JPS58218185A - Variable output laser device - Google Patents

Abstract

PURPOSE:To stabilize the laser output by a simple constitution variable regulating the outputs from the maximum values to zero while miniaturizing the device at low manufacturing cost with its absorbing body eliminating a cooling system by a method wherein one of the parallel flat plates made of laser beam permeable member is turned utilizing a laser beam axis as a turning axis while the laser beams reflecting from the turning parallel falt plate are absorbed into a heat resistant energy absorbing body. CONSTITUTION:A total reflecting mirror 21 and an output mirror 22 constitute a laser resonator. The first Brewster's window 23 is arranged at the Brewster's angle of thetaB with a laser beam axis while the second Brewster's window 24 is arranged at an angle of 90 deg.-thetaB with the beam axis in a resonator. The second Brewster's window 24 is a parallel flat plate formed of a laser beam permeable member. Assuming the angle of the first and second Brewster's windows 23, 24 with the incident flat surface to be phi, the permeability T of said Brewster's windows 23, 24 will be the function of phi. In other words, a loss value 1-T fluctuated by phi may be inserted into the laser resonator to fluctuate the laser output variable regulating the same.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable output radar device used for medical purposes or small-scale processing, and more particularly to an improvement in means for varying the radar output within a radar resonator.

Conventional radar devices of this type include discharge excitation CWCO and radar devices with an output of several tens of watts. This CO laser device is excited and oscillates by glow discharge in a low-pressure mixed gas of about several tens of torr. Although the output of such a laser device can be varied by changing the discharge current, it has the following drawbacks.

(,) High voltage (several KV~
A current stabilization control circuit of several tens of kilovolts (KV) is required, and the circuit elements for such high voltage current control are large and expensive.

If the discharge current is not in the stable region and the discharge current is changed, the stability of the discharge will be deteriorated and the stability of Raded oscillation will be impaired. Therefore, it is desirable to fix the discharge current and voltage to optimal values.

(c) By controlling the discharge current, it is possible to stably change the output only to a low output range of about 30 inches from the maximum output due to the reason (b).

(d) The current control element becomes a factor that determines the life of the device.

In order to eliminate the above drawbacks, the present inventors have devised a means for controlling the output of a linearly polarized oscillation laser device outside the excavator. This is a special application from 1977-xs7c+
The applicant has already filed an application for the application as No. sj'', but its outline will be explained in Figure 1 and Figures 1 and 2.・'( In Figure 1, 10 is CO , a laser oscillator, which has a Brewster window 11, a Rede light extraction mirror 12, etc., and outputs a laser beam 13. In this case, the Rede light 13 is directed toward the paper surface as shown as 13a in the figure. The light is linearly polarized.Therefore, a parallel plate 14 made of a Raded light-transmitting material such as Ge or Zn5s is installed so that the Raded light 13 is incident on the Raded optical axis at the Brewster angle θB. Therefore, the transmittance of the Rede light 13 to the parallel plate 14 becomes 100% according to Brewster's law.In this case, the laser beam 13 is incident on the parallel plate 14 as 1004P polarized light.From this state, the parallel plate 14 14 is rotated about the optical axis of the laser beam 13 as the rotation axis, and the plane of incidence of the Lehde beam 13 on the parallel plate 14 is rotated by a rotation angle of φ, the P-polarized component of the Lehde beam 13 on the parallel plate 14 decreases, 4□Instead of i-orbital, the S-polarized component increases.68 and L[-'90',
81 Kawaa 1001, l1l) Nowadays, the transmittance of the LED light will be the minimum. Thus, by changing the rotation angle φ of the parallel plate 14, the amount of radiation of the Raded light 13 can be varied.

FIG.
O, using a laser oscillator, using a parallel plate 14 made of Ge with a refractive index n = 4.0 for Raded light of the above wavelength, and changing the transmittance of the laser beam 13 with respect to the rotation angle φ of the parallel plate 14. FIG. As is clear from FIG. 2, the rotation angle φ of the parallel plate 140 is θ~90
When the laser beam transmittance is changed to 100% to 2°
It varies up to 2%.

