JPH0487386A - Pulse dye laser system - Google Patents

Abstract

PURPOSE:To obtain a dye laser light containing no noise composition and having high output by setting the timing for the first excited laser light to match the irradiating timing for longer than output pules width of the second excited laser light and by setting it to pulse waving shape to rise within a period of the fluorescent life of coloring matter. CONSTITUTION:The timing for output of dye laser light L from a dye laser oscillator 23 is set by a control portion 29, in accordance with the timing of enter an excited laser light L2 into each dye laser amplifier 24a to 24d after the output of it from an excited laser device 25. As a result, laser light L can be efficiently amplified. The pulse wide P3 of an excited laser light L1 which is output from the first excited laser device 21 is set fully longer than the pulse width P4 of laser light L2. As a result, the oscillator 23 is excited in the portion which has more than threshold value T of the laser light L1, and the pulse width P5 of the laser light L can be as the same as the pulse width PV4 or longer than that. Therefore, time difference t between laser light L and L2 becomes zero, and noise components are not generated, with amplification loss eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) This invention relates to a pulsed dye laser system equipped with a dye laser amplification section.

(Prior Art) A pulsed dye laser system oscillates dye laser light by exciting a dye laser oscillator, which is made up of a dye cell in which a dye solution is circulated, with excitation laser light output from a copper vapor laser, for example. It has become. The laser light output from the dye laser oscillator is incident on the dye laser amplifier, which also includes a dye cell. This dye laser amplifier is excited by an excitation laser beam, whereby the laser beam incident on the dye laser amplifier is amplified and emitted.

Conventionally, a pulsed dye laser system having such a configuration has been configured as shown in FIG. 5 or 6. That is, the pulsed dye laser system shown in FIG. 5 includes an excitation laser device 1 such as a copper vapor laser. Excitation laser light output from this excitation laser device 1. is split into a first excitation laser beam L1 that is reflected by the beam splitter 2 and a second excitation laser beam L2 that is transmitted through the beam splitter 2. The first excitation laser beam L1 enters a dye solution oscillator 3 made up of a dye cell and excites the dye solution. When the dye solution is excited, the dye laser oscillator 3 outputs dye laser light. Dye laser oscillator 3
The laser light outputted from the dye laser oscillator 3 is incident on a dye laser amplifier 4 which is composed of a dye cell like the dye laser oscillator 3.

On the other hand, the second excitation laser beam L2 transmitted through the beam splitter 2 is transmitted to a delay optical system 6 consisting of a plurality of reflection mirrors.
The light enters the dye laser amplifier 4 through the above, and excites the dye solution in the dye laser amplifier 4. Thereby, the dye laser light outputted from the dye laser oscillator 3 and incident on the dye laser amplifier 4 is amplified and emitted as B radiation.

The pulsed dye laser system shown in FIG. 6 has almost the same configuration as the pulsed dye laser system shown in FIG. It is designed to be amplified by a pump laser amplifier 11. This excitation laser amplifier]1 amplified dye laser light. is split into a first excitation laser beam L1 that is reflected by the beam splitter 2 and a second excitation laser beam L2 that is transmitted through the beam splitter 2. Second excitation laser light L2
is further divided by a plurality of beam splitters 12. The divided excitation laser beams L2 of each node 2 are made to respectively enter a plurality of dye laser amplifiers 4 optically connected in series to the dye laser oscillator 3.

Therefore, according to such a configuration, the laser beam output from the dye laser oscillator 3 is sequentially amplified by the plurality of excitation laser amplifiers 11 excited by the second excitation laser beam L2 having sufficient intensity. , and eventually the fifth
Higher output dye laser light can be obtained compared to the laser device shown in the figure.

