JPS6043629A - Spectroscopy method and spectroscopic element - Google Patents

Abstract

PURPOSE:To improve resolution by a simple method by arranging plural diffraction grating surfaces radially and in parallel to an axis, and bending an objective beam of spectral distribution and performing relative spectral distribution several times, and forming a spiral track. CONSTITUTION:Four diffraction grating plates 3a-3d having the same diffraction grating surfaces formed of a hologram are arranged radially at intervals of 90 deg., and the spaces between diffraction grating plates are charged with transparent media 5a-5d such as lens bond. When the diffraction grating of this constitution performs spectral distribution, an incident beam C as the objective beam of spectral distribution is projected slightly slantingly to a plene perpendicular to the axis Z of the arrangement of the diffraction grating plates 3a-3d so that a beam reflected by a mirror surface 4d is incident to the diffraction grating plate 3a at an angle of incidence of about 45 deg. and then the incidence beam C is refracted repeatedly to make three turns in the diffracting element, and diffracted by the diffraction grating plate 3d for the 12th time to obtain a projection beam Ca, which is reflected by a mirror surface 4a and guided out.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to spectroscopy, and particularly to a spectroscopic method requiring high resolution and a spectroscopic element used therein.

Background of the technology Spectroscopy is a technology that has been known for a long time and is widely used as a means of analysis, but the range of wavelengths it targets is generally wide. On the other hand, in recent years, technology related to laser light has developed, and it has become necessary to perform laser light spectroscopy.However, since laser light has an extremely narrow wavelength width, it is necessary to increase the resolution when performing spectroscopy. It is hoped that it will be possible.

fcl Prior Art and Problems Figure 1 is a diagram showing an example of a spectroscopic method using a conventional spectroscopic element, and Figure 2 is a diagram showing another example.
is a prism, 1a is an incident surface, 1h is an exit surface, 2 is a diffraction grating plate, 2d is a diffraction grating surface, Δ·B is an incident beam, ^a is a refracted beam, and Ab-Ba is an output beam.

In FIG. 1, since the prism J made of optical glass has a refractive index that differs depending on the wavelength, the incident beam A, which is the beam to be separated, which is incident on the prism 1, is refracted and separated at the entrance surface 1a to become the refracted beam Aa, and then The beam is refracted and separated at the output surface 1b and output as an output beam. By observing this emitted beam Ab at a distance from the prism 1, the distribution according to wavelength can be determined. The resolution is mainly controlled by the size of the refraction angle between the incident beam A and the outgoing beam Ab, and the length of the distance from the prism 1 to the observation position.

In this way, when performing spectroscopy with the prism L1, the method is simple, but because the refraction angle is about 604 and there is a restriction that the distance to the observation position cannot be increased arbitrarily, The disadvantage is that the resolution cannot be increased.

In the embodiment shown in FIG. 2, a diffraction grating plate 2 is used in place of the prism l in the case of FIG. The diffraction grating surface 2
Since the diffraction angle of the diffraction grating at d differs depending on the wavelength, the incident beam B is diffracted and separated by the diffraction grating interplanar system to become the output beam l(a), which can be observed in the same way as in the case of Fig. 1.Diffraction grating plate 2 In the case of , the diffraction angle is determined by the grating interval of the diffraction grating, but from a practical point of view it is about 120 degrees or less, and although it is a simple method as in the case of prism 1, it is still
There is a drawback that the ηi ability cannot be increased.

(dl) Purpose of the Invention In view of the above-mentioned drawbacks of the conventional art, the purpose of the present invention is to provide a spectroscopic method that is as simple as the conventional method but can improve resolution, and a spectroscopic element used therein.

(8) Structure of the Invention The above object is to provide a spectroscopic method characterized by performing spectroscopy in which a beam to be separated is bent in the same direction a plurality of times, and making the locus of the beam spiral, in which a plurality of diffraction grating surfaces are The diffraction grating surfaces are arranged parallel to the axis and radially, and any one of the diffraction grating surfaces diffracts the beam to be separated which is incident from one of the adjacent diffraction grating surfaces on both sides, and diffracts the beam to be separated from the other one. This is achieved using a spectroscopic element characterized by having a diffraction grating that emits light by bending toward a diffraction grating surface.

In this spectroscopic element, when the beam to be separated is incident at an angle with respect to the axis, the beam repeats sequential order diffraction on the plurality of diffraction grating surfaces within the spectroscopic element and advances in a spiral shape. is extracted as an outgoing beam after diffraction a desired number of times (0 times), and the degree of spectralization of the outgoing beam is magnified n times that of one spectral, so the resolution can be greatly improved. A is possible.

Further, according to the present invention, it is preferable that the first and second diffraction surfaces of the spectroscopic element are holograms. It has a diffraction efficiency (outgoing light amount/incoming light amount) of 1 compared to other diffraction grating surfaces.
It's because it's ugly.

Furthermore, it is desirable that the spaces between the surfaces of the plurality of diffraction gratings be filled with a transparent medium. Generally, the diffraction grating surface is formed on the surface of a transparent plate, and the surface reflection of the transparent plate causes a loss of the incident beam and reduces the light intensity of the output beam. This is because the reflection loss can be reduced by filling the transparent medium, which has a large effect in this case.

ffl　Embodiments of the invention The embodiments of Kisuke and Akira will now be described with reference to the drawings.

FIG. 3 is a perspective view (a) and a plan view (b) showing an example of the ino-spectroscopy method using an example of the spectroscopic element of the present invention;
Figures 5 and 6 respectively show other embodiments of the spectroscopic element, including 3a, 3b, 3C, 3d & J diffraction grating plates,
4a and 4b are mirror surfaces, 5a to 5d and 6a to 6d are transparent media, 7 is a junction moon, 8 is a diffraction grating plate, C is an incident beam, Ca is an output beam, and Z is an axis set to 7, respectively.

The diffraction element shown in FIG. 3 is a polygon, and four diffraction grating plates 3a to 3d having the same diffraction grating surface are arranged radially at intervals of <90 degrees as shown in the figure, and there is a lens between them, for example. It is filled with transparent media 5d to 5d such as bond. Here, the diffraction grating on the diffraction grating surface is, for example, as shown in FIG.
As shown in b1, the beam incident on the diffraction grating plates 3a to 3b at an incident angle of approximately 45 degrees is diffracted by the diffraction grating surface of the diffraction grating plate 3b, and is directed toward the diffraction grating plate 3C at an outgoing angle of approximately 45 degrees. It is a diffraction grating that emits light. Furthermore, although the transparent media 5a5b and 5C are sold on the entire surfaces of the diffraction grating plates 38 to 3d, filling of the transparent medium 5d is carried out on the upper and lower parts of the diffraction grating plates 3d and 3a, as shown in Figure (a). mirror surfaces 4d and 4a for reflecting the beam on the upper surface of the remaining diffraction grating plate 3d and the lower surface of 38.
are formed respectively.

In order to perform spectroscopy using a diffraction element with this configuration, as shown in FIG. The incident beam C, which is the beam to be separated, may be projected so that the beam reflected by the mirror surface 4d is incident on the diffraction grating plate 3a at an incident angle of approximately 45 degrees. The incident beam C undergoes the first diffraction on the diffraction grating plate 3a, and then repeats the diffraction as 3b, 30, etc. In the illustrated example, it rotates through this diffraction element three times, performs the 12th diffraction at 3d, and becomes an output beam. becomes Ca, and the mirror surface 4a
It is reflected and pulled out. In this case, since the holograms with high diffraction efficiency are used as the diffraction grating plates 38 to 3d, and the transparent medium Wj5a to 5d is filled to suppress surface reflection, the output beam Ca is diffracted 12 times. It still has a sufficient amount of light. Therefore, the degree of spectral separation of this output beam Ca is approximately 12 times that of one spectral beam, and the amount of light is also sufficient. It becomes possible to easily observe the distribution.

Other embodiments of the diffraction element will be listed below, but in any case, the principle and method of spectroscopy are the same as above.

In Fig. 4, the transparent media 5d to 5d in the case of Fig. 3 are not filled, and the surface reflection of the diffraction grating plates 38 to 3d is larger than in the case in Fig. 3, so the number of possible diffractions is greater than in the case in Fig. 3. limited.

FIG. 5 shows an example in which the transparent media 5a to 5d in FIG. It is best to join at 7.

FIG. 6 shows an example of a configuration with three diffraction grating plates 8, and the configuration may be in any of the configurations shown in FIGS. 3, 4, and 5.

However, since the angle of diffraction is different, it is necessary to change the grating spacing of the diffraction grating.

Note that the diffraction elements configured according to the present invention cannot be used in a wide range of wavelengths even if they are the same, so it is necessary to use a diffraction element that matches the wavelength of the incident beam to be considered. Therefore, it is not a big burden, and the simplicity of the spectroscopic method is actually a great advantage.

(g) Effects of the Invention -] As explained in 2, the configuration of the present invention provides a spectroscopic method that is as simple as the conventional method but allows the resolution to be modified, and a spectroscopy method used therein. For example, the present invention has the effect of making it possible to easily observe the distribution of light even in the case of light having a small wave width such as laser light.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of a spectroscopic method using a conventional spectroscopic element, Fig. 2 is a diagram showing another embodiment, and Fig. 3 is a diagram showing a spectroscopic method using an embodiment of the spectroscopic element of the present invention. A perspective view ta+ and a plan view (BL, Figures 4 and 5) showing the embodiment of
FIG. 6 is a diagram showing other embodiments of the spectroscopic element. In the drawing, ζ, 1 is a prism, la is an incident surface, ■b is an exit surface, 2, 3a to 3d, and 8 are diffraction grating plates, 2a is a diffraction grating surface, 4d and 4b are mirror surfaces, 5a - 5d and 6a
6d is a transparent medium, 7 is a bonding material, A-B-C is an incident beam, Aa is a refracted beam, Ab-Ba-Ca is an outgoing beam, and Z is an axis. 11..., 勺 v-1 Figure 1 Cow 2 possible

Claims (4)

[Claims] (1) A spectroscopy method characterized by performing spectroscopy multiple times in which the beam to be separated is bent in the same direction, and making the 1li1H trace of the beam into a spiral shape. (2) A plurality of diffraction grating surfaces are arranged parallel to the axis and radially, and one of the diffraction grating surfaces has a single force of the diffraction grating surfaces on both sides of it. A spectroscopic element characterized by having a diffraction grating that diffracts a beam to be separated which is incident on the beam and outputs the beam to the diffraction grating surface of external force. (3) The spectroscopic element according to claim (2), wherein the +J4 minor surface is a hologram. (4) The spectroscopic element according to claim (2), wherein in the arrangement, spaces between the surfaces of the plurality of diffraction gratings are filled with a transparent medium.