JPH04316381A - Solid-state laser - Google Patents

Abstract

PURPOSE:To stabilize an output of a solid-state laser by effectively absorbing an exciting light to a laser medium of the laser and preventing instability of the output due to a thermal lens phenomenon. CONSTITUTION:A filter layer 10 for transmitting only a wavelength of an absorption band of a laser medium 4 of wavelengths of an exciting light source 3 is provided on an outer wall of a flow tube 6 for cooling the light source 3 to pass only the wavelength range to be easily absorbed to the medium of a light emitted from a light source 3 thereby to stabilize the output of the laser.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state laser device excited by light from a flash lamp or arc lamp used in industrial or medical equipment.

0002

[Prior Art] In recent years, solid-state laser devices have been used as industrial machines in the semiconductor field for devices such as trimming, scribing, marking, soldering, welding, cutting, etc.
The fields of its use are expanding year by year. In the medical field, its use as a therapeutic device is rapidly expanding.

A conventional solid-state laser device will be explained below with reference to the drawings. 4 and 5 show the configuration of a solid-state laser device excited using a conventional flash lamp or arc lamp. As shown in FIG. 4, a light source 3 using a flash lamp or an arc lamp made of xenon or krypton is installed inside a structure (hereinafter referred to as a cavity) 1 having a reflecting surface 2 that reflects lamp light inside for excitation. It constitutes a light source for use.

On the other hand, a laser section is composed of a laser medium 4 and a laser medium protection tube 5 that protects it. The excitation light source 3 is housed in a flow tube 6 for improving the cooling effect of a cooling medium, and the cooling medium cools the heat generated by the lamp light, and the entire laser device is inside this cooling medium.

The operation of the laser device configured as described above will be explained below. Excitation light emitted from the light source 3 enters the laser medium 4 and is absorbed. The light that has passed through without being absorbed is reflected by the reflecting surface 2 and enters the laser medium 4 again. The absorbed light energy is shown in Figure 5.
An optical resonator surrounded by a partial reflection mirror 7 and a total reflection mirror 8 shown in FIG.

[0006] At this time, the laser light absorption coefficient of the laser medium 4 has a strong wavelength dependence, and it is necessary that the laser medium effectively absorbs a wavelength range of 750 nm to 810 nm, which is an effective wavelength range for laser oscillation. FIGS. 6 and 7 show the emission spectra of the xenon lamp and krypton lamp. As can be seen from the figure, the light emitted by flash lamps and arc lamps includes light in a wide wavelength range. Among this light, light with a wavelength other than that effective for laser oscillation turns into thermal energy, causing an increase in the temperature of the laser device. Accordingly, it is necessary to increase the cooling capacity of the cooling medium, which is a negative factor for the laser device.

[0007]

[Problems to be Solved by the Invention] However, with such a conventional configuration, it is difficult to make the laser medium 4 absorb light effectively, and furthermore, the unabsorbed light becomes heat, so the cooling ability of the cooling medium is reduced. If you don't design it big,
There was a problem in that the temperature of the laser medium 4 increased and a thermal lens phenomenon occurred in the laser medium 4, making it difficult to obtain a laser device with stable laser output.

The present invention solves these problems, and provides a solid-state laser device that can efficiently absorb light from a light source, improves laser oscillation energy efficiency, and is also thermally stable. The purpose is to

[0009]

[Means for Solving the Problems] In order to achieve this object, the solid-state laser of the present invention uses a filter that transmits only light in a certain wavelength range on the outer wall of the flow tube when the excitation lamp light is absorbed into the laser medium. It is made up of layers.

0010

[Operation] With this configuration, the filter layer transmits the energy of only the light having a certain wavelength range out of the light emitted from the excitation light source, so the energy emitted from the light source is efficiently absorbed by the laser medium. Ru. Therefore,
The temperature rise of the laser medium is reduced, the laser medium is sufficiently cooled, and a thermally stable solid-state laser can be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A solid-state laser device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a solid-state laser device according to an embodiment of the present invention. In this embodiment, the same components as those in the conventional example are designated by the same numbers, and the explanation thereof will be omitted. As shown in the figure, an excitation light source 3 including a light source such as a xenon lamp or an arc lamp is provided inside the cavity 1. On the other hand, a laser section is composed of a laser medium 4 and a protective tube 5 that protects it. The excitation light source 3 is housed in a flow tube 6 and is cooled by a cooling medium. A filter layer 10 is formed on the outer wall of the flow tube 6, and is configured to emit only light in a wavelength range that excites the laser medium 4.

