JP7271066B2 - Optical measuring device - Google Patents

Description

The present invention relates to an optical measuring apparatus that irradiates a measurement area in which an object to be measured is arranged with a light beam, scans the light beam in the scanning direction, and measures the dimensions of the object to be measured in the scanning direction.

A polygon mirror with multiple reflecting surfaces, a light emitting device that irradiates the polygon mirror with a light beam, an irradiation optical system that guides the light beam reflected by the polygon mirror to a measurement area, and a light beam that has been irradiated onto the measurement area. A first light receiving section that receives light and outputs a first light receiving signal, a second light receiving section that receives a light beam irradiated to a region different from the measurement region and outputs a second light receiving signal, and a first light receiving signal. a counting circuit that counts clock pulses between the rising or falling timing and the rising or falling timing of the second light reception signal and outputs an edge count value; An optical measuring device is known that includes an arithmetic processing unit that outputs dimension data indicating dimensions (Patent Document 1).

For example, when measuring the outer diameter of an object to be measured by such an optical measuring device, the object to be measured is placed in the measurement area, the polygon mirror is irradiated with a light beam, and the polygon mirror is rotated to scan the light beam. do. When the light beam reaches the object to be measured, the light beam is blocked by the object to be measured, and the light beam is no longer received by the first light receiving section. Along with this, the first light receiving signal falls, and counting of clock pulses corresponding to the first edge count value is started. Further, when the light beam passes through the object to be measured, the light beam passes through the measurement area and is received by the first light receiving section. Along with this, the first light receiving signal rises, and counting of clock pulses corresponding to the second edge count value is started. Further, when the light beam reaches the second light receiving section, the second light receiving signal rises, and the first and second edge count values are acquired. For example, the difference between the first and second edge count values is multiplied by the distance scanned by the light beam per clock, and the result is output as dimension data indicating the dimension of the object to be measured.

In such an optical measuring apparatus, an error may occur in the edge count value due to manufacturing errors, spherical aberration of the lens, and the like. Therefore, in a conventional optical measuring apparatus, the edge count value is corrected using a correction table, and dimension data is calculated based on the corrected edge count value (Patent Document 2).

JP-A-9-138115 JP 2015-190869 A

In such an optical measuring apparatus, when the polygon mirror is rotated and the light beam is sequentially scanned by a plurality of reflecting surfaces, the waveform of the first received light signal changes each time scanning is performed, and the edge count value and the dimension data are changed. There were times when it was scattered. As a result of diligent studies by the inventors, it was found that such variations in edge count values are caused by assembly errors, manufacturing errors, etc. of the polygon mirror, and that the edge count values periodically fluctuate according to the rotation of the polygon mirror. I found that there is a case.

Such variations in edge count values can be suppressed by, for example, rotating the polygon mirror once, obtaining edge count values or dimension data corresponding to all reflecting surfaces, and calculating the average value of these values. can be done. However, such an optical measuring apparatus may require high-speed and high-precision measurement, and it is desirable to obtain an accurate edge count value without rotating the polygon mirror once.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical measuring apparatus capable of high-speed and high-precision measurement.

In order to solve this problem, an optical measuring apparatus according to one embodiment of the present invention includes a rotatable polygon mirror having m (m is an integer equal to or greater than 3) reflecting surfaces, and a light beam directed to the polygon mirror. a light emitting device for irradiation, an irradiation optical system for guiding the light beam reflected by the polygon mirror to a measurement area, a first light receiving section for receiving the light beam irradiated on the measurement area and outputting a first light reception signal, a measurement A second light-receiving unit that receives a light beam irradiated to a region different from the region and outputs a second light-receiving signal, a rising or falling timing of the first light-receiving signal, and a rising or falling of the second light-receiving signal A counting circuit that counts clock pulses between the timing of and and outputs an edge count value, an arithmetic processing unit that outputs dimension data indicating the dimension of the object to be measured based on the edge count value, and a correction of the dimension data and a storage device that stores correction parameters that are referred to when performing the correction. Further, when obtaining the dimension data, the arithmetic processing unit sequentially obtains m kinds of correction parameters from the storage device while the polygon mirror rotates once.

Here, m kinds of edge count values output during one rotation of a polygon mirror having m reflecting surfaces contain the influence of the above-mentioned periodic variation in m kinds of manners. . Such variations in edge count value can be suitably suppressed by using m different correction parameters corresponding to m reflecting surfaces. Therefore, in one embodiment of the present invention, when acquiring dimension data, m different correction parameters are sequentially acquired during one rotation of the polygon mirror. This makes it possible to cancel out the effects of the periodic fluctuations contained in each of the m edge count values. As a result, an accurate edge count value can be obtained without rotating the polygon mirror once. Therefore, it is possible to provide an optical measuring device capable of high-speed and high-precision measurement.

For example, when acquiring the dimension data, the arithmetic processing unit may generate m×n values that periodically change in accordance with the rotation of the polygon mirror while the polygon mirror rotates n times (n is an integer equal to or greater than 2). By obtaining the edge count value, it is possible to obtain m kinds of correction parameters n times from the storage device.

The arithmetic processing unit performs, for example, a correction process for canceling out the effects of periodic fluctuations from m×n edge count values based on m correction parameters, and m×n values corrected by the correction process. m×n dimension data can be output based on the edge count value of .

When obtaining the correction parameters, the arithmetic processing unit obtains m×n edge count values while the polygon mirror rotates n times (where n is an integer equal to or greater than 2), and corresponds to each of the m reflecting surfaces. The average value of the n edge count values is obtained as the m first average value, the average value of the m×n edge count values is obtained as the second average value, and the m different first average values are obtained. The value and information indicative of the second average value can be entered in the storage device as a correction parameter.

An optical measuring device according to an embodiment of the present invention comprises m (m is an integer of 3 or more) reflecting surfaces, a rotatable polygon mirror, a light emitting device for irradiating a light beam on the polygon mirror, an irradiation optical system that guides the light beam reflected by the polygon mirror to the measurement area; Between the second light receiving section that receives the irradiated light beam and outputs the second light receiving signal, the rising or falling timing of the first light receiving signal, and the rising or falling timing of the second light receiving signal a counting circuit that counts clock pulses and outputs an edge count value; and an arithmetic processing unit that outputs dimension data indicating the dimension of the object to be measured based on the edge count value. Further, when obtaining the dimension data, the arithmetic processing unit calculates m×n edges that periodically change in accordance with the rotation of the polygon mirror while the polygon mirror rotates n times (n is an integer equal to or greater than 2). A count value is obtained, the influence of periodic fluctuations in the edge count value is canceled, and m×n dimension data are output.

According to the present invention, it is possible to provide an optical measuring device capable of high-speed and highly accurate measurement.

1 is a perspective view showing the configuration of an optical measuring device according to a first embodiment of the present invention; FIG. It is a typical block diagram which shows the structure of the same optical measuring device. Schematic showing the state of the received light signal S1, the edge signal S2, the reset signal RST, and the edge count value ECV (E1 to E4) acquired when the outer diameter D1 of the measurement object W is measured by the optical measuring device graph. 5 is a schematic graph showing how an edge signal S2, a reset signal RST, and an edge count value ECV (E1 to E4) obtained when the polygon mirror is rotated multiple times; 5 is a schematic graph showing an edge count value ECV that periodically varies according to rotation of the polygon mirror; FIG. 4 is a schematic diagram for explaining assembly errors, manufacturing errors, etc. of a polygon mirror; 5 is a schematic flow chart illustrating a method of acquiring correction parameters; 5 is a schematic graph illustrating a method of acquiring correction parameters; FIG. 4 is a schematic diagram illustrating a correction table; FIG. 4 is a schematic graph illustrating a method of correcting an edge count value ECV; 4 is a schematic graph illustrating a method of correcting an edge count value ECV;

[First embodiment]
An optical measuring device according to a first embodiment of the present invention will be described below with reference to the drawings.

[Outline configuration]
As shown in FIG. 1 , the optical measuring device according to this embodiment includes a measuring section 100 and a control section 200 that controls the measuring section 100 . The measurement unit 100 includes a measurement area 101 in which the measurement object W is arranged, and a light beam scanning that irradiates the measurement area 101 with a light beam (laser light L) and scans the light beam in the scanning direction (−Z direction). a light receiving unit 120 that receives the light beam that has passed through the measurement area 101; and a connecting unit that connects the light beam scanning unit 110 and the light receiving unit 120.