However, the following problems remain with the above-mentioned method: (1) Despite the very large value of the refractive index n = 4.0, when the parallel plate 14 is composed of one The output variable range is from 100% to about 20% of the maximum output, and it is not possible to reduce the output to a level smaller than this.

Low When the output is lowered, the reflected light 15 reflected by the parallel plate 14 becomes larger, and how to deal with it becomes a problem. That is, for example, the radar light 13 from the laser oscillator 10
If the output of the parallel plate 14 is 90 degrees, the reflected light 15 will have an energy of about 80 watts. Therefore, in such a case, a very large energy absorber must be installed on the optical path of the reflected light. Furthermore, since the optical path of the reflected light 15 is not constant but changes depending on the size of φ, it is necessary to dispose the energy absorber over a wide area, and it is also necessary to provide a cooling means.

The present invention was made based on these circumstances,
The purpose of this is not only to be able to stably and variably control the radar output with a simple configuration, but also to make the output variable range from the maximum value to zero. It is an object of the present invention to provide a variable output laser device that not only can be manufactured compactly and inexpensively without requiring a cooling means, but also has extremely high safety.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 is a diagram showing the basic configuration of the present invention, in which 20 is a laser tube such as a laser discharge tube, 21 is a total reflection mirror, 22 is a small laser beam collecting mirror, 23 is a first Brewster window, and 24 is a laser tube such as a laser discharge tube. Second
This is the Brewster window. Total reflection mirror 21 and extraction mirror 22
constitutes a laser resonator, and the first Brewster window 23 is installed with an inclination of Brewster angle θB with respect to the Rede optical axis. Further, the second Grew Star window 24 is located on the optical axis within the resonator at a 90° angle with respect to this optical axis.
It is installed at an angle of °-θB. This second Brewster window 24 is a parallel flat plate made of a Rede light transmitting member.

If the angle formed by the plane of incidence of the first Brewster window 23 and the second Brewster window 24 is φ, then these first,
Second filter: The transmittance T of the Lewster window 23°24 is φ
becomes a function of .

Now, as shown in Fig. 3, if the 1st Brewster window 23, 24 is parallel or 1 state is φ-0, then the transmittance for P-polarized light, that is, linearly polarized light having a plane of polarization within the plane of the paper, is Tit,T=1, and the transmittance Tit,T(1) has a predetermined value in the state of φNO.

Therefore, due to the existence of the first and second Brewster windows 23 and 24, a loss of 1-T whose value changes with φ is inserted into the Rade resonator. As the loss value changes, the laser output naturally changes, and the laser output can be variably controlled.

In Figure 4, a CO2 laser oscillator with an oscillation wavelength of 1096 μm and a maximum output of 25 watts is used as a laser oscillator.
, is a diagram showing the output and loss characteristics when the second Brewster window 23.degree. 24 is made of Zn5e and has a refractive index n' of n=2.4 with respect to Rede light of the above wavelength. As shown in Fig. 4, the loss t(φ)=1
-T(φ) changes ↓ as shown by the broken line in the figure. In addition, in response to changes in the above-mentioned loss t(φ), the Radhe output P(A) taken out from the Radhe oscillator changes as indicated by the solid line in the figure. In other words, the output becomes zero when P C'hn400,t'';=0.4.Thus, the radar output changes from 0 to
It can be changed by 100 degrees.

Note that although the reflected light reaches its maximum at about 50L16 in the variable region, it is only about 2% of the maximum output and is extremely weak. Therefore, it is not necessary to provide special cooling means for the energy absorber.

Next, a specific embodiment based on the above principle will be described.