By the way, in the pulsed dye laser device having the configuration shown in FIGS. 5 and 6, the first excitation laser beam is split by the beam splitter 2 that excites the dye laser oscillator 3 and the dye laser amplifier 4; and second excitation laser beam L
2 has the same output pulse width. However, the first
Since the pulse width of the dye laser beam outputted from the dye laser oscillator 3 by being excited by the excitation laser beam L1 is shorter than that of the excitation laser beam L1, the second excitation laser beam L2 that excites the dye laser amplifier 4 The pulse width will be shorter than the pulse width of Then, the second excitation laser beam L2
Even if the timing at which the dye enters the dye laser amplifier 4 is matched by the delay optical system 6, there is a time when the dye is amplified by the second excitation laser beam L2 without input from the dye laser oscillator 3. The output from the laser amplifier 4 is amplified 5pon.
There have been cases where noise components such as taneous ea+1ssfon) are included.

FIGS. 7(a) and 7(b) explain the cause of noise components. That is, when the first excitation laser beam indicated by Ll in FIG. 6(a) enters the dye laser oscillator 3, the dye laser oscillator 3
The oscillation occurs in a portion with an intensity equal to or greater than the threshold value 1 of 1.

Therefore, the first excitation laser beam L1 and the dye laser beam output from the dye laser oscillator 3 are different from each other as shown in FIG. 7(a).
A time indicated as t1t2 occurs. In other words, when the dye laser oscillator 3 is excited by the first excitation laser beam L1, the laser light output from the dye laser oscillator 3 is different from the first excitation laser beam as shown in FIG. 7(b). , the above-mentioned time difference 1. It is output with a short pulse width P2 corresponding to 12 minutes.

In this way, the dye laser amplifier 4, into which the dye laser beam with the pulse width P2 is incident, receives the first excitation laser beam as shown in FIG. 7(b).

It is excited by the second excitation laser beam L2 having the same pulse width P. In other words, the dye laser light has a pulse width P
It is excited by the second excitation laser beam L2 having a pulse width P1 longer than 2.

Therefore, using the delay optical system 6 shown in FIGS. 5 and 6, the dye laser beam incident on the dye laser amplifier 4 and the second
Even if the incident timing of the excitation laser beam L2 is made to match,
Since the time indicated by t and (tl + t2) in the figure also occurs between the dye laser light and the second excitation laser light L2, the part indicated by N in the figure becomes a noise component and is emitted from the dye laser amplifier 4. It will be output.

This noise component N is inevitably amplified and becomes larger as the dye laser amplifiers 4 are provided in multiple stages as shown in FIG.

(Problems to be Solved by the Invention) As described above, in the conventional pulsed dye laser system, the pulse width of the laser light output from the dye laser oscillator by being excited by the first excitation laser light is Since the pulse width is shorter than the pulse width of the second excitation laser beam that excites the amplifier, there is a period of time during which amplification by the second excitation laser beam is performed without input from the dye laser oscillator. There were cases where noise components were included in the output.

This invention was made based on the above-mentioned circumstances, and its purpose is to ensure that the laser light that is amplified and output by the dye laser amplifier contains almost no noise components, and that the dye laser has a high output power. An object of the present invention is to provide a pulsed dye laser system that can obtain laser light.

[Structure of the Invention (Means and Effects for Solving the Problems) In order to solve the above problems, the present invention provides dye laser output means that is excited by a first excitation laser beam and outputs a dye laser beam; 2
dye laser amplification means provided in one or multiple stages for amplifying the dye laser beam with an excitation laser beam; and the dye laser amplification of the dye laser beam or the amplified dye laser beam and the second excitation laser beam. control means for matching respective incident timings to the means, the first excitation laser beam is set to have an output pulse width longer than the output pulse width of the second excitation laser beam, and the first excitation laser beam is set to have an output pulse width longer than the output pulse width of the second excitation laser beam, and It is characterized in that the pulse waveform is set to rise in a time approximately equal to or shorter than the fluorescence lifetime of the dye used in the method.

