JPH05121794A - Confirming method of dye laser parasitic oscillation - Google Patents

Abstract

PURPOSE:To eliminate manpower required for measuring ASE by a method wherein a branched laser beam is directly measured by a power meter keeping a laser beam shut off or not shut off. CONSTITUTION:A reflection mirror 19 is provided to the optical path of an output beam 11 which is guided by a second dye flow cell 10 and amplified by a pump beam second amplifier 2, and a power meter which measures a beam reflected by the mirror 19 is provided. Induced florescence generated in a first dye flow cell 4 is put in a resonant state between a resonant end mirror 8 and a grating 7, and a laser beam starts oscillating. As ASE is contained in this laser beam, the laser beam is cut off by an electric shutter 12 so as to ascertain this state, and an output is measured by the power meter 14. In this case, the output is also measured when the laser beam is not cut off, and the waveform ratio of these outputs is measured and processed by computation, if necessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dye laser and a parasitic oscillation light (hereinafter referred to as ASE) of a dye laser generated in a dye laser amplifier.

[0002]

2. Description of the Related Art ASE is parasitic oscillation light that oscillates similarly to a laser due to light reflected by a surface of glass or the like inside a dye cell that is directly involved in laser oscillation inside a dye laser and a dye laser amplifier. This ASE
If the value increases, the amplification factor of the laser beam originally required decreases, and the output of the required laser beam decreases.

The generation of ASE cannot be eliminated as long as a dye laser and a dye laser amplifier are used, but the generation of ASE is suppressed as much as possible and a laser beam containing no ASE is required. Conventionally, when it is attempted to strictly measure the situation of occurrence of this ASE, it is necessary to split a part of the laser beam oscillated from a dye laser, a dye laser amplifier, etc., and make it enter a spectroscope, etc., and measure its laser spectrum. ..

The proportion of ASE is evaluated from the spectrum measured by this method. This evaluated ratio can be replaced by the ratio of the laser intensity, and is divided into the required laser intensity and the ASE intensity for evaluation.

[0005]

The spectroscopic analysis using the laser method is a method of performing excitation and ionization by tuning the laser oscillation wavelength to a wavelength that resonates with the excitation level of the atom. The laser light used in this laser method is
Its characteristics become very important. There is a problem of ASE in the characteristics of this laser light. As described above, if this ASE increases, the amplification factor of the laser beam originally required decreases, and the output of the required laser beam decreases, which is not preferable.

Since this phenomenon greatly affects the excitation efficiency in spectroscopic analysis, it is necessary to measure and evaluate it as necessary. The confirmation and evaluation methods were performed by spectral analysis using a spectroscope, and the results are reflected in the laser intensity. However, the method of confirming ASE using a spectroscope has a problem in that it takes time and labor required for measurement in order to respond promptly during the test.

The present invention has been made in order to solve the above-mentioned problems. It utilizes the characteristics of ASE and can be measured by a simple method, responding promptly to confirming the occurrence of ASE. It is to provide a method of confirming parasitic oscillation light of a dye laser for enabling prompt feedback to a test.

[0008]

According to the present invention, a part of a laser beam oscillated from a dye laser and a dye laser amplifier is branched, and the branched laser beam is directly used as a laser beam (seed) using a power meter. It is characterized in that measurement is performed with and without cut, and the generation state of parasitic oscillation light is confirmed from the ratio of the intensities.

[0009]

[Operation] The output intensity of the branched laser beam is directly measured by the power meter. At this time, the laser beam (seed) emitted by the first die flow cell and the wavelength selection element is cut by the electric shutter. In this case, the output of the laser and the output of the laser that is not cut are measured, and the occurrence status of ASE is confirmed from the ratio of these laser output intensities. Further, according to the present invention, it becomes possible to evaluate the ASE occurrence state in parallel with the test even during the test.
The time and labor required for ASE measurement can be reduced.

[0010]

EXAMPLES The mechanism of ASE oscillated from a dye laser and a dye laser amplifier will be briefly described using the dye laser shown in FIG. A dye laser is used by selecting a dye as necessary and dissolving it in a solvent such as methanol. However, the dye laser alone cannot oscillate the laser, and other pumping lasers (excimer laser, YAG laser, etc.) for exciting the dye are required.

By irradiating the dye with the laser oscillated from this pumping laser, it becomes possible to extract the laser of the required wavelength from the dye laser. Here, the laser beam amplified by the pump beam oscillator / preamplifier 1 is focused on the first die flow cell 4 via the focusing lens 3.

A part of the induced fluorescence emitted from the dye excited in the first diflow cell 4 is passed through the beam expander 5 to a wavelength selection element of the intra-cavity etalon 6 and the grating 7 so that only a necessary wavelength is obtained. Is selected, and the resonator is brought into resonance with the resonator end mirror 8. From this state, part of the beam expander 5
And a laser beam (seed) having a very weak output is obtained by being reflected by the surface of the grating 7.

Next, the obtained laser beam is expanded by the beam expanding telescope 9 and guided to the second die flow cell 10. The guided laser beam is further amplified by the pump beam second amplifier 2 to become the output beam 11.

In this output mechanism, in the ASE, the induced fluorescence emitted in the first die flow cell 4 is reflected by the glass surface inside the first die flow cell 4, and the reflected light is the beam expander 5 and the grating 7. It is the light of parasitic oscillation that is reflected by the surface of and oscillates like a laser.

Therefore, in the case where the laser beam contains ASE before being amplified by the pump beam second amplifier 2, the amplification factor in the pump beam second amplifier 2 is equally distributed to the laser beam and ASE, which is necessary. The output of the laser beam is reduced, and the evaluation of the laser intensity will be incorrect in the end.

FIG. 2 is a block diagram showing an example of an apparatus applied to the method for confirming the ASE occurrence state by measuring the laser output intensity with a power meter such as a Joule meter without using a spectroscope for the measurement of ASE according to the present invention. It is shown in the diagram. In FIG. 2, an electric shutter 12 is installed between the beam expander 5 and the first die flow cell 4.
The electric shutter 12 is opened and closed by a drive device 13.

Output beam guided by the second die flow cell 10 and amplified by the pump beam second amplifier 2.
A reflection mirror 19 is installed in the middle of the optical path of 11, and a power meter 14 such as a Joule meter for measuring the reflected beam reflected by the reflection mirror 19 is installed. Power meter
14 is connected to interface 15, interface
15 is connected to a computer 17 via a cable 16.

In FIG. 2, the induced fluorescence generated in the first die flow cell 4 resonates between the resonator end mirror 8 and the grating 7, and the laser beam (seed) oscillates. This laser beam contains ASE, and in order to confirm this situation, the laser beam (seed) is cut by the electric shutter 12 and its output is measured by the power meter 14.

FIG. 3 shows a conventional example in which ASE is measured by using a spectroscope and an example of the present invention in which the same state is measured by a power meter such as a Joule meter. The upper part is a conventional example measured by using a spectroscope, and the lower part is an example of the present invention measured by a power meter. From the left, the states in which ASE is included are (small), (middle), and (large). The lower example of the present invention shows the laser output waveforms in each state when the laser beam (seed) is cut using the moving shutter 12 and when it is not cut.

When the proportion of ASE contained is small, there is a large difference in the output waveform between when the laser beam (seed) is cut and when it is not cut. When the ASE content gradually increases from this state, the difference disappears, and the output waveforms of the laser beams containing a large amount of ASE have no difference.

That is, the laser output waveform of the laser beam containing a large amount of ASE does not change even if the laser beam (seed) is cut. In other words, it can be seen that it is not amplified. When this measurement result is used, it is not necessary to use a spectroscope for measurement, and the ratio of output waveforms depending on the presence or absence of a laser beam (seed) is measured as necessary and computer processing is performed, so that the ASE occurrence status is sufficient. Can be monitored.

[0022]

According to the present invention, the ASE occurrence status can be confirmed and the ASE occurrence status can be evaluated in parallel with the test even during the test, and the labor required for the ASE measurement can be reduced.

[Brief description of drawings]

FIG. 1 is a system diagram showing an optical system for explaining the mechanism of ASE in a method of measuring parasitic oscillation light of a dye laser according to the present invention.

FIG. 2 is an apparatus layout diagram systematically showing an example of a measuring apparatus for applying the method of the present invention.

FIG. 3 is a spectrum diagram showing a comparison between parasitic oscillation light and a laser beam in the method of the present invention and a conventional example.

[Explanation of symbols]

1 ... Pump beam oscillator / preamplifier, 2 ... Pump beam second amplifier, 3 ... Focusing lens, 4
… First die flow cell, 5… Beam expander, 6
… Intra-cavity etalon, 7… Grating,
8 ... Resonator end mirror, 9 ... Beam expanding telescope, 10 ... Second die flow cell, 11 ...
Output beam, 12 ... Electric shutter, 13 ... Driving device, 14 ... Power meter, 15 ... Computer interface, 16 ...
Cable, 17 ... Calculator, 18 ... Pumping laser, 19 ...
Reflective mirror.

Claims (1)

[Claims] 1. A part of a laser beam oscillated from a dye laser and a dye laser amplifier is branched, and the branched laser beam is cut directly or not by using a power meter. A method for confirming the parasitic oscillation light of a dye laser, which comprises measuring the case and confirming the generation state of the parasitic oscillation light from the intensity ratio.