JPS60114750A - Surface defect measuring apparatus - Google Patents

Abstract

PURPOSE:To enable accurate measurement on the presence of any surface defect of an object to be measured by monitoring reflected lights from the surface thereof and beam passing the surface thereof when a light beam varying in the optical axis is irradiated on the surface and side of the object being measured. CONSTITUTION:A light beam from a laser 16 is irradiated on the surface and the side of work 14 supported movably according to the rotation of a scanner 18. The beam reflected from the surface of the work 14 is incident into a detector 32 while the beam passing the surface thereof into a detector 38. Judgment can be done as follows: A foreign matter is attached to the surface of the work when the reflection signal VS differs from the reference level while the side passage signal VP does from another reference level; any defect develops on the surface thereof 14 when the reflection signal VS differs from the reference level while the side passage signal VP coincides with the reference level; and the work should be accepted when the output signals VS and VP coincide with the corresponding reference levels.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a surface defect measuring device, and particularly to a surface defect measuring device suitable for measuring surface defects of various objects to be measured.

[Background of the invention]

Conventionally, as a device for opening surface defects of each object to be measured,
An optical surface defect measurement device was used.

This conventional device irradiates the surface of the object to be measured with light, receives the reflected light from the surface of the object, and detects defects on the surface of the object based on the amount of received light. It was configured to determine whether or not it occurred.

However, with conventional devices, even if there is dust or the like attached to the surface of the object to be measured, it is determined that there is a defect such as a scratch on the surface of the cedar meter, and it is judged that it is a good product with no scratches. There was a risk that even a product could be discarded as a defective product. Therefore, when inspecting using conventional equipment, it is necessary to either manually inspect the defective products, or to install a cleaning machine in the previous process to clean the surface of the object to be measured. It was Therefore, when conventional equipment is used to measure surface defects on objects to be measured, there are problems such as a decrease in yield, an increase in the number of re-inspection steps, or an increase in equipment investment. , [Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to use an electrocardiogram (8 ) is provided to the defect measuring device fi'.

[Summary of the invention]

In order to achieve the above object, the present invention provides a first light emitting unit that irradiates a source whose optical axis changes onto the surface of a target η[side control, and a light source whose optical axis changes The second beam illuminates the side of the
a first light tX converter that receives all of the reflected light irradiated on the surface of the object to be measured and outputs electricity No. 48 at a level corresponding to the amount of received light; a second photoelectric conversion unit that receives at least the light that has passed through the surface side of the object to be measured out of the irradiated light, and outputs two systems of electrical signals with different levels depending on the position of the optical axis of the received light; , an arithmetic unit that measures the level ratio of the electrical signals of each system output from the second charging conversion unit and outputs a signal according to the determined ratio; and an output signal of the arithmetic unit and an output of the first photoelectric conversion unit. a detection unit that samples each signal at a predetermined timing, sequentially captures the level of each signal according to the sampling period, and outputs a defect signal when the level of any signal at each timing exceeds the level at the previous timing; , a plurality of reference levels are set, the output signals of the defect signal calculation unit and the first photoelectric conversion unit are compared with the reference level, and the measurement result for the object to be measured is determined based on the results of these comparisons. , a determination unit that outputs a determination result, and a full-include, pre-NC
The determination unit is configured to set a first reference level in which the level of the output signal of the first photoelectric conversion unit is associated with the output signal of the first photoelectric conversion unit as a level when the object to be measured is a non-defective item. In contrast, when the level of the output signal of the calculation section is different from the second reference level, which is set in association with the output signal of the calculation section as the level when the object to be measured is a non-defective item, the surface of the object to be measured is When it is determined that an object has adhered to the surface of the object to be measured, if the first photoelectric conversion unit ρ output signal differs from the first reference level and the level of the output signal of the calculation unit matches the second reference level, the surface of the object to be measured is detected. It is determined that a defect such as a scratch has occurred in the 311 The present invention is characterized in that it is configured to determine that the object to be measured is a non-defective item when the measured object is a non-defective item.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the configuration of a preferred embodiment of the present invention.

In FIG. 1, an object to be measured (hereinafter referred to as a work) 1 supported by a jig 1o and movable according to the drive of a motor 12
The surface of the workpiece 14 is irradiated with light from the first light projecting section, and the side surface of the workpiece 14 is irradiated with light from the second light projecting section.

That is, the laser beam emitted from the laser oscillator 16 passes through the optical scanner 18 and the lens 20't to the surface of the workpiece 140, the optical scanner 18, and the slit 22.
, a lens 24, and a reflecting mirror 26 to illuminate the side surface of the workpiece 14.

The optical scanner 18 is configured to be able to rotate within a range of angle θ1 by a drive signal S output from the measurement unit 28. When the optical scanner 18 rotates within the range of angle θ1, the optical axis of the laser beam irradiated onto the lens 24 through the slit 22 changes to an angle θ2.
The light changes within the range of 2 and irradiates the reflecting mirror 26, and this reflecting mirror irradiates the side surface of the workpiece 14. Furthermore, when the optical scanner 18 rotates within the range of angle θ1, the lens 20
The optical axis of the light irradiated on the workpiece 1 changes within the range of 03.
The surface of 4 is irradiated.

The laser beam irradiated onto the surface of the workpiece 140 is reflected by the surface of the workpiece 14, and a portion of the reflected light is transmitted to the light receiving element 32 via the lens 30. Lens 30, light receiving element 32
, and an amplifier 34 is configured to receive the reflected light of the light irradiated onto the surface of the workpiece 14 and output an electric signal Vsk at a level corresponding to the amount of received light. ing. That is, when the light reflected from the surface of the workpiece 14 is transmitted to the light receiving element 32 via the lens 30, the light receiving element 32 outputs an electrical signal at a level corresponding to the amount of received light, and this electrical signal is input to the amplifier 34 to a predetermined level. It is amplified to a degree of amplification and output.

In this way, the light receiving element 32 is configured to output an electrical signal at a level corresponding to the amount of light received, so the amplifier 3
As shown in FIG. 2, the level of the output signal VS of No. 4 is υ when something such as dust is attached to the surface of the workpiece 14, and when there is no defect such as a scratch on the surface of the workpiece 140. , a high level v1 due to less diffused reflection,
On the other hand, if there is something attached to the surface of the workpiece 14 or if there is a defect such as a scratch on the surface of the workpiece 14, diffused reflection increases and the amount of received light decreases, so the voltage v1 also decreases to a low level. . That is, the output signal Vs of the amplifier 34
The level decreases when something adheres to the surface of the workpiece 14 or when a defect such as a scratch occurs on the surface of the workpiece 14.

On the other hand, the laser beam irradiated onto the side surface of the workpiece 14 is transmitted to the light receiving element 38 via the lens 36.

The second photoelectric conversion unit, which is composed of a lens 36 and a light-receiving element 38, receives at least the laser light that has passed through the surface side of the workpiece 140 out of the laser light irradiated onto the side surface of the workpiece 14, and converts the laser light into a It is configured to output two systems of electrical signals with different levels depending on the position.

When the side surface of the workpiece 14 is irradiated with a laser beam, as shown in FIG.
However, if dust 40 or the like adheres to the surface of the workpiece 14, the laser beam 102 will not be transmitted to the light receiving element 38, and the laser beam 1 (14) will be transmitted to the light receiving element 38.

Therefore, in this embodiment, in order to easily determine whether dust or the like has adhered to the surface of the workpiece 14,
Among the laser beams irradiated on the side surface of the workpiece 14, the laser beams that have passed through the front side of the workpiece 14 are received by the light receiving element 38, and two systems of electrical signals with different levels are outputted depending on the position of the laser beam received by the light receiving element 38. I am planning to output it.

Electrical signals from each system of the light receiving element 38 are supplied to amplifiers 44 and 46 of the arithmetic unit 42.

The arithmetic unit 42 is composed of amplifiers 44, 46 and an arithmetic unit 48. The amplifiers 44 and 46 each have a light receiving element 38.
The output signals vA and vB from the arithmetic unit 48 are amplified to predetermined levels V A / and V n /, respectively.
is configured to supply. The arithmetic unit 48 divides the outputs of the amplifiers 44 and 46, i.g. It is configured to output a signal VpCv(person'-1-VB'/VA'-Val). Therefore, the signals vA/, V n / shown in FIGS. 4(a) and (b) are supplied to the calculator 48, and when there is dust 40 etc. attached to the surface of the workpiece 140, the signals vA/ and V n / shown in FIG. As shown in (C), the computing unit 48
outputs a signal of a higher level than the level v2 when no object is attached to the surface of the workpiece 140. The output signal vP of the arithmetic unit 48 is transmitted to the measurement unit and the detection section 50.
supplied to

As shown in FIG. 5, the detection unit 50 includes an oscillator 52,
Timing circuit 54, controller 56.58, setting tube 60.62, and gate 64, 66.68.70,
Analog switch 72.74.76.78, averaging circuit 80.82.84.86, multiplication circuit 88.90.92,
94, sample hold circuit 96.98.100.10
2. Analog switch 104.106.108.110
, comparators 112, 114.

The output signal of the oscillator 52, which generates the pulse signal, is supplied to a timing circuit 54. The timing circuit 54 is
When the start signal ST from the measurement unit 28 is applied, a clock signal C! synchronized with the output pulse of the oscillator 52 is generated. It is configured to output timing signals F and B'i. Clock signal C, timing signal F, B
Each has a total of 6111 units 28, motor driver 1
20, and timing signals F and B are each supplied to one input terminal of an AND gate 64.66.68.70. The AND gates 64, 66, 68, and 70 are configured to generate an output signal when both the output signal from the comparator 56 and the timing signal F and B from the timing circuit 54 are applied. Here, in this embodiment, the laser light irradiated onto the surface and side surfaces of the workpiece 14 is irradiated over a wide range, and the electric signals Vs and Vp based on these laser lights are also the light of the laser light. Since it is output as a signal according to the axis, only <41@Vs-Vp is supplied to the comparator 56.58 based on the beam light irradiated to a certain area on the surface and side surface of the workpiece 14. When rc, the comparator 56
．． The configuration is such that a signal is supplied from 58 to each AND gate 64, 66, 6B, 70.

That is, the level corresponding to a certain area on the surface and side surface of the workpiece 14 is set in the setter 60.62, and among the signals Vs and Vp supplied to the comparator 56.58, the level corresponding to a certain area on the surface and side surface of the workpiece 14 is set. Only the signals v8 and Vp based on the laser beam irradiated to a certain area of the comparator 56
．． 5B, a signal is output from the comparators 56 and 58.

When a signal is output from the AND gate 64, 66, 68, 70, the analog switch 72, ? 4.76.78.10
4.106.108.110 circuits are opened and averaging circuit 80.82.84.86, multiplication circuit 88.90
．． The signals outputted from 92 and 94 are held by sample and hold circuits 96, 98, 100 and 102, respectively. That is, when the signal Vs is opened by the analog switches 72 and 74 in synchronization with the timing signals F and B,
Depending on the timing, the signal Vs k is supplied to a sample hold circuit 96.98 via an averaging circuit 80.82 and a multiplication circuit 88.90, respectively, and its level is temporarily held by the sample hold circuits 96, 98. and,
This held level is supplied to the comparator 112 when the analog switch 104, 1060 circuit is opened at the next timing. Analog switch 104,1
The signal vB output from the amplifier 34 and the analog switch 104.10 at the timing when the circuit 06 is opened.
When the level of the output signal Vs from the amplifier 34 exceeds the level output from the analog switches 104 and 106, it is determined that a defect has occurred on the surface of the workpiece 14. Ill is configured to output a defect signal ail.

Also, for the signal Vp, similarly to the signal v8,
The signal Vp output from 2 and the analog switch 108
, 110 is the level output from the comparator 114.
When the level of the signal Vp outputted from the calculation unit 42 exceeds the level outputted from the analog switch 108, 110, it is determined that a defect has occurred on the surface of the workpiece 14, and a defect signal b1 is output. be done.

In this way, the output signal Vp of the detection unit 50 and the calculation unit 42 and the output signal vB of the amplifier 34 in this embodiment are sampled at the required timing, and each 4K signal V s
, V p levels are sequentially captured according to the sampling period, and when the level of any code at each timing exceeds the level at the previous timing, defect 1g a1, bi is configured to be output. . Each defect signal ai, bi is supplied to the measuring unit 28 as 2'L8. Note that the multiplication circuits 88, 90, 92.
94 functions as a circuit that shapes the waveforms of the signals Vs and Vpe averaged by averaging circuits 80, 82, 84, and 86, respectively.

The measurement unit 28 includes a determination section and a drive section. Of these, the drive IMJ section is configured to output all of the drive signal S for driving the optical scanner 18 and the drive signal DP for driving the motor driver 120. The drive signals S and DP are output in synchronization with the γL timing signals F and B, respectively. That is, the measurement unit 28
When the drive signal S is supplied to the optical scanner 8 in synchronization with the timing signals F and B, the optical scanner 18 is driven in synchronization with the timing signal F, and the laser beam is irradiated from the optical scanner 8 to the lens 24 and 20 side. moves from the left side to the right side in the drawing, and when the optical scanner 18 is driven to rotate in synchronization with the timing signal B, the beam light irradiated onto the lenses 20 and 24 moves from the right side to the left side in the drawing.

A plurality of reference levels are set in the determination section, and the determination section compares the output signals Vs and vP with the reference levels, respectively, and determines the measurement result for the workpiece 14 based on the results of these comparisons. The system is configured to display the determination result on the display 122.

Among the reference levels set in the determination section, the 10th basic level is associated with the output signal vE3 and is
The second reference level is set to the level when the workpiece 14 is a good product, that is, the level v1 shown in FIG. It is set corresponding to the current level, that is, the level v2 shown in FIG. 4(C).

FIG. 6 shows an embodiment in which the measurement unit 28 is configured with a microcomputer.

In FIG. 6, the measurement unit 28 includes the CPU 130, R
OMI 32, RAM134, A/D converter 136
, digital input/output circuit 138, digital output circuit 140
, a D/A converter 142, a multiplexer 144, a CPU 130, a ROM 132, and a RAM.
134, an A/D converter 136, a digital input/output circuit 138, a digital output circuit 140, and a D/A converter 142 are connected by a path line 146, respectively.

The output signals Vs and Vp are each sent to a multiplexer 144.
The signal is supplied to the A/D converter 136 via the A/D converter 136. The measurement command M, the origin command O, the timing signals F and B, the defect signals ai and bi, and the clock signal C1 are each supplied to the digital input/output circuit 13B.

Furthermore, data regarding the first and second reference levels described above is stored in the ROM 132. And CPU130
receives data based on the output signals v8 and Vp, determines the measurement results for the workpiece 14, and displays the determination results on the display 122 via the all-digital output circuit 140.
is configured to output to . Further, a drive signal S for driving the optical scanner 18' is outputted via the D/A converter 132. Note that the drive signal S is output as a triangular wave signal.

In the device in the practical implementation configured as described above, when the drive signal I'L is applied from the measurement unit 28 to the optical scanner 18, the optical scanner 18 rotates within the range of angle θ1, and the signal from the laser oscillator 16 is Laser light is irradiated onto the front surface i and side surface of the workpiece 14 through the lens 20.24.

On the other hand, at this time, together with the drive fJJJ signal S, the drive signal DP
is applied to the motor driver 120, and the workpiece 14 is moved by the rotational drive of the motor 12. As the optical scanner 18 and workpiece 14 move, the measurement unit 2
8, signals Vs and Vp based on laser beams irradiated onto the front and side surfaces of the workpiece 14 are applied for each scan at timings synchronized with the movement of the optical scanner 18, respectively.

When output No. 4 Vs, Vp is given to the measurement unit 28 for each scan, the measurement unit 28 compares the output signals vs, vp with the first and second reference levels, and based on the results of these comparisons, Then, a process is performed to determine the comparison result for the workpiece 14 and output the determination result.

That is, as shown in FIG. 7(a), the output signal vs.
When the output signal Vp is different from the first reference level v1 and the output signal Vp is different from the second reference level v2, it is determined that objects such as chips and dust have adhered to the surface of the workpiece 14, and (b) in FIG.
), when the level of the output signal Vs is different from the first reference level v1, the level of the output signal Vp is different from the first reference level v1.
When the output signal Vs matches the reference level V2, it is determined that a defect such as a scratch or a blowhole has occurred on the surface of the workpiece 140, and as shown in FIG. 7(c), the output level of the output signal Vs reaches the first When the level of the output signal Vp matches the second reference level v1, the workpiece 14
is determined to be A product. These determination results are displayed on the screen of the display 122 via the digital output circuit 140.

In this embodiment, the measurement results for the workpiece 14 are displayed on the screen of the display device 122, so the operator can measure the workpiece by looking at the open side results displayed on the screen of the display device 122. Is there something false on the surface of 14?
Alternatively, it is possible to easily check whether something has adhered to the surface of the workpiece 140 or whether the workpiece 14 is a good product.

In addition, in this embodiment, by the method described above, a workpiece master having scratches, cavities, etc. formed on its surface is opened, and the laser beam angle is adjusted as shown in FIG. Measurements can be made quickly.

In addition, in FIG. 8, α and β indicate the distribution characteristics of flaws and blow holes on workpiece masters with different degrees of defects, respectively, and the defect size A and the laser beam angle θl are respectively expressed as al and β. By setting a2, α3, βl, β2, β3, etc., the defective part of the workpiece 14 can be measured quickly and accurately. The shaded area shown in FIG. 8 indicates the area where the defect size is A and is not allowed.

The process of measuring the presence or absence of a dragonfly defect in the workpiece 140 using the soak master is performed based on the flowchart shown in FIG.

First, when the mouth measurement command M is given to the measurement unit 28 and the start signal St is given to the timing circuit 54,
Data sampling processing (step 200) is performed using signals v8, Vp, defect signals a1, bi-timing signals F, B in synchronization with clock signal CI, and step 2
The process moves on to step 02.

In the process of step 202, the phase of the signals v8 and Vp is corrected and the defect signals ai and bi are corrected in units of one scan.
Phase correction is performed, and then a search for a defective portion of the workpiece 14 is performed (step 204). Thereafter, the process moves to step 206, and it is determined whether or not a defect has occurred in the workpiece 14 by monitoring the output of the defect signals ai and bi.

If neither of the defect signals ai and bj is generated in step 206, it is assumed that no defect has occurred on the surface of the workpiece 14, and the process proceeds to step 208, in which the workpiece 1
Assuming that there is no defect on the surface of display 122
In step 21, the workpiece 14 is displayed as a good product.
Move on to processing 0. In the process of step 210, it is determined whether the measurement of all parts of the workpiece 14 has been completed. If the determination in this step is NO, the process moves to step 200 and the above-described process is performed again.

If the determination in step 206 is YES, and it is determined that a defect has occurred on the surface of the workpiece 14, the process moves to step 212, where a process for determining the size of the defect level A of the defective part of the workpiece 14 is performed. Then, the process moves to step 214. In step 214, the defect size A memorized and learned by the work master is compared with the measured value, and the defect size is classified into classes according to the comparison result, and the process moves to step 216. In step 216, the data for scratches or dust on the defective portion of the workpiece 14 is classified based on the defect size A, and the process proceeds to step 218.

In step 218, the workpiece 1 is
4, it is determined whether or not a defect such as a scratch has occurred. If it is determined YES in this step, step 22
0, the display 122 indicates that a defect such as a scratch or a blowhole has occurred in the workpiece 14.

On the other hand, if the determination in step 218 is No, the process moves to step 222 and displays on the display 122 that objects such as dust and chips have adhered to the surface of the workpiece 14.

After the processing in steps 220 and 222, the process moves to step 210, in which it is determined whether all parts of the workpiece 14 have been measured in the same way as described above. The process moves to step 200, and if the determination is YES, the process in this routine ends.

In this manner, in this embodiment, when a defect such as a scratch or a blow hole occurs in the workpiece 14, the content of the defect can be classified based on its size.

Furthermore, in the previous example, the program corresponding to the function of the detection section 500 can be stored in the ThRAM 134 in advance, thereby eliminating the need for the detection section 50'. Furthermore, when there is a large amount of data and speeding up needle side processing,
CPU 130 of measurement unit 28, ROMI 32, R
It is also possible to reduce the processing time by combining all the calculation units in which the AM 134 is grouped.

As described above, according to this embodiment, on the surface of the workpiece 14,
Since products with chips or the like attached to them are not determined as defective products due to scratches or the like, there is no need to re-inspect defective products, and there is no need to install a washing machine in the previous process. Therefore, according to this embodiment, it is possible to improve yield, reduce re-inspection man-hours, and reduce equipment investment.

Furthermore, according to the embodiment, the surface defects on the workpiece 140 can be reliably measured without visually inspecting the surface defects on the workpiece 14, so that the efficiency of the measurement work can be improved and the quality can be improved. be able to.

〔Effect of the invention〕

As explained above, according to the present invention, the surface and side surface of the object to be measured are irradiated with laser light, and the light reflected from the surface of the object to be measured and the light passing through the side surface of the object to be measured are separated. The light is received by each light-receiving element, and based on the output level r of each light-receiving element, it is determined whether the object to be measured is a good product, whether something has adhered to the surface of the object to be measured, or if there is a defect such as a scratch on the surface of the object to be measured. The output level of each light-receiving element? : FIi is sampled at a fixed timing, and the level of each signal is sequentially captured in all sampling periods. When the level of any signal at each timing exceeds the level at the previous timing, a defect signal is generated and a defect is detected in the object to be measured. Since it is determined early whether or not a defect has occurred, surface defects on the object to be measured can be measured reliably and quickly, and the work efficiency for surface defect measurement can be improved.
This has the excellent effect of reducing equipment costs, improving the quality of the object to be measured, and eliminating the need for a washing machine in the previous process.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing one embodiment of the present invention, Fig. 2 is a diagram showing the relationship between laser beam angle and voltage, and Fig. 3 is a diagram showing the relationship between laser beam angle and voltage.
A diagram for explaining the configuration of the second 9゛α conversion section shown in the figure, (a) to (c) of FIG. 4 are waveform diagrams for explaining the operation of the calculation section shown in FIG. 5 is a specific configuration diagram of the detection unit shown in FIG. 1, FIG. 6 is a specific configuration diagram of the measurement unit 28 shown in FIG. 1, and (a) to (c) of FIG.
) are diagrams showing the relationship between laser beam angle and voltage, Figure 8 is a diagram showing the relationship between laser beam angle and defect size, and Figure 9 explains the operation of the device shown in Figure 1. This is a flowchart for 12...Motor, 14...Work, 16...Laser oscillator, 18...Optical scanner, 20.24
．． 3o, 36... Lens, 28... Needle side unit,
32.38... Light emitting element, 42... Arithmetic unit, 50...
...detection unit, 122...indicator. Agent Tatsuyuki Unuma (and 1 other person) Fig. 7 Lehr 1: °-A' River degree θ Fig. 8 Laser beam angle e+

Claims (1)

[Claims] (1) A first light projector that irradiates the surface of the object to be measured with light whose optical axis changes; a second light projector that irradiates the side surface of the object with light whose optical axis changes; A first photoelectric conversion unit that receives reflected light of the light irradiated on the surface of the object to be measured and outputs an electrical signal of a level corresponding to the amount of received light; a 20th photoelectric conversion unit that receives light and sound that has passed through the surface side of the measurement object and outputs two systems of electrical signals with different levels depending on the position of the optical axis of the received light;
an arithmetic unit that measures the level ratio of the electrical signal of the system output from the second photoelectric conversion unit and outputs a signal according to the determined ratio; and an output signal of the arithmetic unit and the first photoelectric conversion unit. The output signal of each is sampled at a predetermined timing, and the level of each signal is sequentially sampled several times according to the sampling period. When any signal at each timing exceeds the level at the previous timing, a defect signal is output. A section and a plurality of reference levels are set, and each output signal of the defect signal, the calculation section, and the first photoelectric conversion section is compared with the reference level, and the measurement of the object to be measured is performed based on the results of these comparisons. a determination unit that determines the result and outputs the determination result, and the determination unit is configured to determine whether the level of the output signal of the tenth photoelectric conversion unit is
The level of the output signal of the calculation section is different from the first reference level, which is set in association with the output signal of the first photoelectric conversion section as the level when the object to be measured is a good product. When the level differs from the second reference level, which is set in association with the output signal of the calculation unit as the level for a non-defective product, it is determined that something has adhered to the surface of the object, and the first photoelectric conversion is performed. When the level of the output signal of the calculation section is different from the first reference level and the level of the output signal of the calculation section matches the second reference level, it is determined that a defect such as a scratch has occurred on the surface of the object to be measured; Determining that the object to be measured is a good product when the level of the output signal of the first photoelectric conversion section matches a first reference level and the level of the output signal of the calculation section matches a second reference level. A surface defect measuring device featuring: