JP2851389B2 - Circulating phase conjugator for liquids - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid circulating phase conjugation apparatus that generates a phase conjugate wave of a laser beam incident on a container enclosing a liquid.

[Prior art and its problems] Conventionally, there has been an apparatus of this type shown in FIG. In this figure, a tubular container 1 has transparent walls at both ends.
2a and 2b are integrally formed, and a liquid having a high tertiary electric susceptibility, such as normal hexane, is sealed therein.

On the axis of the container 1, a convex lens 4 for incidence is provided on one side at a predetermined distance from one end thereof.

Next, the operation shown in FIG. 2 will be described. That is, the laser beam 3 passes through the convex lens 4 and is refracted by the lens at that time, further enters the container 1 through the light transmitting wall 2a, and forms a focal point 5 therein. At this focal point, when the energy density of the laser beam exceeds a certain threshold, stimulated Brillouin scattering occurs at the focal point 5, whereby the phase conjugate wave 6, ie, having the same wavefront as the incident beam, and in the opposite direction The light which propagates to is generated.

Since the conventional phase conjugation apparatus is configured as described above, the liquid is vaporized by the laser beam near the focal point 5 of the laser beam 3 incident on the inside of the container 1, and therefore, when the number of repetitions of the incident laser beam is increased, However, there is a disadvantage that the generation efficiency of the phase conjugate wave 6 is reduced.

[Object of the Invention] The present invention has been made in order to eliminate such a conventional drawback, and removes a deteriorated liquid including bubbles and the like at a focal point of a laser beam incident on a container, and removes the liquid at the focal point. It is an object of the present invention to provide a device for stably generating a phase conjugate wave with respect to a laser beam incident at a high repetition rate by keeping the purity high.

[Summary of the Invention] In order to achieve the object, the present invention provides a tubular container filled with a liquid, a portion of the laser beam incident on the container located at the focal point of the laser beam, and a center of the laser beam. A pair of nozzles that intersect with the laser beam are inserted through a circulation path, a circulation pump, and a liquid retainer, and the liquid flows at the focal point of the laser beam. Is generated stably.

An embodiment of the present invention will be described below with reference to FIG.

The description of the same parts as those of the conventional device is omitted.

That is, a pair of nozzles 7 and 8 are provided opposite to each other symmetrically with respect to the axis of the container 1, that is, the focal point of the laser beam, at a position corresponding to the focal point 5 of the laser beam incident on the container 1. The other end of each nozzle is connected to a circulation path 9, a circulation pump 10 and a liquid reservoir 11.
Are in communication with each other.

Generally, the laser beam incident into the container has a diameter at its focal point of less than about 0.1 mm. For this reason, the liquid altered by the laser beam is in a cylinder with a diameter of 0.1 mm or less, and when the liquid flows from the side to the beam, the flow rate is about 1 m / s and the incidence repetition rate of the incident beam is reduced. Even if the frequency is increased to 250 Hz, the generation efficiency of the phase conjugate wave 6 due to stimulated Brillouin scattering does not decrease. In addition, when the liquid flows, a turbulent flow is easily generated, and the turbulent flow deteriorates the condensing property of the laser beam, and the generation efficiency of the phase conjugate wave 6 is easily reduced. Therefore, it is important to remove the deteriorated portion of the liquid at a flow velocity as low as possible. For this purpose, the method of flowing the liquid from a direction intersecting the axis of the beam is effective.

Then, the laser beam 3 incident into the container 1 through the convex lens 4 and the light transmitting wall 2a forms a focal point 5 in the container 1. When the liquid is heated at this focal point, the liquid is likely to evaporate. When the pump 10 is driven at this time, the liquid is sent from one nozzle 7 through the focal point 5 and toward the other nozzle 8. As a result, bubbles generated at the focal point 5 are removed while passing through the liquid reservoir 11, and the liquid is used again.

In the above embodiment, the liquid was circulated in order to remove the altered liquid from the focal point, but instead of circulating the liquid, the cell containing the liquid was vibrated in a direction perpendicular to the axis of the cell. It is also possible to move the position of the focal point.

[Effects of the Invention] The present invention provides a pair of nozzles that intersect with the axis of the container filled with liquid as described above, at the portion located at the focal point of the laser beam incident and converged into the container. The nozzle is connected through a circulation path, a circulation pump, and a liquid reservoir, so that the generation of bubbles near the focal point can be prevented. Therefore, a phase conjugate wave can be stabilized with respect to a beam repeatedly incident. Can be generated. Therefore, there is an effect that a laser beam having a high repetition rate, an excellent light-collecting property, and a stable directivity can be obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of a liquid phase conjugation apparatus according to the present invention, and FIG. 2 is a side sectional view showing a conventional liquid phase conjugation apparatus. DESCRIPTION OF SYMBOLS 1 ... Container 2 ... Translucent wall 3 ... Laser beam 4 ... Convex lens 5 ... Focus 6 ... Phase conjugate wave 7 ... Nozzle 8 ... Nozzle 9 ... Circulation path 10 ... Circulation pump 11 ... Reservoir

Claims (1)

(57) [Claims] A liquid container is sealed in a tubular container having light-transmitting walls at both ends, and a portion of the container corresponding to a focal point of a laser beam incident and condensed into the container through the light-transmitting wall. A circulating phase conjugating device for a liquid, comprising: a pair of nozzles intersecting the axis of the laser beam, the nozzles communicating with each other via a circulation path, a circulation pump and a liquid reservoir.