Spectroscopic measurement apparatus and spectroscopic measurement method

Abstract

To provide a spectrometry apparatus and a spectrometry method capable of inexpensively and accurately performing spectrometry with a simple configuration.SOLUTION: The spectral measurement device 1A includes a light source 3 that outputs light L1 whose wavelengths temporally change, an emission optical system 4 that emits the light L1 from the light source 3 to the object S, a photodetector 5 that detects the light L2 from the object S and outputs signal G1 based on a detection result, and a synchronous control unit 6 that synchronously operates the light source 3 and at least one of the emission optical system 4 and the photodetector 5.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] An example of a conventional spectroscopic measurement device is the spectroscopic measurement device described in Patent Document 1. This conventional spectroscopic measurement device includes a conveying means for conveying an object to be measured, a line-type hyperspectral camera for acquiring a hyperspectral image of the object to be measured on the conveying means for each field of view extending in a direction perpendicular to the conveying direction of the conveying means, an adjusting means for adjusting the field of view width of the hyperspectral camera, and a control means for controlling at least one of the conveying speed of the object to be measured, the frame rate of the hyperspectral camera, and the field of view width of the hyperspectral camera so that the resolution in the field of view width direction and the resolution in the conveying direction in the hyperspectral image acquired by the hyperspectral camera match. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-156777 Summary of the Invention [Problem to be solved by the invention]

[0004] The spectroscopic measurement device described in Patent Document 1 employs a so-called post-spectroscopic method in which diffusely reflected light from an object is separated by a spectroscope placed immediately before the light receiving unit. However, this type of spectroscopic method tends to have a relatively complicated configuration, and the manufacturing costs of the device are likely to increase.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a spectroscopic measurement device and a spectroscopic measurement method that can perform spectroscopic measurement with a simple configuration, at low cost, and with high accuracy. [Means for solving the problem]

[0006] The gist of the present disclosure is as follows.

[0007] [1] A spectroscopic measurement device comprising: a light source that outputs light whose wavelength changes over time; an irradiation optical system that irradiates an object with the light from the light source; a photodetector that detects the light from the object and outputs a signal based on the detection result; and a synchronization control unit that synchronizes the operation of the light source with at least one of the irradiation optical system and the photodetector.

[0008] This spectroscopic measurement device uses light whose wavelength changes over time, allowing the light to be split into multiple wavelengths and then irradiated onto an object. This spectroscopic measurement device is a so-called pre-spectroscopic method in which light that has been split into multiple different wavelengths in advance is irradiated onto the object. In the pre-spectroscopic method, the spectroscopic configuration can be separated from the detection side, and by changing the wavelength of the light quickly over time, spectroscopic measurement can be performed inexpensively and accurately with a simple configuration.

[0009] [2] The spectroscopic measurement device according to [1], further comprising a processing unit that generates spectroscopic data based on the signal output from the photodetector. By including the processing unit, it is possible to suitably measure various parameters based on the spectroscopic data.

[0010] [3] The spectroscopic measurement device according to [1] or [2], wherein the light source is a tunable light source configured to be able to control the wavelength of light. In this case, the tunable light source can precisely control the temporal change in wavelength, thereby improving the accuracy of spectroscopic measurement.

[0011] [4] The spectroscopic measurement device according to any one of [1] to [3], wherein the irradiation optical system includes an irradiation control unit that spreads or scans the light from the light source over the object, thereby enabling rapid acquisition of spectroscopic data over a wide range of the object.

[0012] [5] The spectroscopic measurement device according to any one of [1] to [4], wherein the photodetector is configured by a point sensor. In this case, the light from the object can be acquired with high accuracy by the point sensor.

[0013] [6] The spectroscopic measurement device according to any one of [1] to [4], wherein the photodetector is configured by an image sensor including a line sensor or an area sensor. In this case, light from the object can be acquired over a wide range by the line sensor or the area sensor.

[0014] [7] The spectroscopic measurement device according to any one of [1] to [6], wherein the synchronization control unit is included in the light source, and the light source outputs a synchronization signal to at least one of the irradiation optical system and the photodetector. With this configuration, synchronization between the light source and at least one of the irradiation optical system and the photodetector can be suitably performed.

[0015] [8] The spectroscopic measurement device according to any one of [1] to [6], further comprising a signal generator constituting the synchronization control unit, the signal generator outputting a synchronization signal to the light source and at least one of the irradiation optical system and the photodetector. With this configuration, synchronization between the light source and at least one of the irradiation optical system and the photodetector can be suitably performed.

[0016] [9] The spectroscopic measurement device according to any one of [1] to [8], wherein the irradiation optical system has an optical element that guides the light reflected by the object to the photodetector. In this case, the light reflected by the object (direct light) can be efficiently guided to the photodetector.

[0017]

[10] The spectroscopic measurement device according to any one of [1] to [9], further comprising a transport unit that transports the object in a predetermined direction in synchronization with the light source and at least one of the irradiation optical system and the photodetector under the control of the synchronization control unit. In this case, spectroscopic measurement of the object can be performed continuously. Furthermore, by controlling the movement speed of the object and synchronizing it with the light source and at least one of the irradiation optical system and the photodetector, the accuracy of the spectroscopic measurement can be ensured without performing complex correction calculations.

[0018]

[11] The spectroscopic measurement device according to

[10] , further comprising: a camera that captures an image of the position of the object being transported by the transport unit and outputs a signal based on the image capture result; and an output control unit that controls the light source so that light is output from the light source when the object is transported to a predetermined position based on the signal output from the camera. In this case, the light from the light source is irradiated onto the object at the timing when the object is transported to the predetermined position, thereby saving energy of the light source.

[0019]

[12] A spectroscopic measurement method comprising an output step of outputting light whose wavelength changes over time, an irradiation step of irradiating an object with the light, and a detection step of detecting light from the object and outputting a signal based on the detection result, wherein in the output step, the irradiation step, and the detection step, the output of the light is synchronized with at least one of the irradiation of the light onto the object and the detection of light from the object.

[0020] In this spectroscopic measurement method, by using light whose wavelength changes over time, it is possible to irradiate an object with light that has been split into multiple different wavelengths in advance. This spectroscopic measurement method is a so-called pre-spectroscopic method in which light that has been split into multiple different wavelengths in advance is irradiated onto the object. In the pre-spectroscopic method, the configuration for splitting the light can be separated from the detection side, so that by changing the wavelength of the light over time at high speed, spectroscopic measurement can be performed inexpensively with a simple configuration and with high accuracy. [Effects of the Invention]

[0021] According to the present disclosure, spectroscopic measurement can be performed inexpensively and accurately with a simple configuration. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a first embodiment of the present disclosure. [Figure 2] FIG. 1 is a block diagram showing the configuration of a pulse generating device which is an example of a light source. [Figure 3] 10(a) and 10(b) are diagrams schematically illustrating an example of spectral data. [Figure 4] 1 is a flowchart illustrating a spectroscopic measurement method according to an embodiment of the present disclosure. [Figure 5] FIG. 4 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a second embodiment of the present disclosure. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a third embodiment of the present disclosure. [Figure 7] FIG. 10 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a fourth embodiment of the present disclosure. [Figure 8] FIG. 10 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a fifth embodiment of the present disclosure. [Figure 9] FIG. 10 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a sixth embodiment of the present disclosure. [Figure 10] 10 is a schematic diagram showing the configuration of a spectroscopic measurement device according to another example of FIG. 9. FIG. [Figure 11] FIG. 13 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a seventh embodiment of the present disclosure. [Figure 12] FIG. 13 is a schematic diagram showing the configuration of a spectroscopic measurement device according to an eighth embodiment of the present disclosure. [Figure 13] FIG. 13 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a ninth embodiment of the present disclosure. [Figure 14] FIG. 14 is a schematic diagram showing the configuration of a spectroscopic measurement device according to another example of FIG. [Figure 15] FIG. 14 is a schematic diagram showing the configuration of a spectroscopic measurement device according to another example of FIG. [Figure 16] FIG. 22 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a tenth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, preferred embodiments of a spectroscopic measurement device and a spectroscopic measurement method according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0024] [First embodiment] FIG. 1 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a first embodiment of the present disclosure. The spectroscopic measurement device 1A shown in FIG. 1 is configured as a device that irradiates an object S with light (light beam) L1 and measures the shape of the object S based on light L2 from the object S. Applications of the spectroscopic measurement device 1A include, for example, film thickness inspection and defect inspection, and foreign matter inspection of foods and processed products. In this embodiment, the object S is a film, and the spectroscopic measurement device 1A is configured as a device that measures the film thickness of the film. As shown in FIG. 1, the spectroscopic measurement device 1A includes a conveying unit 2, a light source 3, an irradiation optical system 4, a photodetector 5, a synchronization control unit 6, and a processing unit 7.

[0025] The transport unit 2 is a part that moves the object S in a predetermined direction at a constant speed. In this embodiment, the transport unit 2 is configured, for example, by a belt conveyor, and transports the object S in the horizontal direction at a speed V. The transport unit 2 may also be configured by other conveyors such as a roller conveyor, a chain conveyor, a vibration conveyor, a screw conveyor, or a fluid conveyor. The transport unit 2 operates in synchronization with the light source 3 and at least one of the irradiation optical system 4 and the photodetector 5 under the control of a synchronization control unit 6 described below. The light source 3, the irradiation optical system 4, the photodetector 5, and at least the irradiation area R of the light L1 in the transport unit 2 may be covered by a dark box. In this case, it is possible to prevent external light from affecting the measurement.

[0026] In the following description, for convenience, a three-dimensional Cartesian coordinate system is defined by the D1-axis, D2-axis, and D3-axis. Here, the movement direction of the object S in the horizontal plane is defined as the D1-axis, the direction perpendicular to the movement direction in the horizontal plane is defined as the D2-axis, and the vertical direction perpendicular to the D1-axis and D2-axis is defined as the D3-axis.

[0027] The light source 3 is a device that outputs light L1 whose wavelength changes over time. Examples of the light source 3 include a wavelength-tunable light source configured to be able to control the wavelength, a wavelength-swept light source that continuously changes the wavelength, and a wavelength-selective light source that selectively outputs light of a specific wavelength from white light. In this embodiment, the pulsed light generating device 11 shown in FIG. 2 is used as the light source 3, which is a wavelength-tunable light source that can change the wavelength over time at high speed.

[0028] As shown in Fig. 2, the pulsed light generating device 11 includes an oscillator 12, a fiber amplifier 13, an acousto-optic modulator 14, a compressor 15, a soliton-shifted fiber 16, and a filter 17. The oscillator 12 generates an ultrashort pulsed light. The fiber amplifier 13 broadens the spectrum of the ultrashort pulsed light generated by the oscillator 12. Here, the fiber amplifier 13 broadens the spectrum and increases the output power of the ultrashort pulsed light by similariton amplification.

[0029] The acousto-optic modulator 14 controls the intensity of the ultrashort optical pulse for each pulse. The compressor 15 compresses the time width of the ultrashort optical pulse. The soliton-shift fiber 16 modulates the wavelength of the ultrashort optical pulse, which has been broadened and increased in power by the fiber amplifier 13, by using soliton self-frequency shift. The soliton-shift fiber 16 lengthens the wavelength of the ultrashort optical pulse to generate solitons. For example, a single-mode anomalous dispersion fiber that exhibits anomalous dispersion in the wavelength band of the ultrashort optical pulse generated by the fiber amplifier 13 can be used as the soliton-shift fiber 16. Solitons of different wavelengths can be generated by controlling the acousto-optic modulator 14. The shift wavelength of each soliton in the soliton train generated from the ultrashort optical pulse can be arbitrarily changed by applying intensity modulation to the pulse train using the acousto-optic modulator.

[0030] The filter 17 is a part that filters the ultrashort optical pulses whose wavelength has been modulated by the soliton shift fiber 16. The filter 17 cuts out non-soliton components of the ultrashort optical pulses. It is preferable to use a filter 17 that has an optical density of 3 or more. The pulsed optical generation device 11 described above can temporally change the wavelength of ultrashort optical pulses oscillated at 50 MHz in as little as 20 ns.

[0031] Returning to FIG. 1 , the irradiation optical system 4 is a system that irradiates the object S with light L1 from the light source 3. The irradiation optical system 4 includes, for example, an irradiation control unit 21 that expands or scans the light L1 from the light source 3 onto the object S, and an optical element 22 that guides the light L2 reflected by the object S to the photodetector 5. In this embodiment, the irradiation control unit 21 is configured with a line generator 23, and the optical element 22 is configured with a beam splitter 24. The line generator 23 can be, for example, a Powell lens. The Powell lens is a lens with a cylindrical aspherical shape that diffuses the incident light L1 in a fan shape to expand it into a line-shaped light having a uniform intensity distribution. In addition to the Powell lens, a cylindrical lens may also be used as the line generator 23.

[0032] The light L1 expanded into a line by the line generator 23 is reflected by the beam splitter 24 in the D3 axis direction, becoming a line of light along the D2 axis direction and irradiating a predetermined irradiation area R of the conveying section 2. As described above, the light L1 from the light source 3 is light whose wavelength changes over time. Therefore, in the irradiation area R, light of the same wavelength extends in a line along the D2 axis direction, while the wavelength of the light L1 changes along the D3 axis direction. As the object S passes through the irradiation area R, it moves in the D1 axis direction at a constant speed V while being irradiated with light L1 whose wavelength rapidly changes in the order of, for example, red, orange, yellow, green, blue, indigo, and purple. The light L2 from the object S is reflected light generated by the reflection of the light L1 on the surface of the object S or scattered light generated on the surface of the object S.

[0033] The photodetector 5 is a device that detects light L2 from the object S and outputs a signal G1 based on the detection result. In this embodiment, the photodetector 5 is configured with a line sensor 25. As the line sensor 25, for example, an InGaAs line sensor can be used. The detection axis of the line sensor 25 is arranged to coincide with the optical axis of the light reflected from the object S, and the line sensor 25 detects the reflected light of the light L2 from the object S that is generated by the reflection of the light L1 on the surface of the object S. The line sensor 25 performs one detection every time the wavelength of the light L2 from the object S, i.e., the wavelength of the light L1 from the light source 3, is switched, and outputs a signal G1 based on the detection result to the processing unit 7.

[0034] The synchronization control unit 6 is a part that synchronizes the operation of the light source 3 with at least one of the irradiation optical system 4 and the photodetector 5. In this embodiment, the synchronization control unit 6 is included in the light source 3, and further includes a delay generator 26. The synchronization control unit 6 controls the light source 3 as a primary and the photodetector 5 and transport unit 2 as secondary via the delay generator 26.

[0035] The light source 3, which functions as the synchronization control unit 6, outputs a synchronization signal G2 to the delay generator 26. The synchronization signal G2 may be a signal corresponding to a clock frequency that serves as a reference for turning pulsed light on and off or for the period of a wavelength that changes over time, or may be an externally output signal for electronic control that switches the wavelength of light L1 from the light source 3 to a specific wavelength. Based on the synchronization signal G2 input from the light source 3, the delay generator 26 synchronizes the frame rate Fr of the photodetector 5 and the moving speed V of the object S by the conveyance unit 2 with the period of the wavelength of light L1 that changes over time at the light source 3.

[0036] The processing unit 7 is a part that generates spectroscopic data D based on the signal G1 output from the photodetector 5. The processing unit 7 is physically configured by a computer 27 that includes memories such as RAM and ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, a storage unit such as an SSD or a hard disk, and a display unit such as a display. The processing unit 7 functions by having the CPU execute a program stored in the memory. The processing unit 7 may also be configured by a microcomputer, a PLC (programmable logic controller), an FPGA (field-programmable gate array), or the like.

[0037] Based on the signal G1 received from the photodetector 5, the computer 27 generates three-dimensional spectral data by accumulating two-dimensional luminance information of the object S in the time axis direction. FIGS. 3(a) and 3(b) are diagrams schematically showing an example of spectral data. As described above, the line sensor 25 performs one detection every time the wavelength of the light L1 from the light source 3 is switched. Therefore, the number of pixels in the D2 axis direction of the line sensor 25 is set to P. ny (=y1, y2, ...y n ), and the wavelength of light L1 switches n times during one cycle (=λ1, λ2, ... λ n ), the spectroscopic data for one cycle is as shown in Figure 3(a), P ny ×n two-dimensional luminance information. D is expressed by the following equation (1).

number

[0038] The computer 27 converts the obtained two-dimensional luminance information into spectral data S as shown in FIG. D Line spectrum data (hyperspectral data) L Convert the two-dimensional luminance information into spectral data S D Line spectrum data S from LWhen converting to , for example, averaging processing using weighted data from previous and subsequent cycles may be performed using the following formula (2): This makes it possible to mitigate the influence of positional deviation (movement by the conveying unit 2) of the object S at the timing when light L1 of each wavelength is irradiated.

number

[0039] The computer 27 converts the obtained spectral data S L In this embodiment, the computer 27 calculates predetermined parameters of the object S based on the obtained spectral data S L Based on the spectral data of the brightness information at, for example, two arbitrary positions on the object, the computer 27 plots the brightness against the wavelength at these positions. Based on the spacing between the interference fringes obtained from the plot of brightness against wavelength, the computer 27 calculates the thickness of the film on the object S at each of the arbitrary two positions, and displays the calculation results on the display unit.

[0040] 4 is a flowchart showing a spectroscopic measurement method according to an embodiment of the present disclosure. As shown in FIG. 4, this spectroscopic measurement method includes an output step S01, an irradiation step S02, a transport step S03, a detection step S04, a generation step S05, a calculation step S06, and a display step S07. The spectroscopic measurement method of this embodiment is performed using, for example, the spectroscopic measurement device 1A described above.

[0041] The output step S01 is a step of outputting light L1, whose wavelength changes over time, from the light source 3. The irradiation step S02 is a step of irradiating the light L1 output from the light source 3 onto the object S using the irradiation optical system 4. In the irradiation step S02, the irradiation optical system 4 guides the light L1 to the conveying unit 2, and an irradiation area R is formed in the conveying unit 2. The conveying step S03 is a step of moving the object S in a predetermined direction using the conveying unit 2. The conveying unit 2 moves the object S horizontally toward the irradiation area R at a constant speed V. The detection step S04 is a step of detecting the light L2 from the object S using the photodetector 5 and outputting a signal G1 based on the detection result.

[0042] In the output step S01, the irradiation step S02, and the detection step S04, the light source 3 and at least one of the irradiation optical system 4 and the photodetector 5 are operated in synchronization. In this embodiment, further, in the transport step S03, the transport unit 2 is synchronized with the light source 3 and at least one of the irradiation optical system 4 and the photodetector 5. When the spectroscopic measurement device 1A described above is used, the light source 3 serving as the synchronization control unit 6 outputs a synchronization signal G2 to the delay generator 26. Based on the synchronization signal G2 input from the light source 3, the delay generator 26 synchronizes the frame rate Fr of the photodetector 5 and the moving speed V of the object S by the transport unit 2 with the period of the wavelength of the light L1 that changes over time at the light source 3.

[0043] The generating step S05 is a step of generating spectral data D of the object S. In the generating step S05, three-dimensional spectral data is generated by accumulating two-dimensional luminance information of the object S in the time axis direction based on the signal G1 output in the detecting step S04. In addition, the spectral data S of the obtained two-dimensional luminance information is D The line spectrum data S L Convert the two-dimensional luminance information into spectral data S D Line spectrum data S from L When converting to the above, an averaging process may be performed using data from the previous and next cycles as weighting.

[0044] The calculation step S06 is a step of calculating predetermined parameters of the object S based on the spectral data D. Here, the film thickness of the film, which is the object S, is calculated based on the spectral data D generated in the generation step S05. The display step S07 is a step of displaying the calculation results. In the display step S07, the calculation results in the calculation step S06 are displayed on the display unit of the computer 27.

[0045] As described above, the spectroscopic measurement device 1A uses light L1 whose wavelength changes over time, so that the light L1 can be split temporally or spatially and irradiated onto the object S. This spectroscopic measurement device 1A is a so-called pre-spectroscopic method in which light L1 that has been split into a plurality of different wavelengths in advance is irradiated onto the object S. In the pre-spectroscopic method, the configuration for splitting can be separated from the detection side, so that by changing the wavelength of light L1 over time at high speed, spectroscopic measurement can be performed inexpensively with a simple configuration and with high accuracy.

[0046] In this embodiment, the spectroscopic measurement device 1A includes a processing unit that generates spectroscopic data based on the signal output from the photodetector. By including such a processing unit, it is possible to suitably measure various parameters based on the spectroscopic data. In this embodiment, the light source 3 is a wavelength-tunable light source that is configured to be able to control the wavelength of the light L1. In this case, the wavelength-tunable light source can accurately control the temporal change in wavelength. Therefore, the accuracy of spectroscopic measurement is improved.

[0047] In this embodiment, the irradiation optical system 4 includes a line generator 23 that expands the light L1 from the light source 3 toward the object S. By using such a line generator 23 as the irradiation control unit 21, it is possible to quickly acquire spectral data D for a wide range of the object S. In this embodiment, the photodetector 5 is configured with a line sensor 25. Therefore, the light L2 from the object S can be acquired over a wide range by the line sensor 25.

[0048] In this embodiment, the synchronization control unit 6 is included in the light source 3, and the light source 3 outputs a synchronization signal G2 to the line sensor 25 and the conveying unit 2 via a delay generator 26. With this configuration, the operations of the photodetector 5 and the conveying unit 2 can be suitably synchronized with respect to the temporal change in the wavelength of the light L1 output from the light source 3.

[0049] In this embodiment, the irradiation optical system 4 has a beam splitter 24 as the optical element 22 that guides the light L2 reflected by the object S to the photodetector 5. By employing such a beam splitter 24, the light L2 reflected by the object S (direct light) can be efficiently guided to the photodetector 5.

[0050] In this embodiment, the spectroscopic measurement device 1A includes a transport unit 2 that transports the object S in a predetermined direction in synchronization with the light source 3 and the photodetector 5 under the control of a synchronization control unit 6. In this case, by transporting the object S using the transport unit 2, spectroscopic measurement of the object S can be performed continuously. Furthermore, by controlling the movement speed V of the object S and synchronizing it with the light source 3 and the photodetector 5, the accuracy of the spectroscopic measurement can be ensured without performing complex correction calculations, etc.

[0051] [Second embodiment] Fig. 5 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a second embodiment of the present disclosure. The spectroscopic measurement device 1B shown in Fig. 5 differs from the first embodiment in the configuration of the synchronization control unit 6.

[0052] Specifically, the synchronization control unit 6 of the spectroscopic measurement device 1B includes a signal generator 31 instead of the delay generator 26. The signal generator 31 is a device that outputs a synchronization signal G2 to the light source 3 and at least one of the irradiation optical system 4 and the photodetector 5. In the example of FIG. 5, the signal generator 31 is configured by a pulse generator 32. The synchronization control unit 6 synchronously controls the pulse generator 32 as a primary and the light source 3, the photodetector 5, and the transport unit 2 as secondaries.

[0053] The spectroscopic measurement device 1B as described above also has the same advantageous effects as the first embodiment, and can perform spectroscopic measurement inexpensively and accurately with a simple configuration. Furthermore, by using a signal generator 31 as the synchronization control unit 6, synchronization of the light source 3, the photodetector 5, and the transport unit 2 can be suitably performed.

[0054] [Third embodiment] Fig. 6 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a third embodiment of the present disclosure. The spectroscopic measurement device 1C shown in Fig. 6 differs from the first embodiment in the configuration of the irradiation optical system 4.

[0055] Specifically, the irradiation optical system 4 of the spectroscopic measurement device 1C does not include a beam splitter 24, and light L1 expanded into a line by a line generator 23 is irradiated onto a predetermined irradiation area R of the transport unit 2 in a state inclined with respect to the D3 axis direction. The detection axis of the line sensor 25 is arranged so as not to coincide with the optical axis of the light reflected from the object S, and the line sensor 25 detects scattered light generated on the surface of the object S, of the light L2 from the object S. This spectroscopic measurement device 1C also achieves the same effects as the first embodiment, and can perform spectroscopic measurement inexpensively and accurately with a simple configuration.

[0056] [Fourth embodiment] Fig. 7 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a fourth embodiment of the present disclosure. The spectroscopic measurement device 1D shown in Fig. 7 differs from the first embodiment in the configuration of the irradiation optical system 4.

[0057] Specifically, the irradiation optical system 4 of the spectroscopic measurement device 1D is the same as in the first embodiment in that a beam splitter 24 is arranged, but the detection axis of the line sensor 25 is arranged so as not to coincide with the optical axis of the light reflected by the object S, and the line sensor 25 detects the scattered light generated on the surface of the object S out of the light L2 from the object S. In this spectroscopic measurement device 1D as well, the same effects as in the first embodiment are achieved, and spectroscopic measurement can be performed inexpensively and accurately with a simple configuration.

[0058] [Fifth embodiment] 8 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a sixth embodiment of the present disclosure. The spectroscopic measurement device 1E shown in FIG. 8 is configured to be able to sequentially measure a plurality of objects S transported by a transport unit 2.

[0059] Specifically, in the spectroscopic measurement device 1E, a plurality of lanes are set in the conveying unit 2, and the objects S in each lane move sequentially toward the irradiation area R. In the irradiation optical system 4 of the spectroscopic measurement device 1E, a plurality of line generators 23 constituting the irradiation control unit 21 are arranged between the beam splitter 24 and the conveying unit 2 so as to correspond to the respective lanes of the conveying unit 2. The spectroscopic measurement device 1E also includes a camera 41 that captures an image of the position of the objects S conveyed by the conveying unit 2. The camera 41 is arranged, for example, closer to the target than the irradiation area R in the conveying direction of the objects S, and outputs a signal G3 based on the image capture result to the computer 27.

[0060] In the spectroscopic measurement device 1E, the computer 27 also functions as an output control unit 42 that controls the output of light L1 from the light source 3. Based on the signal G3 output from the camera 41, the computer 27 as the output control unit 42 outputs a control signal G4 to the light source 3 so that light L1 is output from the light source 3 when the object S is transported to the irradiation area R. The computer 27 as the output control unit 42 controls the angle of the beam splitter 24 so that light L1 is incident only on the line generator 23 corresponding to the lane through which the object S is transported to the irradiation area R.

[0061] In the spectroscopic measurement device 1E, the synchronization control unit 6 is configured by a pulse generator 32, as in the second embodiment, and performs synchronization control with the pulse generator 32 as the primary and the light source 3, the photodetector 5, and the transport unit 2 as the secondary.

[0062] This spectroscopic measurement device 1E also achieves the same effects as the first embodiment, and can perform spectroscopic measurement inexpensively and accurately with a simple configuration. Furthermore, in the spectroscopic measurement device 1E, light L1 from the light source 3 is irradiated onto the object S at the timing when the object S is transported to a predetermined position (irradiation area R), thereby saving energy from the light source 3. By arranging a line generator 23 for each of the multiple lanes set in the transport unit 2, the irradiance of the light L1 irradiated onto the object S can be sufficiently ensured.

[0063] [Sixth embodiment] 9 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a sixth embodiment of the present disclosure. The spectroscopic measurement device 1F shown in FIG. 9 differs from the first embodiment in that the irradiation control unit 21 is configured with a Powell lens in that the irradiation control unit 21 is configured with a polygon mirror 51. The spectroscopic measurement device 1F also differs from the first embodiment in that the photodetector 5 is configured with a line sensor 25 in that the photodetector 5 is configured with a point sensor 52. For example, an InGaAs pin photodiode or the like can be used as the point sensor 52.

[0064] The polygon mirror 51 is disposed after the beam splitter 24. The polygon mirror 51 reflects light L1 from the light source 3 toward the irradiation area R of the transport unit 2 and scans it in the D2 axis direction. As in the second embodiment, the synchronization control unit 6 synchronizes the pulse generator 32 as a primary and the light source 3, the irradiation optical system 4 (here, the polygon mirror 51), and the transport unit 2 as secondaries.

[0065] The period in which the light L1 scans the irradiation area R once in the D2-axis direction by the polygon mirror 51 is synchronized with the period in which the wavelength of the light L1 switches from one wavelength to the next. By outputting a timing signal G4 indicating the period of the polygon mirror 51 to the computer 27, the spectral data D can be generated in the same manner as in the first embodiment. This spectroscopic measurement device 1F also achieves the same effects as the first embodiment, enabling inexpensive and accurate spectroscopic measurement with a simple configuration. Furthermore, by using the polygon mirror 51, which scans the light L1 from the light source 3 over the object S, as the irradiation control unit 21, spectral data can be quickly acquired for a wide range of the object.

[0066] 9, the period in which the light L1 scans the irradiation area R once in the D2-axis direction by the polygon mirror 51 is synchronized with the period in which the wavelength of the light L1 switches from one wavelength to the next, but as shown in Fig. 10, an embodiment may be adopted in which one cycle of the temporal change in the wavelength of the light L1 is synchronized for each of a plurality of points in the irradiation area R extending in the D2-axis direction while the light L1 scans the irradiation area R once in the D2-axis direction by the polygon mirror 51. Even in such an embodiment, it is possible to quickly acquire spectral data for a wide range of the target object.

[0067] [Seventh embodiment] Fig. 11 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a seventh embodiment of the present disclosure. Similar to the fifth embodiment, the spectroscopic measurement device 1G shown in Fig. 11 is configured to be able to sequentially measure a plurality of objects S conveyed by a conveying unit 2. In the spectroscopic measurement device 1G, a point sensor 52 is used as the photodetector 5. Furthermore, the irradiation control unit 21 is configured by a galvanometer mirror 61, and the synchronization control unit 6 is included in the light source 3 as in the first embodiment, and the light source 3 outputs a synchronization signal G2 to the point sensor 52 and the galvanometer mirror 61 via a delay generator 26.

[0068] As in the fifth embodiment, the spectroscopic measurement device 1G includes a camera 41 that captures an image of the position of the object S being transported by the transport unit 2. The computer 27 also functions as an output control unit 42 that controls the output of light L1 from the light source 3, and outputs a timing signal G4 to the galvanometer mirror 61 to control the angle of the galvanometer mirror 61 so that light L1 is incident only on the lane where the object S has been transported to the irradiation area R. This spectroscopic measurement device 1G also achieves the same effects as the first embodiment, and can perform spectroscopic measurement inexpensively and accurately with a simple configuration. Furthermore, as in the fifth embodiment, light L1 from the light source 3 is irradiated onto the object S when it is transported to a predetermined position (irradiation area R), thereby reducing the energy consumption of the light source 3. Note that in this embodiment, a MEMS (Micro Electro Mechanical Systems) mirror may be used instead of the galvanometer mirror 61.

[0069] [Eighth embodiment] Fig. 12 is a schematic diagram showing the configuration of a spectroscopic measurement device according to an eighth embodiment of the present disclosure. The spectroscopic measurement device 1H shown in Fig. 12 is a modification of the spectroscopic measurement device 1G according to the seventh embodiment so as to detect scattered light generated on the surface of the object S, out of light L2 from the object S.

[0070] Specifically, in the spectroscopic measurement device 1H, a point sensor array 71 including an array of multiple point sensors 52 is disposed above the irradiation area R in the transport unit 2. The detection axis of each point sensor 52 in the point sensor array 71 is disposed so as not to coincide with the optical axis of the light reflected from the object S, and each point sensor 52 detects scattered light generated on the surface of the object S out of the light L2 from the object S. The detection axis of each point sensor 52 may be perpendicular to the transport unit 2 or may be inclined relative to the transport unit 2. The detection axes of each point sensor 52 may be disposed so that those perpendicular to the transport unit 2 and those inclined relative to the transport unit 2 are alternately disposed.

[0071] This spectroscopic measurement device 1H also achieves the same effects as the first embodiment, and can perform spectroscopic measurement inexpensively and accurately with a simple configuration. As in the fifth embodiment, light L1 from the light source 3 is irradiated onto the object S when the object S is transported to a predetermined position (illumination area R), thereby saving energy consumed by the light source 3. Furthermore, by detecting scattered light from the object S using the point sensor array 71, it is possible to eliminate signals G1 from the point sensors 52 affected by reflected light, increase the probability of obtaining signals G1 from areas shaded by light L1, and obtain information that combines the position information of the object S with the brightness of the scattered light. This allows the accuracy of spectroscopic measurement to be maintained regardless of the shape of the object S.

[0072] [Ninth embodiment] Fig. 13 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a ninth embodiment of the present disclosure. In the spectroscopic measurement device 1I shown in Fig. 13, the irradiation control unit 21 is configured with a biaxial galvanometer mirror 61. In the spectroscopic measurement device 1I, the conveying unit 2 is not provided, and the object S is placed on a stage (not shown). Light L1 from the light source 3 is scanned in the D1-axis direction and the D2-axis direction on the surface of the object S by the biaxial galvanometer mirror 61. The photodetector 5 is configured with, for example, an area sensor 81. As the area sensor 81, for example, an InGaAs area sensor can be used.

[0073] This spectroscopic measurement device 1I also achieves the same effects as the first embodiment, and can perform spectroscopic measurement inexpensively and accurately with a simple configuration. The spectroscopic measurement device 1I can easily and quickly scan the surface of the object S with light L1 using the two-axis galvanometer mirror 61. Therefore, this configuration is suitable for spectroscopic measurement of an object S with a relatively large area, such as measuring the film thickness of a semiconductor wafer.

[0074] 14, when scanning the light L1 with the biaxial galvanometer mirror 61, one cycle of the temporal change in the wavelength of the light L1 may be synchronized for each of a plurality of points in the scanning range on the surface of the object S. Even in this mode, scanning of the light L1 on the surface of the object S with the biaxial galvanometer mirror 61 can be performed simply and quickly.

[0075] 15, a configuration may be adopted in which a field lens 91 is disposed on the optical path of the light L1 between the biaxial galvanometer mirror 61 and the object S. The field lens 91 is disposed near the image and adjusts the traveling direction of the light L1 near the image. By disposing the field lens 91, the light L1 can be irradiated onto the object S in a collimated state. This allows a clear image to be obtained not only near the center of the collimated light L1 but also near its periphery. Note that in this embodiment, a biaxial MEMS mirror may be used instead of the biaxial galvanometer mirror 61.

[0076] [Tenth embodiment] 16 is a schematic diagram showing the configuration of a spectroscopic measurement device according to a tenth embodiment of the present disclosure. In the spectroscopic measurement device 1J shown in FIG. 16, the irradiation control unit 21 is configured with a diffuser plate 101. The irradiation optical system 4 also has a dichroic mirror 102 as an optical element 22 that guides light L2 reflected by the object S to the photodetector 5.

[0077] In the spectroscopic measurement device 1J, light L1 diffused by the diffuser plate 101 is irradiated onto the surface of the object S as planar light spreading in the D1-axis and D2-axis directions. This configuration is therefore suitable for spectroscopic measurement of an object S having a relatively large area, such as measuring the film thickness of a semiconductor wafer. The spectroscopic measurement device 1J may also employ the field lens 91 shown in FIG. 15. For example, by arranging the field lens 91 on the optical path of the light L1 between the dichroic mirror 102 and the object S, the planar light L1 spreading in the D1-axis and D2-axis directions can be irradiated onto the object S in a collimated state. [Explanation of symbols]

[0078] 1A to 1J...spectroscopic measurement device, 2...transport unit, 3...light source, 4...irradiation optical system, 5...photodetector, 6...synchronization control unit, 11...pulse generating device (tunable wavelength light source), 21...irradiation control unit, 22...optical element, 26...signal generator, 25...line sensor, 41...camera, 42...output control unit, 52...point sensor, 81...area sensor, L1...light from light source, L2...light from object, D...spectroscopic data, G2...synchronization signal.

Claims

1. a light source that outputs light whose wavelength changes over time; an illumination optical system that illuminates an object with light from the light source; a photodetector that detects light from the object and outputs a signal based on the detection result; a synchronization control unit that synchronizes the light source with at least one of the irradiation optical system and the photodetector.

2. The spectroscopic measurement device according to claim 1 , further comprising a processing unit that generates spectroscopic data based on the signal output from the photodetector.

3. 2. The spectroscopic measurement device according to claim 1, wherein the light source is a variable wavelength light source configured to be able to control the wavelength of light.

4. The spectroscopic measurement device according to claim 1 , wherein the illumination optical system includes an illumination control unit that spreads or scans the light from the light source onto the object.

5. 2. The spectroscopic measurement device according to claim 1, wherein the photodetector is configured by a point sensor.

6. 2. The spectroscopic measurement device according to claim 1, wherein the photodetector is configured by an image sensor including a line sensor or an area sensor.

7. the synchronization control unit is included in the light source, The spectroscopic measurement device according to claim 1 , wherein the light source outputs a synchronization signal to at least one of the irradiation optical system and the photodetector.

8. The synchronization control unit further includes a signal generator. The spectroscopic measurement device according to claim 1 , wherein the signal generator outputs a synchronization signal to the light source and at least one of the illumination optical system and the photodetector.

9. 2. The spectroscopic measurement device according to claim 1, wherein the illumination optical system includes an optical element that guides the light reflected by the object to the photodetector.

10. The spectroscopic measurement device according to any one of claims 1 to 9, further comprising a transport unit that transports the object in a predetermined direction in synchronization with the light source and at least one of the irradiation optical system and the photodetector under the control of the synchronization control unit.

11. a camera that captures an image of the position of the object being transported by the transport unit and outputs a signal based on the image capture result; 11. The spectroscopic measurement device according to claim 10, further comprising: an output control unit that controls the light source so that light is output from the light source when the object is transported to a predetermined position, based on the signal output from the camera.

12. an output step of outputting light whose wavelength changes over time; an irradiation step of irradiating an object with the light; a detection step of detecting light from the object and outputting a signal based on the detection result, A spectroscopic measurement method, wherein the outputting step, the irradiating step, and the detecting step synchronize the outputting of the light with at least one of irradiating the object with the light and detecting the light from the object.

Images