JP2021071489A - Optical inspection device, method, and program - Google Patents

Abstract

To provide an optical inspection device with which contactless internal inspection is possible.SOLUTION: An optical inspection device pertaining to an embodiment of the present invention comprises: a generation unit for generating detection light that includes a plurality of wavelengths; a light receiving unit for receiving detection light generated by the generation unit and having passed through an inspection object as passed light and outputting a received light signal; and a processing circuit for processing the received light signal and acquiring a beam direction of the passed light for each of the plurality of wavelengths, acquiring wavelength dependency of the inspection object pertaining to refractive index distribution on the basis of comparison of the beam direction of the passed light of each of the plurality of wavelengths with a reference beam direction, and acquiring information pertaining to the inspection object on the basis of the wavelength dependency.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to optical inspection devices, methods and programs capable of non-contact internal inspection.

Conventionally, as a technique for measuring the spatial distribution of a desired physical quantity in an object, there have been contact-type internal measurement and internal measurement by fracture. In contact-type internal measurement and internal measurement by destruction, there is a concern that the physical quantity of the object may change during contact or destruction, so there was a demand for accurate measurement.

U.S. Pat. No. 6,349,128

An object to be solved by the present invention is to provide an optical inspection apparatus, method and program capable of non-contact internal inspection.

The optical inspection apparatus according to the embodiment is a light receiving unit that generates detection light including a plurality of wavelengths and a light receiving unit that receives the detection light generated by the generation unit and passed through an object as passing light and outputs a light receiving signal. The unit and the received signal are processed to obtain the light direction of the passing light for each of the plurality of wavelengths, and the subject is based on a comparison between the light direction of the passing light and the reference light direction of each of the plurality of wavelengths. It has a processing circuit that acquires the wavelength dependence related to the refractive index distribution of the inspection object and acquires the information related to the inspection object based on the wavelength dependence.

FIG. 1 is a schematic view showing an outline of a configuration example of an optical inspection device according to a first embodiment. FIG. 2 is a schematic diagram for explaining a measurement principle in the optical inspection apparatus according to the first embodiment. FIG. 3 is a schematic diagram for explaining the measurement principle in the optical inspection apparatus according to the first modification of the first embodiment. FIG. 4 is a schematic view showing an outline of a configuration example of the optical inspection device according to the second embodiment. FIG. 5 is a schematic diagram for explaining the measurement principle in the optical inspection apparatus according to the second embodiment, and shows a state before the acoustic plane wave reaches the refractive index distribution. FIG. 6 is a schematic diagram for explaining the measurement principle in the optical inspection apparatus according to the second embodiment, and shows a state after the acoustic plane wave reaches the refractive index distribution. FIG. 7 is a schematic view showing an outline of a configuration example of the optical inspection device according to the third embodiment. FIG. 8 is a schematic diagram for explaining the measurement principle in the optical inspection apparatus according to the third embodiment, and shows a state before the acoustic plane wave propagating in the test object reaches the interface. FIG. 9 is a schematic diagram for explaining the propagation of strain inside the test object according to the third embodiment, and shows a state before the acoustic plane wave propagating in the test object reaches the interface. FIG. 10 is a schematic diagram for explaining the measurement principle in the optical inspection apparatus according to the third embodiment, and shows a state after the acoustic plane wave propagating in the test object reaches the interface and is reflected. .. FIG. 11 is a schematic diagram for explaining the propagation of strain inside the test object according to the third embodiment, after the acoustic plane wave propagating in the test object reaches the interface and is reflected. Indicates the state.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between the parts, and the like are not necessarily the same as those in reality. Further, even when the same parts are represented, the dimensions and ratios may be different from each other depending on the drawings. In the present specification and each figure, the same elements as those described above with respect to the above-mentioned figures are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.

(First Embodiment)
Hereinafter, the optical inspection apparatus and the optical inspection method according to the present embodiment will be described in detail with reference to the drawings.

First, the configuration of the optical inspection device according to the present embodiment will be described. FIG. 1 shows an outline of a configuration example of the optical inspection device 10 according to the present embodiment as a schematic diagram. In FIG. 1, in addition to the outline of the configuration example of the optical inspection device 10, an example of the light path of the detection light 51 and the test region 30 are schematically shown.

In the following description, the case where the measurement target (object 40) by the optical inspection device 10 according to the present embodiment is a gas will be described, but the present invention is not limited to this. The test object 40 may be a liquid or a solid existing in the test area 30. However, when the test object 40 is a gas, a gas existing in the test area 30, such as a substance filling the test area 30, can be treated as the test object 40.

As shown in FIG. 1, the optical inspection device 10 according to the present embodiment includes a detection light generation unit 12, a light receiving unit 13, and a processing circuit 14.

The detection light generation unit 12 according to the present embodiment radiates the detection light 51 toward the test object 40. The detection light generation unit 12 includes, for example, a light source and a condensing optical system. The condensing optical system includes, for example, a collimator. At this time, the light (electromagnetic wave) radiated from the light source is converged by the condensing optical system to be parallel light, and then is irradiated to the test object 40 as the detection light 51.

The detection light generating unit 12 according to the present embodiment may be configured so that the radiation angle of the detected light 51 to be emitted can be acquired. Here, the radiation angle is, for example, the angle formed by the optical axis of the detection light generation unit 12 and the detection light 51 emitted from the detection light generation unit 12. Further, the radiation angle can be expressed as the light ray direction when the light ray (detection light 51) is emitted. Hereinafter, the light ray direction of the detection light 51 emitted from the detection light generation unit 12 will be referred to as a first light ray direction.

The wavelength of the detection light 51 according to the present embodiment may be any wavelength as long as it can transmit or pass through the test object 40, for example, a substance that fills the inside of the test region 30 when the measurement target is a gas. , It may be selected according to the test object 40. The detection light 51 may be, for example, X-rays, visible light, or microwaves.

Further, the detection light generation unit 12 according to the present embodiment may be configured to radiate light (electromagnetic waves) having a plurality of wavelengths as the detection light 51. Further, the detection light 51 may be a light having a single wavelength or a light having a plurality of wavelengths.

Further, the detection light generation unit 12 according to the present embodiment does not have to be provided with a light source. In this case, the optical inspection device 10 may use light (electromagnetic waves) radiated from a light source outside the optical inspection device 10 instead of the light source, or may use natural light such as sunlight. Further, in this case, for example, an optical element that selectively transmits or reflects light in a specific wavelength range may be used as the detection light generation unit 12. That is, the detection light generating unit 12 according to the present embodiment may be any as long as it can radiate the detection light 51 having characteristics according to the test object to the test object 40.

In the present embodiment, the electromagnetic wave may be described as light, but even if it is expressed as light, it is not intended to indicate only visible light. Hereinafter, in the present embodiment, a case where the detection light generating unit 12 is configured to emit an electromagnetic wave that can be regarded as a single wavelength or a single wavelength as the detection light 51 will be described as an example.

The light receiving unit 13 according to the present embodiment receives the detection light 51 emitted by the detection light generation unit 12. The detection light 51 received by the light receiving unit 13 includes, for example, the detection light 51 that has passed or passed through the test object 40. Further, the light receiving unit 13 is configured to be able to measure or detect the angle of incidence on the light receiving unit 13 with respect to the detected light 51 to be received. Here, it is assumed that the angle of incidence on the light receiving unit 13 is the angle formed by the optical axis of the light receiving unit 13 and the light beam received by the light receiving unit 13. Further, the incident angle can be expressed as the light ray direction when the light ray (detection light 51) is incident on the light receiving unit 13. Hereinafter, the light ray direction of the detection light 51 incident on the light receiving unit 13 will be referred to as a second light ray direction. The light receiving unit 13 outputs the measured or detected information related to the second light ray direction as a light receiving signal to the processing circuit 14.

The light receiving unit 13 includes, for example, at least two light receiving surfaces. Alternatively, the light receiving unit 13 may be formed of a combination of one light receiving surface and a pinhole, or may be formed of a combination of one light receiving surface and a lens. Here, a case where two light receiving surfaces are provided will be described. Each light receiving surface is arranged perpendicular to the optical axis direction of the light receiving unit 13. That is, the light receiving surfaces are arranged parallel to each other. The distance between the light receiving surfaces in the optical axis direction of the light receiving unit 13 is known information such as previously recorded in the light receiving unit 13 or the processing circuit 14. In addition, each light receiving surface can detect and output at which position of the light receiving surface the light is received. Here, for the sake of simplicity, the light receiving unit 13 has two light receiving surfaces, a first light receiving surface and a second light receiving surface arranged on the side of the first light receiving surface facing the test object 40. A case where a surface is provided will be described as an example. At this time, the distance between the first light receiving surface and the second light receiving surface is known. Further, the detection light 51 that has passed through or passed through the first light receiving surface has an intensity that can be detected by at least the second light receiving surface. Further, it is said that the light ray direction of the detection light 51 does not change when transmitting or passing through the first light receiving surface, or the amount of change in the light ray direction of the detection light 51 when transmitting or passing through the first light receiving surface is known. To do. The light receiving unit 13 having such a configuration provides information related to at least the first light receiving position on the first light receiving surface and the second light receiving position on the second light receiving surface as information related to the second light ray direction. Is output to the processing circuit 14.

In the present embodiment, the case where the inclination of the optical axis of the light receiving unit 13 does not change will be described as an example, but the present invention is not limited to this. For example, the inclination of the optical axis of the light receiving unit 13 may change. In this case, the inclination of the optical axis may be detected by the light receiving unit 13 or acquired from the outside.

Further, the relative positions and angles of the respective optical axes of the detection light generating unit 12 and the light receiving unit 13 may be fixed. For example, when the relative angle is not fixed, the angle on the side having a degree of freedom in the angle may be detectable.

The processing circuit 14 according to the present embodiment processes the light receiving signal output by the light receiving unit 13. The process includes, for example, a process of calculating the angle of incidence (second ray direction) of the detection light 51 on the light receiving portion 13. The second light ray direction is formed by, for example, a vector from the first light receiving position to the second light receiving position and a vector from the optical axis position on the first light receiving surface to the optical axis position on the second light receiving surface. Calculated as an angle. The processing circuit 14 according to the present embodiment acquires information related to the reference light ray direction as a reference from, for example, the detection light generation unit 12, the light receiving unit 13, and the like. The processing circuit 14 performs a process of comparing the acquired information related to the second light ray direction with the information related to the reference light ray direction as a reference. Further, the processing circuit 14 according to the present embodiment performs a process of comparing information related to a plurality of second ray directions calculated from information acquired at different timings. That is, the processing circuit 14 performs a process of acquiring a time-series change in the second light ray direction (light receiving signal). Further, the processing circuit 14 according to the present embodiment calculates or acquires information related to the physical quantity inside the test object 40 based on the result of comparing the information related to the light ray direction. The processing circuit 14 may have a function as a determination unit that performs various determinations related to the calculation or acquisition of the information.

The calculation of the second ray direction and the acquisition of the time-series change in the second ray direction may be performed, for example, by the light receiving unit 13. In this case, the light receiving unit 13 calculates the angle of incidence (second light ray direction) of the detection light 51 on the light receiving unit 13 as described above. Further, the light receiving unit 13 outputs the calculated incident angle (second light ray direction) to the processing circuit 14 as information related to the light ray direction of the light ray (detection light 51) transmitted or passed through the test object 40.

The optical inspection device 10 according to the present embodiment further includes a control circuit 18. The control circuit 18 is configured to control the operation of each part included in the optical inspection device 10. The control circuit 18 may be configured to include a processing circuit 14. The control circuit 18 and a part of the control circuit 18 may be provided in each or one of the detection light generation unit 12 and the light receiving unit 13. Although not shown, the optical inspection device 10 according to the present embodiment further includes a power supply device and a recording circuit. The power supply device is configured to supply electric power to each part of the optical inspection device 10. The recording circuit is configured to be able to record, for example, a time-series change in the second ray direction (angle of incidence of the detection light 51 on the light receiving portion 13) calculated and output by the processing circuit 14. Further, a processing program and various parameters used in the optical inspection device 10 are recorded in the recording circuit. Each process related to the operation of the optical inspection device is executed by, for example, each program recorded in the recording circuit. Each program may be recorded in advance inside the optical inspection device 10, or may be read from a recording medium outside the optical inspection device 10. Further, the recording circuit temporarily records, for example, the output value of the light receiving unit 13 and the data being processed in the processing circuit 14. The recording circuit may be a volatile memory or a non-volatile memory. A part of the recording circuit may be provided inside the light receiving unit 13 or the processing circuit 14.

The light receiving unit 13 and the processing circuit 14 are connected so that data can be transferred, for example. The connection between the light receiving unit 13 and the processing circuit 14 may be wired or wireless. Further, for example, when the light receiving unit 13 includes a recording circuit, even if the light receiving unit 13 and the processing circuit 14 are not connected during the measurement of the angle of incidence of the detection light 51 on the light receiving unit 13 by the light receiving unit 13. Good. In this case, the data transfer may be performed via a recording medium external to the optical inspection device 10, such as a Flash memory.

The test region 30 according to the present embodiment is, for example, on the light path of the detection light 51 that can be emitted from the detection light generation unit 12 and incident on the light receiving unit 13, and the detection light generation in which the detection light 51 is emitted is generated. It is between the radiation end of the unit 12 and the incident end of the light receiving unit 13 that receives the detection light 51. Therefore, the size of the test region 30 is the size of a range that can be on the light path of the detection light 51, and at least the distance between the radiation end and the incident end and the detection light generation unit 12 are the detection light 51. It depends on the radiation angle at which the light can be emitted and the light reception angle at which the light receiving unit 13 can receive the detection light 51.

The optical inspection device 10 according to the present embodiment acquires information related to the physical quantity inside the test object 40 without contacting the test object 40. Here, FIG. 2 shows the principle of acquiring information on the refractive index distribution inside the test object 40 as information on the physical quantity inside the test object 40 in the optical inspection device 10 according to the present embodiment. This will be described with reference to the schematic diagram shown. In FIG. 2, for example, it is assumed that light (electromagnetic wave) is radiated from the position A. At this time, consider a light beam radiated from position A and reaching position B.

The light ray (detection light 51) emitted from the position A may have a wavelength capable of transmitting or passing a substance (examination object 40) existing between the position A and the position B. That is, the light emitted from the position A may be selected according to the substance, and may be, for example, X-rays, visible light, or microwaves.

と表される。 Here, suppose that the distance along the optical path is s, the position vector on the optical path is r = r (s), and the refractive index at the point indicated by the position vector r = r (s) is n (r). , The equation of the ray that shows the ray path is

It is expressed as.

となる。ここで、ｒＡは位置Ａを示す位置ベクトルであり、ｒＢは位置Ｂを示す位置ベクトルであり、ｎ（ｒＡ）は位置Ａにおける屈折率であり、ｎ（ｒＢ）は位置Ｂにおける屈折率である。 Further, when the equation (1) is integrated along the ray path from the position A to the position B, the equation (1) becomes.

Will be. Here, rA is a position vector indicating the position A, rB is a position vector indicating the position B, n (rA) is the refractive index at the position A, and n (rB) is the refractive index at the position B. ..

と表される。式（３）を用いると、式（２）は、

と表される。ここで、ベクトルｅＡは位置Ａにおける光線方向を表す単位ベクトルであり、ベクトルｅＢは位置Ｂにおける光線方向を表す単位ベクトルである。 Here, assuming that the unit vector indicating the ray direction at the point indicated by the position vector r = r (s) is e = e (r), the unit vector e is

It is expressed as. Using equation (3), equation (2) becomes

It is expressed as. Here, the vector eA is a unit vector representing the ray direction at the position A, and the vector eB is a unit vector representing the ray direction at the position B.

と表される。したがって、光線経路上に屈折率分布５２が存在しない場合には、光線経路上の位置によらず、光線方向を表す単位ベクトルｅは一定である。この場合、位置Ａから放射されて位置Ｂへ到達できる光線の経路は、図２中に破線５３で示すように、位置Ａと位置Ｂとを通る直線である。 Here, for example, consider the case where the refractive index distribution 52 does not exist on the light path of the light beam radiated from the position A and can reach the position B. When the refractive index distribution 52 does not exist on the light path, the refractive index n (r) becomes constant in the light path. At this time, since n (rA) = n (rB), the equation (4) is:

It is expressed as. Therefore, when the refractive index distribution 52 does not exist on the ray path, the unit vector e representing the ray direction is constant regardless of the position on the ray path. In this case, the path of the light beam radiated from the position A and can reach the position B is a straight line passing through the position A and the position B as shown by the broken line 53 in FIG.

On the other hand, when the refractive index distribution 52 exists on the ray path, the vector eA and the vector eB are different because n (rA) = n (rB) is not satisfied. That is, when the refractive index distribution 52 exists on the ray path, the ray direction at the position A of the ray radiated from the position A and can reach the position B is different from the ray direction at the position B. In this case, the path of the light beam radiated from the position A and can reach the position B is different from that of the broken line 53, as shown by the solid line 54 in FIG. 2, for example. That is, when the vector eA and the vector eB are different, it can be expressed that the refractive index distribution 52 exists on the ray path.

In this way, the presence or absence of the refractive index distribution 52 on the ray path can be confirmed by comparing the vector eA and the vector eB. Further, when the vector eA is constant, the change in the vector eB can be expressed as indicating a change in the refractive index distribution 52 on the ray path. However, even in this case, if the vector eB in the state where the refractive index distribution 52 does not exist on the ray path (standard state) can be obtained, the change of the vector eB between the standard state and the state at an arbitrary time can be obtained. , It can be expressed as showing the existence of the refractive index distribution 52.

Here, the operation of the optical inspection device 10 according to the present embodiment will be described. In the present embodiment, the case where the test object 40 is a gas will be described as an example. Therefore, in the optical inspection device 10 according to the present embodiment, for example, as shown in FIG. 1, the radiation end of the detection light generating unit 12 corresponds to the above-mentioned position A, and the incident end of the light receiving unit 13 corresponds to the above-mentioned position B. Corresponds to. That is, the optical inspection device 10 acquires information related to the refractive index distribution on the light path of the detected light 51 between the detected light generating unit 12 and the light receiving unit 13 as information related to the physical quantity inside the test object.

When the test object 40 is a liquid or a solid, the light beam path in the test object 40 may be considered among the light path paths in the test region 30. In this case, the light ray direction of the detection light 51 also changes when the detection light 51 enters the test object 40 in the test area 30 and when the detection light 51 emits from the test object 40 in the test area 30. Can be. Therefore, for example, in the light path in the subject 40, the end (front surface) on the detection light generating portion 12 side may be set to position A, and the other end (light receiving portion 13 side, back surface) may be set to position B.

First, consider, for example, a case where the optical inspection device 10 according to the present embodiment can acquire the first light ray direction (vector eA). In this case, the processing circuit 14 acquires the first light ray direction as a reference direction. The light receiving unit 13 measures the second light ray direction (vector eB) of the detection light 51 that has passed through the light receiving object 40. The light receiving unit 13 outputs the measured information related to the second light ray direction to the processing circuit 14. The processing circuit 14 acquires the second light ray direction as the passing light ray direction of the passing light (detection light 51) that has passed through the test object 40. The processing circuit 14 compares the acquired reference ray direction with the passing ray direction. Based on the comparison result, the processing circuit 14 acquires information on the presence or absence of the refractive index distribution 52 on the light path of the detection light 51 as information on the physical quantity inside the test object 40. Here, when the reference ray direction and the passing ray direction are the same, it is determined that the refractive index distribution 52 does not exist on the ray path of the detection light 51 (passing light). On the other hand, when the reference ray direction and the passing ray direction are different, it is determined that the refractive index distribution 52 exists on the ray path of the detection light 51 (passing light). Such a determination is made by, for example, the processing circuit 14, but is not limited to this. Various determinations related to the acquisition of information related to the physical quantity inside the test object 40 may be performed by a processing circuit outside the optical inspection device 10 or by the user. In these cases, the processing circuit 14 may output information necessary for the determination. In this way, the optical inspection device 10 according to the present embodiment inspects the inside of the test object 40 in a non-contact manner, and refracts the inside of the test object 40 as information related to the physical quantity inside the test object 40. It can be obtained by detecting the presence or absence of a rate distribution.

When the first ray direction (vector eA) can be acquired as described above, the first ray direction (vector eA) may be calculated or acquired based on the output of the light receiving unit 13 in the standard state. .. Here, the standard state may include, for example, a state in which the refractive index distribution 52 does not exist inside the test object 40, a state in which the test object 40 does not exist inside the test region 30, and the like. Whether or not the refractive index distribution 52 does not exist inside the test object 40, such as when it is desired to perform an internal inspection of the test object 40 when pressure, temperature, stress, or the like is applied to the test object 40. It goes without saying that there may be cases where the is known. The first light ray direction (vector eA) may be calculated or acquired based on the output of the detection light generation unit 12, or may be calculated in advance according to the configuration of the detection light generation unit 12, and the optical inspection device 10 It may be recorded inside the.

Further, when the first ray direction (vector eA) can be acquired as described above, the light receiving unit 13 according to the present embodiment further acquires information related to the time-series change in the passing ray direction and sends the processing circuit 14 to the processing circuit 14. Output. The processing circuit 14 may update the reference ray direction based on the time series change. For example, the processing circuit 14 uses the acquired passing ray direction as the reference ray direction and compares it with the current passing ray direction. As a result of the comparison, when the reference ray direction and the passing ray direction are different, it is determined that the refractive index distribution 52 has changed. Based on such a comparison, the optical inspection device 10 according to the present embodiment inspects the inside of the test object 40 in a non-contact manner, and provides information on the physical quantity inside the test object 40 as information on the inside of the test object 40. It can be obtained by detecting the presence or absence of a change in the refractive index distribution.

Next, for example, in the optical inspection apparatus 10 according to the present embodiment, a case where it can be guaranteed that at least the first light ray direction (vector eA) is constant will be considered. In this case, the processing circuit 14 acquires a time-series change in the second ray direction (vector eB) of the detection light 51 that has passed through the received subject 40. The processing circuit 14 acquires the second ray direction in the standard state from the time series change as the reference ray direction. Here, the standard state is a state in which the refractive index distribution on the light path is constant or can be regarded as constant. The acquisition of the reference ray direction is performed, for example, when the refractive index distribution is known to be constant before the start of the experiment, or when the displacement in the passing ray direction (incident angle) becomes less than a specific threshold value in a predetermined time. Etc. can be done. After that, the processing circuit 14 acquires the second ray direction as the passing ray direction and compares it with the reference ray direction. The processing circuit 14 acquires information relating to a change in the refractive index distribution 52 on the light path of the detection light 51 (passing light) based on the comparison result between the reference light direction and the passing light direction. When the reference light direction and the passing light direction are different, the processing circuit 14 determines that the refractive index distribution 52 on the light path of the detection light 51 (passing light) has changed. In this way, the optical inspection device 10 according to the present embodiment performs an internal inspection of the test object 40 in a non-contact manner, and the test object is based on a time-series change in the second light ray direction (passing light ray direction). As information related to the physical quantity inside the 40, it is possible to detect and acquire a change in the refractive index distribution inside the test object 40.

When it can be determined that the refractive index distribution 52 does not exist on the ray path when the reference ray direction is acquired, it is the same as the case where the first ray direction (vector eA) described above can be acquired. In addition, the presence or absence of the refractive index distribution 52 on the light path of the detection light 51 (passing light) can be acquired. That is, the optical inspection device 10 according to the present embodiment inspects the inside of the test object 40 in a non-contact manner, and based on the time-series change in the second light ray direction (passing light ray direction), the inside of the test object 40. As the information related to the physical quantity of, it can be expressed that the presence or absence of the refractive index distribution inside the test object 40 can be detected and acquired.

The case where the first ray direction and the second ray direction (passing ray direction) in the standard state are used as the reference ray direction has been described as an example, but the present invention is not limited to this. For example, the reference light direction may be the direction of the optical axis of the light receiving unit 13 or any direction of the user, and in any case, the same effect as described above can be obtained. In this case, it suffices if the relationship between the reference ray direction and the first ray direction is known.

As described above, the object for which the optical inspection device 10 according to the present embodiment detects the presence or absence or change of the refractive index distribution 52, that is, the test object 40 may be a gas, a liquid, or a liquid. It may be solid. The refractive index of a gas can vary, for example, depending on the type and density of the gas. Also, the density of a gas can change with the temperature and pressure of the gas, as explained by the equation of state of the gas. Further, the density of the gas may change depending on the component ratios constituting the gas, such as when different gas species are mixed. The refractive index of a liquid or solid can vary depending on, for example, the type of liquid or solid, internal stress, strain, density, temperature, pressure, or a combination thereof. In addition, the refractive index of the liquid or solid can change depending on the component ratios of the liquid or solid. Further, a pressure wave such as a sound wave propagating in a gas, a liquid, or a solid causes a density sparseness in the propagating medium, so that a refractive index can be generated in the medium. Therefore, the information related to the physical quantity inside the test object 40 acquired by the optical inspection device 10 according to the present embodiment is not limited to the information related to the presence or absence or change of the refractive index distribution, and the test object such as the above-mentioned density and the like. It may contain information on physical quantities that can affect the refractive index inside the 40.

Further, the target for the optical inspection device 10 according to the present embodiment to detect the presence / absence or change of the refractive index distribution may be a liquid or a solid moving in the gas, or a gas or a solid moving in the liquid. It may be a gas or a liquid that moves in a solid. That is, the optical inspection device 10 according to the present embodiment is a substance through which the detection light 51 can pass or pass, and the presence of the test object 40 in the test region 30 where the refractive index of the detection light 51 can change. It is also possible to detect and acquire the presence or absence of.

(Modification example related to acquisition of ray direction)
The acquisition of the second light ray direction (vector eB) when the detection light 51 is incident on the light receiving unit 13 is not limited to the method described in the above-described embodiment.

For example, the light receiving unit 13 may be configured such that a light receiving surface including a plurality of light receiving elements is arranged in a spherical shape. In this case, among the plurality of light receiving elements included in the light receiving unit 13, the light receiving element that has received the detection light 51 outputs the light receiving signal to the processing circuit 14. Further, the processing circuit 14 calculates the second light ray direction (vector eB) based on the position information in which the light receiving element is arranged. Even with such a configuration, the same effect as that of the above-described embodiment can be obtained. As long as the light receiving element can output the light receiving position, the same applies even if the light receiving surface of the light receiving element is formed in a spherical shape. Of course, in order to improve the detection accuracy, a plurality of spherical light receiving surfaces may be arranged in the optical axis direction of the light receiving unit 13.

For example, if the first light ray direction (vector eA) is constant, the light receiving unit 13 may be a luminance sensor or the like configured to detect the luminance distribution of a plane orthogonal to the vector eA. In this case, for example, the light beam diameter of the detection light 51 may be expanded according to the light receiving area of the luminance sensor and the light receiving optical system. Even with such a configuration, when a refractive index distribution occurs on the light path and the light direction changes, a luminance distribution can occur on the light receiving surface, so that the same effect as that of the above-described embodiment can be obtained. Can be

For example, if the first light ray direction (vector eA) when the detection light 51 is emitted is known, the light receiving unit 13 detects only the presence or absence of light reception for the light ray in the first light ray direction. May be. That is, the processing circuit 14 acquires the first ray direction as the reference ray direction. Further, the processing circuit 14 acquires the presence or absence of light reception of the detection light 51 in the reference light direction as information related to the passing light direction from the light receiving unit 13. When the light receiving unit 13 detects the detection light 51, the processing circuit 14 determines that the reference light direction and the passing light direction are the same, and determines that the refractive index distribution does not exist. Even with such a configuration, the effect of detecting and acquiring the presence or absence of the refractive index distribution can be obtained in the same manner as in the above-described embodiment.

For example, when a part of the detection light 51 (passing light) is scattered on the ray path, the ray position or the ray direction is acquired based on the scattered light on the ray path of the detection light 51 (passing light). It may be possible. In this case, for example, the light receiving unit 13 receives the scattered light and acquires an image including the light path of the passing light incident on the light receiving unit 13 as information related to the light ray direction. The processing circuit 14 performs image processing on the image, and can acquire the passing light direction based on the result of the image processing and the information related to the imaging direction of the light receiving unit 13. The light receiving unit 13 may include a scattering medium for the detection light 51 in the imaging range.

(Modified example of the first embodiment)
In the first embodiment, the optical inspection device 10 for measuring the second light ray direction (vector eB) of the detection light 51 by the light receiving unit 13 and acquiring information related to the physical quantity inside the test object 40 has been described. However, the measurement method is not limited to the above method. FIG. 3 shows a schematic diagram for explaining the measurement principle in the optical inspection device 10 according to the present modification. Hereinafter, the optical inspection apparatus 10 according to this modification will be described in detail with reference to the drawings.

As shown in FIG. 3, the light receiving unit 13 according to this modification has a light receiving optical system 16 that emits an incident light ray as a light ray position corresponding to the light ray direction at the time of incident light beam, and a light receiving surface that detects the light ray position. It includes an image sensor. The light receiving optical system 16 includes an imaging lens that forms an image of light rays emitted from the position A on the imaging surface 17 of the image pickup device. Here, for the sake of simplicity, a case where the optical axis of the imaging lens and the optical axis of the light receiving unit 13 are aligned and the imaging surface 17 is orthogonal to these optical axes will be described as an example. Here, it is assumed that the distance d between the imaging lens and the imaging surface 17 is known.

When the refractive index distribution 52 does not exist on the ray path, the ray path of the detection light 51 becomes a straight line as described above with reference to FIG. For example, consider a case where the light ray direction when the detection light 51 is emitted from the detection light generation unit 12 is the optical axis direction of the imaging lens, and the radiation end of the detection light generation unit 12 is on the optical axis. In this case, the detection light 51 is emitted from the position A as shown by the broken line 55 in FIG. 3, passes through the point C on the imaging lens, and is incident on the point A1 on the imaging surface 17. .. Here, the point C is a point on the optical axis of the imaging lens, and the light path passing through the position A, the point C, and the point A1 is a straight line.

On the other hand, when the refractive index distribution 52 exists on the light path, for example, as shown by the solid line 56 in FIG. 3, the refractive index distribution 52 exists in the light ray direction of the detection light 51 emitted from the position A. It is changed as it passes through the area of light. Therefore, the light ray direction (vector eB) of the detection light 51 when incident on the imaging surface 17 has an inclination with respect to the optical axis of the imaging lens. Therefore, the incident position of the detection light 51 shown as the position B in FIG. 3 on the imaging surface 17 changes according to the inclination angle φ which is the angle formed by the vector eB and the optical axis.

With such a configuration, the optical inspection device 10 according to the present modification can calculate the inclination angle φ as φ = arctan (Δl / d). Here, Δl is the distance between the point A1 and the position B.

As described above, the optical inspection device 10 according to the present modification is the second detection light 51 incident on the light receiving portion 13 based on the information on the incident position of the detection light 51 on the imaging surface 17 (light receiving surface). The ray direction (passing ray direction) can be obtained. That is, the optical inspection device 10 according to the present modification has the same advantages as the optical inspection device 10 according to the first embodiment.

In the optical inspection device 10 according to this modification, when the position A is sufficiently far from the imaging lens, the light ray direction of the detection light 51 radiated from the position A and reaches the imaging lens is imaged. It can be considered to be parallel to the optical axis of the lens. That is, if the first light ray direction (vector eA) when the detection light 51 is emitted is the optical axis direction, known information can be obtained without measurement. In this case, the processing circuit 14 acquires the optical axis direction as the reference ray direction.

Here, for example, consider the case where the refractive index of the ambient environment at the position A sufficiently far from the imaging lens and the position B on the imaging surface 17 are equal. At this time, the second term on the right side of the equation (4) is eA. That is, if the optical inspection device 10 according to the present modification acquires the second ray direction (vector eB) of the detection light 51 at the position B as described above, the first first detection light 51 is emitted. Since the light ray direction (vector eA) is known, it is possible to obtain information relating to the refractive index distribution 52 on the light ray path represented by the first term of the equation (4).

The optical inspection device 10 according to this modification can obtain the same effect as that of the above-described embodiment without calculating the light ray direction. In this case, the light receiving unit 13 outputs the information related to the position of the passing ray to the processing circuit 14 as the information related to the direction of the passing ray. Here, the calculation of the light beam position may be performed by the light receiving unit 13 or may be performed by the processing circuit 14. The processing circuit 14 acquires a reference ray position corresponding to the reference ray direction as information relating to the reference ray direction. The reference ray position may be measured in advance and recorded inside the optical inspection device 10, or the passing ray position corresponding to the passing ray direction in the standard state may be acquired and used. The processing circuit 14 compares the reference ray position (information related to the reference ray direction) and the passing ray position (information related to the passing ray direction). When the reference ray position and the passing ray position are different, the processing circuit 14 determines that the refractive index distribution exists on the ray path of the passing light (detection light 51). In this way, the optical inspection device 10 according to the present modification performs the internal inspection of the test object 40 in a non-contact manner without calculating the light ray direction, and uses it as information relating to the physical quantity inside the test object 40. , The presence or absence or change of the refractive index distribution inside the test object 40 can be detected and acquired.

The optical inspection device 10 according to the above-described embodiment and modification may use light rays having a plurality of wavelengths as the detection light 51. Similarly, the detection light 51 may be a light ray containing a plurality of wavelengths. As described above, the refractive index differs depending on the internal density of the test object 40 and the like, but even if the test object 40 is in the same state, it may differ depending on the wavelength of the electromagnetic wave used as the detection light 51. Are known. It can also be expressed that the wavelength dependence of the refractive index distribution 52 differs for each substance. That is, if the optical inspection device 10 uses light rays having a plurality of wavelengths as the detection light 51, information related to the refractive index distribution can be acquired for each of the detection lights 51 having a plurality of wavelengths. In this case, the light receiving unit 13 is configured to be able to output information related to the ray direction for each of at least two wavelengths. With such an optical inspection device 10, it is possible to acquire the wavelength dependence of the passing light (detection light 51) on the refractive index distribution. The optical inspection device 10 identifies a substance (examination object 40) existing in the test region 30 or limits a substance that may be present in the test region 30 based on the wavelength dependence. It has the effect of being able to do things.

According to the optical inspection device 10 according to the present embodiment, the following can be said.

The optical inspection device 10 according to the present embodiment has a light receiving unit 13 that outputs information related to the light ray direction of the received light beam (for example, the detection light 51) as a light receiving signal, and processes the received light signal to serve as a reference light beam. Based on the result of acquiring the information related to the direction and the information related to the passing light direction of the passing light passing through the test object 40 and comparing the information related to the reference light direction with the information related to the passing light direction. A processing circuit 14 for acquiring information related to the physical quantity inside the test object 40 is provided.

According to this configuration, when the first ray direction can be obtained as the reference ray direction from the outside and when the refractive index distribution does not exist inside the test object 40, the first ray direction is measured and used as the reference ray direction. If it can be obtained, the presence or absence of the refractive index distribution 52 inside the test object 40 is used as information related to the physical quantity inside the test object 40 from the comparison between the reference light ray direction and the measured passing light ray direction, and is not contacted. Can be detected and acquired with.

Further, according to this configuration, when the first ray direction is guaranteed to be constant, the change in the refractive index distribution 52 inside the test object 40 is obtained from the time-series change in the measured notification ray direction. Can be detected and acquired in a non-contact manner as information relating to the physical quantity inside the test object 40.

The optical inspection method according to the present embodiment receives the passing light (detection light 51) that has passed through the object 40, acquires the information related to the reference light direction as the reference light information, and receives the light. Based on the acquisition of the information related to the passing light direction of the passing light (detection light 51) as the passing light information, the comparison between the reference light information and the passing light information, and the result of the comparison. , Acquiring information on the physical quantity inside the test object 40. Here, the reference ray information is the reference ray direction, the output value of the light receiving unit 13 that can be converted into the reference ray direction, the reference ray position corresponding to the reference ray direction, and the light receiving light that can be converted into the reference ray position corresponding to the reference ray direction. The output value of unit 13 and the like are included. Further, the passing ray information can be converted into the passing ray direction, the output value of the light receiving unit 13 that can be converted into the passing ray direction, the passing ray position corresponding to the passing ray direction, and the passing ray position corresponding to the passing ray direction. Includes 13 output values and the like. According to this method, the above-mentioned effect can be obtained.

The optical inspection device 10 according to the present embodiment further includes a detection light generating unit 12 that emits detection light 51 having a wavelength capable of transmitting (or passing through) the test object 40 in the reference light direction as the light beam. The detection light generation unit 12 is, for example, an optical element such as a filter or a collimator. Further, the detection light generation unit 12 may further include a light source. According to this configuration, in addition to the above-mentioned effects, it is possible to easily use the first ray direction as known information as the reference ray direction and ensure that the first ray direction is constant. Further, the wavelength of the detection light 51 suitable for the object 40 can be selected.

The processing circuit 14 included in the optical inspection device 10 according to the present embodiment acquires the time-series change of the information related to the ray direction, and acquires the information related to the ray direction in the standard state as the information related to the reference ray direction. .. According to this configuration, the same effect as described above can be obtained even based only on the output of the light receiving unit 13.

The light receiving unit 13 included in the optical inspection device 10 according to the present embodiment can detect the light receiving optical system 16 having the light ray position of the light ray (detection light 51) as the light ray position corresponding to the light ray direction, and the light ray position. A light receiving surface (imaging surface 17) is provided, and the information related to the reference ray direction is the reference ray position corresponding to the reference ray direction, and the information related to the passing ray direction is the passage corresponding to the passing ray direction. The ray position. According to this configuration, in addition to the above-mentioned effect, the presence or absence or change of the refractive index distribution inside the test object 40 is detected in a non-contact manner based only on the information related to the light ray position without calculating the light ray direction. Can be obtained. Further, according to this configuration, when it can be considered that the radiation end of the detection light generation unit 12 is sufficiently far from the light receiving optical system 16, the first light ray direction is parallel to the optical axis of the light receiving optical system 16. Can be considered to be. That is, the first ray direction can be acquired as information related to the reference ray direction without measuring.

The light receiving unit 13 included in the optical inspection device 10 according to the present embodiment outputs information related to the light ray direction for each of at least two wavelengths, and the processing circuit 14 is inside the test object 40 based on the result. Acquires the wavelength dependence of the refractive index distribution 52 on the light path of the passing light (detection light 51), and based on the wavelength dependence, provides information on the substance constituting the test object 40 to the test object 40. It is acquired as information related to the physical quantity inside. According to this configuration, in addition to the above-mentioned effects, it is possible to identify the substance constituting the test object 40 in a non-contact manner.

(Second Embodiment)
Hereinafter, the optical inspection apparatus 10 according to the present embodiment will be described in detail with reference to the drawings. Here, the differences from the first embodiment will be mainly described, and the same parts will be designated by the same reference numerals and the description thereof will be omitted.

First, the configuration of the optical inspection device 10 according to the present embodiment will be described. A schematic diagram of a configuration example of the optical inspection device 10 according to the present embodiment is shown in FIG. In FIG. 4, in addition to the outline of the configuration example of the optical inspection device 10, the test area 30 is schematically shown.

As shown in FIG. 4, the optical inspection device 10 according to the present embodiment further includes an acoustic wave generation unit 19. The acoustic wave generation unit 19 generates and propagates an acoustic plane wave (elastic wave) inside the test object 40. The acoustic plane wave (acoustic wave) may be an ultrasonic wave.

The acoustic wave generation unit 19 according to the present embodiment is an acoustic plane wave inside the test object 40 in a direction along the light path of the detection light 51 emitted by the detection light generation unit 12 according to the present embodiment. Is configured to propagate. At this time, the wave surface of the acoustic plane wave and the line segment connecting the radiation end of the detection light generation unit 12 and the incident end of the light receiving unit 13 are orthogonal to each other. Further, the acoustic wave generation unit 19 can generate an acoustic plane wave capable of generating a diffracted wave inside the test object 40 due to interference with the refractive index distribution on the propagation path. Here, the diffracted wave can change the refractive index distribution on the light path of the detection light 51.

The test object 40 according to the present embodiment may be a gas, a liquid, a solid, or a mixture of at least two of a gas, a liquid, and a solid.

For example, when the test object 40 is a gas, the acoustic wave generation unit 19 generates an acoustic plane wave in the gas (test object 40) existing inside the test region 30. In this case, the acoustic wave generating unit 19 is, for example, a plane wave speaker, a flat panel speaker, or the like. Further, the radiating end of the detection light 51 in the detection light generation unit 12 is set to the position A, and the incident end of the detection light 51 in the light receiving unit 13 is set to the position B.

For example, when the test object 40 is a liquid or a solid, the acoustic wave generation unit 19 generates an acoustic plane wave (elastic wave) inside the test object 40 existing inside the test region 30. In this case, the acoustic wave generation unit 19 may be, for example, a laser oscillator that irradiates the test object 40 with excitation light for generating elastic waves inside the test object 40. Further, the excitation light may be a short pulse laser light. The wavelength of the excitation light is a wavelength included in the absorption wavelength of the test object 40. Further, the end of the test object 40 on the light path of the detection light 51 on the detection light generating portion 12 side is set as the position A, and the other end (the end on the light receiving portion 13 side) is set as the position B.

Hereinafter, as shown in FIG. 4, a case where the test object 40 is a gas and the acoustic plane wave is an elastic wave propagating in the gas will be described as an example. That is, in the present embodiment, the light ray direction on the ray path is considered for the detection light 51 that can be emitted from the position A and incident on the position B.

Next, the operation of the optical inspection device 10 according to the present embodiment will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic diagram for explaining the measurement principle of the optical inspection device 10 according to the present embodiment, and shows a state before the acoustic plane wave 60 reaches the refractive index distribution 52. Further, FIG. 6 is a schematic diagram for explaining the measurement principle in the optical inspection device 10 according to the present embodiment, in which the acoustic plane wave 60 further propagates from the state shown in FIG. 5 in the propagation direction 61, and the acoustic plane wave 60 is further propagated. Shows the state after reaching the refractive index distribution 52.

Here, for example, consider the case where a density distribution exists near the center inside the test object 40. However, it is assumed that the density is constant in other regions near the center. At this time, the refractive index distribution 52 corresponding to the density distribution exists inside the test object 40.

In the following description, for the sake of simplicity, it is assumed that the refractive index n (rA) at the position A and the refractive index n (rB) at the position B are the same. However, as described above, the present technology is established even if the refractive index n (rA) at the position A and the refractive index n (rB) at the position B are different.

The detection light generation unit 12 according to the present embodiment emits the detection light 51 from the position A or so as to pass through the position A. Further, the light receiving unit 13 receives the detection light 51 emitted from the position A or passed through the position A. Here, it is assumed that the light path of the detection light 51 is a straight line passing through the position A and the position B when there is no refractive index distribution between the position A and the position B.

The acoustic wave generation unit 19 according to the present embodiment generates an acoustic plane wave 60 inside the test object 40 so as to propagate along a straight line passing through the position A and the position B, that is, in the propagation direction 61. That is, the wave plane of the acoustic plane wave 60 and the straight line passing through the position A and the position B are orthogonal to each other. Here, the direction from the position A to the position B is defined as the Z direction, and the unit direction vector in the Z direction is defined as the vector eZ.

となる。したがって、位置Ａにおける第１の光線方向と位置Ｂにおける第２の光線方向とは一致し、位置Ａと位置Ｂとの間で光線方向は変化しない。 Here, first, as shown in FIG. 5, consider the state before the acoustic plane wave 60 reaches the refractive index distribution 52. At this time, it is assumed that the refractive index n (rA) at the position A and the refractive index n (rB) at the position B are the same, and there is a refractive index distribution 52 between the position A and the position B. Since it is not done, equation (4) is

Will be. Therefore, the first ray direction at position A and the second ray direction at position B coincide with each other, and the ray direction does not change between position A and position B.

Next, as shown in FIG. 6, consider a state after the acoustic plane wave 60 further propagates from the state shown in FIG. 5 in the propagation direction 61 and the acoustic plane wave 60 reaches the refractive index distribution 52. At this time, the diffracted wave 63 is generated from the interference between the acoustic plane wave 60 and the refractive index distribution 52.

となる。ここで、ベクトルｅｒは、中心位置Ｏを基準とする動径方向の単位ベクトルであり、式（７）の右辺の第１項におけるｇｒａｄ＜ｎ（ｒ）ｅｒ＞は、回折波６３により生じる光線経路上の屈折率の勾配である。式（７）の右辺の第１項の表すベクトル量は、第１項内の被積分の屈折率の動径方向微分が正ならば動径方向を向き、負ならば動径方向と反対方向を向く。すなわち、動径方向に沿って屈折率が高くなる場合、第１項は動径方向へ向くベクトル量を表すこととなる。これにより、光線方向は、動径方向に沿って屈折率が高くなる方向に曲げられることがわかる。すなわち、位置Ａと位置Ｂとの間で光線方向は変化する。また、当該光線方向の変化は、検知光５１の光線経路と回折波６３が発生した位置との位置関係に依存するとも表現できる。すなわち、受光部１３の入射端における検知光５１（通過光）の第２の光線方向（通過光線方向）の変化に係る情報は、被検物４０の内部の屈折率分布５２の位置に係る情報を含む。 The diffracted wave 63 generated in this way propagates from the center position O of the refractive index distribution 52 in the propagation direction d63, for example. Here, the propagation direction d63 is the radial direction with respect to the center position O. After that, the diffracted wave 63 propagating in the propagation direction d63 reaches the light path of the detection light 51 and interferes with the detection light 51. At this time, the equation (4) is

Will be. Here, the vector er is a unit vector in the radial direction with respect to the center position O, and the gradient <n (r) er> in the first term on the right side of the equation (7) is a light ray generated by the diffracted wave 63. The gradient of the refractive index on the path. The vector quantity represented by the first term on the right side of the equation (7) is in the radial direction if the radial differential of the refractive index of the integrand in the first term is positive, and in the opposite direction to the radial direction if it is negative. Turn to. That is, when the refractive index increases along the radial direction, the first term represents a vector amount directed in the radial direction. As a result, it can be seen that the direction of the light beam is bent in the direction in which the refractive index increases along the radial direction. That is, the direction of the light beam changes between the position A and the position B. It can also be expressed that the change in the ray direction depends on the positional relationship between the ray path of the detection light 51 and the position where the diffracted wave 63 is generated. That is, the information related to the change in the second light ray direction (passing light ray direction) of the detection light 51 (passing light) at the incident end of the light receiving unit 13 is the information related to the position of the refractive index distribution 52 inside the test object 40. including.

As described above, the acoustic wave generation unit 19 according to the optical inspection device 10 according to the present embodiment generates an acoustic plane wave 60 inside the test object 40. The acoustic plane wave 60 propagates inside the test object 40 and interferes with the refractive index distribution 52 on the propagation path to generate a diffracted wave 63. The diffracted wave 63 changes the refractive index or the refractive index distribution on the light path of the detection light 51 (passing light). Here, the optical inspection device 10 according to the present embodiment has the same information as the optical inspection device 10 according to the first embodiment, in the information related to the reference light direction and the passing light direction of the detection light 51 (passing light). Obtain and compare with such information. That is, the optical inspection device 10 according to the present embodiment can acquire the presence / absence or change of the refractive index distribution 52 on the propagation path of the acoustic plane wave 60 as the presence / absence or change of the refractive index distribution on the ray path of the detection light 51. That is, the optical inspection device 10 according to the present embodiment detects and acquires the presence / absence or change of the refractive index distribution derived from the density distribution on the propagation path of the acoustic plane wave 60 inside the test object 40 in a non-contact manner. can do. Further, as described above, the range in which the optical inspection device 10 according to the present embodiment can detect the presence / absence or change of the refractive index distribution is not limited to the light path of the detection light 51. That is, the optical inspection device 10 according to the present embodiment can detect and acquire the presence / absence or change of the refractive index distribution that is not on the light path of the detection light 51 by including the acoustic wave generation unit 19.

(First modification of the second embodiment)
In the second embodiment, when the refractive index distribution is generated by the density distribution, the optical inspection device 10 that detects and acquires the presence or absence or change of the density distribution in the test object 40 has been described as an example. Not limited to this.

For example, when the detection target of the optical inspection device 10, that is, the test object 40 is a gas, the refractive index inside the test object 40 depends on the type, temperature, pressure, density, etc. of the gas that is the test object 40. Can change. Further, for example, when the test object 40 is a liquid or a solid, the refractive index inside the test object 40 can change depending on the type, temperature, internal stress, strain, density, etc. of the test object 40. That is, the information related to the physical quantity inside the test object 40 that can be acquired by the optical inspection device 10 according to the present embodiment includes the information related to the physical quantity that can change the refractive index inside the test object 40. As described above, the optical inspection device 10 according to this modification acquires the information related to the passing light direction of the detection light 51 or the information related to the time-series change in the passing light direction, and obtains the acoustic plane wave inside the test object 40. There is an effect that information related to physical quantities on the propagation path of 60 can be detected and acquired in a non-contact manner.

The change in the physical quantity that contributes to the change in the refractive index inside the test object 40 may occur in a part of the inside of the test object 40 as described above, or occurs in the entire test object 40. You may. In any case, the optical inspection device 10 according to the present modification can detect and acquire a change in the physical quantity inside the test object 40 in a non-contact manner.

(Second variant of the second embodiment)
The above-mentioned measurement may be performed by changing the relative position between the test object 40 and the light path of the detection light 51. For example, the optical inspection device 10 according to the above-described embodiment can detect and acquire the refractive index distribution 52 in which direction with respect to the light ray path by acquiring the change in the second light ray direction. That is, according to the optical inspection device 10 according to the present modification, information or passage related to the second light ray direction (passing light ray direction) at each relative position between the test object 40 and the plurality of light ray paths of the detection light 51. By acquiring the time-series change of the information related to the light ray direction, there is an effect that the position of the refractive index distribution can be estimated. Similarly, an optical inspection device 10 capable of reconstructing the shape of the refractive index distribution is also conceivable.

According to the optical inspection device 10 according to the present embodiment, the following can be said.

The optical inspection device 10 according to the present embodiment includes a detection light generating unit 12 that emits detection light 51 having a wavelength capable of transmitting (or passing through) the test object 40 as the light beam in the reference light direction, and a test object. The passing light (detection light) is generated from the interference with the diffraction coefficient distribution 52 on the propagation path of the acoustic wave (acoustic plane wave 60) inside the test object 40 while generating the acoustic wave (acoustic plane wave 60) inside the 40. The processing circuit 14 further includes an acoustic wave generating unit 19 capable of generating a diffracted wave 63 that changes the refractive index distribution on the light path of 51), and the processing circuit 14 is an acoustic wave (acoustic plane wave) inside the test object 40. The presence or absence or change of the refractive index distribution 52 on the propagation path of 60) is acquired as information relating to the physical quantity inside the test object 40. According to this configuration, the presence or absence or change of the refractive index distribution 52 on the path through which the acoustic plane wave 60 inside the test object 40 passes can be detected and acquired in a non-contact manner. That is, the refractive index distribution 52 that can be detected is not limited to the refractive index distribution 52 that exists on the light path of the detection light 51 (passing light). Further, the information related to the change in the second light ray direction (passing light direction) of the detection light 51 (passing light) includes the refractive index distribution 52 inside the test object 40 and the light path of the detection light 51 (passing light). Contains information about the relative position of.

The acoustic wave generation unit 19 included in the optical inspection device 10 according to the present embodiment propagates the acoustic wave (acoustic plane wave 60) along a straight line connecting the detection light generation unit 12 and the light receiving unit 13. According to this configuration, the interference between the acoustic plane wave 60 and the detection light 51 can be reduced, so that an effect that the detection accuracy can be improved can be obtained in addition to the above-mentioned effect.

In the optical inspection device 10 according to the present embodiment, the wave surface of the acoustic wave (acoustic plane wave 60) is substantially orthogonal to the straight line connecting the detection light generation unit 12 and the light receiving unit 13. As described above, in the optical inspection device 10 according to the present embodiment, the straight line and the propagation direction 61 of the acoustic wave (acoustic plane wave 60) are substantially parallel to each other. According to this configuration, the interference between the acoustic plane wave 60 and the detection light 51 (passing light) can be further reduced, so that an effect that the detection accuracy can be further improved can be obtained in addition to the above-mentioned effect.

The acoustic wave generation unit 19 included in the optical inspection device 10 according to the present embodiment radiates a short pulse laser beam toward the test object 40 to generate the acoustic wave (acoustic plane wave 60). According to this configuration, for example, when the test object 40 is a solid, a steep elastic wave (acoustic plane wave 60) can be generated in the vicinity of the surface 41 of the test object 40, so that the detection accuracy is improved. Can be planned.

(Third Embodiment)
Hereinafter, the optical inspection apparatus 10 according to the present embodiment will be described in detail with reference to the drawings. Here, the differences from the second embodiment will be mainly described, and the same parts will be designated by the same reference numerals and the description thereof will be omitted.

FIG. 7 shows an outline of a configuration example of the optical inspection device 10 according to the present embodiment as a schematic diagram. In FIG. 7, a schematic view showing a cross section of the test sample (test object 40) is also shown. In the present embodiment, the case where the test object 40 is a solid will be described as an example. The solid sample used as the test object 40 may be any solid sample, for example, a metal (including an alloy) such as SUS (stainless steel), Au, Al, Cu, W, Ti, or a non-carbon or amorphous carbon. It may be metal. Further, the test object 40 may be a semiconductor such as Si or SiC, or a resin such as acrylic or polycarbonate. Further, the test object 40 may have a structure such as a multilayer film inside.

Hereinafter, in the present embodiment, as shown in FIG. 7, a case where the test object 40 has an interface 64 inside will be described as an example. Further, in the following description, as shown in FIG. 7, the depth direction of the test object 40 is the Z direction, and the direction from the front surface 41 to the back surface 42 of the test object 40 is the Z + direction. The direction from the back surface 42 to the front surface 41 will be described as the Z-direction. Here, the Z-direction position of the front surface 41 of the test object 40 is Z41, the Z-direction position of the back surface 42 of the test object 40 is Z42, and the Z-direction position of the interface 64 is Z64.

As shown in FIG. 7, the optical inspection device 10 according to the present embodiment includes an excitation light generating unit 11. The excitation light generation unit 11 according to the present embodiment generates an elastic wave (acoustic plane wave) propagating in the Z direction inside the test object 40 inside the test object 40. That is, the excitation light generation unit 11 according to the present embodiment may be included in the acoustic wave generation unit 19 according to the second embodiment. The excitation light generation unit 11 according to the present embodiment includes, for example, a light source and a condensing optical system. With this condensing optical system, the light from the light source can be irradiated in a spot shape on the irradiation surface. The excitation light generating unit 11 irradiates the excitation light 65 toward the surface 41 of the test object 40. The excitation light 65 emitted from the excitation light generation unit 11 is absorbed near the surface of the test object 40 or the inner surface of the test object 40. At this time, stress is generated inside the test object 40 according to the distribution of the light absorption density, and elastic waves (acoustic waves) are generated in the vicinity of the irradiation surface (surface 41). The pulse width (thickness in the Z direction) of the elastic wave is about the same as the light penetration length of the excitation light 65. Here, the light penetration depth represents a typical Z-direction depth at which light can penetrate the test object 40.

The light source included in the excitation light generating unit 11 according to the present embodiment is, for example, a YAG laser. Further, it is assumed that the excitation light 65 emitted by the excitation light generation unit 11 is a short pulse laser light. Here, in the present embodiment, for the short pulse laser light used as the excitation light 65, the pulse width (pulse width with respect to the time-series change of the laser intensity) is, for example, picoseconds or less, for example, several hundred fs (femtoseconds). Suppose there is. Further, it is assumed that the wavelength of the excitation light 65 is, for example, 532 nm (second harmonic).

However, the light source included in the excitation light generating unit 11, the wavelength of the light emitted by these light sources, and the pulse width are not limited to the above description. For example, the light source of the excitation light 65 may be selected according to the physical properties of the sample used as the test object 40, the wavelength required for the excitation light 65, and the like, even if it is a solid-state laser such as a YVO4 laser or a YLF laser. It may be a gas laser such as an excitation laser.

The detection light generation unit 12 according to the present embodiment includes, for example, an X-ray light source and a condensing optical system. With this condensing optical system, the light emitted from the X-ray light source can be irradiated in a spot shape on the irradiation surface as parallel light. The detection light generating unit 12 irradiates the detection light 51 so as to enter the surface 41 of the test object 40 at an incident angle θ. Here, the incident angle θ has an angle in the vicinity of the Bragg angle that satisfies the Bragg condition of the crystal structure of the test object 40 as a perspective angle. That is, the sum of the incident angle θ and the Bragg angle is a value near π / 2.

The light receiving unit 13 according to the present embodiment includes a light receiving surface 20. The light receiving unit 13 is configured to be able to detect the incident position (light ray position) of the detection light 51 emitted from the detection light generation unit 12 and transmitted or passed through the inside of the test object 40 to the light receiving surface 20. The light receiving unit 13 outputs the acquired light beam position to the processing circuit 14. The light receiving unit 13 may be a light receiving element such as a line sensor or an area sensor that can measure the light receiving position (light ray position) of X-rays.

Next, the operation of the optical inspection device 10 according to the present embodiment will be described with reference to the drawings.

As shown in FIG. 7, for example, the detection light generating unit 12 according to the present embodiment detects an X-ray ray so as to enter the surface 41 of the test object 40 at an incident angle θ whose perspective angle is close to the Bragg angle. It radiates as light 51. The detection light 51 that has entered the inside of the test object 40 from the front surface 41 passes through or passes through the test object 40 and is emitted from the back surface 42. At this time, the light ray direction of the detection light 51 is refracted and changed in the interface 64, but returns to the state when it is incident on the interface 64 when it leaves the interface 64. That is, it can be considered that the light ray direction of the detection light 51 according to the present embodiment does not change even if it passes through the interface 64. The detection light 51 (passing light) emitted from the back surface 42 is received by the light receiving surface 20 included in the light receiving unit 13. At this time, the light receiving unit 13 detects the light ray position P on the light receiving surface 20 and outputs the information related to the light ray position P to the processing circuit 14 as a light receiving signal. The processing circuit 14 uses information related to the light beam position P of the detection light 51 (passing light) before the excitation light 65 is irradiated, that is, before the elastic wave is excited to the test object 40, as information related to the reference light beam position. It is acquired from the light receiving unit 13 and recorded. The record here may be a temporary retention of the value.

As shown in FIG. 7, for example, the excitation light generating unit 11 according to the present embodiment irradiates the surface 41 of the test object 40 with the excitation light 65. The excitation light 65 is absorbed in the vicinity of the surface 41 of the test object 40. At this time, stress is generated in the vicinity of the surface 41 according to the light absorption density distribution of the test object 40, and an acoustic plane wave (elastic wave) is generated in the vicinity of the irradiation surface (surface 41). The pulse width (thickness in the Z direction) of the elastic wave generated in this way is substantially equal to the light penetration length of the excitation light 65.

Here, FIG. 8 shows a diagram showing the state of the optical inspection device 10 and the test object 40 before the acoustic plane wave (elastic wave 66) propagating inside the test object 40 reaches the interface 64, as a schematic diagram. .. The elastic wave 66 generated in the vicinity of the surface 41 propagates in the Z + direction inside the test object 40, as indicated by the propagation direction 67. Here, the position of the elastic wave 66 in the Z direction is referred to as Z66. That is, the state shown in FIG. 8 can be expressed as a state in which the elastic wave 66 propagates in the Z + direction and the position Z66 of the elastic wave 66 is between the position Z41 and the position Z64. ..

The elastic wave 66 propagating inside the test object 40 in this way propagates the local strain of the test object 40 based on the stress generated in the vicinity of the surface 41 inside the test object 40. Here, an example of the strain distribution inside the test object 40 in the state shown in FIG. 8 is shown in FIG. 9 as a schematic diagram. In the graph shown in FIG. 9, the horizontal axis shows the position in the Z direction inside the test object 40, and the vertical axis shows the strain amount σ inside the test object 40. As shown in FIG. 9, strain is locally generated at the position Z66 where the elastic wave 66 exists. Further, this strain distribution is propagated in the Z + direction indicated by the direction 70 as the elastic wave 66 propagates in the Z + direction.

As shown in FIG. 8, X-rays (detection light 51) incident on the inside of the subject 40 at an incident angle θ in which the perspective angle is close to the angle satisfying the Bragg condition are in the direction of the strain propagating by the elastic wave 66. Depends on causing side slip. That is, the light path (light ray position) of the detection light 51 (passing light) after passing through the elastic wave 66 is changed by the elastic wave 66. For example, as shown in FIG. 8, the ray path of the passing light (detection light 51) after the ray position is changed is on an extension of the ray path before reaching the elastic wave 66 as shown by the broken line 68. There is no light path, and the light path is parallel to the broken line 68. The direction of the strain described above does not mean the direction in which the strain is propagated as shown in the direction 70, but means the positive or negative of the strain amount σ.

The detection light 51 slid sideways by the elastic wave 66 is emitted from the back surface 42 and incident on the light receiving surface 20. The light receiving unit 13 detects a light ray position Q (light receiving position) on the light receiving surface 20 of the detection light 51 (passing light) slipped sideways by the elastic wave 66, and information related to the light ray position Q (information related to the passing light beam position). Is output to the processing circuit 14 as a light receiving signal.

In the processing circuit 14, the light receiving unit receives information related to the light beam position Q of the detection light 51 that has caused lateral slip after the excitation light 65 is irradiated, that is, the elastic wave is excited to the test object 40 as information related to the passing light beam position. Obtain from 13 and record. The record here may be a temporary retention of the value. Further, the processing circuit 14 compares the light ray position P (information related to the reference light ray position) and the light ray position Q (information related to the passing light ray position), and sets the lateral slip amount Δx as the light receiving surface 20 which is an X-ray light receiving element. The amount of deviation of the light ray position in is calculated.

Here, FIG. 10 shows a diagram showing the state of the optical inspection device 10 and the test object 40 after the acoustic plane wave (elastic wave 66) propagating inside the test object 40 reaches the interface 64, as a schematic diagram. .. The elastic wave 66 that has reached the interface 64 is reflected at the interface 64 due to the difference in the refractive index of the test object 40 through the interface 64. The elastic wave 66 reflected at the interface 64 propagates in the Z- direction as indicated by the propagation direction 71. That is, the state shown in FIG. 10 is expressed as a state in which the elastic wave 66 propagates in the Z- direction and the position Z66 of the elastic wave 66 is between the position Z41 and the position Z64. it can.

Here, an example of the strain distribution inside the test object 40 in the state shown in FIG. 10 is shown in FIG. 11 as a schematic diagram. In the graph shown in FIG. 11, the horizontal axis shows the position in the Z direction inside the test object 40, and the vertical axis shows the strain amount σ inside the test object 40. As shown in FIG. 11, strain is locally generated at the position Z66 where the elastic wave 66 exists. Further, this strain distribution is propagated in the Z-direction indicated by the direction 74 as the elastic wave 66 propagates in the Z-direction.

When the elastic wave 66 is reflected at the interface 64, the sign of the direction of the strain propagated by the elastic wave 66 (positive or negative of the strain amount σ) is reversed by the density difference of the test object 40 through the interface 64. For example, as shown in FIG. 9, after the elastic wave 66 propagating a positive strain amount σ from the surface 41 in the Z- direction is reflected at the interface 64, the elastic wave 66 becomes negative as shown in FIG. The strain amount σ of is propagated from the interface 64 in the Z + direction.

As described above, in the state shown in FIG. 10, the direction of the propagated strain of the elastic wave 66 is reversed as compared with the state shown in FIG. As described above, the X-ray (detection light 51) incident on the inside of the test object 40 at the incident angle θ whose perspective angle is close to the Bragg angle causes lateral slip depending on the direction of the strain propagating by the elastic wave 66. Wake up. That is, the light path of the detection light 51 (passing light) after passing through the elastic wave 66 shown in FIG. 10 is a broken line as compared with the light path of the detection light 51 after passing through the elastic wave 66 shown in FIG. The ray path is at a position inverted with respect to the extension of the ray path before reaching the elastic wave 66 as shown by 72.

The light receiving unit 13 detects the light ray position R on the light receiving surface 20 of the detection light 51 (passing light) whose light beam position has been changed by being slid sideways by the elastic wave 66 shown in FIG. It is output to the processing circuit 14 as a light receiving signal.

The processing circuit 14 receives the light beam position R of the detection light 51 (passing light) caused by the elastic wave propagating from the interface 64 toward the surface 41 after the elastic wave 66 is reflected at the interface 64. Obtained from, and recorded as information related to the position of the passing ray. The record here may be a temporary retention of the value. Further, the processing circuit 14 compares the light ray position P (information related to the reference light ray position) and the light ray position R (information related to the passing light ray position), and shifts the light ray position on the light receiving surface 20 which is an X-ray light receiving element. Calculate the amount of side slip from the amount. For example, the amount of lateral slip calculated here is −Δx.

In this way, when the elastic wave 66 reaches the interface and is reflected, the sign of the amount of lateral slip detected by the light receiving unit 13 changes, so that the light receiving signal output by the light receiving unit 13 changes. That is, the optical inspection device 10 according to the present embodiment measures the time-series change of the received light signal, so that the elastic wave 66 is excited to the surface 41 and then propagates inside the test object 40 to interface. The time (propagation time) from reaching 64 or after the elastic wave 66 is reflected at the interface 64 to propagating inside the test object 40 and reaching the surface 41 can be calculated.

The elastic wave 66 travels inside the test object 40 at a sound velocity peculiar to the test object 40. For example, the speed of sound of amorphous carbon is about 6 nm / ps. That is, when the velocity of the elastic wave 66 is known in this way, the optical inspection device 10 according to the present embodiment is based on the propagation time of the elastic wave 66 calculated as described above and the sound velocity. Therefore, it has an effect that the film thickness between the surface 41 and the interface 64 in the test object 40 can be measured.

In the present embodiment, the case where the test object 40 has the interface 64 has been described as an example, but the present invention is not limited to this. The elastic wave 66 can also be reflected, for example, on the back surface 42 of the test object 40 which does not have an interface 64 inside. In this case, the refractive index of the test object 40 and the external refractive index of the test object 40 are different from each other through the back surface 42 of the test object 40. That is, the back surface 42 can be expressed as an interface 64 existing inside the test object 40. Therefore, by using the optical inspection device 10 according to the present embodiment, it is possible to measure the thickness of the single-layer test object 40.

According to the optical inspection device 10 according to the present embodiment, the following can be said.

The optical inspection device 10 according to the present embodiment has a light receiving unit 13 that outputs information related to the light ray position of the received light ray as a light receiving signal, and processes the light receiving signal to serve as a reference light ray position (light ray position P). Information related to the above and information related to the position of the passing light ray of the light ray passing through the test object 40 (light ray position Q, light ray position R), information related to the reference light ray position and information related to the passing light ray position. It is provided with a processing circuit 14 for acquiring information related to the physical quantity inside the test object based on the result of comparison (side slip amount). According to this configuration, the presence or absence of distortion such as an acoustic plane wave (for example, elastic wave 66) inside the test object 40 can be detected and acquired in a non-contact manner.

The optical inspection device 10 according to the present embodiment includes a detection light generating unit 12 that emits detection light 51 having a wavelength capable of transmitting (or passing through) the test object 40 to the reference light position as the light beam, and a test object. Sound wave generation that generates an acoustic wave (elastic wave 66) that is reflected at the interface 64 existing inside the 40 and the propagation direction changes, and the position of the passing light beam can be changed according to the change in the propagation direction. A unit 19 (excitation light generation unit 11) is further provided, and the processing circuit 14 is based on the propagation speed of the acoustic wave (elastic wave 66) and the time-series change of the passing ray position with respect to the reference light position. As information related to the physical quantity inside the 40, the thickness between the surface 41 on the side where the acoustic wave generating portion 19 (excitation light generating portion 11) of the test object 40 is located and the interface 64 is acquired.

According to this configuration, it is possible to generate a side slip of the detection light 51 (passing light) according to the direction of strain of the elastic wave 66 and change the position of the passing light ray with respect to the reference light beam position. That is, the position of the passing ray with respect to the position of the reference ray can be changed according to the propagation direction of the elastic wave 66. Therefore, the elastic wave 66 between the surface 41 and the interface 64 is set as the time from the time when the elastic wave 66 is generated to the time when the sign of the lateral slip amount calculated by comparing the reference ray position and the passing ray position changes. Propagation time can be obtained. The propagation time of the elastic wave 66 between the surface 41 and the interface 64 is a code of the amount of lateral slip calculated by comparing the reference ray position and the passing ray position from the time when the elastic wave 66 is reflected at the interface 64. Can also be calculated as the time until when changes. Here, if the propagation velocity of the elastic wave 66 is known, the thickness (film thickness) between the surface 41 and the interface 64 can be obtained. The back surface 42 may be included in the interface 64 existing inside the test object 40. Therefore, in the case of the single-layer test object 40, the thickness of the test object 40 is obtained.

In the optical inspection apparatus 10 according to the present embodiment, the time-series change of the passing ray position with respect to the reference ray position is from the time when the passing ray position with respect to the reference ray position changes to the time when the ray position further changes. Includes time-related information. Here, the propagation time of the elastic wave 66 is such that the position of the passing light beam changes a plurality of times, such as the time from when the elastic wave 66 starts propagating from the surface 41 to when it reaches the surface 41 again after being reflected at the interface 64. It may be calculated as an average value from the time taken and the number of changes.

The detection light generation unit 12 included in the optical inspection device 10 according to the present embodiment is configured to be capable of radiating X-rays as detection light 51, and detects an object 40 at an incident angle θ near an angle satisfying the Bragg condition. Light 51 is incident. According to this configuration, since the detection light 51 can be incident on the inside of the test object 40, it is possible to generate a lateral slip of the detection light 51 according to the direction of strain of the elastic wave 66. Therefore, it is possible to acquire information related to the physical quantity inside the test object 40 based on the change in the light beam position. Further, by using X-rays having high straightness as the detection light 51, the wave surface of the elastic wave 66 does not have to be orthogonal to the straight line passing through the detection light generation unit 12 and the light receiving unit 13. is there.

The acoustic wave generation unit 19 (excitation light generation unit 11) included in the optical inspection device 10 according to the present embodiment radiates a short pulse laser beam toward the test object 40 to generate an acoustic wave (elastic wave 66). Let me. According to this configuration, for example, when the test object 40 is a solid, a steep elastic wave 66 can be generated in the vicinity of the surface 41 of the test object 40, so that the detection accuracy can be improved. it can.

The acoustic wave generation unit 19 (excitation light generation unit 11) included in the optical inspection device 10 according to the present embodiment propagates an acoustic wave (elastic wave 66) along a straight line connecting the detection light generation unit 12 and the light receiving unit 13. Let me. According to this configuration, the position of the passing light beam of the detection light 51 (passing light) can be changed according to the strain direction of the elastic wave 66.

The optical inspection method according to the present embodiment receives the passing light (detection light 51) that has passed through the object 40, acquires the information related to the reference light position as the reference light information, and receives the light. Based on the acquisition of information related to the position of the passing ray of the passing light (detection light 51) as the passing ray information, the comparison between the reference ray information and the passing ray information, and the result of the comparison. This includes acquiring information on the physical quantity inside the test object 40. Here, the reference ray information includes the reference ray position, the output value of the light receiving unit 13 that can be converted into the reference ray position, and the like. Further, the passing ray information includes the passing ray position, the output value of the light receiving unit 13 that can be converted into the passing ray position, and the like. In addition, the comparison result includes the amount of displacement from the reference ray position to the passing ray position, the sign of the displacement amount, the time-series change of the passing ray position with respect to the reference ray position, and the like. According to this method, the above-mentioned effect can be obtained.

It should be noted that one embodiment can be realized by appropriately combining each of the above embodiments and each modification. For example, a modified example relating to the acquisition of the ray direction of the first embodiment, a modified example of the first embodiment and the second embodiment, a first modified example of the first embodiment and the second embodiment, and the like. Can be combined.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.
The inventions described in the claims at the time of filing the patent application of the original application of the present application are added below.
[1]
A light receiving unit that outputs information related to the direction of the light received as a light receiving signal, and a light receiving unit.
The received signal is processed to acquire information related to the reference light direction as a reference and information related to the passing light direction of the passing light passing through the test object, and the information related to the reference light direction and the passing light are obtained. An optical inspection apparatus including a processing circuit for acquiring information related to a physical quantity inside the test object based on a result of comparison with information related to a direction.
[2]
The optical inspection apparatus according to [1], wherein the information relating to the physical quantity inside the test object is the presence or absence or change of the refractive index distribution on the light path of the passing light inside the test object.
[3]
The optical inspection apparatus according to [1], further comprising a detection light generating unit that emits detection light having a wavelength that can pass through the test object as the light beam in the direction of the reference light beam.
[4]
The optical inspection apparatus according to [1], wherein the processing circuit acquires time-series changes in information related to the light ray direction, and acquires information related to the light ray direction in a standard state as information related to the reference light ray direction.
[5]
The light receiving unit includes a light receiving optical system in which the light ray position is set to the light ray position corresponding to the light ray direction, and a light receiving surface capable of detecting the light ray position.
The information related to the reference ray direction is the reference ray position corresponding to the reference ray direction.
The information related to the passing ray direction is the passing ray position corresponding to the passing ray direction.
The optical inspection apparatus according to [1].
[6]
The light receiving unit outputs information related to the light ray direction for each of at least two wavelengths.
Based on the result, the processing circuit acquires the wavelength dependence related to the refractive index distribution of the passing light on the light path inside the test object, and based on the wavelength dependence, the test object. The information related to the substances constituting the test object is acquired as the information related to the physical quantity inside the test object.
The optical inspection apparatus according to [1].
[7]
A detection light generating unit that emits detection light having a wavelength that can pass through the test object as the light beam in the direction of the reference light beam.
An acoustic wave is generated inside the test object, and the refractive index distribution of the passing light on the light path is changed due to interference with the refractive index distribution of the acoustic wave inside the test object. Further equipped with an acoustic wave generator capable of generating a diffracted wave
The processing circuit acquires the presence or absence or change of the refractive index distribution on the propagation path of the acoustic wave inside the test object as information related to the physical quantity inside the test object.
The optical inspection apparatus according to [1].
[8]
The optical inspection apparatus according to [7], wherein the wave surface of the acoustic wave is substantially orthogonal to a straight line connecting the detection light generating portion and the light receiving portion.
[9]
The optical inspection device according to [7], wherein the acoustic wave generating unit emits a short pulse laser beam toward the test object to generate the acoustic wave.
[10]
A light receiving unit that outputs information related to the position of the received light beam as a light receiving signal, and a light receiving unit.
The received signal is processed to acquire information related to the reference light beam position as a reference and information related to the passing light beam position of the light ray passing through the test object, and the information related to the reference light beam position and the passing light beam are obtained. An optical inspection apparatus including a processing circuit for acquiring information related to a physical quantity inside the test object based on a result of comparison with information related to a position.
[11]
A detection light generating unit that emits detection light having a wavelength that can pass through the test object as the light beam at the reference light beam position.
An acoustic wave generating unit that generates an acoustic wave that reflects at an interface existing inside the test object to change the propagation direction and can change the position of the passing light beam according to the change in the propagation direction. Further prepare
The processing circuit uses the acoustic wave of the test object as information relating to the physical quantity inside the test object based on the propagation speed of the acoustic wave and the time-series change of the passing ray position with respect to the reference light beam position. Obtain the thickness between the surface on the side where the generation part is located and the interface.
[10] The optical inspection device according to the above.
[12]
The time-series change of the passing ray position with respect to the reference ray position includes information relating to the time from the change of the passing ray position with respect to the reference ray position to the further change of the ray position [11]. The optical inspection device described.
[13]
The optics according to [11], wherein the detection light generating unit is configured to be capable of radiating X-rays as the detection light, and causes the detection light to be incident on the subject at an angle of incidence near an angle satisfying the Bragg condition. Inspection equipment.
[14]
The optical inspection device according to [11], wherein the acoustic wave generating unit emits a short pulse laser beam toward the test object to generate the acoustic wave.
[15]
The optical inspection device according to [11], wherein the acoustic wave generating unit propagates the acoustic wave along a straight line connecting the detection light generating unit and the light receiving unit.
[16]
Receiving the passing light that has passed through the subject and
Acquiring information related to the reference ray direction or reference ray position as reference ray information as reference ray information,
Acquiring information related to the passing ray direction or the passing ray position of the received passing light as passing ray information, and
Comparing the reference ray information with the passing ray information,
An optical inspection method including obtaining information on a physical quantity inside the test object based on the result of the comparison.

10 ... Optical inspection device, 11 ... Excitation light generator, 12 ... Detection light generator, 13 ... Light receiving unit, 14 ... Processing circuit, 16 ... Light receiving optical system, 17 ... Imaging surface, 18 ... Control circuit, 19 ... Acoustic wave Generating part, 20 ... light receiving surface, 30 ... test area, 40 ... test object, 41 ... front surface, 42 ... back surface, 51 ... detection light, 52 ... refractive index distribution, 60 ... acoustic plane wave, 63 ... diffracted wave, 64 ... Interface, 66 ... elastic wave.

Claims (6)

A generator that generates detection light containing multiple wavelengths,
A light receiving unit that receives the detection light generated by the generating unit and has passed through the test object as passing light and outputs a light receiving signal.
The light receiving signal is processed to obtain the ray direction of the passing light for each of the plurality of wavelengths, and the test object is based on a comparison between the ray direction of the passing light and the reference ray direction of each of the plurality of wavelengths. A processing circuit that acquires wavelength dependence related to the refractive index distribution and acquires information related to the test object based on the wavelength dependence.
An optical inspection device comprising. The light receiving unit has a configuration capable of detecting the light receiving position of the light ray on the light receiving surface.
The processing circuit acquires the light ray direction of the passing light based on the light receiving position of the passing light detected by the light receiving unit.
The optical inspection apparatus according to claim 1. The optical inspection apparatus according to claim 2, wherein the light receiving unit includes an image sensor having the light receiving surface and an imaging lens that forms an image of the passing light that has passed through the test object on the light receiving surface. The optical inspection apparatus according to claim 1, wherein the processing circuit identifies a substance constituting the test object as information relating to the test object. Generates detection light containing multiple wavelengths,
The detection light generated by the generating unit and passing through the test object is received as passing light, and a light receiving signal is output.
The received signal is processed to obtain the light ray direction of the passing light for each of the plurality of wavelengths.
The wavelength dependence related to the refractive index distribution of the test object is obtained based on the comparison between the ray direction of the passing light and the reference ray direction of each of the plurality of wavelengths.
Obtaining information on the subject based on the wavelength dependence,
An optical inspection method that comprises the above. The light receiving signal is processed from the light receiving unit that receives the detection light generated by the generating unit that generates the detection light including a plurality of wavelengths and has passed through the test object as the passing light and outputs the light receiving signal, and the plurality of wavelengths. A function to acquire the light ray direction of the passing light for each, and
A function of acquiring the wavelength dependence related to the refractive index distribution of the test object based on the comparison between the ray direction of the passing light and the reference ray direction of each of the plurality of wavelengths, and
A function of acquiring information related to the test object based on the wavelength dependence, and
Optical inspection program to realize.

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