Composition identification device
Patent Information
- Application Number
- JP2022200073
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-12-15
- Publication Date
- 2025-11-14
AI Technical Summary
Existing methods for identifying resin types in waste materials using Raman scattering face inefficiencies due to gaps between waveguides and decreased Raman signal intensity, hindering high-speed identification.
A composition identification device employing multiple light emitting parts, a projection optical system, a lighting optical system, a spectroscopic element, and a signal processing unit to project light onto non-overlapping positions, collect and separate scattered lights, and determine composition based on spectral signals.
Enables quick and accurate identification of resin types by enhancing Raman signal intensity and overcoming wavelength differences, allowing high-speed resin recognition.
Smart Images
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Abstract
Description
[Technical field]
[0001] The present invention relates to a composition identification device for identifying the composition of an object. [Background technology]
[0002] In response to the growing interest in environmental issues in recent years, attention has been focused on material recycling of waste resin materials generated from discarded automobiles and home appliances. For material recycling, there is a demand for accurate and high-speed identification of the various types of resins contained in crushed automobiles and home appliances.
[0003] One method for identifying resins is to analyze the peak of the Raman scattering spectrum, which undergoes a spectral transition specific to the molecular structure of the material when irradiated with a laser. It is generally known that Raman scattering light is weak. For this reason, it takes a long time to obtain a Raman spectrum signal with the required signal strength, and high-speed processing is not possible. It is also known that irradiating a resin with a high-power laser to strengthen the Raman scattering light causes heat denaturation.
[0004] Patent Document 1 proposes an identification device that identifies resins by illuminating a wide area on the resin all at once to prevent the resin from being denatured by heat, receiving Raman scattered light from the wide area with multiple optical waveguides, and acquiring a Raman scattering spectrum.
[0005] Patent Document 2 proposes splitting a single light source and projecting it, and acquiring scattered light while shifting the split projection spots, thereby acquiring in-plane scattering distribution characteristics. [Prior art documents] [Patent documents]
[0006] [Patent Document 1] Patent No. 5265632 [Patent Document 2] Patent No. 5905140 Summary of the Invention [Problem to be solved by the invention]
[0007] However, in Patent Document 1, since light is received by multiple waveguides, Raman signals are missed due to gaps between the waveguides and differences in the outlines of the multiple waveguides relative to the projected spot shape, resulting in poor efficiency, a decrease in the intensity of the acquired Raman signal, and the inability to perform high-speed identification.
[0008] In addition, in Patent Document 2, one light source is branched to illuminate the surface and the scattering distribution characteristics in the surface are acquired, but when identifying the resin type of one resin sample, the irradiation intensity on the resin sample is reduced, and the acquired Raman signal intensity is reduced, which is a problem in that high-speed resin identification is not possible.
[0009] Therefore, one object of the present invention is to provide a composition identifying device capable of quickly identifying the composition of an object. [Means for solving the problem]
[0010] In the composition identification device, A plurality of light emitting units that emit light; a projection optical system that projects the light from the plurality of light emitting units onto different positions on an object in such a way that the light does not overlap; a light collecting optical system for collecting the scattered light from the different positions; a spectroscopic element for dividing each of the scattered lights collected by the light collecting optical system into light beams; a light receiving element that receives each of the scattered light beams dispersed by the spectroscopic element and obtains each spectroscopic signal; and a signal processing unit that determines a composition of the object based on the respective spectroscopic signals acquired by the light receiving elements. Effect of the Invention
[0011] According to the present invention, it is possible to provide a composition identifying device capable of quickly identifying the composition of an object. [Brief description of the drawings]
[0012] [Figure 1] FIG. 1 is a schematic diagram showing a configuration example of a composition identifying device according to a first embodiment of the present invention. [Diagram 2] 13A and 13B are diagrams showing examples of projected images of the light exiting portion projected onto a resin sample so as not to overlap each other. [Diagram 3] FIG. 3A is a schematic diagram showing the spectroscopic unit of Example 1, FIG. 3B is a diagram explaining the light beam of Raman scattered light incident on the spectroscopic unit 400, and FIG. 3C is a diagram showing the Raman spectrum on a CMOS. [Figure 4] FIG. 11 is a schematic diagram showing a configuration example of a composition identifying device according to a second embodiment. [Diagram 5] FIG. 11 is a schematic diagram showing a configuration example of a light source unit of a composition identifying device according to a second embodiment. [Figure 6] FIG. 11 is a schematic diagram showing a configuration example of a light source unit of a composition identifying device according to Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Hereinafter, the embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment. In each drawing, the same members or elements are given the same reference numerals, and duplicated descriptions are omitted or simplified. EXAMPLES
[0014] Fig. 1 is a schematic diagram showing an example of the configuration of a composition identifying device according to a first embodiment of the present invention. In Fig. 1, a composition identifying device 1000 identifies the composition of a resin sample 100 as an object, in which 200 indicates a light source unit, 300 indicates a light collecting unit including a projection optical system and a light collecting optical system, 400 indicates a spectroscopic unit, and 700 indicates a Raman signal processing unit.
[0015] Each unit such as 200, 300, 400, 700, etc. indicates a functional block. In this embodiment, the composition identification device 1000 identifies the composition of the resin sample 100 as an object, but the object to be identified in terms of composition is not limited to resin.
[0016] In addition, the signal processing unit 700 has a built-in CPU or the like as a computer, and functions as a control means that controls the operation of each part of the composition identifying apparatus 1000 as a whole based on a computer program stored in a memory as a storage medium.
[0017] The light source unit 200 has a plurality of light emitting parts 201, 202 each consisting of a semiconductor laser or the like for emitting light. The light emitting parts 201, 202 may be laser light sources such as a semiconductor pumped solid-state laser or a gas laser. The light collecting unit 300 projects light from the light emitting parts onto the resin sample 100 and collects Raman scattered light scattered from the resin sample 100.
[0018] Light collecting unit 300 is composed of a projection optical system having collimator lens 301 and lens 302, a light collecting optical system having lens 302 and condenser lens 304, and a dichroic mirror 303. The projection optical system projects light from a plurality of light emitting parts onto different positions on an object so that the light does not overlap with each other.
[0019] In this embodiment, the lens 302 functions as a condenser lens in the projection optical system, and functions as a collimator lens in the light collecting optical system. That is, the lens included in the projection optical system is used as a part of the light collecting optical system.
[0020] In this embodiment, the projection optical system has the collimator lens 301 and the lens 302, but is not limited to this configuration. Also, the light collecting optical system has the lens 302 and the condenser lens 304, but is not limited to this configuration.
[0021] The light emitted from the light emitting parts 201 and 202 enters the same (common) projection optical system and is guided to the dichroic mirror 303 by the collimator lens 301. That is, the light incident on the dichroic mirror 303 is reflected by the dichroic mirror 303, collected by the lens 302, and projected onto the resin sample 100.
[0022] That is, in this embodiment, the projection optical system includes a common lens (collimator lens 301 and lens 302) for projecting light from multiple light emitting sections onto different positions on the object so that the light rays do not overlap.
[0023] Fig. 2 is a diagram showing an example of projected images of the light emitting portion projected onto a resin sample so as not to overlap, and shows a state in which two images 101 and 102 of the light emitting portion are projected onto a resin sample 100. As shown in Fig. 2, the images of the light emitting portion are projected onto one resin sample 100 so that the light from the two light sources does not overlap. From each projected image, Raman scattered light is scattered toward the longer wavelength side than the projection wavelength.
[0024] The light collecting optical system collects scattered light from the projection images 101 and 102 at different positions. That is, the light collecting optical system guides the Raman scattered light scattered by the projection images 101 and 102 of the light emitting parts 201 and 202 on the resin sample 100 to the dichroic mirror 303 by the lens 302 and transmits it. The Raman scattered light beams from the projection images 101 and 102 that have transmitted through the dichroic mirror are guided to the spectroscopic unit 400 by the condenser lens 304 so that they do not overlap each other.
[0025] Fig. 3(A) is a diagram showing the details of the spectroscopic unit 400. The spectroscopic unit 400 shown in Fig. 3 is viewed from a different perspective than in Fig. 1. Fig. 3(B) is a diagram showing a beam of Raman scattered light incident on the spectroscopic unit 400. Reference numeral 400a denotes a conjugate plane of the surface of the resin sample 100 with respect to the light-collecting optical system, and two beams of Raman scattered light 406 and 407 from the focusing lens 304 in Fig. 1 enter the spectroscopic unit 400 without overlapping with each other in the Y direction in Fig. 3.
[0026] The imaging lens 401 collimates the two Raman scattered light beams incident on the spectroscopic unit 400 and causes them to enter a long-pass filter 402. The long-pass filter 402 cuts out light in the wavelength band of the light source light and transmits light in the band wavelength of the Raman scattered light. The Raman scattered light that has transmitted through the long-pass filter 402 enters a diffraction grating 403.
[0027] The diffraction grating 403 separates the Raman scattered light and disperses the wavelength components in the lateral direction. Here, the diffraction grating 403 functions as a dispersing element for separating the scattered light beams collected by the light collecting optical system.
[0028] An imaging lens 404 forms an image of the spectrum of the Raman scattered light dispersed by the diffraction grating 403 on a light receiving element 405 such as a CMOS image sensor.
[0029] The spectra of the two Raman scattered light beams 408 and 409 are imaged on the light receiving element 405 so as not to overlap each other. Here, the Raman scattered light beams 408 and 409 correspond to the light beams 406 and 407, respectively.
[0030] The light receiving element 405 receives the Raman scattered light split by the spectroscopic element on the light receiving surface as a spectrum, acquires the respective spectroscopic signals, and transfers them as spectrum data to the signal processing unit 700. In this embodiment, a CMOS image sensor is used as the light receiving element 405, but a CCD image sensor may also be used. Also, multiple line cameras may be used as the light receiving element.
[0031] The signal processing unit 700 determines the composition of the object based on each spectroscopic signal (spectral data) acquired by the light receiving element. That is, the signal processing unit 700 extracts and analyzes a Raman spectrum based on spectral data obtained by adding and synthesizing multiple spectral data acquired by the light receiving element, thereby identifying the resin type of the resin sample.
[0032] Specifically, for example, the spectroscopic signals obtained by receiving light with the light receiving element 405 are added together to synthesize them. Here, the signal processing unit 700 functions as a signal processing means for synthesizing the spectroscopic signals, and the S / N is improved by the synthesis. The method of identifying the resin is a general publicly known method, and is implemented by checking the characteristic peaks of the Raman spectrum or by comparing with known spectra.
[0033] Generally, when light from a light source is projected onto a resin sample, the resin sample may generate strong fluorescence, which acts as background light, along with Raman scattered light. For this reason, the Raman spectrum signal acquired by the light receiving element is significantly affected by shot noise caused by background light, which depends on the intensity of the incident light, due to readout noise, which does not depend on the intensity of the incident light.
[0034] In particular, when the Raman scattered light is particularly weak, such as in the case of black resins, the main cause is shot noise caused by background light rather than readout noise, which deteriorates the S / N ratio of the Raman spectrum signal and leads to errors in resin identification.
[0035] In this embodiment, in order to reduce the shot noise effect of this background light, light from multiple light sources is projected and the total amount of projected light on the same resin sample is increased. As a result, the S / N ratio of the Raman spectrum signal is improved, the resin identification rate is improved, and high-speed resin recognition is possible.
[0036] Even with the same type of light source, individual differences can cause differences in wavelength. The Raman spectrum shifts in the spectral direction depending on the wavelength of the light projected onto the resin sample. For this reason, if light from multiple light sources with different wavelengths is projected onto a resin sample so that they overlap, the Raman scattering spectrum signals, which shift differently for each wavelength, will overlap, making it impossible to correctly identify the resin.
[0037] In this embodiment, the light from the multiple light emitting parts is projected onto the same resin sample without overlapping, thereby increasing the total amount of projected light and separating the light with different projection wavelengths for each light source. Furthermore, the Raman scattered light from the separated projected images of each light source is split separately by a splitting unit to obtain individual spectral signals without overlapping on the light receiving element.
[0038] In this manner, in this embodiment, each scattered light from different positions on the object is guided to a conjugate position of the light-collecting optical system so as not to overlap with each other, each scattered light is dispersed by a dispersing element, and each dispersed scattered light is received at a non-overlapping position on the light-receiving element.
[0039] Alternatively, wavelength information of each light source may be acquired, and the shift of the spectrum direction of each spectrum may be corrected based on the wavelength information. That is, the signal processing unit 700 may add and combine each spectrum signal after correcting the wavelength-dependent shift of the spectrum direction based on the wavelength information of each light source, and perform resin identification based on the combined spectrum.
[0040] When there is substantially no difference in wavelength of the light from the multiple light emitting portions, the light can be simply added together to generate a composite spectrum, and the Raman spectrum can be extracted based on the composite spectrum. EXAMPLES
[0041] In contrast to Example 1, Example 2 is configured such that Raman scattered light from a plurality of spatially separated light collecting units can be distinguished by one spectroscopic unit by guiding light from the light collecting unit 300 to the spectroscopic unit 400 using a fiber. Note that, also in Example 2, light from each light source is projected onto the resin sample 100 so as not to overlap.
[0042] In addition, since the Raman scattered light from the projected images of the light emitting parts on the resin sample 100 is separated on the conjugate plane of the projected image of the light collecting optical system, it is sufficient to guide it to individual fibers. Then, the Raman scattered light from the fibers of the multiple light collecting units is separated into spectra by the spectroscopic unit 400. The separated spectra are collectively received and processed by a two-dimensional array of light receiving elements such as a CMOS or CCD, enabling high-speed resin recognition.
[0043] 4 is a schematic diagram showing a configuration example of a composition identifying device according to Example 2. Detailed description of components that are the same as those in Example 1 will be omitted. Each of the Raman scattered lights from non-overlapping projected images 101 and 102 of the light emitting portion on one resin sample 100 is individually coupled (optically connected) to receiving optical fibers 305 and 306 by a light collecting optical system.
[0044] The Raman scattered light coupled to the receiving optical fibers 305, 306 is transmitted by the receiving optical fibers 305, 306, respectively, and enters the spectroscopic unit 400 without overlapping. In addition, Raman scattered light from multiple light collecting optical systems (not shown) having a similar configuration is routed by fibers and enters the spectroscopic unit 400.
[0045] In the spectroscopic unit 400, the Raman spectra separated by the diffraction grating 403 as a spectroscopic element are received collectively without overlapping by a two-dimensional array of light receiving elements 405. The received Raman spectrum is transferred to a signal processing unit 700, and the resin of the resin sample 100 is identified.
[0046] In this embodiment, it is preferable to couple the light from the light emitting parts 201 and 202 to a fiber once. Fig. 5 is a schematic diagram showing a configuration example of a light source unit of a composition identifying apparatus according to embodiment 2. In the light emitting part 201, light from a semiconductor laser 501 is coupled to a fiber 505 via a lens 503, and the light from the fiber emitting part is made to enter a projection optical system.
[0047] Similarly, in the light emission unit 202, light from the semiconductor laser 502 is coupled to a fiber 506 via a lens 504, and the light from the fiber emission unit is made incident on the projection optical system. At this time, a spot-shaped image, which is an image of the fiber core, is projected onto the resin sample.
[0048] In this manner, in this embodiment, the light from the multiple light emitting sections is transmitted to the projection optical system via separate fibers, and the projection optical system projects the light from the multiple light emitting sections in the form of spot shapes onto different positions on the object.
[0049] The spot-shaped projected images 101, 102 are guided to the receiving optical fibers 305, 306 in Fig. 4 arranged on a conjugate plane via a light collecting optical system. That is, the light collecting optical system guides each scattered light to the multiple receiving optical fibers 305, 306 arranged at conjugate positions. This makes it possible to collect the light in the same shape as the receiving optical fiber core, and allows efficient collection in the receiving optical fibers 305, 306, making it possible to obtain a stronger Raman signal. EXAMPLES
[0050] In the third embodiment, a multi-emitter semiconductor laser consisting of multiple emitters (light emitting units) is used as the light source, and light from each emitter of the semiconductor laser is individually incident on the projection optical system. That is, in the third embodiment, the multiple light emitting units are configured by multiple emitters of the semiconductor laser.
[0051] Compared to a single-emitter semiconductor laser, a multi-emitter semiconductor laser has a higher total optical output and can obtain more Raman scattering signals. However, since the multiple emitters are close to each other, they are generally considered as a single light source rather than as independent light sources.
[0052] However, when projecting light from a light source onto a projection surface, a smaller light source size allows for a smaller projection NA. Therefore, by treating multiple emitters as individual light sources, the light source size can be made more compact.
[0053] A smaller light source size allows efficient coupling to a fiber with a smaller core diameter, and the size of the light incident on the projection optical system (fiber core diameter) can be reduced. As a result, the projection NA can be reduced without increasing the spot size on the projection surface of the projection optical system, and the spot size variation in the depth direction (height direction of the resin sample) can be reduced. Therefore, it is possible to efficiently receive a large amount of Raman scattered light even from resin samples with steps or different heights.
[0054] 6 is a schematic diagram showing a configuration example of a light source unit of a composition identifying apparatus according to Example 3. A light source 601 is a multi-emitter semiconductor laser, and includes, for example, two separate emitters (light emitting parts) 602 and 603. In this example, a semiconductor laser including two emitters will be described as an example, but the number of emitters is not limited to this.
[0055] The emitted light from each emitter 602, 603 is coupled to a separate fiber of a bundle fiber 605, which is a bundle of two fibers, via a lens 604. Then, the light from the multiple emission parts of the bundle fiber is incident (transmitted) on a projection optical system such as that shown in Fig. 1. Note that the distance between the emitters of the multi-emitter semiconductor laser is close, on the order of several hundred µm, so it is desirable to use a handle fiber that allows easy coupling adjustment.
[0056] However, the present invention is not limited to this, and each emitter may be coupled to an individual fiber by increasing the distance between the emitters on the fiber surface by increasing the magnification of the lens 604. Also, a type of fiber in which the emission part of the bundle fiber 605 is separated into two fibers may be used. Alternatively, the semiconductor laser may be directly incident on the projection optical system without passing through a fiber.
[0057] After each emitter light is individually incident on the projection optical system, the configuration may be the same as in Example 1 or Example 2. Note that, although the configuration of one multi-emitter semiconductor laser is shown in Example 3, each emitter of a plurality of multi-emitter semiconductor lasers may be individually guided to the light collecting unit 300.
[0058] As described above, in Examples 1 to 3, by projecting light from multiple emission parts of the light source, the total amount of projected light on the same resin sample can be increased and a strong Raman signal can be obtained, enabling high-speed resin recognition.
[0059] In addition, in order to prevent the deterioration of resin identification ability due to wavelength differences between light sources, light from multiple emission parts from the light source is projected onto the same resin sample without overlapping, and light with different projection wavelengths for each light source is separated. This prevents the deterioration of resin identification ability due to wavelength differences and enables faster resin identification.
[0060] Although the present invention has been described in detail based on the preferred embodiments, the present invention is not limited to the above embodiments, and various modifications are possible based on the spirit of the present invention, and are not excluded from the scope of the present invention. The above embodiments include the following combinations.
[0061] (Configuration 1) A composition identification device comprising: a plurality of light emitting sections that emit light; a projection optical system that projects light from the plurality of light emitting sections onto different positions on an object so that the light does not overlap; a light collecting optical system that collects each scattered light from the different positions; a spectroscopic element that disperses each of the scattered lights collected by the light collecting optical system; a light receiving element that receives each of the scattered lights dispersed by the spectroscopic element and obtains each spectroscopic signal; and a signal processing unit that determines the composition of the object based on the each spectroscopic signal obtained by the light receiving element.
[0062] (Configuration 2) A composition identification device as described in Configuration 1, characterized in that each of the scattered lights from the different positions is guided to a conjugate position of the light-collecting optical system so as not to overlap with each other, each of the scattered lights is dispersed by the dispersing element, and each of the dispersed scattered lights is received at a non-overlapping position on the light-receiving element.
[0063] (Configuration 3) The composition identifying device according to configuration 2, wherein the light collecting optical system guides each of the scattered lights to a plurality of fibers arranged at the conjugate positions.
[0064] (Configuration 4) The composition identifying device according to any one of configurations 1 to 3, wherein the projection optical system projects the light from the plurality of light emitting parts in a spot shape onto different positions on the object.
[0065] (Configuration 5) The composition identifying device according to any one of configurations 1 to 4, wherein each of the plurality of light emitting parts has an emitter of a semiconductor laser.
[0066] (Configuration 6) The composition identifying device according to any one of configurations 1 to 5, wherein the light from the plurality of light emitting parts is transmitted to the projection optical system via separate fibers.
[0067] (Configuration 7) A composition identifying device described in any one of configurations 1 to 6, characterized in that each of the multiple light emitting units has a semiconductor laser emitter, and light from the multiple emitters is transmitted to the projection optical system via a separate fiber, and the projection optical system projects the light from the multiple light emitting units onto different positions on the object.
[0068] (Configuration 8) A composition identifying device described in any one of configurations 1 to 7, characterized in that the projection optical system includes a common lens for projecting light from the multiple light emitting sections onto different positions on the object so that the light does not overlap.
[0069] (Configuration 9) The composition identifying device according to any one of configurations 1 to 8, wherein a lens included in the projection optical system is used as a part of the light collecting optical system.
[0070] (Configuration 10) The composition identifying device according to any one of configurations 1 to 9, further comprising a signal processing means for synthesizing the respective spectroscopic signals.
[0071] (Configuration 11) The composition identifying device according to configuration 10, wherein the signal processing means corrects deviations in the spectral directions of the respective spectroscopic signals based on wavelength information from the plurality of light emitting portions, and combines the signals.
[0072] (Configuration 12) The composition identifying device according to any one of configurations 1 to 11, wherein the object contains a resin.
[0073] In order to realize a part or all of the control in the above embodiment, a computer program that realizes the functions of the above embodiment may be supplied to the composition identification device, etc. via a network or various storage media. Then, a computer (or a CPU, MPU, etc.) in the composition identification device, etc. may read and execute the program. In this case, the program and the storage medium storing the program constitute the present invention. [Explanation of symbols]
[0074] 100: Resin sample to be identified 200: Light source 300: Daylighting unit 400: Spectroscopic unit 700: Raman signal processing section
Claims
1. a plurality of light emitting units that emit light; a projection optical system that projects the light from the plurality of light emitting units onto different positions on an object so that the light does not overlap; a light collecting optical system for collecting the scattered light from the different positions; a spectroscopic element for separating the scattered light beams collected by the light collecting optical system; a light-receiving element that receives each of the scattered lights dispersed by the spectroscopic element and acquires each spectroscopic signal; a signal processing unit that determines the composition of the object based on each of the spectroscopic signals acquired by the light receiving element.
2. 2. The composition identification device according to claim 1, wherein the scattered light from the different positions is guided to a conjugate position of the light collection optical system so as not to overlap with each other, the scattered light is dispersed by the dispersing element, and the dispersed scattered light is received at a non-overlapping position on the light receiving element.
3. 3. The composition identifying device according to claim 2, wherein the light collecting optical system guides the scattered light beams to a plurality of fibers arranged at the conjugate positions.
4. 2. The composition identifying device according to claim 1, wherein the projection optical system projects the light from the plurality of light emitting portions in the form of spots onto different positions on the object.
5. 2. The composition identifying device according to claim 1, wherein each of said plurality of light emitting units has an emitter of a semiconductor laser.
6. 2. The composition identifying device according to claim 1, wherein the light from said plurality of light emitting portions is transmitted to said projection optical system via separate fibers.
7. 2. The composition identifying device according to claim 1, wherein each of the plurality of light emitting units has a semiconductor laser emitter, and light from the plurality of emitters is transmitted to the projection optical system via a separate fiber, and the projection optical system projects the light from the plurality of light emitting units onto different positions on the object.
8. 2. The composition identifying device according to claim 1, wherein the projection optical system includes a common lens for projecting the light from the plurality of light emitting portions onto different positions on the object so that the light does not overlap.
9. 2. The composition identifying device according to claim 1, wherein a lens included in said projection optical system is used as a part of said light collecting optical system.
10. 2. The composition identifying device according to claim 1, further comprising signal processing means for combining the respective spectroscopic signals.
11. 11. The composition identifying device according to claim 10, wherein the signal processing means synthesizes the spectroscopic signals by correcting deviations in the spectral directions of the respective spectroscopic signals based on wavelength information from the plurality of light emitting portions.
12. The composition identification device of claim 1 , wherein the object comprises a resin.
13. A projection step of projecting light from a plurality of light emitting portions onto different positions on an object so that the light does not overlap; a light-receiving step of collecting the scattered light from the different positions using a light-collecting optical system, dispersing the collected scattered light using a spectroscopic element, and receiving the dispersed scattered light using a light-receiving element to obtain respective spectroscopic signals; a signal processing step of determining the composition of the object based on each of the spectroscopic signals acquired in the light receiving step.