15, and is projected onto the object to be measured 16. The reflected light from the object to be measured 16 passes through the objective lens 15 and the collimating lens 14, is reflected by the beam splitter 13 constituting the half mirror, and enters the photodiode 18 through the pinhole 17 a of the optical diaphragm 17. .

  The signal photoelectrically converted by the photodiode 18 is input to the amplifier 19, and the output signal X is input to the arithmetic unit 20. A peripheral portion of the objective lens 15 is attached to the tip of one side long portion of the tuning fork 21 formed in a U shape. The objective lens 15 is vibrated with a predetermined amplitude in the optical axis direction of the light emitted from the laser diode 12 by the vibration of the tuning fork 21. A tuning fork amplitude detection unit 22 is disposed as a position detection unit on the side of the tip side of the long side of the tuning fork 21. The tuning fork amplitude detection unit 22 can use, for example, a sensor using magnetism, light, or capacitance, and detects the position of the objective lens 15 connected to the tuning fork 21 by detecting the amplitude position of the tuning fork 21. In addition to detecting the tuning fork amplitude in this way, the position detection unit may be configured to directly detect the position of the objective lens connected to the tuning fork and vibrated.

  The detected amplitude signal detected by the tuning fork amplitude detector 22 is input to the amplifier 23, and the output signal Y is input to the calculator 20. A solenoid 24 for vibrating the tuning fork 21 is disposed on the side of the leading end side of the other long portion of the tuning fork 21.

  The solenoid 24 is driven by a control current supplied from the tuning fork amplitude control unit 25. The tuning fork amplitude controller 25 is configured to be supplied with the output signal of the amplifier 23 and to be controlled so as to make the amplitude of the tuning fork 21 constant. As the tuning fork 21, for example, one that vibrates at 800 Hz and an amplitude of ± 0.3 mm can be used. The displacement signal calculated and output by the calculation unit 20 is input to the distance conversion unit 50.

  In this displacement meter, the position of the objective lens 15 at the time when the amount of light received by the photodiode 18 becomes maximum is detected by the tuning fork amplitude detection unit 22, and based on this, the reflection point of light on the object 16 to be measured, that is, The displacement of the surface is calculated by the calculation unit 20 and the distance conversion unit 50 which are displacement calculation units.

  Next, the operation of the displacement meter configured as described above will be described. When a current is supplied from the tuning fork amplitude controller 25 to the solenoid 24, a magnetic field is generated by the solenoid 24. This generated magnetic field causes the tuning fork 21 to vibrate with a predetermined amplitude, causing the objective lens 15 to vibrate in the direction of the optical axis of the light passing therethrough. The tuning fork amplitude detector 22 detects the amplitude of the tuning fork 21, that is, the amplitude of the objective lens 15, and outputs a sine wave signal as the amplitude of the objective lens 15. The sine wave signal is amplified by the amplifier 23, and the output signal Y output from the amplifier 23 is input to the arithmetic unit 20.

  On the other hand, when a drive current is supplied from the laser power control unit 11 to the laser diode 12, the laser diode 12 emits laser light. The emitted light passes through the beam splitter 13, the collimating lens 14, and the objective lens 15 and is projected onto the object 16 to be measured. The reflected light reflected by the DUT 16 passes through the objective lens 15 and the collimating lens 14 and is reflected by the beam splitter 13 and projected to the optical diaphragm 17 side, and only the light transmitted through the pinhole 17a is incident on the photodiode 18. . Therefore, the latent light generated by the object to be measured 16 and the reflected light caused by the stray light generated by the laser diode 12 are blocked by the pinhole 17a and do not pass through the pinhole 17a. Only the in-focus light generated in the light enters.

  By the way, since the objective lens 15 is vibrated, the distance between the objective lens 15 and the object to be measured 16 changes, and when the distance reaches a predetermined distance, the focal point of the light projected on the object to be measured 16 is changed. When it occurs in the measurement object 16, the light reception output of the photodiode 18 is instantaneously maximized, and a signal corresponding to this light reception output is input to the amplifier 19, and the output signal X is output from the amplifier 19 and input to the arithmetic unit 20. The arithmetic unit 20 can accurately detect the point in time when the focal point of the light projected on the DUT 16 is generated by detecting the maximum value of the output signal X. The arithmetic unit 20 samples the level of the output signal Y at the time when the output signal X reaches the maximum value, that is, the amplitude of the objective lens 15, and outputs it as a displacement signal S. Then, the sampled displacement signal S is input to the distance conversion unit 50, and the displacement signal S is converted into a distance corresponding to the displacement signal S, and the displacement of the surface of the DUT 16 is measured.

  In this example, the displacement of the objective lens 15 is directly obtained by sample-holding the sine wave signal output from the tuning fork amplitude detector 22. However, the method for acquiring the displacement of the objective lens 15 is not limited to this method. For example, as disclosed in Japanese Patent No. 3300803, which is Patent Document 1, the signal output from the tuning fork amplitude detection unit 22 is a sine wave signal having a known amplitude and phase. A method of indirectly acquiring the displacement of the objective lens 15 from the phase or phase difference at the time when the in-focus point occurs can also be used.

  As another embodiment of the vibration unit, not only the objective lens 15 but also the collimating lens 14 may be connected to the tuning fork 21 as shown in FIG. In the example of FIG. 4, the peripheral portion of the objective lens 15 is attached to the tip of one long portion of the tuning fork 21 and the periphery of the collimator lens 14 disposed on the same optical axis as the objective lens 15 at the tip of the other long portion. The part is installed. The objective lens 15 and the collimating lens 14 are both configured to be able to vibrate. If it does in this way, the weight of one side long part and other side long part of tuning fork 21 can be balanced, and tuning fork 21 can be shaken efficiently. Furthermore, the tuning fork 21 can be vibrated by fixing a piezoelectric element to each of the outer surface of the long side of the tuning fork 21 and the outer surface of the long side of the other side and applying a voltage to the piezoelectric element.

  As such a method for calculating the displacement at an arbitrary point on the object 16 to be measured, for example, the method described in Patent Document 1 above, other known methods, or a method developed in the future can be used as appropriate. Will be omitted.

[Measurement area]
As described above, the displacement meter measures the displacement amount at the designated measurement point. Furthermore, the displacement meter can designate a plurality of measurement points. Specifically, the measurement area to be measured is designated by the measurement area designation unit 51. The measurement area is designated by a line such as an arc or a straight line. As a designation method by the measurement region designation unit 51, for example, a method for designating a start point and an end point of a line segment, a method for directly designating a free curve, and the like can be appropriately used. Further, it is possible to designate a scanning step which is an interval between measurement points in a straight line or a curve of the designated measurement region. Alternatively, the user may directly specify a plurality of positions to be measured as measurement points. Alternatively, the displacement meter may automatically set the measurement area based on the position designated by the user. For example, with the designated position as a reference, the interval between measurement points is also set to a predetermined value.

