JP2824375B2 - Optical delay circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical delay circuit for delaying an incident pulse laser beam and emitting the delayed laser beam to the outside.

[0002]

2. Description of the Related Art FIG.
Spring Annual Meeting ”(March 28-30, 1992, Tokai Univ.), Laser-J Experimental machine Main test laser system operation results (II) is there. In the figure, reference numeral 1 denotes a pulsed laser beam incident from a laser oscillator (not shown);
Is a plane partial reflecting mirror that is installed at a predetermined angle about the optical axis of the optical branching point.
a while transmitting the pulsed laser beam 1 incident on
A part of the pulsed laser light 1 is reflected in a direction perpendicular to the incident direction to split the pulsed laser light 1 into transmitted light and reflected light.

[0003] Reference numeral 3a denotes a total reflection mirror for reflecting the reflected light incident from the planar partial reflecting mirror 2 at right angles downward, and 3b reverses the reflection direction of the reflected light incident from the total reflecting mirror 3a to the total reflecting mirror 3a. 3c is a total reflection mirror that reflects the light incident from the total reflection mirror 3b upward at a right angle, and 3d is a plane partial reflection that reflects the light incident from the total reflection mirror 3c. It is a total reflection mirror that reflects light to a light branch point 2a of the mirror 2.

The total reflection mirrors 3d and 3a are arranged at equal distances in the left-right direction with respect to the plane partial reflection mirror 2. The total reflection mirror 3c is arranged so that each reflection surface faces a diagonal line with respect to the total reflection mirror 3a. Further, the total reflection mirror 3b is arranged so that respective reflection surfaces face each other diagonally with respect to the total reflection mirror 3d.

Next, the operation will be described. The incident pulse laser beam 1 is split at a light splitting point 2a into transmitted light that travels in the same direction as the direction of incidence on the plane partial reflecting mirror 2 and reflected light that is reflected in a direction perpendicular to the direction of incidence. The pulse laser beam 1 reflected by the plane partial reflecting mirror 2 is reflected by the total reflecting mirror 3
The light is reflected downward at a right angle by a, and is incident on the total reflection mirror 3b.

The total reflection mirror 3b reflects the incident pulse laser beam 1 in a direction opposite to the direction of incidence on the total reflection mirror 3a and makes the pulse laser beam 1 incident on the total reflection mirror 3c. And the total reflection mirror 3c
Reflects the incident pulsed laser light 1 upward at right angles to be incident on the total reflection mirror 3d. As a result, the pulsed laser beam 1 returns to the light branching point 2a of the plane partial reflecting mirror 2, and again travels in the same direction as the reflected light reflected downward by the plane partial reflecting mirror 2 at right angles to the incident direction. It is split into transmitted light.

The reflected light branched at this time becomes the pulse laser light 1 which is emitted with a delay determined by the delay optical path length from the time when the pulse laser light 1 enters the optical delay circuit. The split transmitted light is again transmitted to the total reflection mirrors 3a to 3d.
The light is incident on the plane partial reflecting mirror 2 while being reflected between the light, and is split into reflected light and transmitted light. At this time, the light intensity of the pulsed laser light 1 emitted from the optical delay circuit as reflected light from the planar partial reflecting mirror 2 depends on the reflectance of the planar partial reflecting mirror 2 and the light intensity of the incident pulsed laser light 1. It is determined by the pulse width, laser oscillation frequency, and delay optical path length.

Further, the optical axis of the pulse laser beam 1 affected by the optical delay circuit is determined by the material of the plane partial reflector 2 constituting the optical delay circuit, the dimension including the thickness of the plane partial reflector 2, and the pulse laser beam. 1 is determined by the angle of incidence on the flat partial reflecting mirror 2. Therefore, when a mismatch occurs between any of these optical axis determining elements and the incident pulse laser beam 1, the optical axis of the pulse laser beam 1 emitted from the optical delay circuit shifts. Therefore , the distance between the plane partial reflecting mirror 2 and the entire reflecting mirrors 3a to 3d and the reflecting mirrors 2 and 3a are set such that the optical axis of the pulsed laser beam 1 emitted from the optical delay circuit always coincides with the preset optical axis. Adjust the mounting angle of 3d, etc. When the incident angle of the pulse laser beam 1 incident on the plane partial reflecting mirror 2 from the laser oscillator through the optical system is shifted, the pulse laser beam emitted from the optical delay circuit is corrected after the incident angle is corrected by the optical system. The distance between the planar partial reflecting mirror 2 and the entire reflecting mirrors 3a to 3d, the mounting angles of the reflecting mirrors 2, 3a to 3d, and the like are adjusted so that the optical axis of the first mirror coincides with the preset optical axis.

[0009]

Since the conventional optical delay circuit is constructed as described above, it is necessary to match the optical axis of the pulse laser light emitted from the optical delay circuit with a preset optical axis. In addition, it is necessary to adjust the optical axis by adjusting the mounting position of the plane partial reflecting mirror or the entire reflecting mirror. However, when the number of reflecting mirrors, which are components of the circuit, increases, the optical axis adjustment becomes complicated, and even after the optical axis adjustment, the mounting position of each reflecting mirror changes over time to stabilize the optical axis for a long time. It was difficult. Further, there is a problem in that the optical axis is not stable due to the optical wavefront distortion of the pulse laser light and the optical axis fluctuating due to the fluctuation of air in the optical delay circuit.

The present invention has been made to solve the above problems, and has as its object to provide an optical delay circuit that can easily adjust the optical axis and stabilize the optical axis for a long time.

[0011]

According to a first aspect of the present invention, there is provided an optical delay circuit having a first window and a second window, wherein the laser beam incident from the first window is transmitted to the second window. A vacuum container that emits out of the window from the window, and a light branching unit that is provided in the vacuum container, transmits the incident laser light, and reflects the laser light in a direction perpendicular to the laser light incident path. A first reflection means and a second reflection means provided in the vacuum vessel and arranged so that both reflection surfaces face each other with the light branching means therebetween, and a laser reflected by the light branching means. After the light is reflected by the first reflecting means toward the second reflecting means, the laser light reflected by the second reflecting means is transmitted by the light branching means toward the first reflecting means, and Second
It is made to reflect on the window of.

[0012]

[0013]

In the optical delay circuit according to the first aspect of the present invention, when the laser light incident from the first window of the vacuum vessel is reflected by the light branching means toward the first reflecting means, the laser light is transmitted to the first reflecting means. Reflected from the reflecting means toward the second reflecting means,
Further, the light is reflected by the second reflecting means and enters the light branching means. As a result, the light branching means transmits a part of the incident laser light to the first reflecting means, and reflects a part of the laser light in the direction of the second window to emit the laser light to the outside of the vacuum vessel. Thus, the laser light incident on the vacuum vessel is emitted with a delay.

[0014]

[0015]

【Example】

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing the configuration of the optical delay circuit in the present embodiment. In FIG. 1, reference numeral 1A denotes a vacuum vessel containing the optical system of the optical delay circuit according to the present embodiment.
And a second window 1A2 for emitting the incident pulsed laser light 1 to the outside of the vacuum vessel 1A.

Further, the optical system of the optical delay circuit housed in the vacuum vessel 1A serves as a light branching means for transmitting the incident pulse laser light 1 and reflecting the pulse laser light 1 in a direction perpendicular to the incident direction. Cube beam splitter 4
After the pulsed laser beam 1 reflected by the cube beam splitter 4 is incident on the slope 5A1, the pulse laser beam 1 is reflected by the first rectangular face 5A2 on the second rectangular face 5A3, and is again directed by the second rectangular face 5A3 toward the slope 5A1. A first prism 5A as first reflecting means for reflecting and emitting, and a pulse laser beam 1 emitted from the first prism 5A on an inclined surface 5B1.
From the first right-angled surface 5B2,
B3, and again the slope 5B by the second right-angled surface 5B3.
A second prism 5 </ b> B as second reflecting means for reflecting the pulsed laser beam 1 toward the cube beam splitter 4. Where 4
a is a light branch point where the incident pulse laser light 1 is branched into reflected light and transmitted light. The slope 5 of the first prism 5A
A1 and the slope 5B1 of the second prism 5B face each other with the cube beam splitter 4 interposed therebetween.

Next, the operation of the first embodiment will be described.
The pulsed laser beam 1 that is incident from a pulse laser oscillator (not shown) and has passed through the first window 1A1 of the vacuum vessel 1A is
When the light enters the light branching point 4a of the cube beam splitter 4, a part of the light is transmitted in the direction of the second window 1A2, and a part of the light is reflected in the direction perpendicular to the incident direction, and the slope 5A of the first prism 5A
1 is incident on the first right-angled surface 5A2. The incident pulsed laser light 1 is reflected downward by the first right-angled surface 5A2 in the right-angle direction, and is incident on the second right-angled surface 5A3. The incident pulsed laser light 1 is applied to the second right-angled surface 5A.
3 is reflected in the right angle direction and is emitted again from the slope 5A1.

The emitted pulse laser light 1 is incident on the first right-angled surface 5B2 from the inclined surface 5B1 of the second prism 5B. The incident pulsed laser light 1 is applied to the first right-angled surface 5B.
2 is reflected upward in a direction perpendicular to the second rectangular surface 5B3.
Is incident on. The pulse laser beam 1 is reflected in the right-angle direction by the second right-angle surface 5B3, and is emitted again from the inclined surface 5B1.

The pulse laser light 1 emitted from the slope 5B1 is incident on the light branching point 4a of the cube beam splitter 4, where it is reflected in the direction of the second window 1A2 and the direction of the slope 5A1 of the first prism 5A. Into a pulsed laser beam that passes through The pulsed laser light reflected here is the time required for the pulsed laser light 1 incident from the first window 1A1 to be determined by the delay optical path length (the sum of the light passing distance in each prism and the light passing distance between the prisms). The light is emitted to the outside from the second window 1A2 with a delay. On the other hand, the transmitted pulse laser light repeats reflection between the first prism 5A and the second prism 5B again and is incident on the cube beam splitter 4.

The light intensity of the pulse laser light emitted from the optical delay circuit is represented by the reflectivity of the cube beam splitter 4, the light intensity and pulse width of the incident pulse laser light, the laser oscillation frequency, and the delay optical path length. Decided.

The queue blanking the beam splitter 4 a first window 1
When installed perpendicular to the optical axis of the pulse laser beam 1 passing through A1, the optical axis of the pulse laser beam 1 emitted from the cube beam splitter 4 does not change. Further, the pulse laser beam 1 reflected by the first prism 5A
Is incident on the optical branching point 4a of the cube beam splitter 4, where the reflected pulsed laser light 1 and the first window 1A
_The pulsed laser beam 1 that has traveled straight through 1 is the first prism
Adjusting the mounting angle of 5A and second prism 5B
Thus, the optical axes can always be easily matched. Also,
By housing the optical system in the vacuum vessel 1A, it is possible to prevent optical wavefront distortion and optical axis fluctuation due to air fluctuation.

In the above description, a case has been described where a prism is used in an optical system for causing the pulsed laser beam 1 reflected by the cube beam splitter 4 to enter the cube beam splitter 4, but one of the techniques related to the present invention is described.
As an example, an optical fiber may be used as a means for causing the pulsed laser beam 1 to enter the cube beam splitter 4.

[0023] The following is a description of the operation. The first laser beam emitted from a pulse laser oscillator (not shown)
When the pulse laser beam 1 transmitted through the window 1A1 is incident on the light branching point 4a of the cube beam splitter 4, a part is transmitted in the direction of the second window 1A2, and a part is reflected in a direction perpendicular to the incident direction. The light is condensed by the first convex lens 6A and is incident on the optical fiber 7. When the incident pulse laser light 1 passes through the optical fiber 7 and is emitted toward the second convex lens 6B, it is condensed by the second convex lens 6B and is incident on the cube beam splitter 4.

As a result, the incident pulse laser beam 1 is incident on the light branching point 4a of the cube beam splitter 4, where it is reflected in the direction of the second window 1A2 and transmitted in the direction of the first convex lens 6A. The light is branched into pulse laser light. The pulse laser light reflected here is delayed from the second window 1A2 to the outside by delaying the pulse laser light 1 incident from the first window 1A1 by a time determined by the delay optical path length (length of the optical fiber 7, etc.). Emitted pulsed laser light 1
Becomes On the other hand, the transmitted pulse laser light is condensed again by the first convex lens 6A and is incident on the optical fiber 7.

With the above configuration, the optical axis of the pulse laser beam 1 emitted from the cube beam splitter 4 is adjusted by adjusting the pulse laser beam 1 emitted from the optical fiber 7.
It is sufficient only to adjust the position of the second convex lens 6B that focuses the light onto the light branch point 4a of the cube beam splitter 4. Further, the use of the optical fiber 7 in the delay optical path simplifies the optical system.

Embodiment 2 FIG. Was to eliminate the optical axis changes in pulse laser beam 1 by using a cube beam splitter 4 as an optical branching unit in the first embodiment, it may be used flat partial reflection mirror 2 to the optical branching unit as in the prior art At this time, a change in the optical axis caused by the thickness of the plane partial reflecting mirror is compensated by a glass compensator having a predetermined thickness.

FIG. 3 is a configuration diagram of an optical delay circuit according to the present embodiment in which a change in the optical axis caused by the plane partial reflecting mirror 2 is compensated by a compensating plate. In the drawings, the same reference numerals as those in FIGS. 1 and 4 indicate the same or corresponding parts. In the figure,
Reference numeral 8 denotes a compensating plate having a constant thickness. The compensating plate 8 is installed at a predetermined angle about the optical axis of the pulsed laser beam 1 transmitted through the second window 1A2 from the plane partial reflecting mirror 2. ing. Since the compensating plate 8 has a certain thickness, the optical axis of the incident pulse laser beam 1 is refracted by the thickness of the compensating plate 8, so that the optical axis of the pulsed laser beam 1 transmitted through the compensating plate 8 is incident. It shifts more than time.

Next, the operation of the third embodiment will be described.
The pulsed laser beam 1 incident on the first right-angled surface 5B2 from the inclined surface 5B1 of the second prism 5B is reflected upward by the first right-angled surface 5B2 in the right-angle direction, and is incident on the second right-angled surface 5B3. Then, the incident pulse laser light 1 is
Reflected in the right angle direction by the right angle surface 5B3, the slope 5
It is emitted from B1.

The pulsed laser beam 1 emitted from the slope 5B1 returns to the light branching point 2a of the plane partial reflecting mirror 2, and then returns to the plane
Reflected downward by the partial reflecting mirror 2 at right angles to the incident direction
Reflected light and transmitted light traveling straight in the same direction as the incident direction
Is done. Pulse rates, which has been straight through the first window 1A ₁ here
The laser light 1 is incident by the refractive index and thickness of the plane partial reflecting mirror 2.
The emitted light is shifted from the optical axis in parallel. However, this path Rusureza light 1 when passing through the compensator plate 8, the optical axis by the thickness of the compensation plate 8 is refracted in the direction of the predetermined light axis.
Therefore, by adjusting the insertion angle of the compensator 8, the optical axis shift caused by the flat partial reflecting mirror 2 can be corrected. Therefore,
The optical axis of the pulsed laser light 1 transmitted through the compensator 8 and emitted from the second window 1A2 to the outside coincides with the optical axis of the pulsed laser light 1 incident on the optical delay circuit.

[0030]

According to the first aspect of the present invention, there is provided a first window and a second window, and the laser light incident from the first window is emitted to the outside from the second window. A vacuum vessel, a light branching means provided in the vacuum vessel, for transmitting the incident laser light, and for reflecting the laser light in a direction perpendicular to an incident path of the laser light, and provided in the vacuum vessel. A first reflecting means and a second reflecting means arranged so that both reflecting surfaces face each other with the light branching means therebetween, and the laser light reflected by the light branching means is reflected by the first reflecting means. After the light is reflected toward the second reflecting means, the laser light reflected by the second reflecting means is transmitted by the light branching means toward the first reflecting means and is reflected by the second window. Temperature change According fluctuation of the optical axis of the laser beam due to the fluctuation of the air, along with eliminating the fluctuation of the wavefront measurably stabilization of the optical axis, there is an effect that the optical axis adjustment becomes very easy.

[0031]

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a configuration of an optical delay circuit according to a first embodiment of the present invention.

FIG. 2 shows an example of a technique related to the first embodiment of the present invention.
It is to figure.

FIG. 3 is a configuration diagram illustrating a configuration of an optical delay circuit according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a configuration of a conventional optical delay circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulse laser beam 1A Vacuum container 1A1, 1A2 1st window, 2nd window 4 Cube beam splitter 5A, 5B 1st prism, 2nd prism 6A, 6B 1st convex lens, 2nd convex lens 7 Optical fiber

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G02B 27/00 H04B 10/10 H04B 10/105 H04B 10/22

Claims (1)

(57) [Claims] A first window and a second window, wherein the first window and the second window are provided.
A vacuum container for emitting the laser light incident from the second window to the outside from the second window, and provided in the vacuum container, transmitting the incident laser light, and with respect to an incident path of the laser light. A light branching means for reflecting a laser beam in a right angle direction, and a first reflecting means and a second reflecting means provided in the vacuum vessel and arranged so that both reflecting surfaces face each other with the light branching means interposed therebetween. After the laser beam reflected by the light branching unit is reflected by the first reflecting unit toward the second reflecting unit, the laser beam reflected by the second reflecting unit is reflected by the light branching unit. An optical delay circuit, wherein the light is transmitted toward the first reflection means and is reflected on the second window.