Patent Publication Number: US-2021162549-A1

Title: Laser ablation device and analysis apparatus

Description:
RELATED APPLICATIONS 
     The present application is a National Phase of International Application No. PCT/JP2018/016026, filed Apr. 18, 2018. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a laser ablation device which ablates a sample and an inductively coupled plasma type analysis apparatus having the laser ablation device, and more particularly, to a laser ablation device and an analysis apparatus suitable for use with a solid sample. 
     BACKGROUND ART 
     As a technique for performing qualitative and quantitative analysis of elements by observing and analyzing light from excited atoms by applying a high voltage to an ionic or particulate sample thereby being changed to plasma, an inductively coupled plasma (ICP) type analysis technique is known in the art. A technique described in Non-Patent Document 1 below is known as the ICP type analysis technique. 
     Non-Patent Document 1 (Fernandez et al.) describes a technique using mass spectrometry (MS) in an inductively coupled plasma method for performing an identification of multi-elements such as copper, zinc, tin, and lead contained in soil. In Non-Patent Document 1, when ablating a solid sample to make it into an aerosol, a femtosecond laser is used to shorten the time taken for the whole analysis. 
     PRIOR ART DOCUMENT 
     Patent Document 
     [Non-Patent Document 1] 
     Fernandez and four other persons, “Direct Determination of Trace Elements in Powdered Samples by In-Cell Isotope Dilution Femtosecond Laser Ablation ICP MS”, Anal. Chem., 2008, 80, 6981-6994 
     SUMMARY OF INVENTION 
     Problems to be Solved by Invention 
     (Problems with the Prior Art) 
     In the technique described in Non-Patent Document 1, an irradiation position of a laser beam can be moved substantially only on one axis (on a long elliptical arc-shaped circumference), and when it is desired to analyze a plurality of arbitrary locations of the sample, it is necessary to arrange the plurality of locations on one axis where the laser beam can move. Therefore, in one lumped sample such as mineral, etc., if there are three or more locations to be analyzed, it is difficult to arrange the sample on one axis. Thereby, when it is desired to change the analysis position, it is necessary to replace the position of the sample, and there is a problem that the time taken for the whole analysis is longer. 
     Further, in the technique described in Non-Patent Document 1, even when it is desired to mix and analyze a plurality of samples, it is also necessary to arrange the samples to be mixed on one axis, and it is necessary to place two (or more) samples within a movable range of the laser beam. In particular, in the technique described in Non-Patent Document 1, since it is to be such a motion in which the laser beam reciprocates on a trajectory (a so-called track-shaped trajectory of athletic sports) along the elliptical arc-shaped circumference at a predetermined speed, there is also a problem that a mixing ratio of the two samples is limited only to a specific mixing ratio. 
     Therefore, the technique described in Non-Patent Document 1 has a problem that there are restrictions in a position where the sample is placed and a position where analysis can be performed. 
     It is a technical object of the present invention to widen the position where a sample is placed and the position where analysis can be performed, as compared to a conventional configuration. 
     Means for Solving Problems 
     In order to solve the above technical object, an invention of a first aspect of the present invention provides a laser ablation device including: 
     a laser light source configured to output a laser beam for ablating a sample housed in a cell, wherein the laser light source outputs a femtosecond pulse laser beam having a pulse width of a femtosecond order; 
     an optical system configured to reflect the laser beam from the laser light source toward the sample, wherein the optical system comprises: a first mirror rotatable about a first axis; a second mirror rotatable about a second axis which is different from the first axis; a first driving source configured to rotate the first mirror about the first axis; and a second driving source configured to rotate the second mirror about the second axis; wherein the laser beam from the laser light source is reflected by the first mirror, and the laser beam reflected by the first mirror is reflected by the second mirror toward an analysis position of the sample; and 
     an irradiation control means configured to control the first driving source and the second driving source based on a coordinate position on two dimensions of the analysis position of the sample to change reflection angles of the first mirror and the second mirror, such that the analysis position is irradiated with the laser beam. 
     An invention of a second aspect of the present invention provides the laser ablation device according to the first aspect of the present invention, wherein, when mixing and analyzing the sample at a plurality of analysis positions, an interval between the laser beams irradiated to the sample is set to a predetermined low frequency, and when analyzing each of the plurality of analysis positions individually, the interval between the laser beams irradiated to the sample is set to a predetermined high frequency. 
     An invention of a third aspect of the present invention provides the laser ablation device according to the first or second aspect of the present invention, 
     including the irradiation control means configured to, when driving the respective driving sources according to the analysis positions, drive the driving sources toward stop positions, and then perform driving in a reverse direction to a direction in which they move toward the stop positions when stopping them at the stop positions, thus to stop the respective mirrors at the stop positions. 
     In order to solve the above technical object, an invention of a fourth aspect of the present invention provides an analysis apparatus including: 
     a cell configured to house a sample; 
     the laser ablation device according to any one of the first to third aspects of the present invention, which is configured to ablate the sample; and 
     a spectrometer into which the sample that has been ablated and sent out from the cell is introduced, and which is configured to perform an analyses of the introduced sample by an inductively coupled plasma method. 
     Advantageous Effects 
     In accordance with the inventions according to the first and fourth aspects of the present invention, it is possible to move an irradiation position of the laser beam in two dimensions by operating two mirrors with two driving sources, and thereby it is possible to widen the position where the sample is placed and the position where the analysis can be performed. 
     In accordance with the invention according to the second aspect of the present invention, it is possible to perform different analyses using one laser ablation device by changing an interval between the laser beams. 
     In accordance with the invention according to the third aspect of the present invention, it is possible to improve an accuracy of the position irradiated with the laser beam, as compared to the case in which the driving in the reverse direction is not performed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an entire view describing an analysis apparatus of Embodiment 1 of the present invention. 
         FIG. 2  is a view describing major parts of a laser ablation device of Embodiment 1. 
         FIG. 3  is a view describing a cell of Embodiment 1. 
         FIG. 4  is a block diagram illustrating each function of a computer device of Embodiment 1. 
         FIGS. 5A to 5D  are views describing an analysis mode that can be performed by the analysis apparatus of Embodiment 1, wherein  FIG. 5A  is a view describing an integration analysis mode,  FIG. 5B  is a view describing a mixing analysis mode,  FIG. 5C  is a view describing an elemental imaging analysis mode, and  FIG. 5D  is a view describing a quantitative analysis mode. 
         FIG. 6  is a view describing a distribution of ablated samples contained in an aerosol derived from the cell. 
         FIG. 7  is a view describing a region where a gas flows in a conventional cell. 
         FIGS. 8A and 8B  are views describing modifications of a diffusion part of the cell, wherein  FIG. 8A  is a view describing Modification 1, and  FIG. 8B  is a view describing Modification 2. 
     
    
    
     MODE FOR CARRYING OUT INVENTION 
     Hereinafter, an embodiment which is a specific example of embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment. 
     Further, in the following description using the drawings, members other than members necessary for the description to facilitate the understanding will not be illustrated and described. 
     Embodiment 1 
       FIG. 1  is an entire view describing an analysis apparatus of Embodiment 1 of the present invention. 
     In  FIG. 1 , an analysis apparatus  1  of Embodiment 1 has a mass spectrometer  2  as an example of a spectrometer. The mass spectrometer  2  of Embodiment 1 is composed of an inductively coupled plasma mass spectrometer (ICP-MS). In addition, the spectrometer is not limited to the ICP-MS, and for example, an inductively coupled plasma-optical emission spectroscopy (ICP-OES) may also be used. Further, as the ICP-MS and ICP-OES, conventionally known ones may be used, for example, they are described in Japanese Patent Laid-Open Publication No. 2013-130492, and the like, and they are known in the art, such that they will not be described in detail. 
     The mass spectrometer  2  is connected with a downstream end of a connection tube  3  as an example of a connection part. An upstream end of the connection tube  3  is connected with a merging joint  4 . The merging joint  4  is connected with a downstream end of an additional gas tube  6  as an example of an additional gas supply part. In Embodiment 1, the additional gas tube  6  is supplied with argon (Ar) gas as an example of an additional gas (make-up gas). In addition, in Embodiment 1, the argon gas is supplied at a flow rate of about 0.5 to 1.2 L/min as an example. 
     The merging joint  4  is connected with a downstream end of a cell connection tube  7  as an example of a cell connection part. An upstream end of the cell connection tube  7  is connected with a cell  11 . The cell  11  is configured to house a sample S therein. The cell  11  is connected with a carrier gas tube  12  as an example of a carrier gas supply part. In Embodiment 1, the carrier gas tube  12  is supplied with helium (He) gas as an example of carrier gas (a conveying gas). In addition, in Embodiment 1, the carrier gas is supplied at a flow rate of about 0.2 to 1 L/min as an example. 
     Further, a laser ablation device  21  is disposed above the cell  11 . The laser ablation device  21  irradiates the sample S in the cell  11  with a laser beam to ablate the sample S. 
     The analysis apparatus  1  of Embodiment 1 has a computer device  31  as an example of an information processing device. The computer device  31  has a computer body  32 , a display  33  as an example of a display unit, and a keyboard  34  and a mouse  35  as an example of an input unit. The computer body  32  may output a signal to control driving of the laser ablation device  21 , receive a detection result from the mass spectrometer  2 , and display it on the display  33 . 
     (Description of Laser Ablation Device) 
       FIG. 2  is a view describing major parts of a laser ablation device of Embodiment 1. 
     In  FIG. 2 , the laser ablation device  21  of Embodiment 1 has a femtosecond laser  22  as an example of a laser light source. The femtosecond laser  22  outputs a femtosecond laser beam  22   a  having a pulse width of a femtosecond order, as an example of the laser beam. The femtosecond laser  22  of Embodiment 1 outputs the femtosecond laser beam  22   a  having a pulse width of 230 fs as an example, but the pulse width is not limited to the exemplified value and may be changed. 
     The femtosecond laser  22  of Embodiment 1 includes a shutter (not illustrated) disposed therein, and is configured to control a frequency of outputting the femtosecond laser beam  22   a  (a reciprocal of an interval at which the femtosecond laser beams  22   a  are output). In Embodiment 1, as an example, the frequency may be controlled between 100 Hz and 1000 Hz. 
     That is, the femtosecond laser beam  22   a  is output from the femtosecond laser  22  at 1000 Hz, the shutter is constantly kept in an open state at 1000 Hz, and nine shots out of ten shots of femtosecond laser beam  22   a  are shielded by the shutter at 100 Hz, such that it is possible to obtain an output of 100 Hz. 
     The femtosecond laser beam  22   a  is introduced into a galvano optical system  23  as an example of an optical system. The galvano optical system  23  of Embodiment 1 has a first galvano mirror  24  as an example of a first mirror and a second galvano mirror  25  as an example of a second mirror. The first galvano mirror  24  reflects the femtosecond laser beam  22   a  from the femtosecond laser  22  toward the second galvano mirror  25 , and the second galvano mirror  25  reflects the femtosecond laser beam  22   a  from the first galvano mirror  24  toward the sample S. 
     The first galvano mirror  24  is rotatably supported about a first mirror axis  24   a.  Driving from a first galvano motor  24   b  as an example of a first driving source is transmitted to the first mirror axis  24   a.  Therefore, according to the driving from the first galvano motor  24   b,  the first galvano mirror  24  rotates and tilts about the first mirror axis  24   a  to change a reflection direction of the femtosecond laser beam  22   a.    
     Similarly to the first galvano mirror  24 , the second galvano mirror  25  also has a second mirror axis  25   a,  and a second galvano motor  25   b  as an example of a second driving source to change the reflection direction of the femtosecond laser beam  22   a.  Further, in Embodiment 1, as an example, the first galvano mirror  24  mainly controls an irradiation position in an X direction along a gas flow direction on a surface of the sample S, and the second galvano mirror  25  mainly controls an irradiation position in a Y direction intersecting the gas flow direction. Therefore, it is possible to scan the femtosecond laser beam  22   a  in two dimensions by controlling the two galvano mirrors  24  and  25 . In Embodiment 1, the femtosecond laser beam  22   a  is configured to be irradiated in a range of 20 cm×20 cm as an example. 
     A lens  26  as an example of an optical member is disposed between the second galvano mirror  25  and the cell  11 . The lens  26  collects the passing femtosecond laser beam  22   a  so that a focus position of the femtosecond laser beam  22   a  is on the surface of the sample S. 
     (Description of Cell) 
       FIG. 3  is a view describing the cell of Embodiment 1. 
     In  FIG. 3 , the cell  11  of Embodiment 1 has a housing part  41  in which the sample S is housed. In addition, the cell  11  includes a gas inflow part  42  as an example of an introduction part, and an aerosol outflow part  43  as an example of a derivation part, which are formed therein. The gas inflow part  42  is connected to the carrier gas tube  12 , and the aerosol outflow part  43  is connected to the cell connection tube  7 . A diffusion part  44  is formed between the gas inflow part  42  and the housing part  41 . The diffusion part  44  has fences  44   a  and  44   b  as an example of a partition member. The fences  44   a  and  44   b  are disposed on the gas inflow part  42  side and the housing part  41  side of the diffusion part  44 . In addition, the fences  44   a  and  44   b  of Embodiment 1 are made of a mesh member. 
     Glass beads  44   c,  which are made of glass balls, are filled between the fences  44   a  and  44   b.  Further, as the glass beads  44   c,  ones having a particle size of about 0.5 mm to 2 mm are preferably used. Therefore, when the carrier gas inflowing from the gas inflow part  42  passes through the diffusion part  44 , the carrier gas continuously collides with the glass beads  44   c  and diffuses in a direction (Y direction) intersecting the gas flow direction (X direction). 
     (Description of Control Unit of Embodiment 1) 
       FIG. 4  is a block diagram illustrating each function of the computer device of Embodiment 1. 
     In  FIG. 4 , the computer body  32  as an example of a control unit has an input/output (I/O) interface for inputting/outputting signals with an outside. In addition, the computer body  32  has a read only memory (ROM) in which a program for performing required processing, information, and the like are stored. Further, the computer body  32  has a random access memory (RAM) for temporarily storing required data. Furthermore, the computer body  32  has a central processing unit (CPU) which performs processing according to the program stored in the ROM or the like. Thereby, the computer body  32  may realize various functions by executing the program stored in the ROM or the like. 
     (Functions of Computer Body  32 ) 
     The computer body  32  has functions of executing processing according to input signals from the signal output elements such as the keyboard  34 , the mouse  35 , the mass spectrometer  2 , and other sensors (not illustrated), and outputting control signals to each control element such as the galvano motors  24   b  and  25   b  and the shutter of the femtosecond laser  22 . That is, the computer body  32  has the following functions. 
       FIGS. 5A to 5D  are views describing an analysis mode that can be performed by the analysis apparatus of Embodiment 1, wherein  FIG. 5A  is a view describing an integration analysis mode,  FIG. 5B  is a view describing a mixing analysis mode,  FIG. 5C  is a view describing an elemental imaging analysis mode, and  FIG. 5D  is a view describing a quantitative analysis mode. 
     C 1 : Analysis Mode Determination Means 
     The analysis mode determination means C  1  determines a mode in which analysis is performed based on the input from the keyboard  34  or the mouse  35 . In  FIGS. 5A to 5D , the analysis apparatus  1  of Embodiment 1 is configured to perform the analysis in the integration analysis mode shown in  FIG. 5A , the mixing analysis mode shown in  FIG. 5B , the elemental imaging analysis mode shown in  FIG. 5C , and the quantitative analysis mode shown in  FIG. 5D . 
     In  FIG. 5A , in the integration analysis mode, by ablating a predetermined position of the sample S at a high speed, a chemical composition of the entire ablated region of the sample S is integrated, and analyses is performed by the mass spectrometer  2 . Therefore, an average amount of the chemical compositions of the ablated regions is measured. 
     In  FIG. 5B , in the mixing analysis mode, a plurality of samples S or a plurality of locations of one sample are alternately ablated at a high speed to mix and measure the chemical compositions of two samples S or a plurality of locations. In the mixing analysis mode, when mixing two samples S, it is possible to change a mixing ratio by changing the number of times of ablation (the number of spots) between one sample and the other sample. That is, it is also possible to mix the samples at a ratio of 5:1 by ablating, every time one sample is ablated five times, the other sample once. Particularly, when the other sample uses a standard sample (a sample whose chemical composition is known in advance), this is preferably used since the standard sample serves as a reference for measurement. 
     In  FIG. 5C , in the elemental imaging analysis mode, by sequentially ablating a predetermined region of the sample S at a low speed, it is possible to individually measure and analyze the chemical compositions of each of the ablated positions (spots, analysis positions) of the sample S. That is, it is possible to analyze and measure the distribution of the chemical compositions in a predetermined region in a map form. 
     In  FIG. 5D , in the quantitative analysis mode, by alternately ablating the analysis region of the sample S 1  to be analyzed and a standard sample S 2 , the chemical compositions of each spot in the analysis region can be analyzed at a ratio with respect to the standard sample, and quantitative analysis can be performed. 
     C 2 : Laser Beam Output Interval Control Means 
     The laser beam output interval control means C 2  controls an output interval (frequency) between the femtosecond laser beams  22   a  according to the analysis mode. In Embodiment 1, when the integration analysis mode and the mixing analysis mode are selected, the femtosecond laser beam  22   a  is output at a high speed (high frequency, 1000 Hz), and when the elemental imaging analysis mode or the quantitative analysis mode is selected, the femtosecond laser beam  22   a  is output at a low speed (low frequency, 10 to 500 Hz). 
     C 3 : Irradiation Control Means 
     The irradiation control means C 3  has a first galvano motor control means C 3 A and a second galvano motor control means C 3 B, and controls the respective galvano motors  24   b  and  25   b  to change reflection angles of the galvano mirrors  24  and  25 , such that a target analysis position of the sample S is irradiated with the femtosecond laser beam  22   a.    
     The first galvano motor control means C 3 A controls the first galvano motor  24   b  based on an X coordinate of the analysis position of the sample S to control the reflection angle of the first galvano mirror  24 . The second galvano motor control means C 3 B controls the second galvano motor  25   b  based on a Y coordinate of the analysis position of the sample S to control the reflection angle of the second galvano mirror  25 . In addition, when driving the respective galvano motors  24   b  and  25   b  according to the analysis positions, the respective galvano motor control means C 3 A and C 3 B drive the respective galvano motors  24   b  and  25   b  toward positions for stopping them, and then perform driving (counter driving) in a reverse direction to a direction in which they move toward the stop positions when stopping them at the stop positions, thus to stop the respective galvano mirrors  24  and  25  at the stop positions. Further, the galvano motors  24   b  and  25   b  can change the irradiation position at a high speed (1000 Hz) according to the output interval (frequency) between the femtosecond laser beams  22   a.    
     C 4 : Analysis Result Processing Means 
     The analysis result processing means C 4  processes a signal from the mass spectrometer  2  and displays it on the display  33 . The analysis result processing means C 4  of Embodiment 1 displays analysis results of the measured chemical compositions in the integration analysis mode and the mixing analysis mode, and displays a map image of the ablated region and an image illustrating the chemical compositions when each analysis position on the map is selected in the elemental imaging analysis mode and the quantitative analysis mode. 
     (Operation of Embodiment 1) 
     In the analysis apparatus  1  of Embodiment 1 having the above-described configuration, when ablating the target analysis position in the sample S, a position where the femtosecond laser beam  22   a  is irradiated is controlled by the galvano optical system  23 . Herein, in the galvano optical system  23  of Embodiment 1, two galvano mirrors  24  and  25  are independently controlled (biaxially controlled) by the galvano motors  24   b  and  25   b.  Therefore, it is possible to ablate any position on two dimensions in the sample S, followed by measuring and analyzing the same. Thereby, it is not necessary to arrange the samples along a straight line as in the conventional technique. Therefore, the analysis apparatus  1  of Embodiment 1 can widen the position where the sample S is placed and the position where analysis can be performed, as compared to the conventional configuration. 
     Further, in the conventional technique, when the positions to be analyzed cannot be arranged on the straight line, it is necessary to replace the target position to be analyzed at a position (on the straight line) that can be irradiated with the laser beam and analyze the same, thus there is a problem that the whole analysis time is longer. On the other hand, in Embodiment 1, it is possible to irradiate any position on two dimensions with the femtosecond laser beam  22   a,  the sample S is less likely to need replacing, and the whole analysis time may be shortened. 
       FIG. 6  is a view describing a distribution of ablated samples contained in an aerosol derived from the cell. 
     Further, in the analysis apparatus  1  of Embodiment 1, an interval, at which the sample is irradiated with the femtosecond laser beams  22   a  (an irradiation interval), is changed according to the analysis mode. The ablated sample is derived from the cell  11  as an aerosol by a carrier gas, but when the irradiation interval between the femtosecond laser beams  22   a  is short, the galvano optical system  23  also moves at a high speed, and a plurality of analysis positions are ablated in a short time. Therefore, in  FIG. 6 , when dividing a region  51  into a plurality of regions by the derived aerosol in the gas flow direction, samples ablated at the same time are mixed in each region  51 . Therefore, the samples ablated from the plurality of regions are sent to the mass spectrometer  2  in a state in which the samples are mixed, and are detected as an average value (in the integration analysis mode) or to be mixed (in the mixing analysis mode). 
     On the other hand, when the irradiation interval between the femtosecond laser beams  22   a  is long, a plurality of analysis positions are ablated at some time intervals. Therefore, in the respective regions  51 , the samples ablated at the respective analysis positions are sent to the mass spectrometer  2  with being individually present. Therefore, the chemical compositions at each analysis position can be individually measured and analyzed (in the elemental imaging analysis mode, and the quantitative analysis mode). 
     Thereby, in Embodiment 1, various analyses can be performed by one analysis apparatus  1  by changing the irradiation interval and frequency of the femtosecond laser beams  22   a.    
     Further, in the analysis apparatus  1  of Embodiment 1, the mixing ratio can be changed by changing a ratio of the spots to be irradiated between one sample and the other sample in the mixing analysis mode. Therefore, as compared to the conventional technique in which the mixing ratio cannot be changed, it is possible for a user to perform the analysis at any mixing ratio desired to be analyzed. 
     Furthermore, in the analysis apparatus  1  of Embodiment 1, when stopping the galvano mirrors  24  and  25  at the stop positions corresponding to the analysis positions, the counter driving is performed by the galvano motors  24   b  and  25   b.  If stopping the galvano motors  24   b  and  25   b  without performing the counter driving, the positions of the galvano mirrors  24  and  25  may excessively move (overshoot) from the stop positions due to inertia. When the overshoot occurs, the femtosecond laser beam  22   a  is not accurately irradiated to the analysis position, and there is a problem that the analysis accuracy is reduced. On the other hand, in Embodiment 1, the galvano mirrors  24  and  25  can be accurately stopped at the stop positions by performing the counter driving. Therefore, the analysis accuracy can be improved as compared to the case in which the counter driving is not performed. 
       FIG. 7  is a view describing a region where a gas flows in a conventional cell. 
     In  FIG. 7 , in the conventional technique in which the cell  11  is not provided with the diffusion part  44 , when He gas having a low viscosity is used for a sample  02  supported by a housing part  01 , it is difficult to diffuse the He gas, and the carrier gas flows only in a substantially linear region  03  toward a derivation part  01   b  from an introduction part  01   a.  Therefore, in the region  04  outside the region  03  in which the gas flows, even if the sample  02  is ablated, the carrier gas is not substantially sent and the measurement may be difficult. Therefore, conventionally, it was necessary to place the sample  02  so that the analysis target position of the sample  02  is located on the region  03 . Thereby, in the conventional technique, there are problems that a wide range of the sample  02  cannot be measured, and if the sample  02  is replaced to change the position thereof, the analysis takes time. 
     On the other hand, in the analysis apparatus  1  of Embodiment 1, the cell  11  is provided with the diffusion part  44 . Therefore, even if He gas having a low viscosity is introduced as the carrier gas, as shown in  FIG. 3 , the He gas diffuses in a width direction (Y direction) intersecting the gas flow direction (X direction) and flows almost uniformly. Thereby, it is possible to send the ablated sample S to the downstream side over a wide range of the sample S. Therefore, it is not necessary to replace the sample S, and the time taken for analysis may be shortened. 
     (Modification of Diffusion Part) 
       FIGS. 8A and 8B  are views describing modifications of a diffusion part of the cell, wherein  FIG. 8A  is a view describing Modification 1, and  FIG. 8B  is a view describing Modification 2. 
     In the above-described embodiments, the diffusion part  44  using the glass beads  44   c  has been exemplified as shown in  FIG. 3 , but it is not limited thereto. As shown in  FIG. 8A , a configuration, in which a plurality of screen-shaped diffusion walls  44   d  which radially expand toward the downstream side in the gas flow direction are arranged as the diffusion part  44 , may also be possible. In addition, as shown in  FIG. 8B , a configuration, in which a carrier gas is allowed to pass therethrough, but a plurality of filter members  44   e  that serve as flow path resistance are disposed, may also be possible. Further, in addition to the configurations illustrated in  FIGS. 8A  and  8 B, any configuration capable of diffusing the gas flow in the width direction (Y direction) by disposing a member that serves as a flow path resistance of the introduced carrier gas may be employed. 
     (Modification) 
     Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above-described embodiments, and various modifications may be made within the scope of the present invention described in the claims. Modifications (H01) to (H08) of the present invention will be described as an example below. 
     (H01) In the above-described embodiments, as the sample S, the case of one sample or two samples has been exemplified, but three or more samples may also be possible. 
     (H02) In the above-described embodiments, the galvano optical system  23  having the biaxial control configuration has been exemplified, but it may also be configured to have a triaxial control or more. 
     (H03) In the above-described embodiments, the specific shape can be optionally changed according to the design, specifications and the like. For example, the shape and the like of the housing part  41  of the cell  11  can be optionally changed. 
     (H04) In the above-described embodiments, it is preferable to use the glass beads  44   c  for the diffusion part  44 , but it may also be configured to use a material other than the glass. For example, it is possible to use metal particles (beads) or plastic beads. In addition, when using plastic beads, mercury (Hg) attached to the plastic beads may be easily detected by the mass spectrometer, therefore it is desirable to use the glass beads. 
     (H05) In the above-described embodiments, it is preferable to use He gas as the carrier gas, but it is not limited thereto. For example, it is possible to change to hydrogen gas, neon gas, or argon gas according to the type of sample to be analyzed and the required accuracy. 
     (H06) In the above-described embodiments, the configuration, in which four analysis modes are possible, has been exemplified, but it is not limited thereto. It may also adopt a configuration having one, two or three analysis modes, or a configuration having five or more modes as the analysis mode. Thereby, when there is only one analysis mode or when the irradiation interval between the femtosecond laser beams  22   a  is common in the executable analysis modes, it may also adopt a configuration, in which the irradiation interval is not adjusted, that is, the shutter of the femtosecond laser  22  is not provided. 
     (H07) In the above-described embodiments, as the configuration for adjusting the irradiation interval between the femtosecond laser beams  22   a,  the configuration using the shutter has been exemplified, but it is not limited thereto. For example, it is not impossible to dispose a shielding optical system that reflects the femtosecond laser beam  22   a  in a direction in which the sample S is not irradiated between the femtosecond laser  22  and the galvano optical system  23 , or configure so as to reflect the laser beam in a direction in which the sample S is not irradiated with the galvano optical system  23 . 
     (H08) In the above-described embodiments, when using the carrier gas having a relatively high viscosity, it may also be possible to adopt a configuration having no diffusion part.