JP2011122862A - Ranging method and laser ranging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ranging method and a laser ranging apparatus while suppressing a load on a calculation section, and enabling accurate ranging. <P>SOLUTION: In the ranging method and the laser ranging apparatus of the invention, an intensity of a combined light is monitored. The symmetry of intensity data before and after a peak position having a predetermined intensity or above is confirmed. Position information on a measurement position of a to-be-measured object and a corresponding reflection point is obtained. A distance to the to-be-measured object or a distance in the thickness direction between two measurement points of the to-be-measured object is measured based on the position information. The calculation quantity based on the intensity data can be reduced. While a load on the calculation section is suppressed, the accurate ranging can be implemented by utilizing the coherency of a laser light. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a distance measuring method and a laser distance measuring apparatus for measuring a distance to a measurement object or a distance in a thickness direction between measurement points of the measurement object using interference of a laser beam.

  In a conventional laser distance measuring method using laser light, for example, the laser light is divided into reference light and measurement light, and the optical path difference between the reference light and measurement light reflected by the object to be measured is obtained. Measure the distance to the object to be measured. In the conventional laser distance measuring method that performs distance measurement based on the time difference between the reference light and the measurement light, the distance measurement accuracy is far from the wavelength level of the laser light, that is, the order of nm (nanometer).

  Therefore, as shown in [Patent Document 1] below, the inventor of the present application uses a plurality of laser beams having different wavelengths, and further changes the optical path difference so as to utilize the coherence characteristic of the laser beams. Inventions related to a laser distance measuring method and a laser distance measuring apparatus were made.

International Publication No. 2008/099788 Pamphlet

  According to the invention disclosed in [Patent Document 1], the distance to the object to be measured can be measured with high accuracy. However, in the invention disclosed in [Patent Document 1], light / dark data (intensity of interference light) Data) and distance measurement is performed by calculation based on the brightness data, and there is a problem that the load on the calculation unit is heavy.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a distance measuring method and a laser distance measuring apparatus capable of performing highly accurate distance measurement while suppressing a load on a calculation unit.

The present invention
(1) Two or three laser beams having different center frequencies are divided into a reference beam and a measurement beam, and all the reference beams are reflected by reflection points that can move in the direction in which the optical path length is changed and all measurements are performed. The light is reflected at the measurement point S of the object to be measured 6, and the measurement of the object to be measured 6 is performed based on the intensity data of the combined light in which each reference light reflected by the reflection point and each measurement light reflected by the measurement point S are combined. A distance measuring method for measuring the distance to point S,
An acquisition step of irradiating all laser beams while moving the position of the reflection point and acquiring intensity data of the combined light corresponding to the position of the reflection point;
A recording step for recording the position information of the reflection point that is symmetrical before and after the intensity data has an intensity peak of a predetermined value or more, and
A measurement step for calculating a distance from the reference point to the measurement point based on the position information and the position information of the reference point acquired in advance;
The above-described problem is solved by providing a distance measuring method characterized by comprising:
(2) Two to three laser beams having different center frequencies are divided into reference light and measurement light, all measurement light is further divided into first measurement light and second measurement light, and all reference light is Reflection is performed at a reflection point that can move in the direction in which the optical path length is changed, all the first measurement light is reflected at the first measurement point S1 of the measurement object 6, and all the second measurement light is further reflected. The reference light reflected at the second measurement point S2 and the first measurement light reflected at the first measurement point S1 and the second measurement light reflected at the second measurement point S2 are combined. A distance measuring method for measuring a distance L in the thickness direction between the first measurement point S1 and the second measurement point S2 of the device under test 6 based on the intensity data of the combined light,
An acquisition step of irradiating all laser beams while moving the position of the reflection point and acquiring intensity data of the combined light corresponding to the position of the reflection point;
The intensity data takes a peak of intensity greater than or equal to a predetermined value, and records the first position information of the first position O (S1) and the second position information of the second position O (S2) that are symmetrical before and after the peak. Recording steps to
A measurement step for calculating a distance L in the thickness direction between the first measurement point S1 and the second measurement point S2 based on the first position information and the second position information;
The above-described problem is solved by providing a distance measuring method characterized by comprising:
(3) An origin acquisition step of recording the position of the reflection point where the optical path length of the first measurement light and the optical path length of the second measurement light and the optical path length of the reference light are equal as the origin position information in an unmeasured object state. And
The first measurement light is reflected at the first measurement point S1 of the object to be measured 6 and the second measurement light is reflected at the second measurement point S2 located on the back surface of the first measurement point S1,
By providing the distance measuring method according to (2) above, wherein the measuring step calculates the thickness t of the object 6 based on the first position information, the second position information, and the origin position information. Solve the above problems.
(4) Two to three laser irradiation units having different center frequencies, a dividing unit 12 that divides all laser beams emitted from the laser irradiation units into reference light and measurement light, and reflects the reference light In addition, the reflection unit 14 that can move in the direction in which the optical path length of the reference light changes, the position information acquisition unit 24 that acquires the position information of the reflection point of the reflection unit 14, and all the reference lights reflected by the reflection unit 14 The light receiving unit 18 that receives all the measurement light reflected from the measurement point S of the object 6 and outputs the intensity data of the combined light, the intensity data, and the position information from the position information acquisition unit 24. And a calculation unit 20 that generates intensity data of the combined light corresponding to the position of the reflection point 14 based on the above and further performs a predetermined calculation,
Provided are laser distance measuring devices 50a and 51a that perform the acquisition step, the recording step, and the measurement step described in (1) above, and measure the distance from a preset reference point to the measurement point S. This solves the above problem.
(5) Two to three laser irradiation units having different center frequencies, a dividing unit 12 that divides all laser beams emitted from the laser irradiation units into reference light and measurement light, and reflects the reference light In addition, the reflection unit 14 that can move in the direction in which the optical path length of the reference light changes, the position information acquisition unit 24 that acquires the position information of the reflection point of the reflection unit 14, and the measurement light as the first measurement light and the second measurement light. Measurement light dividing unit 28 that divides into measurement light, first emission port 16a that emits first measurement light, second emission port 16b that emits second measurement light, and all reference light reflected by reflection unit 14 And all of the first measurement light reflected at the first measurement point S1 of the object to be measured 6 and all of the second measurement light reflected at the second measurement point S2 of the object to be measured 6 and the intensity of the combined light The light receiving unit 18 for outputting the data, the intensity data and the position information. Includes a calculation unit 20 for creating further predetermined operation of the intensity data of the combined light corresponds to the position of the reflection point based on the position information from the acquisition unit 24, a,
The laser distance measuring apparatus characterized in that the distance L in the thickness direction between the first measurement point S1 and the second measurement point S2 is measured by performing the acquisition step, the recording step, and the measurement step described in (2) above. The above problems are solved by providing 50b and 51b.
(6) Two to three laser irradiation means having different center frequencies, a dividing unit 12 that divides all laser beams emitted from the laser irradiation means into reference light and measurement light, and reflects the reference light In addition, the reflection unit 14 that can move in the direction in which the optical path length of the reference light changes, the position information acquisition unit 24 that acquires the position information of the reflection point of the reflection unit 14, and the measurement light as the first measurement light and the second measurement light. The measurement light dividing unit 28 that divides the measurement light into the measurement light, the first emission port 16a that emits the first measurement light and the second measurement light that is provided at a position facing the measurement object 6 with the arrangement position of the measurement object 6 therebetween. 2nd exit 16b, all the reference lights reflected by the reflection part 14, all the 1st measurement lights reflected in 1st measurement point S1 of to-be-measured object 6, and the 2nd measurement located in the back surface of 1st measurement point S1 All the second measurement lights reflected at the point S2 are received and combined. A light receiving unit 18 for outputting the intensity data of the light, and the intensity data of the combined light corresponding to the position of the reflection point based on the intensity data and the position information from the position information acquisition unit 24, and further performing a predetermined calculation And an arithmetic unit 20 for performing
By providing the laser distance measuring devices 50c and 51c characterized in that the origin acquisition step, the acquisition step, the recording step, and the measurement step described in (3) above are performed to measure the thickness t of the object 6 to be measured. Solve the above problems.

  According to the distance measuring method and the laser distance measuring device according to the present invention, the distance to the object to be measured or the distance in the thickness direction between two measurement points of the object to be measured is measured with high accuracy while reducing the load on the calculation unit. can do.

It is a figure which shows schematic structure of the laser ranging apparatus of the 1st form which concerns on this invention. It is a figure explaining selection of a laser irradiation means. It is a figure which shows schematic structure of the modification of the laser range finder of the 1st form which concerns on this invention. It is a figure which shows the usage example of the laser distance measuring device of the 1st form which concerns on this invention. It is a figure which shows schematic structure of the laser ranging apparatus of the 2nd form which concerns on this invention. It is a figure which shows schematic structure of the laser ranging apparatus of the 3rd form which concerns on this invention. It is a figure which shows schematic structure of the modification of the laser ranging apparatus which concerns on this invention. It is a figure which shows schematic structure of the modification of the laser ranging apparatus of the 3rd form which concerns on this invention.

  Embodiments of a distance measuring method and a laser distance measuring apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a laser range finder 50a according to a first embodiment of the present invention. In addition, the broken line in FIG. 1, FIG. 3-7 shows the optical path of a laser beam. A laser distance measuring device 50a according to the present invention shown in FIG. 1 includes a first laser irradiation means 10a and a second laser irradiation that respectively emit two laser beams (first laser beam and second laser beam) having different center frequencies. And means 10b.

  There are no particular limitations on the types of the first laser irradiation means 10a, the second laser irradiation means 10b, and the third laser irradiation means 10c described later, and a gas laser such as a helium neon laser, an argon laser, a krypton ion laser, or a helium cadmium laser, A solid laser such as a ruby laser or a YAG laser, a metal laser, a semiconductor laser, or the like can be used. Among these, it is preferable to use a laser irradiation means of multi-longitudinal mode oscillation having a relatively broad frequency distribution. The laser beam of multi-longitudinal mode oscillation means that the frequency distribution of the oscillating laser beam is broad, and this includes the one whose frequency distribution is broadened as a result of performance, stability, variation, etc. To do. Therefore, the laser distance measuring device 50a and the laser distance measuring devices 50b, 50c, 51a, 51b, 51c described later do not necessarily require expensive laser irradiation means having high frequency stability and a stable emission spectrum. An inexpensive laser irradiation means with relatively inferior emission spectrum stability can be used. Therefore, it is particularly preferable to use an inexpensive semiconductor laser as the laser irradiation means to be used. By using this semiconductor laser, it is possible to reduce the component costs of the laser distance measuring devices 50a to 51c, and to provide the laser distance measuring devices 50a to 51c at a lower cost. If at least one of the laser irradiation means to be used has an oscillation wavelength in the visible light region of 400 nm to 750 nm, the irradiation position of the laser light can be visually confirmed and workability can be improved. it can.

  The first laser light emitted from the first laser irradiation means 10a is reflected by the mirror 4a provided on the optical path of the first laser light and travels toward the dividing section 12. The second laser light emitted from the second laser irradiation means 10b is reflected by the half mirror 4b provided on the optical path of the second laser light, passes through the same optical path as the first laser light, and travels to the dividing unit 12.

  A half mirror, a beam splitter, or the like is used as the dividing unit 12, and the first laser light and the second laser light that reach the dividing unit 12 are divided into two at the dividing point of the dividing unit 12. One is directed to the reflecting portion 14 as reference light, and the other is directed to the measured object 6 side as measurement light.

  The reference light of the first laser beam and the second laser beam divided by the dividing unit 12 is reflected at the reflection point of the reflecting unit 14, passes through the dividing unit 12, and reaches the light receiving unit 18. In addition, the moving unit 22 is installed in the reflecting unit 14, and the reflecting unit 14 moves in a direction in which the distance from the reflecting point to the dividing point, that is, the optical path length of the reference light is changed by the operation of the moving unit 22.

  The position information acquisition unit 24 operates the moving unit 22 in response to a signal from a device control unit (not shown), and outputs the position information of the reflection point that changes according to the operation of the moving unit 22 to the calculation unit 20. As the moving means 22, it is preferable to use a sliding ultrasonic motor or the like that moves about 5 to 10 nm in one step. In addition, since the reflection part 14 and the reflection point are fixed, and the relative position is more important than the absolute position of the reflection point in the present application, the position information of the reflection point is indirectly substituted with the position information of the reflection part 14. Is also possible.

  The measurement light of the first laser beam and the second laser beam divided by the dividing unit 12 is emitted from the emission port 16. Then, as shown in FIG. 1B, the measurement light of the first laser light and the second laser light emitted from the emission port 16 is reflected at the measurement point S of the object 6 to be received via the dividing unit 12. Part 18 is reached.

  The light receiving unit 18 receives the measurement light of the first laser light and the second laser light reflected at the measurement point S and the reference light of the first laser light and the second laser light reflected at the reflection point, and receives these lights. The combined intensity data of the combined light is converted into an electrical signal and output to the arithmetic unit 20.

  At this time, the position information acquisition unit 24 operates the moving unit 22 to move the position of the reflection point in the direction in which the optical path length of the reference light changes. When the optical path length of the reference light changes, the optical path difference between the reference light and the measurement light changes, and accordingly, the intensity data of the synthesized light output from the light receiving unit 18 also changes.

  Based on the combined light intensity data from the light receiving unit 18 and the position information of the reflection point from the position information acquisition unit 24, the calculation unit 20 generates continuous intensity data of the combined light corresponding to the position of the reflection point. Then, based on the intensity data, the calculation described later is performed. In the following, the intensity data of the combined light output from the light receiving unit 18 is simply described as “intensity”, and the intensity data of the continuous combined light corresponding to the position of the reflection point created by the calculation unit 20 is “intensity data”. "To distinguish between the two.

  Here, when the optical path length of the reference light and the optical path length of the measuring light are equal and there is no optical path difference, the reference light and the measuring light are intensified regardless of the laser light having any oscillation wavelength. The interference light has a bright peak. In other words, even if the frequency of the laser beam emitted from the laser irradiation unit changes due to the output voltage, temperature, vibration of the laser irradiation unit itself, etc., the interference light does not exist in that there is no optical path difference between the reference beam and the measurement beam. Always keep the bright peaks. On the other hand, when there is an optical path difference between the reference light and the measurement light, there is actually no optical path difference value at which the interference light of the laser light having different oscillation wavelengths simultaneously takes a bright portion. Therefore, as shown in FIG. 2 schematically showing the relationship between the position of the reflection point and the intensity of the interference light, the interference light generated by the interference between the measurement light of the first laser light and the reference light of the first laser light. ((A) in FIG. 2) and interference light ((B) in FIG. 2) generated by interference between the measurement light of the second laser light and the reference light of the second laser light are the optical path length of the reference light. Both take a bright peak at the reflection point position O where the optical path lengths of the measurement light are equal, and the intensity of these combined lights ((C) in FIG. 2) takes the maximum peak intensity. Further, there is no point other than the position O where the peak positions of the interference light (A) by the first laser light and the interference light (B) by the second laser light completely coincide. Therefore, in these synthesized lights, there is no position having a peak intensity equal to or greater than the maximum peak intensity other than the position O.

  However, since the period of the peak of the interference light depends on the frequency of the laser light, the peak of the interference light (A) due to the first laser light and the peak of the interference light (B) due to the second laser light are close (for example, A position O ′) in FIG. 2 exists. At the position where the peak of the interference light (A) and the peak of the interference light (B) by the second laser light are close, the peak intensity of the combined light may approach the maximum peak intensity. If both are discriminated only by the peak intensity, there is a risk of erroneous recognition.

  However, the position O has a characteristic that the intensity data of the synthesized light shows symmetry before and after the position O. On the other hand, symmetry is not shown before and after other peak positions including the position O ′. Accordingly, by confirming the peak intensity of the intensity data and the symmetry before and after the position, the position O of the reflection point where the optical path length of the reference light and the optical path length of the measurement light are equal can be specified. In addition, the peak of the interference light becomes broader as it moves away from the position O, and the peak intensity decreases accordingly. Therefore, if an appropriate threshold value (determination criterion) for the peak intensity is set in consideration of these and the output fluctuations of the first laser irradiation means 10a and the second laser irradiation means 10b, it is substantially only in the vicinity of the position O. The determination of the peak intensity and the confirmation of the symmetry are performed, and it is not necessary to perform the above process on the intensity data in the entire range. In addition, when the longer coherence length of the first laser beam or the second laser beam is Lc, if the optical path difference between the measurement beam and the reference beam is greater than or equal to Lc, the two beams do not interfere with each other, so that no peak appears. .

  The laser distance measuring device according to the present invention is different from the first laser light and the second laser light as shown in the laser distance measuring device 51a in FIG. 3A and the laser distance measuring devices 51b and 51c in FIG. You may provide the 3rd laser irradiation means 10c from which a center frequency differs. By providing the third laser irradiation means 10c, interference light due to the third laser light is generated, and the interference light due to the third laser light is located at the position O similarly to the interference light due to the first laser light and the interference light due to the second laser light. Take the peak of the bright part. However, the probability that the interference light beams by the third laser light, the interference light by the first laser light, and the interference light by the second laser light are all close except at the position O is significantly lower than when two laser lights are used. . Therefore, the difference between the maximum peak intensity at position O and the peak intensity at other positions tends to open more than when two laser beams are used. Therefore, the position O can be identified more easily when three laser beams are used than when two laser beams are used.

  Next, the first distance measuring method according to the present invention will be described together with the operation of the laser distance measuring device 50a. The basic operation of the laser distance measuring device 51a having three laser irradiation means is exactly the same.

  In the first distance measuring method according to the present invention, it is necessary to obtain the position information of the reference point in advance. Therefore, here, a method of acquiring position information of the reference point using the reflection point S ′ of the shutter 5 as a reference point will be described first. The reference point position information acquisition method here is basically the same as the first distance measurement method and the operation of the laser distance measuring device 50a.

  First, as shown in FIG. 1A, the emission port 16 is closed with the shutter 5. Next, the reflection point of the reflection unit 14 is positioned at the starting position. Here, the starting point position is preferably a reflection point position equal to the distance from the dividing point to the exit port 16. Next, the first laser irradiation unit 10a and the second laser irradiation unit 10b are operated to irradiate the first laser beam and the second laser beam simultaneously. As a result, the light receiving unit 18 receives the reference light of each laser beam reflected at the reflection point and the measurement light of each laser beam reflected at the reflection point S ′ of the shutter 5, and determines the intensity of these combined lights. The result is output to the calculation unit 20. In addition, the position information acquisition unit 24 operates the moving unit 22 to move the reflection point in the direction in which the optical path length of the reference light increases together with the reflection unit 14, and the position information of the reflection point that changes according to the operation of the moving unit 22. The result is output to the calculation unit 20.

  The computing unit 20 creates intensity data of the combined light corresponding to the position of the reflection point based on the intensity of the combined light from the light receiving unit 18 and the position information of the reflection point from the position information acquisition unit 24.

  Here, when the reflection point moves and the distance Lr (s ′) reaches the position O (s ′) equal to the distance Lm (s ′), the optical path length of the measurement light 2 × Lm (s ′) and the optical path of the reference light The length 2 × Lr (s ′) is equal. Therefore, the intensity of the synthesized light takes the maximum peak intensity at this position O (s ′). The intensity data shows symmetry before and after this position O (s').

  The computing unit 20 monitors the intensity of the combined light from the light receiving unit 18 and if there is a peak with an intensity exceeding a determination criterion (for example, 90% of the maximum peak intensity), the position of the reflection point (peak position) is calculated. Get location information. Then, when the reflection point is further moved by a predetermined distance and the intensity data in a predetermined range past the peak position is acquired, the calculation unit 20 determines that the intensity data before and after the peak position is symmetrical before and after the peak position. Confirm whether to show. When the symmetry is confirmed, the position information of the reflection point is recorded as the position information of the reference point. Note that the position of this reference point corresponds to the position O (s ′) in FIG.

  Next, the distance to the measurement point S of the DUT 6 is measured. First, the measurement object 6 is installed while removing the shutter 5, and the measurement light of the first laser light and the second laser light is reflected at the measurement point S of the measurement object 6. Thereby, the light receiving unit 18 receives the reference light of each laser beam reflected at the reflection point and the measurement light of each laser beam reflected at the measurement point S of the object 6 to be measured, and the intensity of the combined light. Is output to the arithmetic unit 20. In addition, the position information acquisition unit 24 operates the moving unit 22 to further move the reflection point in the direction in which the optical path length of the reference light increases, and calculates the position information of the reflection point that is changed by the operation of the moving unit 22. Output to.

  The computing unit 20 creates intensity data of the combined light corresponding to the position of the reflection point based on the intensity of the combined light from the light receiving unit 18 and the position information of the reflection point from the position information acquisition unit 24.

  Here, when the distance from the division point to the measurement point S is the distance Lm (s) and the distance from the division point to the reflection point is the distance Lr (s), the reflection point moves and the distance Lr (s) becomes the distance. When the position O (s) equal to Lm (s) is reached, the optical path length 2 × Lm (s) of the measurement light is equal to the optical path length 2 × Lr (s) of the reference light. Therefore, the intensity of the synthesized light takes the maximum peak intensity at this position O (s). The intensity data shows symmetry before and after this position O (s).

  The calculation unit 20 monitors the intensity of the combined light from the light receiving unit 18 and acquires position information of the position of the reflection point (peak position) when there is an intensity peak exceeding the determination criterion. Then, when the reflection point is further moved by a predetermined distance and the intensity data in a predetermined range past the peak position is acquired, the calculation unit 20 determines that the intensity data before and after the peak position is symmetrical before and after the peak position. Confirm whether to show. When the symmetry is confirmed, the position information of the reflection point is recorded. The position information recorded at this time corresponds to the position information of the position O (s). The above corresponds to the acquisition step and the recording step.

Next, the calculation unit 20 uses the position information of the reference point (position information of the position O (s ′)) and the position information of the position O (s) obtained in the recording step to determine the emission port 16 that is the reference point. A distance L from the emission point (corresponding to the reflection point S ′ of the shutter 5) to the measurement point S of the DUT 6 is calculated. The calculation method of the distance L is, for example, when the position information value of the reference point is POs ′, the position information of the position O (s) is POs, and the position information value increases as the reflecting unit 14 moves away from the dividing unit 12. ,
L = Lm (s) −Lm (s ′) = Lr (s) −Lr (s ′) = POs−POs ′
It becomes. The above corresponds to the measurement step.

  Since the moving means 22 is a mechanical device such as a motor, it may be difficult to completely position the reflection point at each position, particularly at the peak position, depending on the accuracy of the moving means 22. In such a case, the intensity data of the missing position is supplemented by calculation from the obtained intensity data, and the position of the reflection point having the maximum intensity is obtained and the symmetry of the intensity data is confirmed. May be. The same applies to a second distance measuring method and a third distance measuring method described later.

  Further, as shown in FIG. 4A, the reference point is not the inner surface of the shutter 5, but is set as the first measurement point S1 of the object 6 to be measured, and after the position information of the first measurement point S1 is acquired, FIG. As shown in FIG. 4, if the laser distance measuring device 50a or the object to be measured 6 is translated to reflect the measurement light at the second measurement point S2 of the object to be measured 6, the obtained distance L is the first measurement point. This is the distance in the thickness direction between S1 and the second measurement point S2. In this case, the positional relationship between the first measurement point S1 and the second measurement point S2 is grasped in advance, and the side closer to the laser distance measuring device 50a (the first measurement point S1 in the example of FIG. 4) is used as a reference point. It is preferable that the far side (second measurement point S2 in the example of FIG. 4) be the measurement point. When the direction of movement of the moving means 22 is the direction in which the optical path length of the reference light decreases, the side far from the laser distance measuring device 50a (second measurement point S2 in the example of FIG. 4) is used as a reference point. It is preferable to use the near side (the first measurement point S1 in the example of FIG. 4) as the measurement point.

  Next, a laser range finder 50b according to a second embodiment of the present invention will be described. A laser distance measuring device 50b according to the present invention shown in FIG. 5 includes a measurement light dividing unit 28 for dividing the measurement light into a first measurement light and a second measurement light in addition to the laser distance measurement device 50a of the first embodiment. have. Then, the first measurement light of the first laser light and the second laser light divided by the measurement light dividing unit 28 is emitted from the first emission port 16a to the measured object 6 side. Further, the second measurement light of the first laser light and the second laser light divided by the measurement light dividing unit 28 is reflected by the mirror 8 and emitted from the second emission port 16b to the object to be measured 6 side. Note that the optical path difference (2 × Ld) in the apparatus between the first measurement light and the second measurement light is longer than the longer coherence length of the first laser light and the second laser light. Therefore, the distance Ld is a distance longer than ½ of the longer coherence length of the first laser beam and the second laser beam.

  Next, the second distance measuring method according to the present invention will be described together with the operation of the laser distance measuring device 50b. The basic operation of the laser distance measuring device 51b shown in FIG. 7A having three laser irradiation means is exactly the same.

  In the laser distance measuring device 50b according to the present invention, it is necessary to obtain in advance a distance Ld that is a half value of the optical path difference between the first measurement light and the second measurement light inside the device. A method for obtaining the distance Ld suitable for the laser distance measuring device 50b will be described later. The distance Ld need not be obtained every measurement, and may be recorded at the time of shipment of the laser distance measuring device 50b and recorded in a memory or the like.

  In the second distance measuring method according to the present invention, first, as shown in FIG. 5 (a), the first measuring light is measured at the first measuring point S1 of the device under test 6 and the second measured at the second measuring point S2. Install so that the measurement light is irradiated vertically. Next, the reflection point of the reflection unit 14 is positioned at the starting position. The starting position here is preferably a position of a reflection point equal to the distance from the dividing point to the first exit port 16a.

  Next, the first laser irradiation unit 10a and the second laser irradiation unit 10b are operated to irradiate the first laser beam and the second laser beam simultaneously. Thereby, the reference light of the first laser light and the second laser light is reflected at the reflection point and reaches the light receiving unit 18. Further, the first measurement light of the first laser light and the second laser light divided by the measurement light dividing unit 28 is emitted from the first emission port 16a, and then reflected by the first measurement point S1 of the object 6 to be measured. The light reaches the light receiving unit 18 via the measurement light dividing unit 28 and the dividing point. Further, the second measurement light of the first laser light and the second laser light is emitted from the second emission port 16b and then reflected by the second measurement point S2 of the object 6 to be measured, and the mirror 8, the measurement light dividing unit 28, It reaches the light receiving unit 18 via the dividing point. The light-receiving unit 18 includes a reference beam for the first laser beam and the second laser beam, a first measurement beam for the first laser beam and the second laser beam, and a second measurement beam for the first laser beam and the second laser beam. And outputs the intensity of the combined light, which is a combination of all the lights, to the arithmetic unit 20. Then, while maintaining this state, the position information acquisition unit 24 operates the moving unit 22 to move the reflection point in the direction in which the optical path length of the reference light increases together with the reflection unit 14. Further, the position information acquisition unit 24 outputs the position information of the reflection point to the calculation unit 20.

  The computing unit 20 creates intensity data of the combined light corresponding to the position of the reflection point based on the intensity of the combined light from the light receiving unit 18 and the position information of the reflection point from the position information acquisition unit 24.

  When the reflection point moves and the distance from the division point to the reflection point reaches a position O (s1) equal to the distance from the division point to the first measurement point S1, the optical path length of the first measurement light and the optical path length of the reference light And become equal. At this position O (s1), the intensity of the synthesized light is substantially equal to the maximum peak intensity. The intensity data shows symmetry before and after this position O (s1). It should be noted that the maximum peak intensity in the second distance measuring method and the third distance measuring method, which will be described later, is in a state where one measurement light does not interfere. That is, the maximum peak intensity in the second distance measurement method and the third distance measurement method is the interference light (at the position O in FIG. 2) of the first laser beam by the first measurement light (second measurement light). The intensity peak, the intensity peak of interference light (at position O in FIG. 2) due to the first measurement light (second measurement light) of the second laser light, and the optical path difference exceeds the coherence length and is constant intensity as will be described later. And the intensity of the second measurement light (first measurement light) of the first laser light and the second laser light. Then, a criterion value is set according to the maximum peak intensity, the output fluctuation range of the laser irradiation means, and the like.

  The calculation unit 20 monitors the intensity of the combined light from the light receiving unit 18 and acquires position information of the position of the reflection point (peak position) when there is an intensity peak exceeding the determination criterion. Then, when the reflection point is further moved by a predetermined distance and the intensity data in a predetermined range past the peak position is acquired, the calculation unit 20 determines that the intensity data before and after the peak position is symmetrical before and after the peak position. Confirm whether to show. When the symmetry is confirmed, the position of the reflection point is recorded as the first position information of the first position (= position O (s1)).

  Note that laser light whose optical path difference between the reference light and the measurement light exceeds the coherence length does not interfere. Here, since the distance Ld is longer than the coherence length of the first laser light and the second laser light, the first measurement light and the reference light interfere near the position O (s1), but the optical path difference exceeds the coherence length. The second measurement light and the reference light, and the second measurement light and the first measurement light do not interfere with each other. Therefore, the second measurement light is received by the light receiving unit 18 as light having a constant intensity, and the second measurement light does not adversely affect the acquisition of the first position information.

  Next, when the reflection point further moves and the distance from the division point to the reflection point reaches a position O (s2) equal to the distance from the division point → the measurement light dividing unit 28 → the mirror 8 → the second measurement point S2, This time, the optical path length of the second measurement light becomes equal to the optical path length of the reference light. At this position O (s2), the intensity of the synthesized light is substantially equal to the maximum peak intensity. The intensity data shows symmetry before and after this position O (s2).

  The computing unit 20 monitors the intensity of the combined light from the light receiving unit 18 and acquires position information of the position of the reflection point (peak position) if there is an intensity peak exceeding the determination criterion. Then, when the reflection point moves further by a predetermined distance and the intensity data in a predetermined range past the peak position is acquired, the calculation unit 20 determines that the intensity data before and after the peak position is symmetrical before and after the peak position. Confirm whether to show. When the symmetry is confirmed, the position of the reflection point is recorded as the second position information of the second position (= position O (s2)). The above corresponds to the acquisition step and the recording step of the second distance measuring method. Since the distance Ld is longer than the coherence length of the first laser beam and the second laser beam as described above, the optical path difference between the first measurement beam and the reference beam exceeds the coherence length in the vicinity of the position O (s2). The first measurement light does not interfere with the reference light and the second measurement light. Therefore, the first measurement light does not adversely affect the acquisition of the second position information.

Next, the calculation unit 20 determines between the first measurement point S1 and the second measurement point S2 of the DUT 6 from the first position information, the second position information, and the value of the distance Ld acquired in advance. A distance L in the thickness direction is calculated. The calculation method of the distance L is, for example, when the value of the first position information is Ps1, the second position information is Ps2, and the value of the position information increases as the reflecting unit 14 moves away from the dividing unit 12.
L = Ps2-Ps1-Ld
It becomes. The above corresponds to the measurement step of the second distance measuring method.

  Next, a method for obtaining the distance Ld inside the apparatus between the first measurement light and the second measurement light will be described. The distance Ld acquisition method described below is basically the same as the operation of the second distance measuring method and the laser distance measuring device 50b according to the present invention. Further, the method for obtaining the distance Ld shown below is suitable for the laser distance measuring device 50b according to the present invention, but this method is not necessarily used.

  First, as shown in FIG. 5B, the flat plate 5 having a smooth surface is irradiated with the first measurement light perpendicularly to the first measurement point S1 ′ and the second measurement light perpendicularly to the second measurement point S2 ′. Install as follows. At this time, the distance from the first exit 16a to the first measurement point S1 'is made equal to the distance from the second exit 16b to the second measurement point S2'. Next, the reflection point of the reflection unit 14 is positioned at a position where the optical path length of the reference light is slightly shorter than the starting position.

  Then, the acquisition step and the recording step are performed, and the first position O (s1 ′) of the reflection point where the distance from the division point to the first measurement point S1 ′ of the flat plate 5 is equal to the distance from the division point to the reflection point. ) And the second position O () of the reflection point where the distance from the dividing point → the measuring light dividing unit 28 → the mirror 8 → the second measuring point S2 ′ is equal to the distance from the dividing point to the reflecting point. s2 ′) second position information is recorded.

Next, the computing unit 20 calculates the distance Ld from the obtained first position information and second position information. The calculation method of the distance Ld is, for example, when the value of the first position information is Ps1 ′, the second position information is Ps2 ′, and the value of the position information increases as the reflecting unit 14 moves away from the dividing unit 12.
Ld = Ps2′−Ps1 ′
It becomes.

  Next, FIG. 6 shows a laser range finder 50c according to a third embodiment of the present invention. The laser range finder 50c according to the third embodiment has a thickness direction between a first measurement point S1 located on one surface side of the object 6 to be measured and a second measurement point S2 located on the back surface of the first measurement point S1. By measuring the distance, the thickness t of the DUT 6 is measured. Therefore, the configuration is basically the same as that of the laser distance measuring device 50b of the second embodiment except that the optical paths of the first measurement light and the second measurement light are different.

  In the laser distance measuring device 50c, the first measurement light divided by the measurement light dividing unit 28 is reflected by the mirror 8a, the mirror 8b, and the mirror 8c and is directed from the first emission port 16a to the second emission port 16b. And exit. The second measurement light split by the measurement light splitting unit 28 is reflected by the mirror 8d and the mirror 8e, and exits from the second exit 16b toward the first exit 16a. In addition, the 1st output port 16a and the 2nd output port 16b are provided in the position which opposes, and the to-be-measured object 6 is arrange | positioned between this 1st output port 16a and the 2nd output port 16b. Then, as shown in FIG. 6A, in the case of an unmeasured object state in which nothing exists between the first emission port 16a and the second emission port 16b, the first emitted from the first emission port 16a. The measurement light again enters the laser distance measuring device 50c from the second exit 16b, is reflected by the mirror 8e and the mirror 8d, and returns to the measurement light splitting unit 28. The second measurement light emitted from the second emission port 16b is incident on the laser distance measuring device 50c again from the first emission port 16a, reflected by the mirror 8c, the mirror 8b, and the mirror 8a, and returned to the measurement light dividing unit 28. To do. Therefore, in the non-measurement state, the first measurement light and the second measurement light travel on the same optical path in opposite directions and return to the measurement light splitting unit 28. Accordingly, the optical path lengths of the first measurement light and the second measurement light at this time are equal. It should be noted that the optical path length of the first measurement light from the measurement light dividing unit 28 to the first emission port 16a and the optical path length of the second measurement light from the measurement light division unit 28 to the second emission port 16b need to be completely equal. Although there is no equivalent, the optical path of the first measurement light and the second measurement light in the unmeasured object state from the measurement light splitting unit 28 to the measurement light splitting unit 28 (ie, the measurement light splitting in the first measurement light) The intermediate point P0 between the first exit port 16a and the second exit port 16b is an intermediate point P0 of the section 28 → mirror 8a → mirror 8b → mirror 8c → mirror 8e → mirror 8d → light path to the measurement light splitting section 28) It is preferable to be in the vicinity.

  Next, a third distance measuring method according to the present invention will be described together with the operation of the laser distance measuring device 50c. The basic operation of the laser distance measuring device 51c shown in FIG. 7B having three laser irradiation means is exactly the same.

  In the third distance measuring method according to the present invention, first, the position of the reflection point (origin position O) where the optical path lengths of the first measurement light and the second measurement light are equal to the optical path length of the reference light is obtained to obtain the origin. An origin acquisition step of recording as position information is performed. The origin position information is preferably acquired as follows.

  First, the reflection point of the reflection unit 14 is positioned at the starting position in the state of no measurement object. The starting position here is preferably a position of a reflection point that is slightly longer than the optical path of the measuring light from the dividing point to the intermediate point P0.

  Next, in this state, the first laser irradiation unit 10a and the second laser irradiation unit 10b are operated to simultaneously irradiate the first laser beam and the second laser beam. As a result, the reference light reaches the light receiving unit 18 along the optical path of the dividing point → the reflection point → the dividing point → the light receiving unit 18. Further, the first measurement light is divided at the division point → measurement light division unit 28 → mirror 8a → mirror 8b → mirror 8c → first emission port 16a → second emission port 16b → mirror 8e → mirror 8d → measurement beam division unit 28 → division. The light path from the point to the light receiving unit 18 is reached and reaches the light receiving unit 18. Further, the second measurement light is divided at the division point → measurement light division unit 28 → mirror 8d → mirror 8e → second emission port 16b → first emission port 16a → mirror 8c → mirror 8b → mirror 8a → measurement light division unit 28 → division. The light path from the point to the light receiving unit 18 is reached and reaches the light receiving unit 18.

  Then, while maintaining this state, the position information acquisition unit 24 operates the moving unit 22 to move the reflection point in the direction in which the optical path length of the reference light decreases together with the reflection unit 14. Further, the position information acquisition unit 24 outputs the position information of the reflection point to the calculation unit 20.

  When the reflection point moves and reaches the origin position O where the optical path length of the reference light and the optical path lengths of the first measurement light and the second measurement light become equal, the reference light of the first laser light and the first light are transmitted at the origin position O. The interference light caused by the first measurement light and the second measurement light of the laser light and the interference light caused by the reference light of the second laser light and the first measurement light and the second measurement light of the second laser light are all in the bright part. Take a peak. Here, since the maximum peak intensity in the third distance measuring method is that in which one of the measurement lights does not interfere, the intensity of the combined light at the origin position O is about twice the maximum peak intensity. Take. Therefore, the criterion for obtaining the origin position information is increased accordingly. Further, the intensity data shows symmetry before and after the origin position O.

  The calculation unit 20 monitors the intensity of the combined light from the light receiving unit 18 and, when there is a peak of intensity exceeding the determination criterion at the time of acquisition of the origin position information, the position information of the position of the reflection point (peak position) is obtained. get. Then, when the reflection point is further moved by a predetermined distance and the intensity data in a predetermined range past the peak position is acquired, the calculation unit 20 determines that the intensity data before and after the peak position is symmetrical before and after the peak position. Confirm whether to show. When the symmetry is confirmed, the position of the reflection point is recorded as the origin position information of the origin position O. The above corresponds to the origin acquisition step. The origin position O on the optical path of the reference light corresponds to the intermediate point P0 on the optical path of the measurement light in FIG.

  The method for acquiring the origin position information has the highest accuracy and is suitable for the laser distance measuring device 50c according to the present invention, but this method is not necessarily used. The acquisition of the origin position information is preferably performed for each measurement. However, this is not the case when a highly accurate measurement value is not required.

  Next, as shown in FIG. 6B, the DUT 6 is disposed between the first exit port 16a and the second exit port 16b. At this time, the measured object 6 overlaps the intermediate point P0, and the difference between the distance L1 from the intermediate point P0 to the first measurement point S1 and the distance L2 from the intermediate point P0 to the second measurement point S2 is the first laser beam. It is preferable that the distance is longer than the half of the longer coherence length of the second laser beam.

  Here, if the DUT 6 is arranged so as not to overlap the intermediate point P0, either the optical path length of the first measurement light or the optical path length of the second measurement light at the time of measurement is the optical path length of the reference light at the origin position. Longer and the other shorter. In this case, in the distance measuring method of the present application, it is necessary to move the moving means 22 in the reverse direction during the measurement to move it in the direction of increasing or decreasing the optical path length of the reference light. When the machine such as a motor that is the moving means 22 is operated in a certain direction, there is no great difference between the position information and the actual position. An error occurs. If the DUT 6 is arranged so as to overlap the intermediate point P0, the optical path length of the first measurement light and the optical path length of the second measurement light at the time of measurement are both shorter than the optical path length of the reference light at the origin position, The reflection unit 14 only needs to move from the origin position in the direction of decreasing the optical path length of the reference light, and the moving unit 22 does not need to operate in reverse. Therefore, highly accurate thickness measurement can be performed.

  Further, if the difference between the distance L1 and the distance L2 is set to be a distance longer than ½ of the coherence length, the second measurement light interferes when measuring the first measurement point S1 by the first measurement light described later. In addition, the first measurement light does not interfere when measuring the second measurement point S2 by the second measurement light. Accordingly, the distance measurement of the thickness t of the DUT 6 by the laser distance measuring device 50c can be efficiently performed. If the thickness t of the device under test 6 is smaller than ½ of the coherence length and the above condition cannot be satisfied, the device under test 6 is shifted from the intermediate point P0, and the first measurement light and the second measurement light Is equal to or greater than the coherence length. In this case, the moving means 22 requires reverse operation and an error due to backlash occurs. However, if a highly accurate actuator is used for the moving means 22, the repeat position accuracy including backlash is about 20 nm, and the required measurement is performed. Depending on the accuracy, it can be used sufficiently.

  The laser distance measuring device 50c sets the optical path of the measurement light as shown in FIG. 8, and the optical path difference between the first measurement light and the second measurement light inside the device is either the first laser light or the second laser light. The distance may be longer than the longer coherence length. According to this configuration, since the optical path difference between the first measurement light and the second measurement light inside the apparatus is already set longer than the coherence length, the measurement object 6 can be measured regardless of the installation position of the measurement object 6. Distance measurement of the thickness t can be performed. However, in this case, the reverse operation of the moving means 22 is required.

  Next, the first laser irradiation unit 10a and the second laser irradiation unit 10b are operated to irradiate the first laser beam and the second laser beam simultaneously. Thereby, the reference light of the first laser light and the second laser light is reflected at the reflection point and reaches the light receiving unit 18. Further, the first measurement light of the first laser light and the second laser light divided by the measurement light dividing unit 28 is emitted from the first emission port 16a, and then reflected by the first measurement point S1 of the object 6 to be measured. The light reaches the light receiving unit 18 via the mirror 8c, the mirror 8b, the mirror 8a, the measuring light dividing unit 28, and the dividing point. Further, the second measurement light of the first laser light and the second laser light is emitted from the second emission port 16b and then reflected at the second measurement point S2 of the object 6 to be measured, and the mirror 8e, the mirror 8d, and the measurement light division. The light reaches the light receiving part 18 via the part 28 and the dividing point. The light-receiving unit 18 includes a reference beam for the first laser beam and the second laser beam, a first measurement beam for the first laser beam and the second laser beam, and a second measurement beam for the first laser beam and the second laser beam. And outputs the intensity of the combined light, which is a combination of all the lights, to the arithmetic unit 20.

  Then, while maintaining this state, the position information acquisition unit 24 operates the moving unit 22 to move the reflection point in the direction in which the optical path length of the reference light decreases together with the reflection unit 14.

  When the reflection point moves and reaches the position O (s1) where the distance from the division point to the reflection point is equal to the optical path length of one way of the first measurement light from the division point to the first measurement point S1, the first measurement light is reached. Is equal to the optical path length of the reference light. At this position O (s1), the interference light from the first laser light of the first measurement light and the interference light from the second laser light of the first measurement light have a bright peak, and at this position O (s1). The intensity of the synthesized light is substantially equal to the maximum peak intensity. The intensity data shows symmetry before and after this position O (s1).

  The calculation unit 20 monitors the intensity of the combined light from the light receiving unit 18 and acquires position information of the position of the reflection point (peak position) when there is an intensity peak exceeding the determination criterion. Then, when the reflection point is further moved by a predetermined distance and the intensity data in a predetermined range past the peak position is acquired, the calculation unit 20 determines that the intensity data before and after the peak position is symmetrical before and after the peak position. Confirm whether to show. When the symmetry is confirmed, the position of the reflection point is recorded as the first position information of the first position (= position O (s1)). The distance from the origin position O to the position O (s1) corresponds to the distance L1. At this time, by arranging the DUT 6 to be shifted from the intermediate point P0 by a predetermined amount, the optical path difference between the first measurement light and the second measurement light is longer than the coherence length of the first laser light and the second laser light. Therefore, the second measurement light does not interfere in the vicinity of the position O (s1), and the second measurement light does not adversely affect the acquisition of the first position information.

  Next, when the reflection point further moves and reaches a position O (s2) where the distance from the division point to the reflection point is equal to the optical path length of one way of the second measurement light from the division point to the second measurement point S2, This time, the optical path length of the second measurement light becomes equal to the optical path length of the reference light. At this position O (s2), the interference light by the first laser light of the second measurement light and the interference light by the second laser light of the second measurement light have a bright peak, and the combined light at this position O (s2). The intensity of is substantially equal to the maximum peak intensity. The intensity data shows symmetry before and after this position O (s2).

  The calculation unit 20 monitors the intensity of the combined light from the light receiving unit 18 and acquires position information of the position of the reflection point (peak position) when there is an intensity peak exceeding the determination criterion. Then, when the reflection point is further moved by a predetermined distance and the intensity data in a predetermined range past the peak position is acquired, the calculation unit 20 determines that the intensity data before and after the peak position is symmetrical before and after the peak position. Confirm whether to show. When the symmetry is confirmed, the position of the reflection point is recorded as the second position information of the second position (= position O (s2)). Note that the distance from the origin position O to the position O (s2) corresponds to the distance L2. At this time, by arranging the DUT 6 to be shifted from the intermediate point P0 by a predetermined amount, the optical path difference between the first measurement light and the second measurement light is longer than the coherence length of the first laser light and the second laser light. Therefore, in the vicinity of the position O (s2), the first measurement light does not interfere and the first measurement light does not adversely affect the acquisition of the second position information. The above corresponds to the acquisition step and the recording step of the third distance measuring method.

Next, the calculation unit 20 calculates the distance in the thickness direction between the first measurement point S1 and the second measurement point S2 of the object 6 to be measured, based on the first position information, the second position information, and the origin position information. The thickness t of the DUT 6 is calculated. The calculation method of the thickness t is, for example, when the origin position information is Po, the first position information value is Ps1, and the second position information is Ps2, and the position information value increases as the reflecting portion 14 moves away from the dividing portion 12. ,
t = (Po−Ps1) + (Po−Ps2) = 2Po−Ps1−Ps2
It becomes. The above corresponds to the measurement step of the third distance measuring method.

  As described above, the distance measuring method and the laser distance measuring device according to the present invention monitor the intensity of the synthesized light and confirm the symmetry of the intensity data before and after the peak position above the predetermined intensity. The position information of the reflection point corresponding to the measurement point of the measurement object is acquired. Based on the position information, the distance to the object to be measured or the distance in the thickness direction between two measurement points of the object to be measured is measured. Accordingly, it is possible to reduce the calculation amount based on the intensity data, and it is possible to perform highly accurate distance measurement using the coherence of the laser light while suppressing the load on the calculation unit.

  Since the laser distance measuring devices 50a to 50c and 51a to 51c described above are examples suitable for the present invention, the optical paths of the reference light, measurement light, first measurement light, and second measurement light are partially light. In addition to replacement with a fiber, the configuration of each part, each optical path, and the like can be changed and implemented without departing from the scope of the present invention.

6 DUT
12 divisions
14 Reflector
16a 1st exit port
16b 2nd exit port
18 Light receiver
20 Calculation unit
24 Location information acquisition unit
28 Measurement beam splitter
50a-50c, 51a-51c Laser ranging device
S measuring point
S1 First measurement point
S2 Second measurement point
L distance
t (Thickness of measured object)

Claims (6)

Splitting two to three laser beams having different center frequencies into a reference beam and a measuring beam,
Reflect all the reference light at the reflection point that can move in the direction of changing the optical path length and reflect all the measurement light at the measurement point of the object to be measured.
A distance measurement method for measuring a distance to a measurement point of an object to be measured based on intensity data of a combined light in which each reference light reflected at a reflection point and each measurement light reflected at a measurement point are combined.
An acquisition step of irradiating all laser beams while moving the position of the reflection point and acquiring intensity data of the combined light corresponding to the position of the reflection point;
A recording step for recording the position information of the reflection point that is symmetrical before and after the intensity data has an intensity peak of a predetermined value or more, and
A measurement step for calculating a distance from the reference point to the measurement point based on the position information and the position information of the reference point acquired in advance;
A ranging method characterized by comprising: Splitting two to three laser beams having different center frequencies into a reference beam and a measuring beam,
All measurement light is further divided into first measurement light and second measurement light,
All the reference light is reflected by a reflection point that can move in the direction of changing the optical path length, all the first measurement light is reflected by the first measurement point of the object to be measured, and all the second measurement light is received. Reflected at the second measurement point of the object to be measured,
Based on the intensity data of the combined light in which each reference light reflected by the reflection point, each first measurement light reflected by the first measurement point, and each second measurement light reflected by the second measurement point are combined, A distance measuring method for measuring a distance in a thickness direction between a first measurement point and a second measurement point,
An acquisition step of irradiating all laser beams while moving the position of the reflection point and acquiring intensity data of the combined light corresponding to the position of the reflection point;
A recording step of recording the first position information of the first position and the second position information of the second position that are symmetrical before and after the intensity data has an intensity peak greater than or equal to a predetermined value;
A measurement step for calculating a distance in the thickness direction between the first measurement point and the second measurement point based on the first position information and the second position information;
A ranging method characterized by comprising: An origin acquisition step of recording, as origin position information, the position of the reflection point at which the optical path length of the first measurement light and the optical path length of the second measurement light and the optical path length of the reference light are equal in an unmeasured object state;
Reflecting the first measurement light at the first measurement point of the object to be measured and reflecting the second measurement light at the second measurement point located on the back surface of the first measurement point;
3. The distance measuring method according to claim 2, wherein the measuring step calculates the thickness of the object to be measured based on the first position information, the second position information, and the origin position information. Two to three laser irradiation means having different center frequencies;
A dividing unit that divides all laser light emitted from the laser irradiation unit into reference light and measurement light;
A reflecting portion that reflects the reference light and is movable in a direction in which the optical path length of the reference light changes;
A position information acquisition unit that acquires position information of a reflection point of the reflection unit;
A light receiving unit that receives all the reference light reflected by the reflection unit and all the measurement light reflected by the measurement point of the object to be measured and outputs data of the intensity of the combined light;
A calculation unit that generates intensity data of the combined light corresponding to the position of the reflection point based on the intensity data and the position information from the position information acquisition unit, and further performs a predetermined calculation;
2. A laser distance measuring apparatus comprising: performing an acquisition step, a recording step, and a measurement step according to claim 1, and measuring a distance from a preset reference point to the measurement point. Two to three laser irradiation means having different center frequencies;
A dividing unit that divides all laser light emitted from the laser irradiation unit into reference light and measurement light;
A reflecting portion that reflects the reference light and is movable in a direction in which the optical path length of the reference light changes;
A position information acquisition unit that acquires position information of a reflection point of the reflection unit;
A measurement light splitting unit that splits the measurement light into a first measurement light and a second measurement light;
A first emission port for emitting the first measurement light and a second emission port for emitting the second measurement light;
Receiving all the reference light reflected by the reflector, all the first measurement light reflected by the first measurement point of the object to be measured, and all the second measurement light reflected by the second measurement point of the object to be measured; A light receiving unit for outputting the intensity data of the combined light;
A calculation unit that generates intensity data of the combined light corresponding to the position of the reflection point based on the intensity data and the position information from the position information acquisition unit, and further performs a predetermined calculation;
3. A laser distance measuring apparatus, comprising performing an acquisition step, a recording step, and a measurement step according to claim 2, and measuring a distance in a thickness direction between the first measurement point and the second measurement point. Two to three laser irradiation means having different center frequencies;
A dividing unit that divides all laser light emitted from the laser irradiation unit into reference light and measurement light;
A reflecting portion that reflects the reference light and is movable in a direction in which the optical path length of the reference light changes;
A position information acquisition unit that acquires position information of a reflection point of the reflection unit;
A measurement light splitting unit that splits the measurement light into a first measurement light and a second measurement light;
A first emission port that emits first measurement light and a second emission port that emits second measurement light, which are provided at positions facing each other with the arrangement position of the object to be measured;
All of the reference light reflected by the reflection unit, all of the first measurement light reflected by the first measurement point of the object to be measured, and all of the second measurement light reflected by the second measurement point located on the back surface of the first measurement point And a light receiving unit that outputs data of the intensity of the combined light,
A calculation unit that generates intensity data of the combined light corresponding to the position of the reflection point based on the intensity data and the position information from the position information acquisition unit, and further performs a predetermined calculation;
4. A laser distance measuring apparatus comprising: measuring the thickness of an object to be measured by performing an origin acquisition step, an acquisition step, a recording step, and a measurement step according to claim 3.

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