  Within the measurement region set in this way, the displacement meter measures the amount of displacement at each of a plurality of measurement points. Based on the measured displacement amounts at a plurality of positions, the surface state of the measurement object 16 can be known. For example, a profile for displaying the concavo-convex shape in the measurement region, inclination, maximum height, minimum height, average height, height difference, thickness, and the like are calculated and displayed as necessary.

  Of course, it is needless to say that the objective lens scanning unit 52 can be stopped and the displacement amount of only one arbitrary point can be measured.

[Objective lens scanning unit 52]
The measurement point is moved by moving the objective lens 15. The objective lens 15 is moved in a direction orthogonal to the optical axis of the light, and is moved in the horizontal direction in FIG. Light incident on the objective lens 15 from the light emitting portion is converted into parallel light by the intervening collimator lens 14. As a result, even if it is moved in the direction orthogonal to the parallel light as shown in FIG. 5, the focal length in the optical axis direction is unchanged and the focal point can be focused on the object 16 to be measured, so that displacement measurement is possible. Become. The size of the objective lens 15 is preferably made smaller than the diameter of the collimating lens 14 so that parallel light can be received even if the objective lens 15 is moved, and the movable range of the objective lens 15 is the collimating lens. It is set to fit within a diameter of 14.

  The objective lens 15 is moved by the objective lens scanning unit 52. The displacement meter shown in FIG. 3 includes a servo motor 52A as the objective lens scanning unit 52, and a rotation angle of the servo motor 52A as the objective lens movement detection unit 53 that detects the position where the objective lens 15 is moved by the objective lens scanning unit 52. Is provided with a rotation angle sensor 53A. The servo motor 52 </ b> A rotatably couples the excitation unit via a rotation shaft 54 provided on a tuning fork holder 56 that holds the tuning fork 21 that constitutes the excitation unit. The rotation shaft 54 is positioned so that the objective lens 15 connected to the excitation unit moves along a plane orthogonal to the optical axis. In FIG. 3, the rotation shaft 54 is passed through the rear end of the tuning fork holder 56 to rotate the tuning fork 21 in a horizontal plane so that the parallel light from the collimating lens 14 can be received vertically by the objective lens 15. Yes. The rotation of the servo motor 52A is controlled by a scanning position control unit 57 connected to the servo motor 52A. The scanning position control unit 57 controls the rotation of the servo motor 52A based on the scanning position control signal output from the arithmetic processing unit 58.

[Objective Lens Movement Detection Unit 53]
A rotation angle sensor 53A is attached to the rotation shaft 54 of the servo motor 52A as the objective lens movement detection unit 53, and the position of the objective lens 15 is detected by the rotation angle sensor 53A. The rotation angle sensor 53A sends an objective lens movement position signal to the scanning position control unit 57, and the scanning position control unit 57 can accurately control the position of the objective lens 15 based on the objective lens movement position signal and the scanning position control signal. Further, the scanning position control unit 57 reports the position information of the objective lens 15 to the calculation unit 20. Thereby, the displacement meter can scan while grasping the measurement position. The calculation unit 50 receives the position information of the objective lens 15, calculates the displacement amount for each measurement point by the distance conversion unit 50, and outputs the calculation result to the calculation processing unit 58. The arithmetic processing unit 58 includes a memory unit 59 and holds a displacement amount at each measurement point. Then, predetermined calculation processing is performed, and the result is output as necessary. For example, it is displayed on a display, printed on a printer, stored in a storage medium, or sent to an external device for other processing. The output unit 66 can use a display unit such as a display, a printing unit such as a printer, a medium recording unit such as a storage device, an external device such as a computer, or the like according to these processes. Note that the calculation unit 50 and the calculation processing unit 58 can be configured by an IC such as a system LSI, and these can also be configured by the same circuit.

[Measurement area designating part 51]
The displacement meter shown in FIG. 3 includes a measurement area designating unit 51 for the user to designate a desired measurement area. The measurement area designates an area to be measured with a line. For the measurement region designating part 51, input means such as a console, a keyboard, a mouse, and a touch panel can be used as appropriate. In addition to being provided in the displacement meter, the measurement region designating part 51 is connected to the displacement meter body by wire or wireless as a detachable member. Alternatively, an input device connected to a computer connected to the displacement meter may be used.

  The measurement area designating unit 51 is connected to the arithmetic processing unit 58. When the user designates the measurement region from the measurement region specifying unit 51, the arithmetic processing unit 58 outputs the tuning fork position control signal and the scanning position control signal to the tuning fork amplitude control unit 25 and the scanning position control unit 57, respectively, based on this information. And control these. FIG. 6 shows an outline of the scanning position control signal. The measurement area includes a scanning width that is a range in which the objective lens 15 is moved, a scanning center that is a movement center position, a scanning cycle when the objective lens 15 is periodically moved, a scanning step that is a movement amount per time, and the like. Determined by For example, when the user designates a scanning step and a scanning width, the objective lens 15 is moved stepwise at the designated scanning step, and when the user moves by the scanning width, the objective lens 15 turns back and moves in the opposite direction, and periodically moves to move the objective lens 15. Scan the surface of the object. In addition, when the user designates an arbitrary point on the object to be measured in order to simplify the designation, the scanning area may be automatically set with the scanning width and the scanning step set in advance with this point as the scanning center. it can. Alternatively, the method is not limited to the method in which the objective lens 15 is periodically scanned, and such a path or point is specified so that the objective lens 15 is moved along an arbitrary path specified by the user or the displacement at an arbitrary point is measured. You may comprise so that it may carry out.

  The time or scanning speed required for scanning is mainly determined by the scanning step and the scanning width. The larger the scanning step and the narrower the scanning width, the faster the scanning speed. On the other hand, the smaller the scanning step, the higher the scanning accuracy and the finer displacement measurement becomes possible. Therefore, the measurement region and its parameters are set to desired values according to the balance between speed and accuracy.

  On the other hand, as shown in FIG. 6, in parallel with the scanning position control signal, the tuning fork position signal is sent from the arithmetic processing unit 58 to the tuning fork amplitude control unit 25. Therefore, while the objective lens 15 is moved along a plane perpendicular to the optical axis, the objective lens 15 is vibrated in the direction of the optical axis by the vibration unit, and the maximum value of the light receiving unit is detected as described above. The displacement is calculated. Preferably, the objective lens 15 is amplified by one or more periods in the optical axis direction by the vibration unit for each scanning step so that the displacement can be measured for each step. For this purpose, the scanning position control signal and the tuning fork position detection signal are output by the arithmetic processing unit 58 in synchronization.

[Displacement measurement procedure]
Next, a method of measuring a predetermined range of displacement using the above displacement meter will be described. As shown in FIG. 7, the displacement meter can change the position of the objective lens in the vertical direction of FIG. 7 by vibrating the objective lens using a tuning fork. The movement (vibration) of the objective lens in the optical axis direction is detected as a vibration position by the tuning fork amplitude detection unit 22 which is a position detection unit. On the other hand, the measurement point is moved by moving the tuning lens in the horizontal direction in FIG. 7 by swinging the tuning fork in the horizontal plane by the objective lens scanning unit. In this way, the amount of received light is measured by the light receiving unit while moving the vibration position of the objective lens at each measurement point.

