JPS61272985A - Slab type solid-state laser oscillator - Google Patents

Abstract

PURPOSE:To prevent the thermal breakdown of a solid-state laser medium by forming both end surfaces into a Brewster angle, housing the solid-state laser media divided into the plural into a transparent vessel and filling the vessel with matching oil having the same refractive index as the solid-state laser media. CONSTITUTION:A vessel 1 is constituted by a case in which both end surfaces 2, 2' formed at a Brewster angle and oppositely faced upper and lower both surfaces 3, 3' mutually running parallel are made transparent. Antireflection multilayer films are attached at both ends 2, 2'. A laser medium 4 is supported into the vessel 1 by the lower surface 3' of the vessel, and divided into the plural in parallel regarding the direction of course of beams. The laser medium 4 and the space of the vessel 1 are filled with matching oil 6 having the same refractive index as the laser medium 4, and the matching oil passes through a large number of inflow ports 7 and outflow ports 8 shaped on both sides of the vessel 1 to cool the laser medium. Lamp houses 9, 9' are fitted, and flash lamps 10, 10' are installed into the lamp houses. The lamps 10, 10' are cooled by a coolant passing through inflow ports 11, 11' and outflow ports 12, 12'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a slab-type solid-state laser oscillation device.

[Prior Art] In general, a solid-state laser oscillates laser light by pumping light with a flash lamp or the like, but during bombing, light absorption by laser active ions in the laser medium occurs, so the temperature rises from the surface of the laser medium. This creates a temperature gradient that causes significant thermal strain in the laser medium.

This thermal strain disturbs the oscillation pattern and mode of the laser beam, and in severe cases, it becomes impossible to emit the laser beam. In order to solve this problem, a slab-type solid-state laser oscillator has been proposed (Laser Handbook, edited by the Laser Society of Japan, 1932).
(Published December 15, 2007, 231 pages).

This is a method in which the solid-state laser medium is formed into a slab shape and light is passed in a zigzag pattern using total internal reflection, thereby preventing the above-mentioned adverse effects caused by thermal distortion. Since light passes in a zigzag pattern between opposing planes of the medium, all the light passes through the high-temperature surface and the low-temperature center for the same optical path length, so no optical path difference occurs, and the mode of laser light Even if temperature distribution occurs in the medium, laser light can be oscillated without disturbing the mode or oscillation pattern until the medium is destroyed by thermal strain.

However, conventional slab-type solid-state laser oscillation devices
In particular, devices using a glass laser medium have the disadvantage that when the size is increased, the medium is destroyed by thermal strain, making it difficult to obtain a high-output oscillation device.

[Object of the Invention] The present invention aims to eliminate the drawbacks of the above-mentioned conventional devices, and to provide an unattended slab-type solid-state laser oscillator that can be used for a long period of time and prevents destruction of the solid-state laser medium due to thermal strain. This is the purpose.

[Structure 1 of the Invention] In order to achieve the above-mentioned object, this invention has both end faces formed at Brewster's angle, and both end faces and side faces facing parallel to each other are transparent. It has a structure in which it houses a solid-state laser medium and is filled with matching oil having the same refractive index as the solid-state laser medium.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention shown in the drawings will be described.

Figure 1.2 shows an embodiment of the present invention, in which 1 is a container in which both end surfaces 2.2'' formed at Brewster's angle and upper and lower surfaces 3.3' facing each other in parallel are transparent. Both end surfaces 2.2' and upper and lower surfaces 3 and '3' are formed by optically mirror-polishing the surfaces of appropriate transparent members.Furthermore, both end surfaces 2.2' are coated with anti-reflection coatings. 111
g1 is added to prevent loss due to reflection of laser light. Reference numeral 4 denotes a laser medium supported within the container 1 by the lower surface 3' of the container, which is divided into a plurality of pieces parallel to the direction in which the light travels. A space formed between the laser medium 4 and both end surfaces 2.2' and upper and lower surfaces 3.3' of the container is filled with matching oil 6 having the same refractive index as the laser medium 4, and the matching oil 6 is filled with a matching oil 6 having the same refractive index as the laser medium 4. The oil 6 is admitted through preferably multiple inlet lowers and outlet ports 8 on both sides of the container 1! By flowing through the inside of the laser medium '314, it acts as a cooling medium for the laser medium '314.

The container 1 can be assembled, for example, as follows. Two thick stainless steel plates are used on both sides of the container.
The surface of a transparent sapphire plate with a thickness of 2 mm is polished to an optical mirror surface, and an anti-reflection film against light with a wavelength of 1.05 μm is deposited on it as a constituent member of both end surfaces 2.2'. A two-layer transparent sapphire plate whose surface has been polished to an optical mirror surface is used as the upper and lower surfaces 3.3' constituent members, and these are each screwed to the aforementioned stainless steel plate via a backing material to prevent liquid leakage. It can be made by As the laser medium 4, for example, Nd
Phosphate laser glass LHG8 containing (neodymium)
(manufactured by Hoya Glass Co., Ltd.), diamond whetstone 320
Polished to a thickness of Qms, width of 40m+, length of 150jII
A prismatic body with both end faces inclined at 30 degrees can be used in parallel with the traveling direction of the laser beam, and a cylindrical body can also be used in place of the prismatic body. Furthermore, the laser medium may be a spherical body, and a plurality of spherical bodies may be used. The refractive index of the glass laser medium 114 is dissolved by dissolving chloronaphthalene in carbon tetrachloride.

It can be used by adjusting the refractive index to -1,52005.

Reference numeral 9.9' denotes a lamp house which is placed between the upper and lower surfaces 3.3' of the container 1, and whose inner surface is a reflective surface, and inside the lamp house there is a flash lamp 10.9 as an excitation light source.
10' are installed respectively.

Preferably, a large number of inlets 11.11' and outlet ports 12.12' are provided on the left and right sides of the lamp house 9.9', through which the flash lamps 10.10'
A cooling medium (generally water) is allowed to flow through the cooling medium. In a state in which the cooling medium is removed from the lamp house 9.9', the container 1 can be attached to and removed from a predetermined position between the lamp houses 9.9' while containing the laser medium 4. 13 is a total reflection mirror with a multilayer film that reflects 100% of the laser beam, and 14 is a semireflection mirror with a multilayer film that reflects about 50 s% of the laser beam.

The above laser oscillation device is a flash lamp 10.10
When the light is bombed with Since the oil 6 is filled, the laser beam is not reflected on the surface of the laser medium 4, but is reflected on the inner surface (both upper and lower surfaces) of the container 1. In addition, thermal strain occurs in the laser medium due to light absorption, but since the laser medium of the present invention is divided into multiple pieces, if the same volume of laser medium is used, the thermal strain may become excessive. It never becomes.

In the above embodiment, sapphire plates were used as the constituent members of both end surfaces 2.2' and upper and lower surfaces 3.3' of the container 1, but they are transparent and chemically stable, and are more refractive than matching oil. These can be used instead of sapphire plates if the ratio is large, for example L
E 3G (alkali-free glass manufactured by Shahoya Glass Co., Ltd.) can be used. Further, in the above embodiment, the matching oil 6 is made to flow through the container 1, but it may be sealed in the container 1 with an appropriate stopper. Furthermore, although LHG8 was illustrated as the laser medium 4 in the above embodiment, the present invention is not limited thereto.

Incidentally, even in the case of a laser medium with a refractive index different from LHG8, the mixture ratio of 2-chloronaphthalene and carbon tetrachloride was compatible with that laser medium.

It is possible to adjust the refractive index of the matching oil.

In addition, not only 2-chloronaphthalene, but also 2-bromonaphthalene, tricresyl phosphate, etc., which are mating oils used for measuring the refractive index of crystals and which do not change over time, can be used in the present invention. be able to. Carbon tetrachloride has significantly lower reactivity with phosphate glass than those with OH groups such as water, and is superior in that it does not alter the glass surface even if it comes into contact with it for a long period of time. Other than carbon chloride, those that do not react with glass and can dissolve the above-mentioned matching oil can be used, and among them, those with a high boiling point are preferred.

In particular, for a laser medium with a low optical refractive index, for example, ethylene glycol and water or alcohol can be used as a matching oil. Furthermore, by forming the solid laser medium divided into a plurality of pieces into a cylindrical body, the cooling effect of the matching oil can be further improved.

[Effects of the Invention] Since the present invention is constructed as described above, the laser medium is divided into a plurality of parts, so even if the laser medium is increased in size as a whole, it will not be destroyed by thermal strain, and it can be used to increase output. becomes possible. The laser light is not reflected from the surface of the laser medium, but from the inner surface of the container, so as long as the reflective surface of the container is kept mirror-like and parallel, the laser medium can perform optical polishing on its surface. Not only is it not necessary, there are no restrictions on the shape, and not only glass but also crystal, for example, can be used as the laser medium. Moreover, it is much easier to keep both the top and bottom of the container mirror-like than to keep the surface of the laser medium mirror-like, so the device of the present invention can be used safely for a long period of time. It has extraordinary effects, such as being able to

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being a longitudinal sectional front view and FIG. 2 being a longitudinal sectional side view. DESCRIPTION OF SYMBOLS 1... Container, 2. 2'... Container end surface, 3... Container top surface, 3'... Container top surface, 4... Laser medium, 6...
...Installing oil, 7.11.11'...Inlet, 8.12.12'...Outlet, 9.9'...Lamp house, 10.10'...Flash lamp, 13
...Total reflection mirror, 14... Half reflection mirror. Applicant Black January Hiroshi Human
Hoya Co., Ltd.

Claims (1)

[Claims] 1. A container having both end faces formed at Brewster's angle and having transparent both end faces and side faces facing parallel to each other. A slab-type solid-state laser oscillation device, characterized in that it houses a medium and is filled with matching oil having the same refractive index as the solid-state laser medium. 2. The slab-type solid-state laser oscillation device according to claim 1, wherein the matching oil is used as a cooling medium for cooling the solid-state laser medium. 3. The slab-type solid-state laser oscillation device according to claim 1, wherein excitation light energy is introduced into the container through the transparent side surface. 4. The slab-type solid-state laser oscillation device according to claim 1, wherein the solid-state laser medium is a glass laser medium. 5. The slab-type solid-state laser oscillation device according to claim 1, wherein the matching oil comprises 2-chloronaphthalene and carbon tetrachloride. 6. Claim 1, in which the dividing plane of the solid-state laser medium divided into a plurality of pieces is parallel to the traveling direction of the laser beam.
The slab-type solid-state laser oscillation device described in . 7. Claim 1, wherein each solid-state laser medium divided into a plurality of pieces has a circular cross-section when viewed from the direction in which the laser beam travels.
The slab-type solid-state laser oscillation device described in . 8. The slab-type solid-state laser oscillation device according to claim 1, wherein the plurality of independent solid-state laser media are spherical.