Spectroscopic measurement device and spectroscopic measurement method

Abstract

To provide a spectroscopic measurement device and a spectroscopic measurement method with which it is possible to adjust an optical system easily with good accuracy when spatial resolution need to be improved, and the environmental resistance performance of which is high.SOLUTION: According to a spectroscopic measurement device and a spectroscopic measurement method, light from a light source is divided into measurement light and reference light by a first splitter, and when a region on the surface of a sample and including two or more linear areas is irradiated with measurement light, light from the region is divided by a second splitter to generate divided light for each linear area. The direction of a divided light corresponding to the longer direction of the linear area pertaining to the divided light is adjusted by an adjuster. A spectrum is generated by a spectroscope, in which interference light for each linear area obtained by causing reference light to interfere with the divided light is spectroscopically separated at multiple points aligned in a direction corresponding to the longer direction. Then, the spectrum is acquired by an acquisition unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a spectroscopic measurement device and a spectroscopic measurement method. [Background technology]

[0002] Patent Document 1 discloses a two-dimensional spectroscopic measurement method for extracting optical information of a sample using an optical frequency comb. The two-dimensional spectroscopic measurement method generates a first optical frequency comb whose repetition frequency is four times the offset frequency, divides the first optical frequency comb into second to fifth optical frequency combs, and shifts the phases of the fourth and fifth optical frequency combs on the time axis by 90° from each other. The envelope intensity of the interference signal of the third and fourth optical frequency combs, either of which contains the optical information of the sample, and the interference signal of the third and fifth optical frequency combs, either of which contains the optical information of the sample, is obtained. Then, the optical information of the sample is extracted based on the envelope intensity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 167478 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the technology described in Patent Document 1, the phases are shifted by 90° by providing a delay distance to generate an interference signal, but in order to shift the phases accurately, the delay distance must be maintained with high precision. Also, the offset frequency, which is easily changed by environmental factors such as temperature changes, must be maintained with high precision. Therefore, there is a problem that it is difficult to adjust the optical system with high precision when improving the spatial resolution, and the environmental resistance is low.

[0005] The present disclosure has been made in view of the above-mentioned circumstances. That is, an object of the present disclosure is to provide a spectroscopic measurement device and a spectroscopic measurement method that are capable of easily and accurately adjusting an optical system when improving spatial resolution and have high environmental resistance. [Means for solving the problem]

[0006] The spectroscopic measurement device according to the present disclosure includes a first splitter, a second splitter, an adjuster, a spectroscope, and an acquisition unit. The first splitter splits light from a light source into a measurement light and a reference light. When the measurement light is irradiated onto an area including two or more linear areas on a surface of a sample, the second splitter splits reflected light from the area to generate split light for each of the linear areas. The adjuster adjusts the direction of the split light corresponding to the longitudinal direction of the linear area related to the split light. The spectroscope generates a spectrum by dispersing interference light for each of the linear areas, which is obtained by causing the reference light to interfere with the split light, at multiple points arranged in a direction corresponding to the longitudinal direction. The acquisition unit acquires the spectrum.

[0007] The spectroscopic measurement device may further include a slit, and the slit may shape a cross section of the divided light for each of the linear areas into a shape corresponding to the linear area.

[0008] The slit may be disposed at least at any one of an optical path of the divided light and an optical path of the interference light.

[0009] The light source may generate low coherence light or an optical frequency comb.

[0010] The adjuster may be constituted by at least one of a Dove prism and a mirror.

[0011] The acquisition unit may be configured with at least one of a light receiving element and an imaging camera.

[0012] Two or more of the interference lights may be introduced into the spectrometer.

[0013] The two or more interference lights may be arranged in series in a direction corresponding to the longitudinal direction of the linear area and introduced into the spectrometer.

[0014] Optical information relating to the shape of the linear area may be obtained based on the spectrum.

[0015] The optical information may be acquired continuously over time.

[0016] The acquisition unit may be connected to a controller, and the controller may calculate a shape of the linear area based on the spectrum.

[0017] The spectroscopic measurement method according to the present disclosure relates to a spectroscopic measurement device including a first splitter, a second splitter, an adjuster, a spectroscope, and an acquisition unit. The first splitter splits light from a light source into a measurement light and a reference light. When the measurement light is irradiated onto an area including two or more linear areas on a surface of a sample, the second splitter splits reflected light from the area to generate split light for each of the linear areas. The adjuster adjusts the direction of the split light corresponding to the longitudinal direction of the linear area related to the split light. The spectroscope generates a spectrum by dispersing interference light for each of the linear areas, which is obtained by causing the reference light to interfere with the split light, at multiple points arranged in a direction corresponding to the longitudinal direction. The acquisition unit acquires the spectrum. Effect of the Invention

[0018] According to the present disclosure, it is possible to provide a spectroscopic measurement device and a spectroscopic measurement method that can easily adjust an optical system with high accuracy when improving spatial resolution and have high environmental resistance. [Brief description of the drawings]

[0019] [Figure 1]FIG. 1 is a configuration diagram of a spectroscopic measurement device according to an embodiment of the present disclosure. [Diagram 2] 4 is a flowchart showing a processing procedure performed by the spectroscopic measurement device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, some exemplary embodiments will be described with reference to the drawings. In addition, common parts in each drawing are given the same reference numerals, and duplicated explanations will be omitted.

[0021] [Spectroscopic measurement equipment configuration] Fig. 1 is a configuration diagram of a spectroscopic measurement device according to an embodiment of the present disclosure. As shown in Fig. 1, the spectroscopic measurement device 1 includes a first splitter SP1, a second splitter SP2, an adjuster, a spectrometer PR, and an acquisition unit RV. In Fig. 1, the second splitter SP2 is shown as second splitters SP21 to SP24. The adjuster is shown as Dove prism DP1 and Dove prism DP3.

[0022] The spectroscopic measurement device 1 may include a slit M (slits M1 to M4). The spectroscopic measurement device 1 may also include a light source LD and a controller CP.

[0023] The light source LD generates low-coherence light or an optical frequency comb. The light source LD may include a light emitting element such as a laser diode that emits a continuous wave laser beam of a single frequency. Instead of the continuous wave laser beam of a single frequency, the light source LD may be a pulsed laser beam having an optical frequency comb.

[0024] Here, the light source capable of emitting the "low coherence light" is not particularly limited. For example, the light source LD may be any of various broadband light sources such as a super luminescent diode (SLD) or a super continuum light source.

[0025] An "optical frequency comb" is light with a comb-like frequency spectrum formed from multiple discrete, equally spaced lines. Despite being broadband light, an optical frequency comb has high coherence, so it can be used to measure shapes on the order of centimeters or more on the surface of a sample TG. An optical frequency comb can be used for interpulse interferometry, not only by interfering with its own pulse, but also by interfering with pulses that come before and after it in time. This makes it possible to measure even larger objects.

[0026] The first splitter SP1 splits the light from the light source LD into a measurement light and a reference light. In FIG. 1, the "measurement light" is shown as light traveling from the first splitter SP1 toward the sample TG. The "reference light" is shown as light traveling from the first splitter SP1 toward the mirror group G. The split ratio of the measurement light and the reference light by the first splitter SP1 may be preset or may be appropriately adjusted during measurement. The first splitter SP1 may be a half mirror.

[0027] The measurement light travels from the first splitter SP1 toward the sample TG and is irradiated onto the surface of the sample TG. FIG. 1 shows a state in which the measurement light is irradiated onto an area LR on the surface of the sample TG. Here, the area LR includes two or more linear areas. In FIG. 1, the area LR includes linear areas AR1 to AR4. The number and positional relationship of the linear areas included in the area LR are not limited to the example given here.

[0028] Each of the linear areas AR1 to AR4 is an area that extends in one direction, and each has a longitudinal direction. For example, the linear areas AR1 to AR4 are rectangular. Meanwhile, the lateral length of each of the linear areas AR1 to AR4 is sufficiently smaller than the longitudinal length. When the spatial resolution is to be increased when measuring the shape of the surface of the sample TG, the lateral length is determined according to the spatial resolution.

[0029] When the measurement light is irradiated onto the region LR, the reflected light from the region LR is guided to the second splitter SP2. In Fig. 1, the reflected light from the sample TG is guided to the second splitter SP2 via the intermediate splitter SP3. The reflected light from the region LR includes the reflected light from the linear areas AR1 to AR4.

[0030] The second splitter SP2 (second splitters SP21 to SP24) splits the reflected light from the region LR to generate split lights for each linear area. More specifically, the second splitter SP2 splits the reflected light so that the reflected light from a linear area is included in the split light associated with that linear area, to generate split lights equal to the number of linear areas.

[0031] For example, FIG. 1 shows how the reflected light from the region LR is split into four split lights. The split lights output from the second splitter SP21 include the reflected light from the linear area AR1. The split lights output from the second splitter SP22 include the reflected light from the linear area AR2. The split lights output from the second splitter SP23 include the reflected light from the linear area AR3. The split lights output from the second splitter SP24 include the reflected light from the linear area AR4. The number of second splitters is not limited to the example given here.

[0032] The split light generated by the second splitter SP2 then passes through a slit M (described later) and an adjuster (described later), and is then introduced into the spectrometer PR together with the reference light from the first splitter SP1. Therefore, the spectrometer PR receives interference light obtained by causing the reference light to interfere with the split light.

[0033] The split light generated by the second splitter SP2 may pass through the adjuster after passing through the slit M, or may pass through the adjuster and then pass through the slit M. In other words, the order of the slit M and the adjuster may be reversed. In the following, as shown in FIG. 1, the split light generated by the second splitter SP2 will be described as passing through the adjuster after passing through the slit M.

[0034] The slits M (slits M1 to M4) shape the cross section through which the divided light passes into a shape corresponding to each linear area. That is, the slits M pass a part of the divided light so that the divided light includes only the light reflected from the linear area. For example, if the linear areas AR1 to AR4 have a rectangular shape, the slits M1 to M4 have rectangular cuts corresponding to the linear areas AR1 to AR4, respectively. The slits M1 to M4 are configured to pass only the light reflected from the linear areas AR1 to AR4 through the cuts.

[0035] In FIG. 1, slit M1 shapes the cross section of the divided light so that only reflected light from linear area AR1 is included in the divided light. Slit M2 shapes the cross section of the divided light so that only reflected light from linear area AR2 is included in the divided light. Slit M3 shapes the cross section of the divided light so that only reflected light from linear area AR3 is included in the divided light. Slit M4 shapes the cross section of the divided light so that only reflected light from linear area AR4 is included in the divided light. The number of slits M is not limited to the example given here.

[0036] The slit M may be disposed at least in any one of the optical paths of the divided light and the optical path of the interference light. In other words, the order of the slit M and the adjuster may be reversed.

[0037] The adjuster (Dove prisms DP1 and DP3) adjusts the orientation of the split light beams corresponding to the longitudinal direction of the linear areas of the split light beams. More specifically, the adjuster rotates the split light beams around the traveling direction of the split light beam as a central axis to align the orientations of the split light beams among the multiple split light beams.

[0038] 1, the direction of the divided light including the reflected light from the linear area AR1 (divided light related to the linear area AR1) is the same as the direction of the divided light including the reflected light from the linear area AR3 (divided light related to the linear area AR3). The direction of the divided light including the reflected light from the linear area AR2 (divided light related to the linear area AR2) is the same as the direction of the divided light including the reflected light from the linear area AR4 (divided light related to the linear area AR4).

[0039] However, the direction of the divided light for linear area AR1 and the direction of the divided light for linear area AR3 are different from the direction of the divided light for linear area AR2 and the direction of the divided light for linear area AR4. The adjuster corrects this misalignment. As a result of the adjustment by the adjuster, the directions of the divided light for linear areas AR1 to AR4 are aligned.

[0040] For example, as shown in Fig. 1, when the adjuster is composed of Dove prisms DP1 and DP3, Dove prism DP1 changes the direction of the divided light for linear area AR1. Dove prism DP3 changes the direction of the divided light for linear area AR3. In Fig. 1, the direction of the divided light for linear area AR2 and the direction of the divided light for linear area AR4 are not changed, but they may be changed in the same way as the direction of the divided light for linear area AR1 and the direction of the divided light for linear area AR3. Split light that does not need to have its direction changed does not necessarily need to pass through the adjuster.

[0041] The adjuster may be composed of at least one of a Dove prism and a mirror. A Dove prism is a prism that can rotate or invert an image by setting the rotation angle of the prism or the light incident surface. A Dove prism can invert the incident light (image) upside down, or rotate the prism to rotate the image. Image rotation or inversion may also be achieved by combining multiple mirrors.

[0042] The spectrometer PR separates the interference light for each linear area obtained by causing the reference light to interfere with the divided light. When separating the interference light, the spectrometer PR generates a spectrum by dispersing the interference light at multiple points aligned in a direction corresponding to the longitudinal direction of the linear area.

[0043] For example, the spectrometer PR may be an imaging spectrometer capable of simultaneous multipoint spectroscopy in a linear area. By using the imaging spectrometer, it is possible to generate a spectrum for each point included in the linear area.

[0044] In addition, two or more interference lights may be introduced into the spectrometer PR. Specifically, a plurality of interference lights related to different linear areas may be simultaneously introduced into the spectrometer PR, and a spectrum may be simultaneously generated for the introduced plurality of interference lights. In this case, the two or more interference lights may be arranged in series in a direction corresponding to the longitudinal direction of the linear area and introduced into the spectrometer PR.

[0045] For example, FIG. 1 shows four interference lights related to linear areas AR1 to AR4 being introduced into the same spectrometer PR to generate spectra C1 to C4. Note that it is necessary to align the directions of the split lights among the multiple interference lights so that the multiple interference lights can be simultaneously introduced into one inlet of the spectrometer PR. In other words, it is necessary to align the longitudinal direction of the inlet of the spectrometer PR and the direction of the split light (the direction corresponding to the longitudinal direction of the linear area related to the split light). The adjuster described above is used to align the directions of the split lights related to the interference lights introduced into the same spectrometer PR.

[0046] The spectrometer PR included in the spectroscopic measurement device 1 may be one or more. The number of spectrometers PR is not limited to the example given here.

[0047] The acquisition unit RV acquires the spectrum generated by the spectrometer PR. By acquiring the spectrum by the acquisition unit RV, optical information related to the shape of the linear area can be acquired.

[0048] The acquisition unit RV may be configured with at least one of a light receiving element and an imaging camera. For example, the acquisition unit RV may generate an image by capturing a spectrum. The acquisition unit RV may also generate a video by capturing a spectrum.

[0049] Therefore, the acquisition unit RV may acquire a spectrum at a predetermined timing to acquire optical information at the predetermined timing. Also, the acquisition unit RV may acquire spectra continuously in time to acquire optical information continuously in time.

[0050] The controller CP is connected to the acquisition unit RV and calculates the shape of the linear area based on the spectrum acquired by the acquisition unit RV. Here, the controller CP is a general-purpose computer equipped with a CPU (Central Processing Unit), a memory, and an input / output unit. The controller CP may integrate the calculated shapes of the linear areas to calculate the shape of a region LR on the surface of the sample TG. Information related to the calculated shape may be presented to a user via the input / output unit.

[0051] [Processing procedure using spectroscopic measurement equipment] Next, a process procedure performed by the spectroscopic measurement device according to the present disclosure will be described with reference to a flowchart shown in FIG.

[0052] In step S101, a user of the spectroscopic measurement device 1 sets the optical system so that the shape of the surface of the sample TG corresponds to the region LR to be measured. For example, the optical system included in the spectroscopic measurement device 1 is set so that reflected light from the linear areas AR1 to AR4 is guided toward the spectroscope PR.

[0053] In step S103, the first splitter SP1 splits the light from the light source LD into a measurement light and a reference light.

[0054] In step S105, the area LR on the surface of the sample TG is irradiated with the measurement light.

[0055] In step S107, the second splitter SP2 splits the reflected light from the region LR to generate split light for each linear area.

[0056] In step S109, the adjuster adjusts the directions of the divided beams.

[0057] In step S111, the reference light is made to interfere with the divided light to generate an interference light.

[0058] In step S113, the spectrometer PR separates the interference light to generate a spectrum.

[0059] In step S115, the acquisition unit RV acquires the spectrum generated by the spectrometer PR.

[0060] [Effects of the embodiment] As described above in detail, in the spectroscopic measurement device and spectroscopic measurement method according to the present disclosure, the first splitter splits light from a light source into measurement light and reference light. When the measurement light is irradiated onto an area including two or more linear areas on the surface of a sample, the second splitter splits the reflected light from the area to generate split light for each linear area. The adjuster adjusts the direction of the split light corresponding to the longitudinal direction of the linear area related to the split light. The spectrometer generates a spectrum by dispersing interference light for each linear area obtained by causing the reference light to interfere with the split light at multiple points aligned in a direction corresponding to the longitudinal direction. Then, the acquisition unit acquires the spectrum.

[0061] This allows the optical system to be easily adjusted with high precision when improving spatial resolution, and improves environmental resistance. In addition, optical information related to the surface shape of the sample in multiple linear areas can be acquired all at once. Since only one spectrometer is required to acquire optical information all at once, the number of parts in the entire device can be reduced, enabling simplification. In addition, it is possible to reduce the effects of the distance of the optical path and temperature changes.

[0062] The spectroscopic measurement device may further include a slit. The slit may shape the cross section of the divided light for each linear area into a shape corresponding to the linear area. This allows only the reflected light related to the linear area being measured by the spectrometer to be introduced into the spectrometer. As a result, the accuracy of the spectrum measurement can be improved.

[0063] The slit may be disposed at least at any one of the optical paths of the split light and the optical path of the interference light. By increasing the degree of freedom in designing the optical system, it becomes possible to easily obtain optical information relating to the shape of the surface of the sample.

[0064] The light source may generate low-coherence light or an optical frequency comb. This allows optical information relating to the surface shape of the sample to be obtained with high accuracy. In particular, by using a light source capable of generating an optical frequency comb, it can be used for interpulse interference measurement in which a pulse is interfered with by pulses that come before and after in time. This makes it possible to measure even larger objects.

[0065] The adjuster may be composed of at least one of a Dove prism and a mirror. This allows the orientation of the split light to be adjusted to correspond to the longitudinal direction of the linear area of ​​the split light. As a result, the orientations of the split light associated with the interference light introduced into the same spectrometer can be easily aligned.

[0066] The acquisition unit may be configured with at least one of a light receiving element and an imaging camera. This makes it possible to change the imaging magnification of the spectrometer and the resolution of the acquisition unit, and to easily increase the spatial resolution when measuring the surface shape of the sample.

[0067] Two or more of the interference lights may be introduced into the spectrometer. This makes it possible to obtain optical information related to the surface shape of the sample in a plurality of linear areas at once. The number of spectrometers can be reduced. This reduces the number of parts in the entire device, enabling simplification. In addition, it is possible to make the device less susceptible to the effects of the distance of the optical path and temperature changes.

[0068] The two or more interference lights may be arranged in series in a direction corresponding to the longitudinal direction of the linear area and introduced into the spectrometer. In this way, by using a spectrometer capable of simultaneous multipoint spectroscopy of the linear area, optical information related to the surface shape of the sample in a plurality of linear areas can be acquired all at once.

[0069] The present invention may be configured to obtain optical information relating to the shape of the linear area based on the spectrum, thereby making it possible to obtain the shape of the surface of the sample.

[0070] The optical information may be acquired continuously over time, thereby making it possible to dynamically acquire the shape of the surface of the sample.

[0071] The acquisition unit may be connected to a controller. The controller may calculate a shape of the linear area based on the spectrum. This makes it possible to acquire the shape of the surface of the sample.

[0072] Although several embodiments have been described, the embodiments can be modified or modified based on the above disclosure. All components of the above embodiments and all features described in the claims may be individually extracted and combined as long as they are not mutually inconsistent. [Explanation of symbols]

[0073] 1. Spectroscopic measurement equipment AR1~AR4 Linear Area C1~C4 spectrum CP Controller DP1, DP3 Dove Prism (Adjuster) LD light source LR area M, M1~M4 slits PR spectrometer RV acquisition department SP1 1st splitter SP2, SP21~SP24 2nd splitter TG sample

Claims

1. a first splitter that splits light from a light source into a measurement light and a reference light; a second splitter that splits reflected light from an area including two or more linear areas on a surface of a sample when the measurement light is irradiated onto the area to generate split light for each of the linear areas; an adjuster for adjusting a direction of the divided light beam corresponding to a longitudinal direction of the linear area of ​​the divided light beam; a spectroscope for generating a spectrum by dispersing interference light for each linear area, which is obtained by causing the reference light to interfere with the divided light, at multiple points arranged in a direction corresponding to the longitudinal direction; An acquisition unit for acquiring the spectrum; A spectroscopic measurement device comprising:

2. The spectroscopic measurement device according to claim 1 , further comprising a slit for each of the linear areas, the slit forming a cross section of the divided light passing through the linear area into a shape corresponding to the linear area.

3. The spectroscopic measurement device according to claim 2 , wherein the slit is disposed at least at one of an optical path of the split light and an optical path of the interference light.

4. The spectroscopic measurement device according to claim 1 , wherein the light source generates low-coherence light or an optical frequency comb.

5. The spectroscopic measurement device according to claim 1 , wherein the adjuster is configured by at least one of a Dove prism and a mirror.

6. The spectroscopic measurement device according to claim 1 , wherein the acquisition unit is configured with at least one of a light receiving element and an imaging camera.

7. The spectroscopic measurement device according to claim 1 , wherein two or more of the interference lights are introduced into the spectroscope.

8. The spectroscopic measurement device according to claim 1 , wherein the two or more interference lights are arranged in series in a direction corresponding to a longitudinal direction of the linear area and are introduced into the spectroscope.

9. The spectroscopic measurement device according to claim 1 , further comprising: a measuring section configured to obtain optical information relating to a shape of the linear area based on the spectrum.

10. The spectroscopic measurement device according to claim 9 , wherein the optical information is acquired continuously in time.

11. 11. The spectroscopic measurement device according to claim 1, wherein the acquisition unit is connected to a controller that calculates a shape of the linear area based on the spectrum.

12. A spectroscopic measurement method for a spectroscopic measurement device including a first splitter, a second splitter, an adjuster, a spectrometer, and an acquisition unit, comprising: The first splitter splits the light from the light source into a measurement light and a reference light; When the measurement light is irradiated onto an area including two or more linear areas on a surface of a sample, the reflected light from the area is split by the second splitter to generate split light for each of the linear areas; adjusting a direction of the divided light beam corresponding to a longitudinal direction of the linear area of ​​the divided light beam by the adjuster; generating a spectrum by the spectroscope, the spectrum being obtained by dispersing interference light for each linear area obtained by causing the reference light to interfere with the divided light at multiple points arranged in a direction corresponding to the longitudinal direction; The spectrum is acquired by the acquisition unit.

Images