  FIG. 8 shows a state in which the amount of received light changes depending on the vibration position. In the figure, the vibration position of the objective lens on the vertical axis that maximizes the amount of received light on the horizontal axis is the position (focal length) in focus. Therefore, the displacement can be calculated by obtaining the vibration position where the amount of received light is maximized. As shown in FIG. 7, in the vicinity of the focal point, the amount of received light varies greatly according to the vibration position of the objective lens. In the figure, the waveform indicated by the broken line indicates the ideal amount of received light, but the actual waveform is a waveform having a plurality of peaks as indicated by the solid line. This is because a plurality of extreme values of the amount of received light are measured within the vibration range of the objective lens because the surface of the object to be measured is rough or foreign matter is attached.

Based on the amount of light received thus measured, the vibration position is determined at each measurement point, and the average displacement can be obtained by averaging these positions. FIG. 9 shows the peaks of the received light amounts respectively measured at _n measurement points P ₀ , P ₁ , P ₂ ,... P _n−1 included in the predetermined area for obtaining the average displacement. In general, the accuracy of measurement depends on the amount of received light, and the higher the amount of received light, the higher the accuracy of the measurement, while the lower the amount of received light, the worse the accuracy. Thus, each measurement point _{P 0, P 1, P 2} , in ··· _{P n-1,} the vibration position _Y 0 the peak amount of received light becomes _{maximum, Y 1, Y 2, ···} Y n-1 Is extracted, and the average of these values is taken as the vibration position of the predetermined region. In this example, (Y ₀ + Y ₁ + Y ₂ +... + Y _n-1 ) / n is defined as an average vibration position, and the average displacement is obtained on the assumption that a focal point is obtained when the objective lens is present at this position.

However, this method does not reflect the amount of received light related to measurement accuracy. For example, only not been obtained in the measurement points P ₁ low amount of light received 9, the measurement accuracy in this point despite seems low, in the calculation of the average displacement in the same status as the other measurement points handling It has been broken. In this case, data with high accuracy and data with low accuracy are not distinguished, and are processed as a simple average with the same weighting. Therefore, the reliability of the calculation result is low, and high-precision displacement measurement cannot be performed.

  Therefore, in this embodiment, taking into account the magnitude of the amount of received light, weighting is applied with the peak of the amount of received light that is related to the measurement accuracy, thereby obtaining a more accurate displacement as an operation that emphasizes highly accurate data with a large amount of received light. ing. The principle of this method will be described with reference to FIG.

FIG. 10 also shows the peaks of the received light amounts measured at _n measurement points P ₀ , P ₁ , P ₂ ,... P _n−1 , as in FIG. The amount of received light measured at each measurement point is only a peak value, and actually the amount of received light is generated with a waveform as shown in FIG. Therefore, the original waveform of the received light amount is approximately restored based on the peak value of the received light amount. The technique shown in FIG. 11 can be used to restore the waveform. FIG. 11A shows a method of approximating the received light amount waveform with a triangular wave whose height is the peak of the received light amount. The restored waveform by the triangular wave can be generated easily and inexpensively, and the result is inferior to other methods in terms of accuracy, which is preferable. FIG. 11B shows a method of approximating the received light amount waveform with a normal distribution waveform centered on the peak. This approximate waveform can be expected to have high accuracy. Further, the present invention is not limited thereto, and a method of approximating with a sine wave or other basic waveform, or a method of constructing a waveform with an actual measurement value of received light as shown in FIG. Note that the broadening of the skirt of the approximate waveform corresponds to the vibration of the objective lens by the tuning fork shown in the vertical direction in FIG. 7, and is therefore determined to be an appropriate value according to the settings and specifications of the optical system of the displacement meter. For example, when the laser spot diameter is narrow, the waveform is narrow and the peak is high, and when the spot diameter is wide, the waveform is broad and the peak is low.

  Furthermore, the peak of the received light amount used here can be selected with a predetermined threshold. For example, when the peak is equal to or lower than a predetermined threshold, the accuracy is improved by excluding the data with poor accuracy from the subsequent calculation by excluding the data. Details of the threshold setting will be described later.

  As described above, an approximate waveform of the amount of received light is generated based on the peak value obtained at each measurement point. Then, as shown in FIG. 10, the obtained received light amount waveform is integrated for all measurement points. The integration is performed by superimposing the received light amount waveforms based on the vibration position. Further, the center of gravity is obtained from the integrated waveform, and the displacement is calculated using the position corresponding to the center of gravity as the vibration position. According to this method, compared to a method in which the vibration position at which the maximum peak in the measurement point is obtained is mechanically extracted, weighting is performed by the amount of received light related to measurement accuracy, and peaks other than the maximum value are also measured. Since the value is also incorporated into the calculation and considered, the vibration position is calculated with higher accuracy, and the resulting displacement measurement is also highly accurate. In particular, the vibration position is not immediately specified at the stage of measuring the amount of received light at each measurement point, and the final vibration position is obtained after integrating the amount of received light at all measurement points. Since this method can be realized with existing equipment without adding special hardware, it can be easily implemented at low cost, and can be applied to an existing displacement meter. In general, in order to improve the measurement accuracy of a displacement meter, it is often costly, such as making the optical system highly accurate, but this embodiment can improve accuracy at low cost with existing equipment. Has excellent advantages.

  As described above, the displacement measurement at each measurement point and the average displacement in a predetermined region can be obtained with high accuracy by the above method, and the surface profile, inclination, etc. can be obtained using this. For example, profiles for displaying uneven shapes in the measurement area, inclination, maximum height, minimum height, average height, height difference, thickness, etc. are obtained by calculation, and numerical values and images are displayed on the screen of the display unit as necessary. To output.

[Measurement flow chart]
Next, a specific procedure for actually measuring the displacement will be described based on a flowchart. Here, when measuring the profile by linearly scanning the surface of the object to be measured with a displacement meter, the line segment of the measurement region is divided into 10 predetermined regions 1 to 10 as shown in FIG. The displacement is measured at nine measurement points P _{1 to} P _{9 in} a predetermined region. Here, one section of the predetermined area divided into 1 to 10 is the resolution of displacement and profile measurement. The size of one section of the predetermined area is adjusted according to the resolution and processing time.

Hereinafter, the methods shown in FIGS. 13 and 14 will be described as methods for obtaining displacement from a plurality of measurement data. First, the method shown in FIG. 13 is a displacement measurement method according to another embodiment 2 of the present invention, in which a measurement value when the amount of received light is maximum in a predetermined area is a measurement value in this predetermined area. Is the method. For example, when the amount of received light is measured while moving the measurement point within a predetermined area, the peak of the amount of received light as shown in FIG. 15 is obtained at the measurement points P ₀ , P ₁ , P ₂ , P ₃ , P ₄ . Suppose. Among these, the measurement point with the largest peak of the amount of received light is selected (measurement point P _{3 in} the example of FIG. 15), and this is used as a measurement value for the calculation of displacement. As described above, since the data having a larger amount of received light has higher accuracy, it is possible to realize high-speed displacement measurement with simplified processing while ensuring accuracy by using the maximum value as the measurement value.

[Use the maximum received light amount within the specified area]
In the method shown in FIG. 13, the spot is first moved to the observation position (step S13-1), the amount of received light at that position is measured, and the measured amount of received light and the vibration position are held in the received light amount peak memory unit 72. (Step S13-2). Step If and determines whether the measurement at the measurement points P ₁ to P ₉ of the predetermined area is completed in step S13-3, in the case of still repeatedly the loop returns to step S13-1, completing Proceed to S13-4. In step _S13-4, among the measurement points P 1 to P _9, selects the measurement point where the light receiving amount is maximized. The amount of light received at the selected measurement point is set as the vibration position of the predetermined area, and the displacement is calculated. In step S13-5, it is determined whether or not measurement of all the predetermined areas 1 to 10 has been completed. If not, the process returns to step S13-1 to repeat the above loop, and if completed, the process ends. . In this method, the data obtained with the highest received light amount is adopted as representative data for the displacement calculation, and other data is discarded. This method does not require complicated arithmetic processing, and has an advantage that it can be performed at a high speed and with a low load as a simple processing and can be realized at low cost. The difference from the method described with reference to FIG. 10 is that the vibration position obtained at each measurement point is not averaged, but the data with the highest received light amount among the measurement points is handled as representative data. Since the data with the maximum amount of received light has high accuracy, a certain level of accuracy can be expected.

  FIG. 16 shows a block diagram of a displacement meter that realizes the procedure of FIG. The displacement meter shown in this figure includes a light receiving unit 118, a tuning fork position detector 22, a received light amount detecting unit 70, a peak detecting unit 71, an objective lens movement detecting unit 53, a received light amount peak memory unit 72, and a received light amount. A data processing unit 73, a received light data memory unit 74, and an output unit 66 are provided. As shown in FIG. 3 and the like, the light receiving unit 118 is configured by a photodiode or the like, and receives the light reflected by the inner beam splitter of the reflected light from the light emitting unit and passing through the optical aperture unit. The amount of received light detected by the light receiving unit 118 is detected by the received light amount detecting unit 70. Further, the peak detector 71 detects a state in which the waveform of the received light amount that changes in real time reaches a peak. When the peak detector 71 detects a peak, the received light amount detected by the received light amount detector 70 at this time is held in the received light amount peak memory unit 72. As described above, the peak detector 71 serves as a trigger for timing to hold the amount of received light. Note that the received light amount detection unit 70, the peak detection unit 71, and the received light amount peak memory unit 72 illustrated in FIG. 16 correspond to the calculation unit 20 in FIG. These members can also be realized by hardware or software such as a predetermined gate array (FPGA, ASIC), or a mixture thereof.

  Similarly, the tuning fork amplitude detection unit 22 uses the peak detection unit 71 as a trigger to detect the position of the tuning fork when the light reception amount reaches a peak, and holds this information in the light reception amount peak memory unit 72. In this way, the peak amount and the tuning fork position (vibration position) at the time when the received light amount reaches the peak are held in the received light amount peak memory unit 72, and information on a plurality of peaks at each measurement point as shown in FIG. Is retained.

  On the other hand, the objective lens movement detection unit 53 detects the scan position by the vibration unit of the objective lens connected to the tuning fork, and detects position information such as the coordinates of the measurement point. Then, the received light amount data processing unit 73 connected to the received light amount peak memory unit 72 and the objective lens movement detecting unit 53 extracts the peak with the largest received light amount from the held peaks, and the data of this measurement point is determined in advance. Select as an area measurement. The displacement is calculated based on the selected data and output from the output unit 66.

[Integrate the amount of light received within the specified area]
On the other hand, the method shown in FIG. 14 is the method described with reference to FIG. 10, and the displacement is calculated by integrating the amount of received light within a predetermined area. Steps S14-1 to S14-3 in FIG. 14 are the same as those in FIG. In step S14-4, The measurement points _P 1 to P ₉ of a predetermined area, integrates the received light amount. The total received light amount is obtained by adding the received light amount based on the vibration position based on the maximum value of the received light amount stored in the received light amount peak memory unit 72 and the vibration position data of the objective lens at this time. A waveform is obtained. In the subsequent step S14-5, the center of gravity position is calculated from the integrated received light waveform, and the displacement is calculated based on this position. An existing algorithm can be used as appropriate for obtaining the center of gravity from the waveform. Further, the above loop is repeated until the measurement is completed for all the predetermined areas in step S14-6. In this method, data obtained at all measurement points is used to perform weighting according to the magnitude of the amount of received light, and therefore, more accurate than the method of FIG. 13 in which only a single data is used and the others are discarded. High displacement measurement can be expected. On the other hand, since the processing is more complicated than that in FIG. 13, the processing time is long and the processing becomes heavy.

[Reproduce the original waveform of received light amount]
Specifically, the method of FIG. 14 can be further realized by the methods of FIGS. The method shown in FIG. 17 is the same method as that shown in FIG. This is a method of accumulating the received light amount by reproducing the waveform of the received light amount based on this data. More specifically, in step S17-1 in FIG. 17, while moving the full width of the tuning fork at each measurement point P ₁ to P _9, and detects the received light amount of the position and the time that the tuning fork received light amount reaches a peak hold To do. Further, in step S17-2, the maximum value of the received light amount and the position of the tuning fork in the predetermined region are selected from the received light amount peak memory unit 72. Then, an approximate waveform of the received light amount is generated based on the selected maximum data, and the received light amount is integrated using the approximate waveform. Here, the approximate waveform is reproduced in the approximate waveform generation memory area, and the generated approximate waveform is sequentially added to the received light amount integration memory area. Thereby, all approximate waveforms based on the peak positions obtained at all measurement points are integrated to obtain integrated waveform data, and the displacement is calculated using the center of gravity of the integrated waveform as the vibration position.

  The displacement meter that realizes the procedure of FIG. 17 can use the same configuration as the block diagram of FIG. Similar to the procedure of FIG. 13, the tuning fork amplitude detection unit 22 and the received light amount detection unit 70 detect the vibration position and the received light amount information at which the received light amount reaches the peak using the peak detection unit 71 as a trigger, respectively. It is held in the memory unit 72. Further, since the received light data processing unit 73 performs the received light amount integration, the data stored in the received light amount peak memory unit 72 is read and sequentially integrated in the received light data memory unit 74. As a result, an integrated waveform of the received light amount is generated in the received light data memory unit 74, and the vibration position is determined by obtaining the center of gravity from the integrated waveform as shown in FIG. After that, as described with reference to FIG. 13, the displacement is calculated from the vibration position and output from the output unit 66. In FIG. 16, the light reception data processing unit 73 and the light reception data memory unit 74 correspond to the arithmetic processing unit 58 and the memory unit 59 in FIG.

