OPTICAL ANALYSIS DEVICE
20170160200 ยท 2017-06-08
Assignee
Inventors
Cpc classification
G01N15/1468
PHYSICS
G01N33/5302
PHYSICS
International classification
G01N33/53
PHYSICS
Abstract
Spectral data such as a CARS spectrum of a sample is acquired at high speed by reducing the amount of data. During scan by emission light focused and emitted onto the sample, the exposed state of a detection unit of a spectroscope that divides light generated from the sample is continued, thereby acquiring spectral data obtained by summing spectra generated at a plurality of positions in the sample.
Claims
1. An optical analyzing apparatus comprising: a light source; a sample holding unit that holds a sample; an emission optical system that focuses and emits a light flux from the light source onto the sample held by the sample holding unit; a light division unit that divides light generated from the sample by light emission; a detection unit that detects the light divided by the light division unit; and an emission control unit that controls the position of light emission onto the sample by the emission optical system, wherein the detection unit continues an exposed state over a plurality of positions of light emission onto the sample by the emission control unit, and outputs a spectrum obtained by summing spectra generated from the positions of light emission.
2. The optical analyzing apparatus according to claim 1, wherein the detection unit outputs a plurality of the summed spectra, and averages the plurality of outputted spectra.
3. The optical analyzing apparatus according to claim 1, further comprising: an image data acquisition unit that acquires image data of the sample held by the sample holding unit; and a shape recognition unit that recognizes the shape of the sample based on the acquired image data, wherein the emission control unit focuses and emits a light flux from the light source onto a specific region of the sample based on the shape of the sample recognized by the shape recognition unit.
4. The optical analyzing apparatus according to claim 1, wherein the spectrum is a CARS spectrum.
5. The optical analyzing apparatus according to claim 1, wherein the emission control unit includes a scan mirror, wherein the scan mirror has a control direction substantially perpendicular to the light division direction of the detection unit.
6. The optical analyzing apparatus according to claim 1, wherein the emission control unit scans the sample in two dimensions.
7. The optical analyzing apparatus according to claim 1, wherein the emission control unit scans the sample in three dimensions.
8. A biomolecule analyzing apparatus comprising: a light source; a sample holding unit that holds a plurality of cells as a sample; an observation unit that observes the cells held by the sample holding unit; an emission optical system that focuses and emits a light flux from the light source onto each cell held by the sample holding unit; a light division unit that divides light generated from the cell by light emission; a detection unit that detects the light divided by the light division unit; an emission control unit that controls the position of light emission onto the cell by the emission optical system; cell destruction means that destroys the cell held by the sample holding unit; and a biomolecule capturing device that captures biomolecules in the cell released from the destroyed cell, wherein the detection unit continues an exposed state over a plurality of positions of light emission onto the cell by the emission control unit, and outputs a spectrum obtained by summing spectra generated from the positions of light emission.
9. The biomolecule analyzing apparatus according to claim 8, wherein the cell destruction means destroys the cell by laser light emission.
Description
BRIEF DESCRIPTION OF DRAWINGS
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DESCRIPTION OF EMBODIMENTS
[0050] Embodiments of the present invention will now be described with reference to the drawings.
First Embodiment
[0051]
[0052] Laser light emitted from a light source, that is, a short-pulse laser light source 101 (a center wavelength of 1064 nm, a pulse width of 900 ps, a repetition frequency of 30 kHz, an average output of 200 mW) that is controlled in light-emission by a driver 10 receiving a command from a computer 11 is divided at a beam splitter 102 into two, including transmitted light as pump light and reflected light. The reflected light is coupled with a photonic crystal fiber 104 via a focusing lens 103, whereby broadband supercontinuum light is generated inside the fiber. The thus generated supercontinuum light is made parallel light via a collimate lens 105, and is incident on a long-pass filter 106, along which components at the wavelength of the short-pulse laser light source and at the wavelengths shorter than that are blocked. Stokes light that has a component at the wavelength longer than that of the pump light and has passed through the long-pass filter 106 is multiplexed with the pump light at a dichroic mirror 108. Herein, the dichroic mirror 108 has the property of reflecting lights at the wavelength of the pump light and in the wavelength band shorter than that, and of transmitting light in the wavelength band longer than the pump light. Then, the pump light is reflected and the Stokes light is transmitted, resulting in multiplexing.
[0053] This multiplexed light flux is focused at one point in a sample 110 via an objective lens 109 (NA of 0.9, and a magnification of 40) configuring an emission optical system that focuses and emits the light flux from the light source onto the sample, whereby CARS light is generated, which reflects the resonant vibrations of molecules present at the focusing position in the sample. The CARS light is then made parallel light via a condenser lens 111 (NA of 0.65), passes through a short-pass filter 112 that blocks the pump light and the Stokes light that are coaxial components, is incident on a spectroscope 113, is divided at a light division unit 114, and is detected by wavelength at a detection unit 115, where the spectrum is outputted as a detected signal.
[0054] Here, the detecting operation of the spectroscope 113 will be described. The spectroscope 113 includes the light division unit 114 that diffracts incident light by wavelength in different directions by a diffraction grating, and the detection unit 115 that detects the light diffracted at the light division unit 114 by a one- or two-dimensional detector array (a CCD camera, or a CMOS camera). In this embodiment, a CCD camera is used as the detection unit 115 that has a light reception unit 201 with pixels 202 arrayed in two dimensions, as illustrated in
[0055] Here, in this embodiment, while the detection unit 115 is in the exposed state, an XYZ stage 12 holding the sample 110 is driven so that the focusing position of the pump light and the Stokes light onto the sample scans the sample in three- or two-dimensions. More specifically, a previously designated, e.g., rectangular parallelepiped region or rectangular region is scanned at a constant speed. Thus, one type of spectral signal is acquired in one sample measurement. The one type of spectrum corresponds to a spectrum obtained by summing spectra generated from the respective positions in the sample on the scan line. The number of data pieces is the number of pixels in the lateral direction of the CCD camera. The acquired signal will be hereinafter called a CARS spectrum. In the conventional method, a large number of CARS spectra are acquired as data because they are acquired each time the focusing position of the pump light and the Stokes light is changed.
[0056] The CARS spectra acquired in this embodiment are subjected to signal processing, such as the method of maximum entropy, to be converted to Raman spectra. The Raman spectra acquired here represent the contents of various chemical species in the sample. The CARS spectra acquired in this embodiment are signals acquired by scanning the position of the pump light and the Stokes light. Thus, from these signals, the total contents of the chemical species in the entire sample (in the scan region) can be found.
[0057] The data acquisition sequence according to this embodiment will be described with reference to
[0058] This embodiment and the conventional method are compared for the data acquisition time and the amount of data. The data acquisition time in the conventional method is obtained by multiplying the sum of the exposure time, the movement time, and the spectral data transfer time of one spectral measurement by the number of measurement points (the number of measuring positions on the sample space). On the contrary, the data acquisition time in this embodiment is approximately the data acquisition time in the conventional method when the data transfer time is assumed to be 0. Thus, when the exposure time is equal to or shorter than the data transfer time, the data acquisition time can be shortened. The amount of data in the conventional method is obtained by multiplying the amount of data in this embodiment by the number of measurement points. Typically, the number of measurement points is some tens of thousands to some millions to acquire an image. Thus, by this embodiment, the amount of data is reduced to the order of a fraction of some millions to a fraction of some tens of thousands.
[0059] The sample position scan in this embodiment may fix the position of the sample during the exposure discretely, that is, at each measurement point, thereby moving it to a different position after the completion of the exposure, or may change the position of the sample continuously, that is, at a predetermined speed. The continuous scan continues to scan the light spot in the sample during the exposure time of the detection unit, and then ends the exposure of the detection unit at the completion of the scan, thereby carrying out the data transfer. The continuous scan can be equivalent to the discrete scan because one measurement point in the conventional method corresponds to the spatial region of the focusing spot size of the pump light and the Stokes light in the sample. That is, the continuous scan is almost equal to the discrete scan when the amount of the position movement is the focusing spot size and the exposure time per measurement point is a pixel dwell time. The pixel dwell time is defined as (the focusing spot size)/(the speed at which the sample is scanned).
[0060] In this embodiment, an emission control unit that controls the position of light emission onto the sample by the emission optical system uses the XYZ stage 12 to scan the position of the sample for scanning the measurement point, but the method for controlling the position of light emission by the emission control unit is not limited to this. For instance, as the emission control unit, a scan mirror such as a galvano mirror or a MEMS mirror that scans the incidence angle of the pump light and the Stokes light onto the sample by external control may be used, or the position of the objective lens 109 may be scanned. Alternatively, a combination of the above methods may be used.
[0061] In particular, an example in which a galvano mirror is used to scan one axis will be described with reference to
[0062] In addition, in this embodiment, the spectroscope is disposed on the opposite side of the incident side of the pump light and the Stokes light onto the sample, but may be disposed on the same side so that backscattering light from the sample is made parallel light at the objective lens 109 to be detected by the spectroscope. In this case, as illustrated in the schematic diagram in
[0063] In this embodiment, as the detector, the CCD camera is assumed, but the detector is not limited to this, and the same effect can be obtained even when a CMOS camera or a line sensor as a one-dimensional detector array is used.
[0064] The scan in this embodiment may be carried out in two- or three-dimensions, but for a relatively thick sample (roughly, above the focal depth of the pump light and the Stokes light focused onto the sample), the three-dimensional scan is used so that the sum amount of signals from the entire sample can be precisely acquired, which is effective. On the contrary, for a thin sample (below the focal depth of the pump light and the Stokes light focused onto the sample), the two-dimensional scan is carried out so that the sum amount of signals can be precisely acquired for a short time.
Second Embodiment
[0065] In this embodiment, the exposing operation is carried out a plurality of times for measuring the sample. The configuration example of an optical analyzing apparatus in this embodiment is the same as the first embodiment.
[0066]
[0067] In this case, one exposure time is shorter than the first embodiment, so that it is possible to avoid the saturation of the light reception unit causing failed normal data output. In addition, a plurality of data pieces are averaged to average noises added for respective spectral data outputs (caused mainly in an amplifier that converts electric charge to voltage), so that the S/N ratio can be higher than the first embodiment.
[0068] Needless to say, one exposure of the detection unit in this embodiment is required to be carried out over a plurality of positions in the sample. In other words, the exposure time of the detection unit is required to be longer than the pixel dwell time. In the conventional method, the exposure time and the pixel dwell time are equal.
Third Embodiment
[0069] In this embodiment, data is acquired from a specific region of the sample.
[0070] In this embodiment, illumination light from a light 401 (halogen lamp) is passed through a Wollaston prism 402, is reflected at a dichroic mirror 403, and is focused onto the sample 110 at the condenser lens 111, so that the differential interference image of the sample 110 is image-formed onto an imaging device, such as a CCD camera 408, by using the objective lens 109, a dichroic mirror 404, a Wollaston prism 405, a polarizer 406, and an image forming lens 407, thereby acquiring the image of the sample. This configuration is the same as the configuration of a well-known differential interference microscope. The dichroic mirrors 403, 404 are designed to reflect the wavelength of the visible light range of the light 401 (400 nm to 700 nm) and to transmit pump light, Stokes light, and CARS light (all of them have a wavelength in a near-infrared range above 700 nm), and do not affect CARS signal generation and detection.
[0071] Here, the image acquired at the CCD camera 408 is transmitted to the computer 11. Then, the computer 11 analyzes the image data for extracting the contour of the sample (such as a cell) at a shape recognition unit that recognizes the shape and structure of the sample. The computer 11 transmits, to the stage 12, a command to scan only the inside of the range of the contour. During the scan time, the detection unit 115 of the spectroscope 113 continues the exposed state to acquire a summed CARS spectrum. At this time, since the scan range of the light spot is limited to the sample measured, the data acquisition time can be shorter than the first embodiment. In addition, the scan range is not always the entire sample, and a CARS spectrum can be acquired from one region, e.g., from only the nuclear portion of the cell. Also in this case, a differential interference image is acquired to extract the contour of the nuclear portion by the computer 11 to scan only the nuclear portion. Further, a CARS spectrum may be acquired from each of, e.g., a plurality of locations in the same sample (e.g., the nuclear of the cell and other portions).
[0072] In this embodiment, the differential interference microscope is used as means for observing the sample. However, since the image data that can extract the contour of the sample has only to be acquired, the differential interference microscope may be replaced with an image data acquisition unit such as a typical bright-field microscope (equivalent to a configuration except for the Wollaston prisms 402, 405, and the polarizer 406) and a phase contrast microscope, or a combination of these may be used.
Fourth Embodiment
[0073] In this embodiment, a spontaneous Raman spectrum and a fluorescence spectrum are acquired in place of a CARS spectrum.
[0074]
[0075] The operation in this embodiment is the same as the first and second embodiments, and a spectrum that reflects the content of chemical species in the sample or the fluorescence label is acquired according to the sequence illustrated in
Fifth Embodiment
[0076] In this embodiment, a biomolecule analyzing apparatus in which the optical analyzing apparatus of the present invention is applied to single cell analysis, and a CARS spectrum is acquired as one form of cell analysis.
[0077]
(The Description of the Optical System Portion)
[0078] The optical system portion of the apparatus illustrated in
(The Description of the Biomolecule Extraction System)
[0079] The biomolecule extraction system 2 illustrated in
[0080] In this embodiment, as the pore array sheet 30, used is a porous membrane of an aluminum oxide that has a thickness of 80 m, and a size of 2 mm2 mm, and in which a large number of through-holes having a diameter of 0.2 m are formed by anodic oxidation. In the pore array sheet 30, isolation walls 31 can be formed to isolate the regions for capturing biomolecules. The isolation walls 31 can be formed of, e.g., polydimethylsiloxane (PDMS) by a semiconductor process so as to have a thickness of approximately 80 m, and can be brought into contact with the pore array sheet 30.
[0081]
[0082] As the array device, in addition to the pore array sheet 30 made of the porous membrane formed by anodically oxidizing aluminum, a large number of through-holes may be formed by anodically oxidizing a silicon material. Further, the array device may be constructed by providing a large number of through-holes in a thin film of a silicon oxide or a silicon nitride by using a semiconductor process.
[0083] As illustrated in
(The Description of an Operation Flow)
[0084] The operation flow of the biomolecule analyzing apparatus according to this embodiment will be described.
[0085] First, a sample including adherent cultured cells 21, 22, and 23 is placed on a petri dish 20. In this embodiment, cells to be measured are previously cultured by using the petri dish 20, and are then made to adhere onto its bottom face, thereby making the cultured cells. When the sample is a frozen piece, it is placed on the petri dish 20. An alternative sample may include a plurality of cells disposed in a gel in three dimensions. Next, the microscope system is used to acquire the differential interference image of target cells, and the user then decides the target cell for extracting and measuring biomolecules. Then, the computer 11 receives the input of information related to the cell or the cell portion to be measured from the user. Typically, the user often uses a plurality of cells to be measured. In that case, the computer 11 decides the order of the cells for capturing biomolecules, and the XYZ stage 12 is then driven so that the first target cell is located at the center of the visual field. Here, by the method described in the third embodiment, the CARS spectrum of the cell located at the center of the visual field is acquired to store the data in the computer 11.
[0086] The computer 11 uses an XYZ stage 34 to bring a specific region of the pore array sheet 30 (e.g., the region 300 at address (1,1)) closer to the vicinity of the cell whose CARS spectrum has been acquired (in the example in
[0087] After the destruction of one cell and the capturing of biomolecules in the cell are completed, the computer 11 drives the XYZ stage 12 to locate the registered second target cell at the center of the visual field. After that, the CARS spectrum of the second cell is acquired to store the data in the computer 11. Then, the computer 11 drives the XYZ stage 34 to bring a specific region of the pore array sheet 30 (e.g., the region 300 at address (1,2)) closer to the vicinity of the second target cell (in the configuration example in
[0088] One cell is destroyed here, but to acquire data with coarser resolution, mRNAs that are released for electrophoresis at the time of the destruction of a plurality of cells may be captured into one region 300 on the array device. In that case, the plurality of cells may be destroyed simultaneously, or may be subsequently destroyed one by one without moving the array device. In addition, in this embodiment, the acquisition of CARS spectra and the capturing of biomolecules are subsequently carried out with respect to different cells, but for instance, after the acquisition of the differential interference image of the sample, all the CARS spectra of target cells may be measured so that the cells are subsequently destroyed for capturing biomolecules.
[0089] By this embodiment, the CARS spectrum and gene expression data of each cell can be acquired. By using this function, the dynamic characteristic of the cell can be confirmed with high precision. To execute such analysis, first, a CARS spectrum is acquired. To confirm the association of the acquired CARS spectrum with the detailed state of a cell selected by the user, the cell is destroyed, and biomolecules in the cell are then captured onto the array device to measure the amount thereof. From the quantification of the biomolecules, the detailed state and type of the cell are identified, thereby associating them with the CARS spectrum, so that the association of the CARS spectrum with the state and type of the cell can be carried out with high precision. The CARS spectrum that can acquire a Raman spectrum can acquire more information related to chemical species to be measured, as compared with a fluorescence confocal microscope that is typically used in single cell analysis, thereby enabling such high precision analysis.
[0090] A method for classifying cells by CARS spectra will be described. After the acquisition of CARS spectra, expression analysis of 20 genes in, e.g., 180 cells is carried out to perform principal component analysis. The results are plotted for two higher-order principal components in
[0091] In this example, the principal component analysis is used for clustering based on gene expression in cells, but various methods, such as hierarchical clustering and k-means, are applicable. In addition, as the machine learning, various methods used in data mining, such as a support vector machine, have been known, and any one of them may be used.
[0092] In this embodiment, a CARS spectrum is used as a light division spectrum acquired from the sample, but even by using a spontaneous Raman spectrum or a fluorescence spectrum, in place of the CARS spectrum, the same effect can be obtained.
[0093] The present invention is not limited to the above embodiments, and includes various modifications. For instance, the above embodiments have been described in detail for clearly understanding the present invention, and do not always include all the above configurations. In addition, part of the configuration of one of the embodiments can be replaced with the configuration of the other embodiments. Further, the configuration of one of the embodiments can be added with the configuration of the other embodiments. Furthermore, part of the configuration of each embodiment can be added with, deleted from, and replaced with the configuration of the other embodiments.
INDUSTRIAL APPLICABILITY
[0094] According to the present invention, the analyzing apparatus that can acquire information at high speed from a large number of samples can be provided, and can accelerate research and development in the field of medicine and pharmaceutical.
LIST OF REFERENCE SIGNS
[0095] 2: biomolecule extraction system, 5: cell destruction laser, 11: computer, 21, 22, 23: adherent cultured cell, 30: pore array sheet, 32: platinum electrode, 101: short-pulse laser light source, 104: photonic crystal fiber, 109: objective lens, 110: sample, 113: spectroscope, 114: light division unit, 115: detection unit, 201: CCD camera light reception unit, 401: light, 407: image forming lens, 408: CCD camera