Regarding the resonator configured as above,
The operation will be explained with reference to FIGS. 1 to 3. Excitation light emitted from the light source 3 enters the laser medium 4 directly or after being reflected by the cavity 1 . At this time, the energy absorbed by the laser medium 4 is expressed by (Equation 1).

[0014]

[Math 1]

In this (Equation 1), ΣA is the emission efficiency of the excitation light, which is determined by the physical structure of the cavity 1, the laser medium 4, and the light source 3.
This value is determined by the placement of ΣB is the incidence efficiency of the excitation light, which is a value determined by the reflectance or absorption of the reflecting surface 2 of the cavity 1, the laser medium 4, the flow tube 5, and the cooling medium, and is expressed by (Equation 2).

[0016]

[Math 2]

ΣB in (Equation 2) changes depending on the wavelength of the excitation light. The wavelength of the excitation light emitted from the light source 3 has a very wide wavelength range as shown in FIGS. 6 and 7, but the main absorption wavelengths of the laser medium 4 are 530, 58, as shown in FIG.
It is at 0,750,810,880 nm. Among these, particularly strong absorption is in the range of 750 to 810 nm, so by adjusting the wavelength of the light emitted from the light source 3 to this absorption band using a filter having the absorption characteristics shown in FIG. Absorbed. By forming a filter layer 10 on the outer wall of the flow tube 6 that transmits only wavelengths that are easily absorbed by the laser medium 4, unnecessary thermal energy absorbed by the laser medium 4 can be reduced and cooling efficiency can be increased. Furthermore, since the laser medium 4 efficiently absorbs the incident light, instability of the oscillation state due to the thermal lens phenomenon that occurs when the excitation energy becomes high can be prevented, and the laser oscillation output can be stabilized. This effect occurs in the laser medium's main absorption wavelength band of 550 nm~
By forming a filter layer that transmits only 900 nm, significant effects such as the ability to eliminate the adverse effects of ultraviolet light on laser oscillation can be obtained.

[0018]

[Effects of the Invention] As is clear from the above description of the embodiments, according to the present invention, a filter layer is formed on the outer wall of the flow tube to transmit only light in a specific wavelength range corresponding to the absorption characteristics of the laser medium. As a result, it is possible to provide a solid-state laser device that has stable output characteristics, in which lamp energy is efficiently absorbed by the laser medium, and thermal lens phenomenon does not occur.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a solid-state laser device according to an embodiment of the present invention.

[
Figure 2: Diagram showing the absorption spectrum of the same laser medium

[Figure 3]
Diagram showing the absorption spectrum of the same filter layer

[Figure 4] Cross-sectional view of a conventional solid-state laser device

[Figure 5] Configuration diagram of the solid-state laser device

[Figure 6] Diagram showing the emission spectrum of a xenon lamp

[Figure 7] Diagram showing the emission spectrum of a krypton lamp

[Explanation of symbols] 1 Cavity 2 Cavity reflective surface 3 Light source 4 Laser medium 5 Laser medium protection tube 6 Flow tube 10 Filter layer

Claims (2)

[Claims] 1. A solid-state laser that oscillates by exciting a solid-state laser medium with a light source such as a flash lamp or an arc lamp, wherein the light source has a flow tube for cooling the lamp as an outer cylinder, and the laser medium is a laser beam. The medium protection tubes are arranged in parallel to each other inside an outer cylinder, and a reflective surface for reflecting the light emitted from the light source is provided on the outside thereof,
The flow tube is a solid-state laser device in which a filter layer is formed on the outer wall of the flow tube to transmit only wavelengths absorbed by the laser medium among the light emitted from the light source. 2. The solid-state laser device according to claim 1, further comprising a filter layer that transmits only light of 550 nm to 900 nm on the outer wall of the laser medium protection tube.