  In this method, the waveform is created based on the highest measured peak value instead of accumulating the actually measured peak values as in the method described later, but the predicted data is also used. Regardless, the actual evaluation yields results that are equivalent to the method described below in terms of accuracy. Further, there is no need to A / D convert the received light amount one by one, and there is an advantage that the processing is relatively easy and can be realized at high speed and low load.

[A / D conversion of measured value of received light amount]
On the other hand, the method of FIG. 18 is a method of constantly measuring the amount of received light and integrating the amount of received light while vibrating the tuning fork for vibrating the objective lens. That is, the received light amount integration is performed based on the actually measured received light amount without using the approximate waveform as in the method of FIG. Specifically, at each measurement point of P _{1 to} P ₉ , the received light amount is measured every time the tuning fork moves by a certain amount as shown in step S 18-1 in FIG. 18, and the received light amount data is A / D converted. Then, the light is accumulated sequentially in the memory area for light quantity accumulation (step S18-2), and the above process is repeated over the moving range of the tuning fork (step S18-3). In this method, since the actual received light amount is measured, not the approximation based on the peak of the received light amount, more accurate displacement measurement can be expected. On the other hand, in order to measure the amount of received light in real time, a high-resolution A / D converter with a high processing speed is required, which complicates the circuit and increases the processing cost.

  FIG. 19 shows a block diagram of a displacement meter that realizes the procedure of FIG. The displacement meter shown in this figure includes a tuning fork amplitude detector 22, an A / D converter 75, an objective lens movement detector 53, a received light data processor 73, and an output unit 66. This displacement meter does not hold the peak of the received light amount, but integrates all detected values. Specifically, the reflected light received by the light receiving unit 118 is converted into a digital signal by the A / D conversion unit 75 and sent to the received light data processing unit 73. At this time, the amplitude displacement of the tuning fork and the objective lens The scan position is detected by the tuning fork amplitude detection unit 22 and the objective lens movement detection unit 53, respectively, and sent to the received light data processing unit 73. The received light data processing unit 73 integrates the digital value of the received light amount sequentially measured in the memory unit 66, and acquires an integrated waveform in which the received light amount is integrated. When the received light amount that has been A / D converted by the A / D converter is integrated, a stepped waveform as shown in FIG. 20 is obtained. Similarly to FIG. 16, the vibration position is determined by obtaining the center of gravity from the obtained integrated waveform.

  In this way, after measuring the amount of light received at each point once, the measured amount of received light is A / D converted and integrated, and the distance data is obtained from the center of gravity of the waveform. The vibration position that is weighted to reflect that is high is acquired. Further, according to this method, since the vibration position is obtained after the actual received light amount is sequentially measured regardless of the prediction of the received light amount, more accurate measurement can be performed. On the other hand, since a high-speed, high-resolution A / D converter is required, the cost increases.

[Variable threshold]
Next, as a third embodiment of the present invention, a procedure for setting a threshold for determining acceptance of a peak value of received light amount will be described with reference to FIGS. In this method, when calculating the displacement from the measured amount of received light, the accuracy is improved by eliminating data with a small amount of received light, that is, data with low accuracy.

  In the method of eliminating data with a low amount of received light, setting a reference threshold value becomes a problem. For example, there is a method in which an average value is obtained from all data of the measured amount of received light, a threshold is set based on this average value, and only data that is equal to or greater than the threshold is used. However, this method has a problem that accurate measurement becomes difficult when measuring an object to be measured in which portions having different reflectivities as shown in FIG. 21 are present. FIG. 22 shows the amount of received light observed in the measurement region set linearly with the DUT of FIG. As shown in this figure, an average high received light amount can be obtained in a portion with high reflectivity, whereas only a low received light amount can be obtained in a portion with low reflectivity. For this reason, if the threshold value is set high, measurement cannot be performed in a region with low reflectivity. Conversely, if the threshold value is set low, data selection is not performed in the region with high reflectivity, and the function as the threshold value is not performed. Thus, as shown by the broken line in FIG. 22, when the data is eliminated with the threshold value being a constant value such as the average value of the whole, a highly accurate displacement measurement cannot be obtained.

  On the other hand, in the method according to the present embodiment, the threshold for the amount of received light is not fixed, but is variable according to the peak value. Specifically, the determination is based on data in the vicinity including the peak to be determined. For example, for the data to be determined, in addition to the data itself, two data before and after are extracted, and an average value is obtained from a total of five data. Then, a threshold is set on the basis of this average value, and data lower than this is excluded. Alternatively, a method may be used in which the observation area of the object to be measured is divided and an average value is obtained for each divided section. With these methods, the threshold value is set based on the amount of received light in the vicinity of a specific part, not the average of the total amount of received light confused with parts having different reflectivities. For this reason, as shown by the solid line in FIG. 22, the threshold is high in the portion with high reflectivity, the threshold is also low in the region with low reflectivity, and an appropriate threshold is set according to the reflectivity. Is appropriately performed, and accurate displacement measurement can be realized regardless of the reflectance distribution.

  The above procedure will be described based on the flowchart of FIG. Here, the threshold is calculated while measuring the amount of received light, and the adoption of the measurement data is determined based on the calculated threshold. However, after measuring the amount of light received at all measurement points in advance, it is also possible to set a threshold value and determine the adoption of data. In addition, the threshold value is calculated based on an average value of peak values within a predetermined section including a plurality of peak values, and the threshold value is set based on this value.

  First, after initializing the apparatus in step S23-1, the measurement point is moved to a predetermined position (step S23-2), and the peak value of the received light amount is measured at the moved position, and the peak of the measured received light amount is measured. The value and the vibration position at that time are held in the received light amount peak memory unit 72 (step S23-3). In step S23-4, it is determined whether or not the measurement is completed until the threshold for the amount of received light can be set. For example, it is determined whether or not the number of samples for calculating the average value of the amount of received light has been prepared. If not, the process returns to step S23-2 to repeat the measurement, and loops until necessary data is obtained for setting the threshold. If it is obtained, a threshold value is set in step S23-5. For example, by calculating an average value in a predetermined section and using it as a threshold value, 50% of the data in the section is validated. Alternatively, it is possible to set so that only data having a large peak is extracted as a threshold larger than the average value, or conversely, as much threshold data as possible can be used as a threshold lower than the average value.

  When the threshold value is determined as described above, the process proceeds to step S23-6, the threshold value is compared with each peak value, and data is excluded and output. The peak value data larger than the threshold value is output by updating the measurement value through step S23-7, and the peak value data lower than the threshold value is not updated through step S23-8. The data is discarded and output (step S23-9). In step S23-10, it is determined whether or not all the data in the section has been output. If not, the process returns to step S23-6 and the determination based on the threshold is repeated. If all the data has been output, the process proceeds to step S23-11 to determine whether or not the measurement has been completed in all the predetermined areas. If not yet, the process returns to step S23-2 and the above loop is repeated. If completed, the process is terminated.