FIG. 5 shows the first embodiment. In this embodiment, the present invention is implemented using a single external mirror type in which a Rade resonator is configured with a total reflection mirror 2 and an extraction mirror 22, and a discharge tube 20 excites a gas mixture containing CO2 to perform Rade oscillation. This is an example in which the first Brewster window 23 is made of Zn5e or the like having a Rede light transmittance, and the discharge tube 2
0 at an angle of 90'-θB. In addition, when the material is Zn5e, the refractive index n is n = 2.4.9
0°-θB becomes 90'-0B; 22°, 36'. The second Brewster window 24 is made of the same Rede light transmitting material as the first Brewster window 23, and is supported on the holder 26 at an angle of 90'-θB on the laser optical axis within the resonator. has been done. Note that the eleventh and second Brewster windows 23 and 24 are covered with a heat-resistant cylindrical energy absorber 25.

The holder 26 has a cylindrical shape, supports the second Brewster window 24 at one open end, has a worm wheel around the outer periphery of the other open end, and has an optical axis as a rotation axis. It can be rotated. Reference numeral 27 denotes a rotary drive shaft equipped with a worm that is compatible with the worm wheel, and is rotated by a drive source (not shown).

This device configured in this manner includes a discharge tube 20, a total reflection mirror 21, an extraction mirror 22, and a first Brewster window 23.
It operates as a gas laser device with a normal single-side mirror configuration. Now the first and second Brewster windows 23.24
When they have the relative angular relationship as shown in Figure 5, the loss is zero for the P-polarized component and the output is at its maximum.

From this state, when the second Brewster window 24 is rotated together with the shield holder 26 by the rotary drive shaft 27 with the optical axis as the rotation axis and φ shown in FIG. 4 is changed, the loss is 1-T.
changes, and the laser output P changes by 100 to θ%.

At this time, the reflected light reflected by the first and second Brewster windows 23 and 24 is absorbed by the cylindrical energy absorber 25. As is clear from FIG. 4, the reflected light in this case reaches its maximum at about 50% of the variable range, and becomes zero when the output is zero because the Raded oscillation itself stops. Furthermore, when the output is maximum, almost no reflection occurs, so the output is close to zero.

Incidentally, in a CO/Rade device with a maximum output of 50 watts, even when reflection is at its maximum, the reflected light energy is at most 0. ,,． It is about 1 to 1 watt. Therefore, the reflective light beam, the energy absorber 25 is forced to be air-cooled or the 78
There is no need for ink etc.

In this way, according to the first embodiment, the output can be variably controlled while the discharge state and gas state are fixed at constant optimum stable values, so there is no need for power supply stabilization means, etc., and the device can be made small and inexpensive. Moreover, stable Raded oscillation can be performed.

In particular, since the radar 3 output can be continuously and variably controlled from zero to the maximum output, it is extremely preferable for medical use and small-scale processing. Furthermore, Brewster window 23.24
Since the reflected light energy is extremely weak, there is no need to provide a cooling means for the absorber that absorbs the reflected light energy, and in this respect as well, the device can be made smaller.

FIG. 6 is a diagram showing another embodiment of the present invention.

In addition to the output control mechanism shown in FIG. 5, this embodiment is an example in which a control system for automatically variable control of the laser output by external setting operation is added. In other words, 30 in FIG. This is a rotation angle detection mechanism attached to the rotation drive shaft 27, and is composed of, for example, a rotary encoder.

Rotation angle information detected by the rotation angle detection mechanism 30: 1'6
The signal is detected as an electrical signal by a rotation angle phase detection circuit 31, converted into a current output by a four-power conversion circuit 32, and displayed by a display circuit 33. On the other hand, when the required laser output is set in the external power setting circuit 35, this set value and the power conversion circuit 3
The two outputs are compared in a comparison circuit 34 and the difference signal is given to an angle conversion circuit 36. Therefore, the circuit 36
An angle signal is sent out from the drive converter circuit 17 and is applied to the drive conversion circuit 17. Then, from this circuit 17, the rotary drive shaft 2
A drive signal is applied to the drive shaft 27, and the drive shaft 27 rotates by a predetermined angle. In this way, the radar output is automatically set to the value set by the setting circuit 35.

In FIG. 6, instead of the detection systems 30, 31, 32, and 33, the laser output light is split by a beam sinter and guided to a 9-watt meter, and the external shutter is used as a radar mirror. The laser beam is guided to a power meter, and furthermore, the rear total reflection mirror is used as a partially transmitting mirror to emit a part of the rear Herede light of the laser oscillator and guided to the power meter. The light may be monitored by a power meter, and the monitored power signal may be supplied to the comparator circuit 34 via the amplifier 38, as shown by the broken line in the figure.

In this way, according to the second embodiment, the radar output can be automatically set to a desired level, which further simplifies handling operations.

Note that both the first embodiment and the second embodiment have the following features.

That is, in the conventional output control system using gas pressure, for example, if the gas pressure is increased beyond the gas pressure that provides the maximum output, discharge cannot be maintained.

Furthermore, when the gas pressure is lowered to a gas pressure range below the minimum output, the discharge current becomes abnormally large, causing spatter. As described above, with conventional devices, it is often impossible to control the output by controlling in one direction, and it is necessary to operate the parameters back and forth.

However, the output control of this device, the 9-rammeter φ, is limited to one direction, increasing or decreasing.

Even if control is performed, there is only a section in which the output is zero, and no destructive phenomenon occurs to the operation of the Rade oscillator. This is an extremely important feature in terms of safety in the event of an operational error or failure of the automatic control system, and is particularly suitable for use in the medical field, where safety is the top priority.

It goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made without departing from the scope of the invention.

As explained above, according to the present invention, the laser output can be variably controlled without controlling the discharge current at all, so not only can stable laser output control be performed, but the output variable range can be extended from the maximum value to zero. It is possible to produce a device small and inexpensively without requiring a special cooler for the absorber that absorbs reflected light energy while being able to send out extremely low level laser output. A highly safe variable radar device can be provided.

[Brief explanation of the drawing]

1 and 2 are an example of a laser output control means in a linearly polarized light oscillation radar device, and FIGS. 3 and 4 are a schematic diagram and a characteristic diagram showing the principle of the present invention. , FIG. 5 is a side sectional view showing the structure of one embodiment of the present invention, and FIG. 6 is a diagram showing the structure of another embodiment of the present invention. 20... Rede tube (discharge tube), 21... Total reflection mirror,
22... Laser light collecting small mirror, 23... First Brewster window, 24... Second Brewster window, 25...
...Heat-resistant cylindrical energy absorber, 26...Holder, 27...Rotation drive shaft. Applicant's Representative: Takehiko Suzue, Commissioner of the Patent Office, Kazuo Wakasugi 1. Indication of the case Japanese Patent Application No. 57-101731 2, Name of the invention ±1 variable laser f device 3, Person making the amendment Relationship to the case Patent applicant (037) Orin ξ Optical Industry Co., Ltd. 4, Agent Address 17th Mori Building, 1-26-5 Toranomon, Minato-ku, Tokyo 105 Phone: 03 (502) 3181 (
Main representative) 6. Full text of the specification subject to amendment

Claims (2)

[Claims] (1) A resonator equipped with a pair of mirrors, and a 90°-(Brewster angle) on the optical axis within this resonator with respect to the optical axis.
two or more parallel flat plates made of a laser beam-transmitting member inserted so as to form the same shape, means for rotating one of the parallel plates with the optical axis as the rotation axis, and the above-mentioned laser beam rotated by the means. and a cylindrical heat-resistant energy absorber provided to absorb reflected laser light from the parallel flat plate,
The parallel plates are Zn5e, Go, TtCt-TtB
A variable output radar device characterized in that it is formed of n. (2) The means for rotating the parallel plate is configured such that the output information obtained by the means for detecting the rotation angle of the parallel plate or the monitor means for monitoring the radar output accompanying the rotation of the parallel plate is set in advance by the output setting means. Claim 1 is characterized in that the rotation angle of the parallel plate is automatically controlled according to the difference between the set value and the set value set by the
) The variable output laser device described in section 2.