In the example of FIG. 1, the light beam scanning section 110 and the light receiving section 120 are spaced apart in the X direction, and the space between the light beam scanning section 110 and the light receiving section 120 is the measurement area 101 . A cylindrical measurement object W extending in the Y direction is arranged in the measurement area 101 . Further, the light beam scanning unit 110 emits a laser beam L traveling in the -X direction through a window 110b provided in a housing 110a of the light beam scanning unit 110, and scans in the -Z direction.

FIG. 2 illustrates configurations of the light beam scanning unit 110 and the light receiving unit 120 of the measurement unit 100 and the control unit 200 .

The light beam scanning unit 110 includes a laser light source 111 that emits a laser beam L, a mirror 112 that reflects the emitted laser beam L, a polygon mirror 113 that further reflects the laser beam L reflected by the mirror 112, a polygon An fθ lens 114 (irradiation optical system) that guides the laser light L reflected by the mirror 113 to the measurement area 101, and a light receiving element such as a photodiode that outputs a reset signal RST (second light receiving signal) when scanning of the laser light L is completed. 115; The light beam scanning unit 110 also includes a motor 116 that rotates the polygon mirror 113, a motor drive circuit 117 that drives the motor 116, and a motor synchronization circuit 118 that inputs a synchronization signal to the motor drive circuit 117 according to the clock signal CLK. And prepare.

The light receiving unit 120 includes a condenser lens 121 that collects the laser light L that has passed through the measurement region 101, a light receiving element 122 that receives the collected laser light L, such as a photodiode, and an output signal from the light receiving element 122. and an amplifier 123 that amplifies and outputs a received light signal S1 (first received light signal).

The control unit 200 includes an edge detection circuit 201 that binarizes the received light signal S1 and outputs an edge signal S2, a segment selection circuit 202 that raises an edge selection signal S3 in accordance with the rise and fall of the edge signal S2, and an edge detection circuit 202. A gate circuit 203 that outputs an AND signal of a selection signal S3 and a clock signal CLK as one or more gate signals S4, a count circuit 204 that counts the number of clock pulses included in one or more gate signals S4, and a correction table. and a memory 205 to be recorded. The control unit 200 also includes a CPU 207 connected to these components via a bus 206, and a clock signal output circuit 208 that outputs a clock signal CLK to these components.

[General operation]
FIG. 3 schematically shows the operation of the optical measuring device according to this embodiment. In the example of FIG. 3, an example of detecting four edges E1 to E4 by the optical measuring device will be described.

The scanning of the laser light L is performed by rotating the polygon mirror 113 (FIG. 2). For example, if the polygon mirror 113 has a regular hexagonal prism shape and has 16 reflecting surfaces, the laser light L is scanned 16 times each time the polygon mirror 113 is rotated once.

At timing t1, the laser beam L reaches edge E1. The edge E1 is, for example, the upper end of the window portion 110b provided in the housing 110a of the light beam scanning portion 110 (see FIG. 1). At timing t1, the laser light L passes through the measurement area 101 and is received by the light receiving section 120. As shown in FIG. Further, the received light signal S1 becomes a value larger than the threshold value Vth, and the edge signal S2 rises. The count circuit 204 also starts counting clock pulses corresponding to the edge E1. Hereinafter, the number of clock pulses corresponding to edge E1 will be referred to as "edge count value ECV(E1)" or the like.

At timing t2, the laser beam L reaches edge E2. The edge E2 is the upper end of the measurement object W, for example. At timing t2, the laser light L is blocked by the measurement object W and does not pass through the measurement area 101. FIG. Further, the received light signal S1 becomes a value smaller than the threshold value Vth, and the edge signal S2 falls. Also, the counting circuit 204 starts counting clock pulses corresponding to the edge E2. Hereinafter, the number of clock pulses corresponding to edge E2 will be referred to as "edge count value ECV(E2)" or the like.

At timing t3, the laser beam L reaches edge E3. The edge E3 is the lower end of the measuring object W, for example. At timing t3, the laser light L passes through the measurement area 101 and is received by the light receiving section 120. As shown in FIG. Further, the received light signal S1 becomes a value larger than the threshold value Vth, and the edge signal S2 rises. Also, the count circuit 204 starts counting clock pulses corresponding to the edge E3. Hereinafter, the number of clock pulses corresponding to edge E3 will be referred to as "edge count value ECV(E3)" or the like.

At timing t4, the laser beam L reaches edge E4. The edge E4 is, for example, the lower end of the window portion 110b provided in the housing 110a of the light beam scanning portion 110 (see FIG. 1). At timing t<b>4 , the laser light L is blocked by the housing 110 a of the light beam scanning unit 110 and does not pass through the measurement area 101 . Further, the received light signal S1 becomes a value smaller than the threshold value Vth, and the edge signal S2 falls. Also, the count circuit 204 starts counting clock pulses corresponding to the edge E4. Hereinafter, the number of clock pulses corresponding to edge E4 will be referred to as "edge count value ECV(E4)".

At subsequent timing t5, the laser light L is received by the light receiving element 115 (FIG. 2) arranged inside the housing 110a of the light beam scanning unit 110, and the reset signal RST rises. Count circuit 204 receives reset signal RST and outputs to CPU 207 four edge count values ECV (E1 to E4) corresponding to edges E1 to E4. Also, the count circuit 204 resets the edge count values ECV (E1 to E4) that it has held. The CPU 207, for example, refers to the correction table recorded in the memory 205, corrects the edge count value ECV, and obtains the corrected edge count value ECV'. Thereafter, for example, the corrected edge count value ECV'(E3) is subtracted from the corrected edge count value ECV'(E2) to obtain a difference value. Also, this difference value is multiplied by the distance scanned by the laser beam L in the −Z direction per clock, and the result is output as dimension data indicating the outer diameter of the object W to be measured.

Although FIG. 3 shows an example of obtaining four edge count values ECV (E1 to E4), the number of edge count values to be obtained can be appropriately adjusted depending on the purpose of measurement. For example, when measuring the outer diameter of the object W to be measured as illustrated in FIG. 3, or when acquiring the correction table recorded in the memory 205, as illustrated in FIG. Edge count values ECV (E1 to E4) can be obtained. Also, six or more edge count values ECV can be obtained depending on the mode of measurement. However, due to the principle of measurement, the number of acquired edge count values ECV is an even number of values corresponding to the rising and falling edges of the light receiving signal S1.

[Dispersion of Edge Count Value ECV]
As shown in FIG. 4A, when the polygon mirror 113 is rotated, the laser light L is scanned by the reflecting surface F1 of the polygon mirror 113, and the edge signal S2 and the reset signal RST are acquired. When the polygon mirror 113 is further rotated, the reflective surface F2 of the polygon mirror 113 is irradiated with the laser light L, scanned by the reflective surface F2, and the edge signal S2 and the reset signal RST are acquired. When the polygon mirror 113 is further rotated, the reflective surface F3 of the polygon mirror 113 is irradiated with the laser beam L, scanned by the reflective surface F3, and the edge signal S2 and the reset signal RST are obtained.

Here, as shown in FIG. 4B, the waveforms of the edge signal S2 and the reset signal RST ( timing of rise and fall) may be different. In such a case, the four edge count values ECV (E1 to E4, F1) corresponding to the reflecting surface F1 and the four edge count values ECV (E1 to E4, F2) corresponding to the reflecting surface F2 are different. value.

Here, for example, the polygon mirror 113 having 16 reflecting surfaces F1 to F16 is rotated n times (n is an integer equal to or greater than 2) to obtain 16×n edge count values ECV (E2, F1 to F16, 1 to n), the edge count value ECV may periodically fluctuate as the polygon mirror 113 rotates, as shown in FIG. For example, the variation among the 16 edge count values ECV (E2, F1 to F16, 1) acquired when the polygon mirror 113 is rotated once becomes relatively large, and n There may be a relatively small variation between edge count values ECV(E2, F1, 1-n).

Such periodic variations in the edge count value ECV are caused, for example, by deviation of the center position 113a of the polygon mirror 113 from the rotating shaft 116a of the motor 116 as shown in FIG. ), the polygon mirror 113 is mounted obliquely with respect to the mounting surface 102, and as shown in FIG. It is thought that this is the cause of the problem.

Such a periodic variation of the edge count value ECV can be obtained, for example, by rotating the polygon mirror 113 once to obtain 16 different edge count values ECV (E2, F1 to F16, 1), and calculating the average value of these values. It can be suppressed by calculating. However, the optical measuring apparatus as described with reference to FIGS. 1 to 3 may be required to perform high-speed and high-precision measurement. It is desirable to be able to obtain the ECV.

Here, the 16 edge count values ECV (E2, F1 to F16, 1) output during one rotation of the polygon mirror having 16 reflective surfaces are affected by the above periodic fluctuations. is included in 16 ways. Such fluctuations in the edge count value ECV can be suitably suppressed by using 16 correction parameters corresponding to the reflecting surfaces F1 to F16. Therefore, in this embodiment, 16 types of correction parameters corresponding to the 16 reflecting surfaces F1 to F16 of the polygon mirror 113 are used to suppress variations in the edge count value ECV as described above. The 16 correction parameters are recorded in the memory 205 as a correction table.

[Acquisition of correction parameters]
Next, with reference to FIGS. 7 to 9 and the like, a method of acquiring correction parameters for the optical measuring apparatus according to this embodiment will be described.

When acquiring the correction parameters, for example, as illustrated in FIG. 8A, the polygon mirror 113 is rotated n times (n is an integer equal to or greater than 2) to obtain the edges E1 to E4, the reflecting surfaces F1 to F16, and the , 4×16×n edge count values ECV (E1 to E4, F1 to F16, 1 to n) corresponding to the number of revolutions 1 to n are obtained (step S101).

Next, for example, as illustrated in FIG. 8B, edge E2, reflective surface F1, and n edge count values ECV (E2, F1, 1 to n) corresponding to rotation numbers 1 to n An average value is calculated and acquired as an average value ECVa (E2, F1) corresponding to the edge E2 and the reflecting surface F1. Further, similar processing is performed on the edges E1 to E4 and the other edge count values ECV corresponding to the reflective surfaces F1 to F16, and 4×16 patterns corresponding to the edges E1 to E4 and the reflective surfaces F1 to F16 are obtained. is acquired (step S102).

Next, for example, as illustrated in FIG. 8C, edge E2, reflective surfaces F1 to F16, and 16×n edge count values ECV (E2, F1 to F16 , 1 to n) are calculated and obtained as an average value ECVb (E2) corresponding to the edge E2. Further, similar processing is performed on other edge count values ECV corresponding to edges E1, E3, and E4, and four average values ECVb (E1 to E4) corresponding to edges E1 to E4 are obtained (step S103). .

Next, for example, as illustrated in FIG. 8D, the average value ECVa (E2, F1) is subtracted from the average value ECVb (E2), and the correction value C (E2, F1) corresponding to the edge E2 and the reflecting surface F1 is calculated. F1). In addition, similar processing is performed on the other average values ECVb and ECVa corresponding to the edges E1 to E4 and the reflective surfaces F1 to F16, and the 4 values corresponding to the edges E1 to E4 and the reflective surfaces F1 to F16. ×16 correction values C (E1 to E4, F1 to F16) are obtained (step S104).

Next, a correction table is generated and recorded in the memory 205 (step S105). For example, as shown in FIG. 9, the correction table includes 4×16 correction values C (E1 to E4, F1 to F16) corresponding to edges E1 to E4 and reflecting surfaces F1 to F16 as correction parameters. . Also, the correction table includes, for example, four average values ECVb (E1 to E4) as correction parameters.

[Correction of edge count value ECV]
Next, an example of a method for correcting the edge count value ECV of the optical measuring apparatus according to the present embodiment will be described with reference to FIGS. 10 and 11. FIG. In the example of FIGS. 10 and 11, an example of measuring the outer diameter of the object W to be measured by calculating the distance between the edge E1 and the edge E2 using an optical measuring device will be described.

When correcting the edge count value ECV, for example, the reflecting surface corresponding to the edge count value ECV to be corrected is specified. For example, the reflecting surface can be specified by using a part of the register in the CPU 207 as a counter, or by providing a counter circuit or the like outside the CPU 207 . The figure shows an example in which the identified reflecting surface is the reflecting surface F1.

Next, as shown in FIG. 10, for example, correction parameters corresponding to the reflecting surface F1 are obtained from the memory 205, and at least two coordinate points p1 to p4 corresponding to the edges E1 to E4 are obtained. The x-axis values of the coordinate points p1 to p4 are the average values ECVa (E1 to E4, F1) corresponding to the edges E1 to E4, respectively. The y-axis values of the coordinate points p1-p4 are the average values ECVb (E1-E4) corresponding to the edges E1-E4, respectively. Note that the average value ECVa (E1 to E4, F1) can be obtained, for example, by subtracting the correction value C (E1 to E4, F1) from the average value ECVb (E1 to E4).

Next, for example, a complementary process such as linear interpolation is performed, and a line segment l1 passing through the coordinate points p1 and p2, a line segment l2 passing through the coordinate points p2 and p3, and a coordinate point p3 and a coordinate point p4 are obtained. At least one of line segments l3 passing through and is obtained. Although the figure shows an example of complementing processing by linear interpolation, other complementing processing such as secondary or tertiary complementation can also be performed.

Next, for example, as shown in FIG. 11, a point on the line segments l1, l2, or l3 having the uncorrected edge count value ECV as the x-coordinate is obtained, and the y-coordinate of this point is calculated as the corrected edge count value ECV. '. For example, FIG. 11 shows an edge count value ECV (E2, F1) before correction, a point p2' on a line segment l2 whose x-coordinate is the edge count value ECV (E2, F1) before correction, and edge count value ECV'(E2) of . FIG. 11 also shows an edge count value ECV (E3, F1) before correction, a point p3' on a line segment l3 whose x-coordinate is the edge count value ECV (E3, F1) before correction, and the subsequent edge count value ECV'(E3).

[effect]
As described with reference to FIG. 5, etc., in an optical measuring apparatus using a polygon mirror, the edge count value ECV may periodically fluctuate in accordance with the rotation of the polygon mirror.

Therefore, in this embodiment, 16 types of correction parameters are sequentially acquired from the memory 205 while the polygon mirror 113 rotates once, and these 16 types of correction parameters are used to obtain the edge count value ECV as described above. Cancels the effects of periodic fluctuations. As a result, variations in the edge count value ECV as described with reference to FIG. 5 and the like can be greatly suppressed. As a result, an accurate edge count value can be obtained without rotating the polygon mirror once. Therefore, high-speed and highly accurate measurement can be performed.

Further, in the optical measuring apparatus according to the present embodiment, it is possible to suppress the effects of errors caused by assembly errors, manufacturing errors, and the like of the polygon mirror 113 . Therefore, it is possible to assemble and manufacture the polygon mirror 113 at a lower cost without lowering the measurement accuracy, thereby reducing the manufacturing cost of the optical measuring apparatus.

Further, in the optical measuring apparatus using the polygon mirror 113, aging deterioration may occur such as bending of the rotating shaft of the motor 116 for rotating the polygon mirror 113. FIG. Even in such a case, the optical measuring apparatus according to the present embodiment can suppress the influence of such aged deterioration by updating the correction parameters. This makes it possible to extend the life of the optical measuring device.

[Modification]
The optical measuring device according to the first embodiment has been described above. However, the first embodiment is merely an example, and specific configurations and the like can be adjusted as appropriate.

For example, in the first embodiment, the polygon mirror 113 has 16 reflecting surfaces F1 to F16, but the number of reflecting surfaces of the polygon mirror 113 can be adjusted as appropriate.

Further, for example, as described with reference to FIGS. 7 to 9, in the first embodiment, an example of obtaining correction parameters using four edges E1 to E4 has been described. However, how many edges are used to obtain correction parameters can be adjusted as appropriate. For example, correction parameters can be obtained using only two edges, or correction parameters can be obtained using six or more edges.

Further, for example, as described with reference to FIGS. 7 to 9, in the first embodiment, the polygon mirror 113 is rotated a plurality of times to acquire a plurality of edge count values ECV, and the plurality of edge count values ECV are acquired. An example of obtaining a correction parameter using an edge count value has been described. However, the specific processing for acquiring correction parameters can be adjusted as appropriate. For example, the edge count value ECV can be obtained by rotating the polygon mirror 113 only once, and the correction parameter can be obtained using this edge count value ECV. Further, for example, it is possible to obtain a plurality of edge count values ECV each time the polygon mirror 113 is rotated once, and obtain a correction parameter by moving average using the plurality of edge count values. In this case, for example, 4×16 edge count values ECV (E1 to E4, F1 to F16) corresponding to the edges E1 to E4 and the reflecting surfaces F1 to F16 each time the polygon mirror 113 rotates. and one of 4×16×n edge count values ECV (E1 to E4, F1 to F16, 1 to n) based on the 4×16 edge count values ECV (E1 to E4, F1 to F16). It is also possible to obtain the average values ECVa and ECVb by updating the part and using the updated 4×16×n edge count values ECV.

Further, for example, as described with reference to FIGS. 7 to 9, in the first embodiment, 4×16 correction values C (E1 to E4, F1 to F16) and 4 correction values C (E1 to E4, F1 to F16) are stored in the correction table. Mean values ECVb (E1-E4) were included. However, the correction parameters included in the correction table may be information indicating the average values ECVa (E1 to E4, F1 to F16) and the average values ECVb (E1 to E4), and the specific correction parameters and the like are appropriately adjusted. can do For example, average values ECVa (E1 to E4, F1 to F16) and average values ECVb (E1 to E4) can be used directly as correction parameters. Also, for example, the intercepts, slopes, etc. of the line segments l1, l2, l3 described with reference to FIGS. 10 and 11 can be used as correction parameters.

Further, the processing described with reference to FIGS. 10 and 11 is schematic, and a specific correction method for the edge count value ECV can be appropriately adjusted. Further, another correction process can be performed before or after the correction process described with reference to FIGS. 10 and 11 is performed.

DESCRIPTION OF SYMBOLS 100... Measurement part, 101... Measurement area, 110... Light beam scanning part, 111... Laser light source, 112... Mirror, 113... Polygon mirror, 114... f-theta lens, 115... Light receiving element, 116... Motor, 117... Motor drive circuit , 118... Motor synchronization circuit 120... Light receiving unit 121... Condensing lens 122... Light receiving element 123... Amplifier 130... Connection unit 200... Control unit 201... Edge detection circuit 202... Gate circuit 203... Count circuit 204 Memory 205 Bus 206 CPU 207 Clock signal output circuit 211 Comparison circuit 212 Threshold adjustment circuit CLK Clock signal S1 Light receiving signal ECV Edge count value .

Claims (4)

a rotatable polygon mirror having m (m is an integer equal to or greater than 3) reflecting surfaces;
a light emitting device for irradiating the polygon mirror with a light beam;
an irradiation optical system that guides the light beam reflected by the polygon mirror to a measurement area;
a first light receiving unit that receives the light beam irradiated to the measurement area and outputs a first light receiving signal;
a second light receiving unit that receives the light beam applied to a region different from the measurement region and outputs a second light reception signal;
a counting circuit that counts clock pulses between the rising or falling timing of the first light reception signal and the rising or falling timing of the second light reception signal and outputs an edge count value;
an arithmetic processing unit that outputs dimension data indicating a dimension of an object to be measured based on the edge count value;
a storage device that stores correction parameters that are referred to when correcting the dimension data;
When acquiring the dimension data, the arithmetic processing unit performs the following operations while the polygon mirror rotates n times (n is an integer equal to or greater than 2):
Acquiring m×n edge count values that vary periodically corresponding to the rotation of the polygon mirror;
Acquiring m types of correction parameters n times from the storage device
Optical measuring device. The arithmetic processing unit is
Based on the m types of correction parameters, performing correction processing for canceling out the effects of the periodic fluctuations from the m×n types of edge count values,
2. The optical measuring apparatus according to claim 1 , wherein m*n kinds of said dimension data are output based on said m*n kinds of edge count values corrected by said correction processing. When acquiring the correction parameter, the arithmetic processing unit
acquiring m×n edge count values while the polygon mirror rotates n times (n is an integer equal to or greater than 2);
obtaining an average value of the n edge count values corresponding to each of the m reflecting surfaces as the m first average value;
obtaining an average value of the m×n edge count values as a second average value;
3. The optical measuring apparatus according to claim 1, wherein information indicating the m different first average values and the second average values is input to the storage device as the correction parameters. a rotatable polygon mirror having m (m is an integer equal to or greater than 3) reflecting surfaces;
a light emitting device for irradiating the polygon mirror with a light beam;
an irradiation optical system that guides the light beam reflected by the polygon mirror to a measurement area;
a first light receiving unit that receives the light beam irradiated to the measurement area and outputs a first light receiving signal;
a second light receiving unit that receives the light beam applied to a region different from the measurement region and outputs a second light reception signal;
a counting circuit that counts clock pulses between the rising or falling timing of the first light reception signal and the rising or falling timing of the second light reception signal and outputs an edge count value;
an arithmetic processing unit that outputs dimension data indicating the dimension of the object to be measured based on the edge count value,
When acquiring the dimension data, the arithmetic processing unit performs the following operations while the polygon mirror rotates n times (n is an integer equal to or greater than 2):
Acquiring m×n edge count values that vary periodically corresponding to the rotation of the polygon mirror;
An optical measuring device that cancels out the influence of periodic fluctuations in the edge count value and outputs the dimension data in m×n ways.

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