  In the procedure of FIG. 23, an appropriate threshold value can be automatically set without manually setting the threshold value, and simple and accurate displacement measurement is realized. In particular, since the peak value data with a low amount of received light can be effectively excluded with reference to the preceding and subsequent data, accurate discrimination is performed, which contributes to improvement in measurement accuracy.

  In addition to obtaining from the average value of the received light amount as described above, the method for setting the received light amount threshold value may extract and average the maximum value and the minimum value of the received light amount from a plurality of light reception data located in the vicinity. Alternatively, it may be obtained by a moving average.

  In this way, the displacement meter measures the amount of received light at each of a plurality of measurement points, can calculate an accurate displacement based on the measured amounts of received light at a plurality of positions, and can know the surface state of the object to be measured. . In the above configuration, the scanning of the measurement point on the surface of the object to be measured is realized by moving the objective lens side without moving the optical axis of the light emitted from the light emitting unit. For this reason, it is not necessary to provide a complicated mechanism for scanning the optical axis of the light emitting unit, and an excellent feature that the scanning mechanism can be configured at a very low cost is realized.

  In addition, since the profile in the measurement region can be accurately measured in this way, the height, height difference, step, width, angle, etc. in the two-dimensional and three-dimensional regions can be measured with high accuracy. In particular, it is possible to perform measurement at multiple positions continuously and make it possible to check the results statistically, eliminating the need to specify measurement points one by one, and further, averaging, maximum value, minimum value, slope calculation, etc. Processing can be easily realized, and an extremely convenient environment is realized.

  The above method can improve the accuracy of displacement measurement by changing only the calculation method for obtaining the displacement. Therefore, there is an advantage that it does not require any special hardware improvement, can be applied by changing only the algorithm of the arithmetic processing using the hardware of the existing displacement meter, and can be implemented at low cost.

[Embodiment 4]
In the configuration shown in FIG. 3, the servo motor 52A is used as the objective lens scanning unit 52, but the objective lens scanning unit is not limited to this. As another embodiment of the present invention, a displacement meter according to Embodiment 4 is shown in FIG. The displacement meter shown in FIG. 24 has substantially the same configuration as that shown in FIG. 3, but employs a rotation mechanism using a voice coil 52B and a voice coil magnet 52C as the objective lens scanning unit 52, and serves as the objective lens movement detection unit 53. A hall element 53B and a hall element magnet 53C are used.

  The voice coil magnet 52C is fixed in a stationary state while holding the rotating shaft 54, and is fixed to the inner surface of the opening portion of the rotating shaft holding portion 55 having the opening portion 60 having a U-shaped cross section. On the other hand, the voice coil 52B protrudes from the upper surface of the tuning fork holder 56 and is fixed to the tuning fork holder 56 so as to oppose the voice coil 52B magnet while being inserted into the opening 60. The displacement meter adjusts the current flowing through the voice coil 52B by the scanning position control unit 57, generates a driving force with the voice coil magnet 52C based on the interaction of the magnetic field intersecting with the current, and rotates the rotating shaft. The objective lens 15 is rotated around 54.

  The moving position of the objective lens 15 is detected by the Hall element 53B and the Hall element magnet 53C. In the example of FIG. 24, the hall element magnet 53C is fixed to the tuning fork holder 56, and the hall element 53B is provided at a position facing the hall element magnet 53C. The Hall element 53B is an element that detects the magnetic field intensity using the Hall effect of GaAs or InSb. The hall element 53B detects the magnetic field intensity according to the distance from the hall element magnet 53C, and outputs the rotation angle or the rotation distance of the tuning fork holder 56 to the scanning position controller 57 as an objective lens movement position signal.

  Furthermore, as a method for moving the objective lens 15, the methods shown in FIGS. 25 and 26 can be used. These drawings are plan views showing a fixed state of the objective lens 15. In FIG. 25, the objective lens 15 is fixed to the leaf spring 61, and is moved in the horizontal plane by vibrating the leaf spring 61. The leaf spring 61 is vibrated by a vibration unit (not shown). This configuration can be configured very inexpensively.

  In any of the above-described objective lens movement methods, the locus is an arc. In this case, the locus can be made closer to a straight line from the arc shape by increasing the radius of the arc.

  In FIG. 26, a slidable linear guide 62 is used to move the objective lens 15 on a straight line. The linear guide 62 can slide on a straight line along the guide rail. Therefore, the objective lens 15 fixed to the linear guide 62 is surely linearly moved. Needless to say, the objective lens movement detector can be provided as appropriate in the systems shown in these drawings.

[Embodiment 5]
Furthermore, as a fifth embodiment of the present invention, an example provided with an imaging monitor 63 is shown in FIG. The displacement meter shown in this figure has substantially the same configuration as that in FIG. 3, in addition to the second half mirror constituting the second beam splitter 64 provided in the optical path of the light emitting unit, and the reflected light from the second half mirror. An image sensor such as a CCD camera and an imaging monitor 63 connected to the CCD camera are provided as the imaging light receiving unit 65 provided on the optical path. The imaging monitor 63 displays the device under test 16 based on the light reception signal detected by the CCD camera. The imaging monitor 63 does not always display the device under test 16 when the objective lens 15 is moved, but can display a focused and clear image by performing imaging only at a specific timing. The timing for capturing an image to be displayed on the imaging monitor 63 is when the objective lens 15 is in focus, and the timing at which the CCD camera captures an image to be displayed on the imaging monitor 63 is that of the objective lens 15 that vibrates and moves. It is a predetermined scanning position within the scanning width, preferably the scanning center, and the time when the objective lens 15 is focused. As a result, even if the scanning position of the objective lens 15 changes every moment, an image in a stationary state at a predetermined scanning position is displayed on the imaging monitor 63. Further, the focal point timing is set to the time point when the light quantity of the light receiving unit becomes the maximum as in the above-described method. A lighting device may be provided as necessary, and the flash may be irradiated in conjunction with this timing. As a result, the in-focus timing can be reliably and instantaneously captured, and an extremely high-performance autofocus function is realized without requiring a special mechanism. The imaging monitor 63 may display only the image captured in this way, and update the image display at a timing when a new imaging is performed. As a result, only a clear image can be displayed on the imaging monitor 63 at all times. Or, depending on the scanning width and scanning step, if the scanning speed of one cycle is slower than the update speed of the imaging monitor 63 (about 60 Hz at the television rate), an image with little flicker can be obtained by providing a frame memory. Can be displayed. The frame memory is a memory that stores image data for one frame, that is, one screen. By holding the captured image data and displaying the same image data repeatedly, a high-quality display that can support double-speed display becomes possible. In this example, the imaging monitor is displayed separately from the output unit, but the imaging monitor may also be used as a display unit that is an example of the output unit.

[Embodiment 6]
In the above example, the amount of light received at different measurement points is detected by moving the objective lens in the objective lens scanning unit, and the displacement of the object to be measured is measured. However, the amount of received light and displacement at a plurality of measurement points can also be measured by moving the object to be measured while the objective lens is fixed. FIG. 28 shows a displacement meter provided with a mechanism for moving a stage 76 on which an object to be measured is placed as a sixth embodiment of the present invention. In FIG. 28, members denoted by the same reference numerals as those in FIG. 3 and the like have the same configuration as in the above embodiment, and detailed description thereof is omitted.

  The displacement meter shown in this figure is replaced with an objective lens scanning unit that moves the objective lens in the horizontal plane, and a stage 76 for placing the object to be measured 16 and a stage moving unit for moving the stage 76 in the horizontal plane. A stepping motor 77 is provided. The stepping motor 77 is controlled by the scanning position control unit 57. The position of the stage 76 moved by the stepping motor 77 is detected by the stage movement detector 78 and sent to the scanning position controller 57. Accordingly, the measurement point can be relatively changed by moving the object to be measured 16 side in the XY direction in the horizontal plane while fixing the vibration position where the laser beam is focused.

  Note that the configuration for changing the measurement point is not limited to the above example. For example, the configuration in which both the objective lens and the stage can be moved, the configuration in which the optical axis passing through the objective lens is polarized and the surface to be measured is scanned, etc. Can also be used.

  The displacement meter and the displacement measuring method of the present invention can be used in a system for measuring and displaying the displacement, altitude difference, inclination, profile, etc. of the surface of metal or resin using the principle of confocal, and the same measurement principle is used. It can also be applied to a thickness meter that measures the thickness of an object to be measured.

It is a typical block diagram which shows an example of the conventional displacement meter. It is the schematic which shows the state where displacement measurement becomes difficult by the surface shape of a to-be-measured object. It is a typical block diagram which shows the displacement meter which concerns on Embodiment 1 of this invention. It is a block diagram which shows other embodiment of a vibration part. It is a schematic diagram which shows the state of the light which enters into an objective lens. It is a graph which shows the outline | summary of a scanning position control signal. It is a conceptual diagram explaining a mode that a vibration position and a measurement point are changed. It is a graph which shows the state from which the light reception amount changes with a vibration position. It is a graph which shows the peak of the received light amount measured in each measurement point. It is a graph which shows the state which decompress | restores and integrates the waveform of received light amount from the peak of received light amount measured in each measurement point. It is a graph which shows the example which restores | restores the waveform of the original received light amount approximately. It is a conceptual diagram which shows the setting of the predetermined area | region and measurement point at the time of measuring by scanning the surface of a to-be-measured object linearly. It is a flowchart which shows the method as a displacement measuring method which concerns on Embodiment 2 of this invention which makes the measured value when the light reception amount becomes the maximum in a predetermined area | region as a measured value in this predetermined area | region. It is a flowchart which shows the method of calculating a displacement by integrating | accumulating the received light quantity in a predetermined area | region as a displacement measuring method which concerns on one embodiment of this invention. It is a graph which shows the state which selects the measurement point containing local maximum from the peak of the light reception amount obtained at the several measurement point. It is a block diagram of the displacement meter which implement | achieves the procedure of FIG. It is a flowchart which shows an example which implement | achieves the method of FIG. It is a flowchart which shows the other example which implement | achieves the method of FIG. It is a block diagram of the displacement meter which implement | achieves the procedure of FIG. It is a graph which shows the waveform which A / D converted the light-receiving amount. It is a top view which shows the state which sets a measurement area | region on the surface of the to-be-measured object from which a reflectance differs. It is a graph which shows the light reception amount observed with the to-be-measured object of FIG. It is a flowchart which shows the method as a displacement measuring method which concerns on Embodiment 3 of this invention which calculates a threshold value from a specific light reception amount peak, and determines adoption of measurement data. It is a typical block diagram which shows the displacement meter which concerns on Embodiment 4 of this invention. It is a block diagram which shows other embodiment of the objective lens scanning part. It is a block diagram which shows other embodiment of the objective lens scanning part. It is a typical block diagram which shows the displacement meter which concerns on Embodiment 5 of this invention. It is a schematic block diagram which shows the displacement meter which concerns on Embodiment 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Laser power control part 12 ... Laser diode 13 ... Beam splitter 14 ... Collimating lens 15 ... Objective lens 16 ... Object to be measured 17 ... Optical aperture part 17a ... Pinhole 18 ... Photodiode 118 ... Light receiving part 19 ... Amplifier 20 ... Calculation part 21 ... Tuning fork 22 ... Tuning fork amplitude detection part 23 ... Amplifier 24 ... Solenoid 25 ... Tuning fork amplitude control unit 50 ... distance conversion unit 51 ... measurement region designation unit 52 ... objective lens scanning unit 52A ... servo motor 52B ... voice coil 52C ... voice coil magnet 53 ..Object lens movement detection unit 53A ... Rotation angle sensor 53B ... Hall element 53C ... Hall element magnet 54 ... Rotation shaft 55 ... Rotation shaft holder 56 Tuning fork holder 57... Scanning position control unit 58 .. arithmetic processing unit 59... Memory unit 60 .. opening 61 .. leaf spring 62 .. linear guide 63. ..Second beam splitter 65 ... Light receiving unit for imaging 66 ... Output unit 70 ... Light receiving amount detecting unit 71 ... Peak detecting unit 72 ... Light receiving amount peak memory unit 73 ... Light receiving data Processing unit 74: Light reception data memory unit 75 ... A / D conversion unit 76 ... Stage 77 ... Stepping motor 78 ... Stage movement detection unit

Claims (11)

A light emitting unit for generating light to be projected onto the object to be measured (16);
An objective lens (15) that receives the light emitted from the light emitting unit and projects it onto the object to be measured (16),
A vibration unit for vibrating the objective lens (15) along a first direction with a predetermined amplitude;
A position detector for detecting the position where the objective lens (15) is moved in the first direction;
An optical aperture section through which reflected light from the object to be measured (16) passes;
A light receiving unit that receives light that has passed through the optical aperture unit;
An objective lens scanning section (52) for moving the objective lens (15) along a second direction orthogonal to the first direction;
When the objective lens (15) is moved along the second direction by a predetermined amount of movement by the objective lens scanning unit (52), the light receiving unit receives light at a plurality of measurement points on the object to be measured (16). The received light amount peak memory unit (72) for storing the maximum value of the received light amount and the vibration position detected by the position detection unit in association with each other,
The maximum value of the received light amount stored in the received light amount peak memory unit (72) is integrated for each vibration position in the first direction of the objective lens (15), and the displacement is calculated based on the integrated received light amount. Received light data processing unit (73),
A displacement meter comprising: A light emitting unit for generating light to be projected onto the object to be measured (16);
An objective lens (15) that receives the light emitted from the light emitting unit and projects it onto the object to be measured (16),
A vibration unit that vibrates the objective lens (15) along a direction of an optical axis of light passing through the objective lens (15) with a predetermined amplitude;
A position detector for detecting the position where the objective lens (15) is moved in the optical axis direction;
An optical aperture section through which reflected light from the object to be measured (16) passes;
A light receiving unit that receives light that has passed through the optical aperture unit;
A measurement region designating part (51) for designating a region to be measured on the device under test (16),
An objective lens scanning section (52) for moving the objective lens (15) along a plane orthogonal to the optical axis direction;
When the objective lens (15) is moved by a predetermined amount of movement along a plane orthogonal to the optical axis direction by the objective lens scanning unit (52), the light reception is performed at each of a plurality of measurement points on the object to be measured (16). Received light amount peak memory unit (72) for storing the maximum value of the received light amount received by the unit and the vibration position detected by the position detecting unit in association with each other,
The maximum value of the received light amount stored in the received light amount peak memory unit (72) is integrated for each vibration position in the optical axis direction of the objective lens (15), and the displacement is calculated based on the integrated received light amount. Received light data processing part (73),
A displacement meter comprising:   3. The displacement meter according to claim 1, wherein the light reception data processing unit (73) is based on a maximum value of the amount of light received by the light reception unit at a vibration position of the objective lens (15). A displacement meter characterized in that a received light waveform indicating a change in received light amount is created, and the displacement is obtained by integrating the created received light waveform.   4. The displacement meter according to claim 3, wherein the light reception data processing unit (73) calculates the displacement by calculating the center of gravity of the received light waveform when calculating the displacement based on the integrated received light waveform. Displacement meter.   5. The displacement meter according to claim 3, wherein the light reception waveform created by the light reception data processing unit (73) is a triangular wave whose height is the maximum value of the amount of received light.   5. The displacement meter according to claim 3, wherein the light reception waveform created by the light reception data processing unit (73) is a normal distribution waveform having a maximum value of the amount of received light. Total. A light emitting unit for generating light to be projected onto the object to be measured (16);
An objective lens (15) that receives the light emitted from the light emitting unit and projects it onto the object to be measured (16),
A vibration unit that vibrates the objective lens (15) along a direction of an optical axis of light passing through the objective lens (15) with a predetermined amplitude;
A position detector for detecting the position where the objective lens (15) is moved in the optical axis direction;
An optical aperture section through which reflected light from the object to be measured (16) passes;
A light receiving unit that receives light that has passed through the optical aperture unit;
An A / D converter (75) for A / D converting the amount of light received by the light receiver;
An objective lens scanning section (52) for moving the objective lens (15) along a plane orthogonal to the optical axis direction;
An objective lens movement detector (53) for detecting a position where the objective lens (15) is moved on an orthogonal plane by the objective lens scanning unit (52);
When the objective lens (15) is moved by a predetermined amount of movement along a plane orthogonal to the optical axis direction by the objective lens scanning unit (52), a plurality of detection points detected by the objective lens movement detection unit (53) The position information of the objective lens (15) at the measurement point and the amount of light received by the light receiving unit at the plurality of measurement points are converted into the A / D conversion unit (75) for each predetermined vibration position of the objective lens (15). A received light amount peak memory unit (72) that stores the A / D-converted value in association with the vibration position in the position detection unit corresponding thereto,
The received light amount stored in the received light amount peak memory unit (72) is integrated for each vibration position in the optical axis direction of the objective lens (15) to change the received light amount at the vibration position of the objective lens (15). A light reception data processing unit (73) for calculating a displacement based on the generated light reception waveform,
A displacement meter comprising: A light emitting unit for generating light to be projected onto the object to be measured (16);
An objective lens (15) that receives the light emitted from the light emitting unit and projects it onto the object to be measured (16),
A vibration unit that vibrates the objective lens (15) along a direction of an optical axis of light passing through the objective lens (15) with a predetermined amplitude;
A position detector for detecting the position where the objective lens (15) is moved in the optical axis direction;
An optical aperture section through which reflected light from the object to be measured (16) passes;
A light receiving unit that receives light that has passed through the optical aperture unit;
An objective lens scanning section (52) for moving the objective lens (15) along a plane orthogonal to the optical axis direction;
An objective lens movement detector (53) for detecting a position where the objective lens (15) is moved on an orthogonal plane by the objective lens scanning unit (52);
When the objective lens (15) is moved by a predetermined amount of movement along a plane orthogonal to the optical axis direction by the objective lens scanning unit (52), a plurality of detection points detected by the objective lens movement detection unit (53) Light reception that stores the positional information of the objective lens (15) at the measurement point, the maximum value of the amount of light received by the light receiving unit at the plurality of measurement points, and the vibration position detected by the position detection unit in association with each other. Amount peak memory part (72),
For each received light amount data stored in the received light amount peak memory section (72), an average value of the received light amount is calculated from a plurality of received light amount data located in the vicinity thereof, and a received light amount threshold value is set. A received light data processing unit (73) for calculating displacement based on received light amount data exceeding the amount threshold value;
A displacement meter comprising: A light emitting unit for generating light to be projected onto the object to be measured (16);
An objective lens (15) that receives the light emitted from the light emitting unit and projects it onto the object to be measured (16),
A vibration unit that vibrates the objective lens (15) along a direction of an optical axis of light passing through the objective lens (15) with a predetermined amplitude;
A position detector for detecting the position where the objective lens (15) is moved in the optical axis direction;
An optical aperture section through which reflected light from the object to be measured (16) passes;
A light receiving unit that receives light that has passed through the optical aperture unit;
A stage (76) capable of moving along a plane orthogonal to the optical axis direction while placing the object to be measured on the upper surface;
A stage movement detector (78) for detecting a position where the stage (76) is moved on an orthogonal plane; and
Objective lenses at a plurality of measurement points detected by the stage movement detection unit (78) when the stage movement detection unit (78) moves the stage (76) by a predetermined movement amount along an orthogonal plane ( 15) the received light amount peak memory unit (72) that stores the positional information in association with the maximum value of the received light amount received by the light receiving unit at the plurality of measurement points and the vibration position detected by the position detecting unit at this time. )When,
The maximum value of the received light amount stored in the received light amount peak memory unit (72) is integrated for each vibration position in the optical axis direction of the objective lens (15), and the displacement is calculated based on the integrated received light amount. Received light data processing part (73),
A displacement meter comprising:   The displacement meter according to any one of claims 1 to 9, wherein the excitation unit uses a tuning fork (21), and the position detection unit detects the amplitude of the tuning fork (21). (22) Displacement meter characterized by the above-mentioned. The light projected from the light emitting unit to the object to be measured (16) is reflected through the oscillating objective lens (15), and the reflected light is detected by the light receiving unit that receives the light that has passed through the inner light diaphragm unit, and is detected. A method for measuring the displacement of the surface of the measurement object (16),
The objective lens (15) that passes the light projected to the object to be measured (16) at a plurality of measurement points in the region to be measured on the object to be measured (16) is connected to the optical axis of the light by the excitation unit. Measure the amount of light received at the light receiving unit while vibrating in the direction, and correlate the amount of received light at the point where the amount of received light reaches a peak with the position of the objective lens (15) that has been vibrated at this point in time. Part (72) to hold,
A step of integrating the maximum value of the received light amount stored in the received light amount peak memory unit (72) for each position in the vibration direction of the objective lens (15), and calculating a displacement based on the integrated received light amount; ,
A displacement measuring method comprising:

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