According to such a configuration, since the pulse width of the first excitation laser beam that excites the dye laser oscillation means is longer than the pulse width of the second excitation laser beam that excites the dye laser amplification means, the dye laser oscillation means The pulse width of the laser beam output from the dye laser oscillation means can be made almost the same as or longer than the pulse width of the second excitation laser beam, and the rise time of the first excitation laser beam is fast. The output of laser light can be increased.

Therefore, the efficiency of the dye laser beam and the second excited dye laser oscillation means can be improved.

(Example) An example of the present invention will be described below with reference to FIG. FIG. 1 shows the overall configuration of a pulsed dye laser system, in which reference numeral 21 denotes a first excitation laser device 21 consisting of a copper vapor laser or the like. This first excitation laser device 21 outputs a first excitation laser beam L1. This first excitation laser beam L1 enters the optical fiber 22, is guided to a dye laser oscillator 23 consisting of a dye cell, and excites this laser oscillator 23. Thereby,
Laser light is output from the dye laser oscillator 23.

The rise of the output pulse of the excitation laser beam L1 is set to be approximately equal to or shorter than the fluorescence lifetime of the dye used in the dye laser oscillator 23. Specifically, the first excitation laser device 2 consisting of a copper vapor laser
1, the pulse width of its output is about 10 to 100 ns, but the rising edge is generally 10 ns or more. However, since the copper vapor laser has a high gain, ASE occurs when a resonator is assembled, and the output brightness decreases when the laser is emitted over a long distance.

However, when the component of the laser output of the first excitation laser device 21 and the ASE included in the output are guided through the optical fiber 22, the ASE component rises quickly, so the first excitation laser emitted from the fiber 22 The rise of the light can be a light pulse that is comparable to or shorter than the fluorescence lifetime of the dye. First excitation laser beam L1
If it is emitted from the optical fiber 22, both the main component and the ASE component can be used as the first excitation laser beam L1 without distinction.

FIG. 3(a) shows the first excitation laser beam L1 with a rise comparable to or shorter than the fluorescence lifetime of the dye, and this first excitation laser beam L1.
The waveform of the excitation laser beam whose rise is slower than that of the excitation laser beam L1 is shown. Moreover, FIG. 3(b) shows the waveforms of the output laser beams LIL-, which are outputted by being excited by the respective laser beams L and L. As is clear from FIG. 3(b), the output laser beam L1 obtained from the dye laser oscillator 23 by being excited by the first excitation laser beam has a faster rise than the excitation laser beam that has a slower rise. It can be seen that the output, that is, the total energy and the maximum output, is sufficiently large compared to the output laser beam Ld' obtained by being excited by light.

The difference in total energy between the output laser beams L, J and Ld' is the area S of the waveform shown in FIG. 3(b).

There is a difference in S2, and S,>S2.

The dye laser oscillator 23 includes a plurality of dye laser amplifiers,
In this embodiment, there are four dye laser amplifiers 24a-24d.
are optically connected sequentially in series. Each of the dye laser amplifiers 24a to 24d is excited by the second excitation laser beam L2. The second pumping laser beam L2 is outputted from a second pumping device 25, such as a copper vapor laser, and then amplified by a pumping laser amplifier 26. The second pump laser beam L2 amplified by the pump laser amplifier 26 is transmitted to the first to third beam splitters 2.
The laser beams 7a to 27c are sequentially divided and incident on the first to third dye laser amplifiers 24a to 24c to excite these amplifiers. Further, the second excitation laser beam L2 transmitted through the third beam splitter 27c is reflected by the reflection mirror 28, enters the fourth dye laser amplifier 24d, and excites this amplifier. Therefore, the laser light output from the dye laser oscillator 23 is sequentially amplified by the first to fourth dye laser amplifiers 24a to 24d.

The first pump laser device 21, the second pump laser device 25, and the pump laser amplifier 26 are controlled by a control section 29.
controlled by In other words, the control unit 29 can indirectly control the oscillation timing of the dye laser oscillator 23 by controlling the oscillation timing of the first excitation laser device 21, so that the dye laser light output from the dye laser oscillator 23 is The timing at which the second excitation laser beam L2 enters the laser amplifiers 24a to 24d can be set to coincide with the timing at which the second excitation laser beam L2 enters each of the dye laser amplifiers 24a to 24d.

Note that the first excitation laser device 21, the second excitation laser device 25, and the excitation laser amplifier 26 as well as the control section 29
A signal for detecting the timing of oscillation is input to the controller 29, and a trigger signal for operating the first pump laser device 21, the second pump laser device 25, and the pump laser amplifier 26 is output from the control section 29. , feedback controlled.

Next, the operation of the pulsed dye laser device configured as described above will be explained. When a trigger signal is input to the first pump laser device 21, second pump laser device 25, and pump laser amplifier 26 from the control unit 29, the first pump laser device 21 emits the first pump laser beam L1. The second excitation laser device 25 outputs a second excitation laser beam L2. The first excitation laser beam L1 excites the dye laser oscillator 23. As a result, dye laser light is output from the dye laser oscillator 23, and this dye laser light is transmitted to the first to fourth dye laser amplifiers 24a to 24.
d will be passed sequentially.

On the other hand, the second pump laser beam L2 output from the second pump laser device 25 is amplified by the pump laser amplifier 26, split by the first to third beam splitters 27a to 27c, and then split by the first to third beam splitters 27a to 27c. 1 to 4th dye laser amplifier 2
4a to 24d. As a result, only the dye laser light output from the dye laser oscillator 23 and sequentially passing through the first to fourth dye laser amplifiers 24a to 24d is amplified.

The timing at which the dye laser beam is output from the dye laser oscillator 23 and the timing at which the second excitation laser beam L2 is output from the second excitation laser device 25 and enter each of the dye laser amplifiers 24a to 24d are as follows: Control part 2
9 is set to match. Therefore, the dye laser light output from the dye laser oscillator 2B is
In each of the dye laser amplifiers 24a to 24d, the second excitation laser beam L2 efficiently amplifies the dye without any timing shift.

Further, as shown in FIGS. 2(a) and 2(b), the pulse width P3 of the first excitation laser beam L1 output from the first excitation laser device 21 is different from that of the second excitation laser beam L1. The pulse width P4 is set to be sufficiently longer than the pulse width P4 of the output second excitation laser beam L2. Therefore, as shown in FIG. 2(a), the dye laser oscillator 23 is excited in the portion of the first excitation laser beam that is equal to or higher than the threshold value 1, and the laser beam width P of the dye laser beam is output. , is the second
As shown in Figure (b), each dye laser amplifier 24a to 24
The pulse width P4 of the second excitation laser beam L2 for amplifying d can be made equal to or longer than the pulse width P4.

Therefore, the time difference t between the dye laser light amplified by each dye laser amplifier 24a to 24d and the second excitation laser light L2 that amplifies the dye laser light is 0.
Therefore, not only will no noise component be generated, but
The occurrence of amplification loss force 5 due to the time difference is also eliminated.

On the other hand, the first excitation laser beam L1 output from the first excitation laser device 21 is transmitted to the optical fiber 2 along with the ASE component.
2, it is possible to create a light pulse with a rise comparable to or shorter than the fluorescence lifetime of the dye used in the dye laser oscillator 23. First excitation laser beam L1
If the rise is fast, then the dye laser oscillator 2
The total energy and maximum output shown by the area S1 of the laser beam outputted from 3 are the output laser beam Ld when excited by the excitation laser beam Ld with a slow rise, as shown by Ll in FIG. 3(b). ' can be made larger than .

According to experiments, the efficiency of the conventional dye laser oscillator 23 is 2
According to this invention, the amount that used to be about 5% has increased to 3 to 8%.
It was confirmed that this improved. In addition, in the case of a multi-stage dye laser system, the first and second dye laser amplifiers 24
The efficiency of a and 24b was 15 to 30%, but according to this invention, it was improved to 20 to 40%. This is considered to be because the dye laser oscillator 23 is excited by the first excitation laser beam L1, so that the rise of the laser light output from the dye laser oscillator 23 also becomes faster.

FIG. 4 shows a configuration in which a laser device in which it is difficult to increase the pulse width is used as the excitation source as the first excitation laser device. In such a case, two laser devices 41a,
41b is used. The timing of the first excitation laser beam L1 with a pulse width P6 outputted from one laser device 41a and the timing of the first excitation laser beam outputted from the other laser device 42b are indicated by t6 in the figure. Just shift the time. The respective first excitation laser beams output from these laser devices 41a141b are made incident on the half mirror 42, and the laser beams reflected by this Hough mirror 42 and the transmitted laser beams are combined to generate the above-mentioned pulse. The first excitation laser beam L11 having a pulse width P7 that is sufficiently longer than the width P6 can be obtained.

In the above embodiment, in order to speed up the rise of the first excitation laser beam, the first excitation laser beam L1 output from the first excitation laser device is transmitted along with the ASE component through an optical fiber. However, as another means, the rise of the first excitation laser beam L1 may be made faster by increasing the rise of the excitation current that excites the first excitation laser device.

Further, as the first excitation laser device, an excimer laser may be used instead of the copper vapor laser.

[Effects of the Invention] As described above, the present invention makes the pulse width of the first excitation laser beam that excites the dye laser output means sufficiently longer than the pulse width of the second excitation laser beam that excites the dye laser amplification means. It was set for a long time. Therefore, the pulse width of the dye laser beam output from the dye laser amplification means by being excited by the first excitation laser beam can be made equal to or longer than the pulse width of the second excitation laser beam. Not only can noise components not be included in the amplified laser beam be eliminated, but also no amplification loss will occur.

Furthermore, since the timing at which the dye laser light is output from the dye laser output means is made to coincide with the timing at which the second excitation laser light enters the dye laser amplification means, the dye laser light is output from the dye laser output means. The laser beam can be amplified reliably and efficiently.

Furthermore, the rise of the first excitation laser beam is set to be approximately equal to or less than the fluorescence lifetime of the dye used in the dye laser output means. Therefore, the output of the laser light excited by the first excitation laser light and output from the dye laser oscillator increases, so that the efficiency of the dye oscillator can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a pulsed dye laser system showing an embodiment of the present invention, FIGS. 2(a) and (b) are also explanatory diagrams of the relationship between laser light and pulse width, and FIG. 3(a) 3(b) is a waveform diagram of two laser beams with different rise speeds, and FIG. 3(b) shows the waveform of the dye laser beam outputted from the dye laser output means by being excited by the two laser beams with different rise speeds shown in FIG. 3(a). FIG. 4 is a configuration diagram of a first excitation laser device showing another embodiment of the present invention, and FIGS. 5 and 6 are configuration diagrams of a conventional pulsed dye laser system, respectively. 7(a) and (b) are the same explanatory diagrams of the relationship between conventional laser light and pulse width. 21... First excitation laser device, 22... Optical fiber, 23... Dye laser oscillator, 24a to 24d...
- Dye laser amplifier, 25... second excitation laser device, 29... control section. Figure 4 Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] a dye laser output means for outputting a dye laser beam excited by a first excitation laser beam; a dye laser amplification means provided in one or multiple stages for amplifying the dye laser beam with a second excitation laser beam; control means for matching the respective incident timings of the dye laser light or the amplified dye laser light and the second excitation laser light with respect to the dye laser amplification means; The pulse width is set to be longer than the output pulse width of the excitation laser beam in step 2, and the pulse waveform is set to a pulse waveform that rises in a time approximately equal to or shorter than the fluorescence lifetime of the dye used in the dye laser output means. A pulsed dye laser system characterized by: