JPH0473983A - Laser pulse stretcher - Google Patents

Abstract

PURPOSE:To provide a pulse width altering unit which does not need a complicated optical regulation and a large place by delaying a light via an optical fiber. CONSTITUTION:High reflection plane mirrors 4-7 of prior art are composed of optical fibers 10, and at one end face of the fiber 10 is formed a first condenser lens 11 for introducing a reflected light L2. A second condenser lens l2 is formed for condensing the light L2 transmitted via the fiber 10 and emitted from the other end face to the reflecting surface 2 of an optical unit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a laser pulse stretcher that arbitrarily changes the pulse width of laser light.

(Prior art) For example, in a dye laser system, when a dye, which is a laser substance, is excited with pulsed laser light from a metal (copper) vapor laser oscillator and the output dye laser light is amplified, the pulse width may be extended. It is being done. Such a change in pulse width is disclosed in Japanese Patent Application Laid-Open No. 6444916, etc., and as shown in FIG. An optical body (3) that partially reflects L2 on a surface (2) opposite to the incident surface (1) to form a composite light L4 with the transmitted light L3; 2) is carried out using a device consisting of four high-reflection plane mirrors (4) to (7). In FIG. 2, the reflected light L2 is temporally delayed by the length of the reflected optical path of the high-reflection plane mirrors (4) to (7), and the change in the original pulse width of the incident light L1 is based on this delay time and the optical body. (3) It is determined by the reflectance (transmittance) of the incident surface (1) and the opposite surface (2).

(Problem to be Solved by the Invention) In the conventional configuration described above, in order to change the delay time, each interval of the high reflection plane mirrors (4) to (7) must be changed, but when changing, the optical adjustment is difficult. The problem was that it took time. Also, if you try to widen the pulse width by overlapping the pulses with a delay of 20 ns, for example,
Since the luminous flux in the air is approximately 3×10 8 (m/S), a distance of approximately 6 m is required to obtain a delay time of 20 nsec. Highly reflective plane mirror (4)
When configured as in (7) above, there is a problem in that the occupied area becomes extremely large. The present invention was made to solve such problems, and an object of the present invention is to provide a pulse width changing device that does not require troublesome optical adjustment and does not take up much space.

[Structure of the invention] (Means and effects for solving the problem) Both the incident surface and the opposite surface to the incident surface are partially reflecting surfaces, and are provided at an angle to reflect the incident light in a direction other than the incident direction. an optical body, a first condenser lens that condenses the light reflected by the incident surface, an optical fiber that transmits the condensed light of the first condenser lens, and light emitted from the optical fiber. and a second condensing lens that condenses light onto a surface on which the reflected light and transmitted light from the incident surface on the opposite surface are superimposed, reducing the area occupied by the device itself.

(Example) Hereinafter, the present invention will be described based on drawings showing examples.

Note that parts common to those in FIG. 2 are given the same reference numerals, and explanations of those parts will be omitted to avoid duplication. That is,
The prior art shown in FIG. 2 is a configuration in which the high-reflection plane mirrors (4) to (7) are configured so that the reflected light L2 is incident on one end surface of the optical fiber (10) and this optical fiber/110. 1
a condenser lens (11), and a second condenser lens (12) that condenses reflected light L2 transmitted through the optical fiber (I[ll) and emitted from the other end surface onto the opposite surface (2) of the optical body (3) ).

Next, the operation of the above configuration will be explained. Incident light L1
The pulse width of T1 is 1, and the reflectance of the incident surface (1) and the opposite surface (2) of the optical body (3) are both R.
Let the delay time between one pulse be Δt. A part of the incident light L1 is reflected by the incident surface (1), and the reflected light L2 whose peak value is R is focused by the first condensing lens (11) and enters the optical fiber (10), and the peak value is R. The transmitted light L3 in which the value becomes (1-R) becomes the first emitted light. The reflected light L2 is emitted from the optical fiber (10), passes through the second condensing lens (12), and is reflected and transmitted on the opposite surface (2), and the reflected light has a peak value R2 and is transmitted through the second condensing lens (12). Δ
They overlap with a delay of t. On the other hand, the light transmitted through the opposite surface (2) has a peak value of (1-R)R, and the optical fiber (1
0), and reflection and transmission are repeated on the opposite surface (2). Through this repetition of reflection and transmission, the waveforms of the optical pulses overlap with a delay of Δt, and the peak value of the emitted light is (
1-R), RR(1-R), R(1-R)...
, R2(1-R)", and the optical pulse waveform seen as a whole is the sum of the respective output pulse waveforms. Therefore, the pulse width can be changed by selecting the reflectance R and the delay time. If 10) is quartz, the speed of light is approximately 2.1XIO3 [m/s], which is 20n
If it is desired to obtain a delay time of sec, the length of the optical fiber (IC) should be approximately 10 m.

[Effects of the Invention] Since the light is delayed using an optical fiber, there is no need for the troublesome optical adjustment required for conventional plane mirrors. Additionally, because the delay distance can be shortened and the device can be installed in a rolled-up state, the area it occupies can be significantly reduced compared to conventional devices.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. (3)...Optical body (10)...9 optical fibers (11)...first condenser lens (12)...second condenser lens

Claims (1)

[Claims] Both the entrance surface and the surface opposite to the entrance surface are partially reflective surfaces, and an optical body is provided at an angle to reflect the incident light in a direction other than the direction of incidence, and a third lens is provided to condense the light reflected from the entrance surface. a condenser lens, an optical fiber for transmitting the light condensed by the first condenser lens, and a light emitted from the optical fiber into reflected light and transmitted light at the incident surface on the opposite surface. A laser pulse stretcher comprising: a second condensing lens that condenses light onto a surface to be superimposed.