JPS6273686A - Isotope separation method by laser - Google Patents

Abstract

PURPOSE:To utilize pulse laser beams effectively by reflecting pulse laser beams onto an incident optical axis, superposing incident beams and reflected beams and forming the focus of reflected beams at the same position on the formation of the focus of pulse laser beams. CONSTITUTION:Pulse laser beams 6 oscillated from a pulse laser device 1 are projected and condensed to a convex lens 2, thus shaping a focus. Photons passing through the focus expand and proceed toward a convex lens 3, are projected to the convex lens 3, and are reflected by a total-reflection plane mirror 5, the reflected beams are condensed by the convex lens again, and move forward to a spot where the focus is shaped previously as incident beams, a focus by reflected beams is formed at the focus forming spot of incident beams, and a cofocus 8 is shaped at the same position. When the cofocus is formed, a large energy region is generated in the cofocus section, and an isotope is decomposed effectively. Accordingly, beams passing through the focus of the incident beams can be used again as reflected beams, and laser beams can be utilized effectively, thus increasing the throughput of samples to be irradiated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to the synthesis and decomposition of chemical substances using directional energy such as laser light, particularly in infrared multiphoton absorption such as tritium isotope separation by laser method. This paper relates to a laser isotope separation method used in the field of laser chemistry for substances with high dissociation energy.

[Prior Art] In order to efficiently perform dissociation of compounds containing isotopes, especially multiphoton dissociation, in which a large number of photons are absorbed and dissociated in a short period of time, pulsed laser light is focused using an optical component such as a lens. It is necessary to emit light so that a reaction occurs only near the focal point, to suppress collisions between molecules by keeping the pressure of the irradiated sample low, and to shorten the laser pulse width to cause dissociation to occur in an extremely short time. This results in a decrease in the absorption efficiency of laser photons by the irradiated sample and a decrease in the throughput of the irradiated sample. In order to deal with these problems, methods using a waveguide, a method for forming multiple focal points in series using a plurality of lenses, and the like have been proposed as improvement techniques.

That is, in the former method, as shown in FIG. 4, the laser beam from the pulsed laser resonance 5a is refracted by mirrors b and c, and then condensed into the inside of the waveguide f through the window e by the convex lens d. While reflecting within the waveguide f, focal points are formed at a plurality of locations. 9
is the irradiation sample inlet. In the latter method, as shown in FIG. 5, a large number of convex lenses d are arranged at appropriate intervals in the longitudinal direction of the hollow container, and a pulserade resonator a is installed at one end of the hollow container. However, a window 1 is provided at the other end of the hollow container so that a large number of focal points are formed each time the laser beam from the pulsed laser resonator a passes through the lens d one after another. j is the pump, k is the vibrator for moving the irradiation sample, ! is the gas working material supply inlet, and kasu is the gas working material outlet.

[Problems to be Solved by the Invention] However, in each of the above-mentioned conventional systems, the equipment for implementing them is complicated, and the focal point is different in each of them, and it is difficult to take into account the synergistic effect of light, etc. Not done.

Therefore, since the conventional irradiation device using the multiple reflection method is complicated, the present invention aims to simplify the device and further improve the effective use of pulsed laser light and increase the energy density. It is something.

[Means for Solving the Problems] The present invention condenses the pulsed laser beam with a convex lens having a focal length R, and from this convex lens the focal length #IR
The above pulsed laser is The incident light and reflected light are superimposed at one point so that the light is reflected on the incident optical axis, and the reflected light is focused at the same position as the pulsed laser light from the pulsed laser resonator is focused. Let them do it.

[Operation] The incident light and reflected light of the copulse laser light are superimposed, and the reflected light is focused at the same position as the focal point formed by focusing the incident light, forming a confocal point.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a convex lens (
a convex lens 3 having the same focal length R as the convex lens 2 and located at a distance 2R from the convex lens 2, an irradiation reaction cell 4 set between the biconvex lenses 2 and 3, and the convex lens 3. Total reflection plane 1 located behind
i5 is used. , 7 is an irradiation sample inlet.

Now, the pulsed laser beam 6 oscillated from the pulsed laser device 1 is incident on the convex lens 2 and condensed to form a focal point. The photons that have passed through this focal point spread out toward the convex lens 3, and after being incident on the convex lens 3, are reflected by the total reflection plane mirror 5. This reflected light is again focused by the convex lens 3, and the incident light is Aim at the point where the focal point is formed,
A focal point is formed by the reflected light at the focal point of the incident light,
A confocal point 8 is formed at the same location.

As a condition for the above-mentioned incident light and reflected light to form the confocal 8, it is necessary that the reflected light focus is formed before the incident light focus is formed and disappears, and this is determined by the pulse width. This is the relationship between the speed of light and the speed of light, and the following optical system is required.

2R+(distance between convex lens 3 and total reflection plane mirror 5)×2〈
Pulse width of laser light (n sec or used) × [
Velocity of Light (C)] When the above-mentioned confocal area is formed, a large energy region is generated in that portion, and isotopes are effectively decomposed.

After the incident light forms a focus, the state in which the reflected light forms a focus at the same position is shown in FIG. 2 over time.

Next, as an example, laser tritium isotope separation using trifluoromethane will be described.

HTO (tritiated water) C)-IF3 (trifluoromethane) is a mixture of H20 and CTFa as a result of hydrogen isotope exchange.
(h-rifluorotritium methane). That is, HT O+ CHF 3';! H20+ CT
Since F3CHF3 and CTFa have different light absorption wavelengths, CHF3 is not decomposed at a certain wavelength, and CTFa is decomposed into CTF3→: CF 2 + T F .

The above disassembly is shown in Figure 2.
The pulsed laser beam of the CO2 laser is made incident on the convex lens 2 and condensed (Fig. 2 (a) (0)).

A CTFa decomposition region begins to form at the focal point formed by the initial condensation of the incident light. Next, the photons that have passed near the focal point spread out toward the convex lens 3.
(-) ). The expanded photons pass through the convex lens 3, are reflected by the reflecting mirror 5, and are condensed, heading toward the point where the focal point is still formed by the incident light (FIG. 2 (e)). The light reflected and focused by the convex lens 3 and the reflecting mirror 5 is
A focal point is formed at the focal point of the incident light, forming a confocal point 8 (see Figure 2).
The photons that are not absorbed by Fa become reflected light and are used again, and moreover, they are focused on a later incident light focusing point, thereby promoting the decomposition efficiency of CTFa and expanding the decomposition area.

FIG. 3 shows another embodiment of the present invention, in which the convex lens 3 and the reflecting mirror 5 in the above embodiment are replaced with a curvature semicircle of R/
In this embodiment, the light is reflected and focused by the concave mirror 9, and isotopes can be separated in the same manner as in the previous embodiment.

Note that the irradiation reaction cell 4 may be integrated with the optical system.

In this case, the optical component needs to be made of a material with which the irradiated sample gas and decomposition products are difficult to react with or adsorb.

[Effects of the Invention] As described above, according to the laser isotope separation method of the present invention,
The pulsed laser incident light that enters the irradiation reaction cell through a convex lens is reflected onto the same optical path, and the focus of the reflected light is formed at the same point as the focus of the incident light, forming a C confocal. The energy density in the optical path of the cell is higher than when a single pulsed laser beam passes through the cell due to the overlap of the incident light and the reflected light. Therefore, it is possible to improve energy efficiency and suppress pulse energy of incident laser light. In addition, the light that has passed through the focal point of the incident light becomes reflected light and can be used again, allowing effective use of the laser light and increasing the throughput of irradiated samples.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an actual example of the present invention, Fig. 2 is a diagram showing the state up to the formation of a confocal area in the present invention, and Fig. 3 is a schematic diagram showing an actual example of the present invention.
The figures are schematic diagrams showing other embodiments of the present invention, Figures 4 and 5.
All figures are schematic diagrams of conventional methods. 1 is a pulsed laser resonator, 2.3 is a convex lens, 4 is an irradiation reaction cell, 5 is a total reflection plane mirror, 6 is a pulsed laser beam, 8
9 indicates a confocal mirror, and 9 indicates a concave mirror. Figure 1 Figure 2

Claims (1)

[Claims] 1) The pulsed laser light from the pulsed laser resonator is made incident on a convex lens having a focal length R in the irradiation reaction cell, and the light is focused at a position separated from the convex lens by a distance twice the focal length R. After that, the laser beam that spreads and travels is reflected and focused on the same optical path as the above incident light by a combination of a concave mirror or a convex lens and a reflecting mirror, and when the incident light is focused and a focal point is formed, it is focused at the same point. A laser isotope separation method that is characterized by concentrating reflected light to form a focal point.