JPH04261083A - Pulse laser device - Google Patents

Abstract

PURPOSE:To shorten the total length of the title pulse laser device provided with amplifiers. CONSTITUTION:Partial reflectors 3a of a pulse width expander 3 are provided on the beam outlet side of a beam diameter enlargement device 2 while the pulse width expander 3 is arranged so that at least an outlet side lens 2b of the beam diameter enlagement device 2 may be located in the space encircled by multiple total reflectors 3b comprising the pulse width expander 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a highly directional and high output pulse laser device, such as a copper vapor laser that excites a dye laser used for isotopic separation of uranium atoms.

0002

2. Description of the Related Art FIG. 4 is a block diagram of a conventional pulse laser device equipped with a beam diameter enlarging device. In the figure, 1 is an oscillator, 2 is a beam diameter expanding device, 3 is a pulse width expanding device, and 4 is an amplifier.

Next, the operation will be explained. Oscillator 1 is
This is an oscillator with a small diameter and short resonator length (approximately 1 m). Therefore, the divergence angle is extremely small (0.1 mrad or less), but the beam diameter is small (about 18 mmφ) and the pulse width is narrow (about 20 ns), so the output is small at about 3 W. The beam diameter is expanded to approximately 65 mmφ by a beam diameter expanding device 2 composed of two convex lenses 2a and 2b.
Next, the pulse width is expanded by the pulse width expansion device 3. The pulse width extension device 3 is composed of one partial reflection mirror 3a with a reflectance of about 63% and four total reflection mirrors 3b, and about 37% of the incident beam travels straight. The remaining approximately 63%
is reflected by the partial reflecting mirror 3a, passes through four total reflecting mirrors 3b, circulates about 6 m in the direction of the arrow, and returns to the partial reflecting mirror 3a with a delay of about 20 ns. Approximately 63% of the reflected beam (approximately 37% of the incident beam goes straight) is reflected and overlaps the beam that went straight ahead, with a pulse width of about 40 ns and heads toward the amplifier 4a.

[0004] The laser whose beam diameter has been enlarged and whose pulse width has been extended is powered by a multi-stage 4a by a large 100W class amplifier 4 with a large diameter (65 mmφ) and long pulse width (approximately 40 ns).
, 4b, 4c. As a result, the laser output is amplified to about 300 W at the third stage, and the divergence angle is 0.3 mrad or less, maintaining high directivity.

[0005]

[Problems to be Solved by the Invention] However, since the conventional pulse laser device is constructed as described above, it has the disadvantage that the overall length becomes long. This invention is
This was done to eliminate the drawbacks mentioned above.
The aim is to obtain a pulsed laser device with a short overall length.

[0006]

[Means for Solving the Problems] In the pulse laser device according to the present invention, the partial reflecting mirror of the pulse width expansion device is disposed on the exit side of the beam diameter expansion device, and at least the exit side lens of the beam diameter expansion device is connected to the pulse width expansion device. It is installed inside the expansion device.

[0007]

[Operation] In this invention, the partial reflection mirror of the pulse width expansion device is located on the exit side of the beam diameter expansion device, and at least the exit side lens of the beam diameter expansion device is surrounded by the plurality of total reflection mirrors constituting the pulse width expansion device. Since it is located in a closed space, the overall length can be shortened.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an oscillator, 2 is a beam diameter expanding device, 3 is a pulse width expanding device, and 4 is an amplifier. A partial reflecting mirror 3a constituting the pulse width expansion device 3 is arranged on the exit side of the beam diameter expansion device so as to circulate the laser beam in the direction of the arrow, and an exit side lens 2b constituting the beam diameter expansion device 2 By installing this inside the pulse width expansion device 3, the pulse width expansion device and the beam diameter expansion device are integrally formed.

Next, the operation will be explained. Oscillator 1 is
This is an oscillator with a small diameter and short resonator length (approximately 1 m). Therefore, the divergence angle is small (less than 0.1 mrad), but
The beam diameter is small (approximately 18 mmφ) and the pulse width is narrow (
(about 20 ns), the output is as small as about 3 W. The beam diameter of the laser beam emitted from the oscillator 1 is expanded to approximately 65 mmφ by a beam diameter expanding device 2 composed of two convex lenses 2a and 2b. This beam is then passed through a single partially reflecting mirror 3
The pulse width is expanded to about twice by a pulse width expansion device consisting of a mirror a and four total reflection mirrors 3b. In the pulse width stretching device, the reflectance of the partial reflecting mirror 3a is about 63%, so about 37% of the incident laser beam goes straight;
The remaining laser is reflected and directed in the direction of the arrow in FIG. 1, circulates around the beam diameter expander by about 6 m by the total reflection mirror 3b, returns to the partial reflection mirror 3a after a delay of about 20 ns, and returns to the partial reflection mirror 3a. % (approximately 37% of the incident beam goes straight) is reflected and overlaps the laser beam that went straight ahead, and the pulse width becomes about 40 ns and heads toward the amplifier 4. The laser beam, whose beam diameter has been expanded and pulse width has been extended, has a large diameter (65 mmφ) and a long pulse width (approximately 40 ns).
A large 0W class amplifier 4 amplifies the signal into multiple stages 4a, 4b, and 4c. As a result, the laser output at the third stage is approximately 30
It is amplified to 0W and the divergence angle is 0.3mrad.
High directivity is maintained below.

In the above embodiment, the laser is circulated in a rectangular manner in the pulse width stretching device, but it may be circulated in a figure 8 shape as shown in FIG. This allows a longer optical path length to be obtained in a smaller space, making it possible to make the pulse laser device even more compact. Further, as shown in FIG. 3, the beam diameter enlarging device 2 may be constructed of a concave lens and a convex lens. In this case, it is shorter and easier to fit inside the pulse width stretching device 3. Also, Figure 1
In the embodiment shown in FIG. A configuration may also be adopted in which a side lens is also installed. This makes it even more compact.

[0011]

As described above, according to the present invention, the partial reflecting mirror of the pulse width expansion device is provided on the exit side of the beam from the pulse width expansion device, and the lens on the exit side of the beam expansion device or all the lenses Since the device is configured to be housed within the pulse width expansion device, the device can be made compact, space-saving, and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a pulse laser device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the invention.

FIG. 3 is a configuration diagram showing a third embodiment of the invention.

FIG. 4 is a configuration diagram of a conventional pulse laser device.

[Explanation of symbols]

1 Oscillator 2 Beam diameter expansion device 2a Entrance side lens 2b Exit side lens 3 Pulse width extension device 3a Partial reflector 3b Total reflection mirror 4 Amplifier 4a 1st stage amplifier 4b 2nd stage amplifier 4c 3rd stage amplifier

Claims (2)

[Claims] Claim 1: In a pulsed laser device comprising an oscillator, a beam diameter expansion device, a pulse width expansion device, and an amplifier, a partial reflecting mirror of the pulse width expansion device is installed on the beam exit side of the beam diameter expansion device, and the beam diameter A pulse laser device characterized in that at least an exit side lens of a magnifying device is installed in a space surrounded by a plurality of total reflection mirrors constituting a pulse width stretching device. 2. The pulse laser device according to claim 1, wherein the optical path of the pulse width stretching device is shaped like a figure eight.