JPH01184887A - Pulse laser oscillator - Google Patents

Abstract

PURPOSE:To enable light quantity of a pulse laser to be sampled and held reliably, by providing an integration timing generating section so that it optically detects main discharge light for exciting a laser oscillator and emits an integration timing signal to an optical integrating section. CONSTITUTION:When main discharge is caused in a gas laser oscillator 20, light generated in the moment of the main discharge is applied to a photoelectric transducer 42 through an optical fiber 41. Output of the photoelectric transducer is amplified and applied to the positive input terminal of a comparator 44. The comparator 44 compares this input with a reference voltage inputted to its negative input terminal from a reference voltage generating circuit 45 and emits a signal to one-shot pulse generating circuits 46, 47. The oneshot pulse generating circuit 46 emits a one-shot pulse P1 to an integrating circuit 34 while the circuit 47 emits a one-shot pulse P2 to a sample-and-hold circuit 35 and arithmetic circuit 37. An optical integrating section 30 samples and holds the integral value based on these signals.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a pulse laser oscillation device having a function of stopping pulsed laser oscillation when the cumulative amount of light of the oscillated pulsed laser reaches a predetermined amount. This invention relates to a laser oscillation device.

(Prior Art) FIG. 3 is a 4M diagram of such a pulse laser oscillation device, and FIG. 4 is an operation timing chart of the same device. The pulse signal sent out from the pulse generating circuit 1 is sent through the gate 2 to the trigger circuit 3, and the trigger signal is applied from the trigger circuit 3 to the thyratron switch constituting the power source 4, thereby making the thyratron conductive. Then, power is supplied to the main electrode of the gas laser oscillator 5, and the pulse laser Q is oscillated from the gas laser oscillator 5.

By the way, the oscillated pulsed laser Q is a half mirror 6.
and one of them is sent to the photoelectric conversion element 8 through the diffusion plate 7.

This photoelectric conversion element 8 converts the received light into a voltage signal corresponding to the amount of light from the pulsed laser Q, and outputs the voltage signal to the sample bold circuit 9. On the other hand, the pulse signal sent out from the pulse generation circuit 1 is delayed by the delay circuit 1o and sent to the sample hold circuit 9 as a sample timing signal. Therefore, when the sample and hold circuit 9 receives the sample timing signal, it holds the voltage signal from the photoelectric conversion element 8 and outputs it to the integration circuit 11. However, integrating circuit 1
1 successively integrates the input voltage signal and sends a voltage signal corresponding to the cumulative amount of received light to the comparator 12, and the comparator 12 integrates this voltage signal and the reference voltage generation circuit 13.
The gate signal is set to low level when the voltage signal level becomes higher than the reference voltage signal level. As a result, when the cumulative amount of received light reaches a predetermined amount, the gate 2 closes and the pulse signal is no longer sent to the trigger circuit 3, thereby stopping the oscillation of the pulse laser Q.

Incidentally, in the above device, the time from the generation of the trigger signal to the time when discharge occurs in the gas laser oscillator 5 and the pulsed laser Q is oscillated is about 1 μSee, and the time is different for each oscillation of the pulsed laser Q and is not constant. In some cases, the time is 0.5 μsec. This is mainly because the gas laser medium is warmed up each time a discharge is generated, and the impedance of the gas laser medium with respect to the power source 4 changes dynamically. However, in the above device, as shown in FIG. 5, the time from trigger signal generation to pulsed laser Q oscillation is set as a delay time in the delay circuit 10, and the pulse signal is delayed by this delay time to adjust the light intensity of pulsed laser Q. This function sets the sample timing of the corresponding voltage signal. Therefore, if the oscillation timing of the pulsed laser Q is shifted, it will become out of synchronization with the sample and hold timing, making it impossible to obtain an accurate integrated light amount. In order to eliminate this problem, the pulse width of the sample timing signal sent from the delay circuit 10 is increased as shown in FIG. However, when the pulse width of the sample timing signal is increased in this manner, noise due to the dark current of the photoelectric conversion element 8 when the pulsed laser Q is not oscillated is also sampled and held and integrated by the integrating circuit 11. Therefore, if the set amount of the integrated light amount is increased, the integrated amount of dark current also increases, making it impossible to obtain an accurate integrated light amount.

(Problems to be Solved by the Invention) As described above, the timing of sampling and holding the light amount of the pulsed laser Q is shifted, and the integrated light amount cannot be determined accurately due to the influence of dark current.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a highly accurate pulsed laser oscillation device that can reliably sample and hold the amount of pulsed laser light and obtain an accurate integrated amount of light.

[Structure of the Invention (Means for Solving the Problems) The present invention oscillates pulsed lasers from a laser oscillator by supplying a trigger signal at each desired timing, and receives these pulsed lasers in an optical integration section to integrate the amount of light. In a pulsed laser oscillation device that calculates a value and stops supplying a trigger signal to the laser oscillator when the integrated value reaches a predetermined value, the main discharge light emission for excitation of the laser oscillator is optically detected and the optical integration is performed at the time of this detection. This is a pulse laser oscillation device that attempts to achieve the above object by including an integration timing generation section that sends an integration timing signal to the pulse laser oscillation device.

(Function) By providing such a means, when the occurrence of discharge in the laser oscillator is detected, the integration timing generation section sends an integration timing signal to the optical integration section, and at this time, the optical integration section outputs an integration timing signal to the optical integration section. is received and calculates the cumulative amount of light. Then, when this integrated amount reaches a predetermined amount, the trigger signal supplied to the laser oscillator is stopped.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a pulsed laser oscillation device.

In the gas laser oscillator 20, a cathode 21 and an anode 22 are arranged facing each other to form a main electrode.
A reflecting mirror 23 and an output mirror 24 are provided on the longitudinal side of the anode 22 to form an optical resonator. Cathode 2
1, an anode 22, and a preliminary electrode (not shown) are connected to a high voltage power source 25.
is connected to the high-voltage power supply 25, and upon receiving a trigger signal from the trigger circuit 6, a thyratron switch is turned on to apply a high voltage between the cathode 21 and the anode 22.

By the way, the pulsed laser Q oscillated from the gas laser oscillator 20 is branched by a half mirror 27, and one of the branches passes through the charge integrator 31 of the light integrator 30 and is irradiated onto the photoelectric conversion element 32. The light integration unit 30 has a function of determining the integrated light amount of the pulsed laser Q and stopping the sending of the trigger signal from the trigger circuit 26 when this integrated light amount reaches a predetermined light amount. Specifically, the configuration is as follows. The photoelectric conversion element 32 converts into a voltage signal according to the amount of light received by the pulsed laser, and this voltage signal is amplified by an amplifier 33 and sent to an integration circuit 34. Then, the integral output of the integrating circuit 34 is sampled and held in a sample hold circuit 35, and this sample hold output is further digitized in an A/D (analog/digital) converter 36 and sent to an arithmetic circuit 37. ing. This calculation circuit 3
Reference numeral 7 has a function of taking in a digital voltage signal, determining the cumulative amount of light, and sending out a low-level trigger stop signal G through the output boat 38 when the cumulative amount of light reaches a predetermined amount.

Note that 39 is an input boat.

Reference numeral 40 denotes an integration timing generating section, which has the function of detecting the occurrence of the main discharge of the gas laser oscillator 20 and sending an integration timing signal to the optical integration section 30 at the time of this detection. The specific configuration is as follows. That is, one end of the optical fiber 41 is inserted into the gas laser oscillator 20, and the other end is inserted into the photoelectric conversion element 4.
It is placed on the front of 2. This photoelectric conversion element 42 is connected to "+" input terminals of a comparator 44 via an amplifier 43. Also, this comparator 44
A reference voltage generation circuit 45 is connected to the "-" input terminals of. Each one-shot pulse generation circuit 46 and 47 are commonly connected to the output terminal of this comparator 43, and one-shot pulse P1 as a settlement timing signal sent from one one-shot pulse generation circuit 46
is sent to the integrating circuit 34, and the one-shot pulse P2 as an integration timing signal sent from the other one-shot pulse generating circuit 47 is sent to the sample-hold circuit 35.
and is sent to the arithmetic circuit 37 through the input port 39.

The trigger stop signal G is sent as a gate signal to one input terminal of a gate 50, and a pulse signal from a pulse generation circuit 51 is input to the other input terminal of this gate 50. The signal is sent to the trigger circuit 26.

Next, the operation of the apparatus constructed as described above will be explained with reference to the operation timing chart shown in FIG. First, the arithmetic circuit 37 sends out a trigger stop signal at a high level. Therefore, the pulse signal sent from the pulse generation circuit 51 is sent to the trigger circuit 26 through the gate 50,
Upon receiving this pulse signal, the trigger circuit 26 applies a trigger signal to the thyratron switch of the high voltage power supply 25. As a result, the thyratron switch becomes conductive and applies a high voltage between the cathode 21 and anode 22 of the gas laser oscillator 20 and to the preliminary electrode. In this way, after preliminary ionization is performed by the discharge of the preliminary electrode, a main discharge occurs between the cathode 21 and the anode 22, and thus the pulsed laser Q is generated by the action of the optical resonator.
oscillates. Then, this pulsed laser Q is branched by a half mirror 27, and one of the branches passes through a charging integrator 31 and is irradiated onto a photoelectric conversion element 32. Then, this photoelectric conversion element 32 converts it into a voltage signal corresponding to the amount of light received, and this voltage signal is amplified by an amplifier 33 and sent to an integrating circuit 34 .

Now, when the main discharge occurs in the gas laser oscillator 20,
The light at the moment of occurrence of this main discharge passes through the optical fiber 41 and is irradiated onto the photoelectric conversion element 42 .

Thus, a voltage signal corresponding to the amount of mourning light outputted from the photoelectric conversion element 42 is amplified by the amplifier 43 and applied to the "+" input terminals of the comparator 44.

At this time, the voltage signal level applied to the "+" input terminals of the comparator 44 becomes higher than the reference voltage level, so the comparator 44 sends a high-level signal to each one-shot pulse generating circuit 46 and 47. Thus,
One shot pulse generation circuit 46 sends one shot pulse P1 to integration circuit 34, and the other one shot pulse generation circuit 47 sends out one shot pulse P2 to sample hold circuit 35 and arithmetic circuit 37.

At this time, that is, the timing at which each one-shot pulse P1, P2 is sent to each circuit 34, 35, 37 is synchronized with the timing at which the pulse laser Q is oscillated. Therefore, when the integrating circuit 34 receives the one-shot pulse P1, it integrates the voltage signal from the amplifier 33 and outputs the integrated value to the sample and hold circuit 35. Further, this sample and hold circuit 35 also performs sample and hold in synchronization with the operation of the integration circuit 34 to sample and hold the integrated value.

Then, this sample hold output is sent to the A/D converter 36.
The data is digitized and sent to the arithmetic circuit 37. In this way, the above operation is performed every time the pulsed laser Q oscillates, and the amount of light from the pulsed laser Q is taken into the arithmetic circuit 37 each time. Therefore, the arithmetic circuit 37 sequentially takes in the digital voltage signals and executes the integration process to obtain the integrated amount of light.

Then, when this integrated light amount reaches a predetermined light amount, the arithmetic circuit 37 sends a low-level trigger stop signal G to the gate 50 through the output 38.

As a result, the gate 50 closes and the passage of the pulse signal is blocked, and as a result, the sending of the trigger signal is stopped and the oscillation of the pulse laser Q is stopped.

In this way, in the above embodiment, the laser oscillator 20
Detecting the occurrence of discharge, the integration timing generating section 40 sends integration timing signals P1 and P2 to the optical integration section 30, and at this time, the optical integration section 30 receives the pulsed laser Q to calculate the integrated amount of light. With this configuration, the integrating circuit 34 and the sample and hold circuit 35 can be operated in synchronization with the oscillation of the pulsed laser Q, and a voltage signal corresponding to the amount of light of the pulsed laser Q can be reliably sampled and held. Therefore, even if the oscillation timing of the pulse laser Q is shifted, the integration and sample-hold operations can be performed in synchronization with this timing shift. Further, since the integration and sample-hold operations can be performed in synchronization with the oscillation of the pulsed laser Q, the integrated light amount can be determined with high precision almost unaffected by the dark current of the photoelectric conversion element 32.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, instead of detecting the main discharge of the gas laser oscillator, the occurrence of preliminary discharge may be detected to generate the integrated timing signal. Further, the means for detecting the discharge generation of the gas laser oscillator may be configured by combining other optical means, for example, a reflecting mirror.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a highly accurate pulsed laser oscillation device that can reliably sample and hold the light amount of a pulsed laser and obtain an accurate integrated light amount.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a pulse laser oscillation device according to the present invention, and FIG. 2 is an operation timing diagram of the device.
FIG. 3 is a configuration diagram of a conventional device, FIGS. 4 and 5 are operation timing diagrams of the same device, and FIG. 6 is an operation timing diagram for explaining the conventional technique. 20... Gas laser oscillator, 25... High voltage power supply, 2
6...Trigger circuit, 30...Light integration unit, 31...
Charging integrator, 32... Photoelectric conversion element, 33... Amplifier, 34... Integrating circuit, 35... Sample hold circuit, 37... Arithmetic circuit, 40... Integration timing generator, 41 ... Optical fiber, 42 ... Photoelectric conversion element, 43 ... Amplifier, 44 ... Comparator, 45
...Reference voltage generation circuit, 46.47...One shot pulse generation circuit, 50...Gate, 51...Pulse generation circuit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A pulsed laser is emitted from a laser oscillator by supplying a trigger signal at each desired timing, and these pulsed lasers are received by a light integrating section to obtain an integrated value of the amount of light, and when this integrated value reaches a predetermined value, the laser oscillator oscillates a pulsed laser. a pulsed laser oscillation device that stops supplying a trigger signal to the laser oscillator, an integration timing generation unit that optically detects main discharge light emission for excitation of the laser oscillator and sends an integration timing signal to the optical integration unit at the time of this detection; A pulsed laser oscillation device characterized by comprising: