KR100269185B1 - Laser apparatus - Google Patents

Abstract

PURPOSE: A laser device is provided to generate a laser light having the wavelength of 1.54 μm using a laser light having the wavelength of 1.064 μm as a pumping light so that it can be used in a distance measurement without damaging eyes of a user. CONSTITUTION: A laser device includes a pumping laser(10) for generating a pumping laser light of a pulse shape. An oscillator(50) converts a laser light having the wavelength of 1.064 μm from the pumping laser(10) by means of the pumping laser light into a laser light of a long wavelength. The oscillator(50) includes a gas cell(70), a focus lens(50) for focusing the incident light and a collimation lens(80) for changing the incident focus light into a parallel light. The gas cell(70) has a chamber(71) for forming a sealed space for containing gases, and a gas inlet(75) provided at one end of the chamber(71).

Description

Laser apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser device, and more particularly, to a laser device that is pumped by a pumping laser to convert light of a pumping laser wavelength into a longer wavelength laser light and output the same.

In general, a long wavelength laser light is used for distance measurement, so as not to damage the user's eyes.

Eye safety for laser light varies depending on the exposure conditions, and the maximum permissible exposure for direct ocular exposure to the laser light is defined as follows.

sec인 경우 허용값은

J/cm^2, 파장이 1.4 mu m` 이상이고 펄스폭이

sec인 경우 허용값은 10^-2J/cm^2로 규정되어 있다. 상기한 규정에 의하면 파장이 1.4 mu m` 이상인 레이저광에 대한 노출 허용값은 파장이 1.064 mu m`인 레이저광에 비해 약 2,000배가 되므로, 이 1.4 mu m`의 파장인 광에 의한 눈의 손상은 거의 무시될 수 있다.That is, the wavelength is 1.064 mu m` and the pulse width

If sec, the allowed value is

J / cm ^ 2, wavelength is over 1.4 mu m` and pulse width

For sec, the allowable value is defined as 10 ^ -2J / cm ^ 2. According to the above provisions, the exposure allowance for laser light having a wavelength of 1.4 mu m` or more is about 2,000 times higher than that of laser light having a wavelength of 1.064 mu m`. Can be almost ignored.

1 is a view showing an optical arrangement of a conventional laser device. Referring to the drawings, the conventional laser device, the Nd: YAG laser rod 5, which is an amplification medium, and a discharge lamp that generates a gain by irradiating light to the laser rod 5 to excite the material of the laser rod 5. (Not shown), first and second reflecting mirrors (1) and (7) constituting a resonator such that light having a wavelength of 1.064 mu m ′ among the light emitted from the excited laser rod 5 is resonated, and the first And a Q-switching element 3 provided between the second reflecting mirrors 1 and 7.

The first reflecting mirror 1 is a total reflecting mirror that totally reflects incident light, and the second reflecting mirror 7 is a partial reflecting mirror having a predetermined transmittance.

In the conventional laser device configured as described above, the Nd ^ 3 + `ions of the laser rod 5 are excited by the excitation light emitted from the discharge lamp, and the light is emitted while the light is emitted. Resonance in the second reflector 1 and 7 causes induced emission from the laser rod 5, and the induced emission light is amplified. And the induced emission light is Q-switched by the Q-switching element 3. Accordingly, the pulsed laser light is emitted through the second reflecting mirror 17.

Therefore, in the conventional laser device as described above, the pulsed laser light of wavelength 1.064 mu m` is emitted.

As described above, the conventional Nd: YAG laser device that emits pulsed laser light having a wavelength of 1.064 μm is widely used as a distance measuring laser device because of its compact structure.

However, pulse laser light with a wavelength of 1.064 mu m` can be absorbed by the human eye, as can be inferred from the allowance for not damaging the user's eyes. However, long exposure time can seriously damage the user's eyes.

On the other hand, a laser device for distance measurement is used also CO ₂ laser apparatus using a CO ₂ gas to the excitation and amplification materials, such CO ₂ laser device is given walking high voltage between the anode plate and cathode plate in the cell and the CO ₂ gas-filled By generating the excitation light, the CO ₂ gas is excited by the excitation light and has a structure such that the light is induced and emitted approximately from the laser light, and the laser light having a wavelength of about 10.6 μm is emitted.

Since the light emitted from such a CO ₂ laser device has a long wavelength of 10.6 μm, it hardly damages the user's eyes when used for distance measurement.

However, such a CO ₂ laser device is generally well known, so that the device is large and difficult to use as a portable device, which is practically impossible to use as a laser device for distance measurement.

The present invention has been made to solve the above problems, the wavelength is 1.54 mu by using a laser light having a wavelength of 1.064 mu m` as a pumping light so that it can be used for distance measurement without damaging the eyes of the user It is an object of the present invention to provide a laser device for generating a laser light of m`.

1 is a view schematically showing an optical arrangement of a laser device according to a conventional example,

2 is a schematic view showing an optical arrangement of a laser device according to an embodiment of the present invention;

3 is a cross-sectional view schematically showing the assembled state of the oscillator of FIG.

4 is a cross-sectional view showing another example of a gas cell according to the present invention;

5 is a view showing another example of a focusing lens according to the present invention;

6 is a schematic illustration of an optical arrangement of a laser device according to another embodiment of the invention.

<Explanation of symbols for the main parts of the drawings>

10 ... pumped laser 50 ... oscillator

60 ... focusing lens 61 ... flat convex lens

61a, 61b ... first and second surface 61c, 66a ... bi-color reflective coating surface

70 gas cell 71 chamber

75 Gas inlet 77 Gas outlet

80 collimating lens 90 filter

In order to achieve the above object, the present invention includes a pumping laser for generating a pumping laser light of a first wavelength in the form of a pulse; An oscillator pumped by a pumping laser light input from the pumping laser to generate a long wavelength laser light, the laser device comprising: a gas cell provided with a gas seal filled therein; A focusing lens installed between the pumping laser and the gas cell to focus the pumping laser light emitted from the pumping laser into the gas cell so that induced scattering may occur by interaction between the pumping laser light and the gas. And generating induced Raman scattering by the interaction between the pumping laser light focused by the focusing lens and a gas, thereby converting light of a first wavelength into light of a second wavelength having a longer wavelength. .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view schematically showing an optical arrangement of a laser device according to an embodiment of the present invention, Figure 3 is a cross-sectional view schematically showing the assembly state of the oscillator of FIG.

Referring to the drawings, the laser device includes a pumping laser 10 for generating a pulsed pumping laser light, and an oscillator 50 pumped by the pumping laser light to generate a long wavelength laser light.

The pumping laser 10 is an Nd: YAG laser rod 15, which is an amplification medium, and a discharge lamp that generates a gain by exciting light of the laser rod 15 by irradiating the laser rod 15 with light. ), First and second reflectors 11 and 17 constituting a resonator such that light having a wavelength of 1.064 mu m ′ among the light emitted from the excited laser rod 15 is resonated; And a Q-switching element 13 provided between the two reflecting mirrors 11 and 17.

Here, the first reflecting mirror 11 is preferably a total reflecting mirror for total reflection of the incident light. In addition, the second reflector 17 is preferably a partial reflector having a predetermined transmittance.

When a high voltage is applied to the discharge lamp by the pumping laser 10, excitation light is emitted from the discharge lamp, and the excitation light excites and transitions the Nd ^ 3 + `ions of the laser rod 15. Release. The emitted light is resonated by the first and second reflectors 11 and 17 and induced emission occurs in the laser rod 15. Therefore, the induced emission light is amplified in the pumping laser 10 and is emitted through the second reflecting mirror 17.

At this time, the Q-switching element 13 is preferably installed between the first reflecting mirror 11 and the laser rod 15, by the Q-switching the guided emission light from the pumping laser 10 pulsed laser Let the light exit.

Therefore, the light emitted from the pumping laser 10 as described above is a pulsed laser light having a wavelength of 1.064 mu m`. The light having a wavelength of 1.064 mu m ′ is used as a pumping laser light for pumping the oscillator 50. Here, the pumping laser 10 substantially corresponds to the conventional Nd: YAG laser device shown in FIG.

The oscillator 50 converts the laser light emitted from the pumping laser 10 into a long wavelength laser light by a pumping laser light input from the pumping laser 10. To this end, the oscillator 50 includes a gas cell 70, a focusing lens 50 for focusing incident light, and a collimating lens 80 for converting the incident focusing light into parallel light.

As shown in FIG. 3, the gas cell 70 includes a chamber 71 forming a sealed space for accommodating gas, and a gas inlet 75 provided at one side of the body of the chamber 71. do.

The chamber 71 is filled with a gas, and a pair of windows 72 and 73 may be provided at opposite ends of the chamber 71 so as to transmit incident light. At this time, the gas is preferably pumped by a pumping laser light having a wavelength of 1.064 mu m`, it is preferable to include a methane gas to generate light having a wavelength of 1.54 mu m`.

The gas inlet 75 is provided to inject gas into one side of the body of the chamber 71. In addition, the gas inlet 75 is provided so that the gas can be blocked to prevent further gas from entering and exiting the chamber 71 at a proper pressure.

Meanwhile, another example of the gas cell 70 is illustrated in FIG. 4. The illustrated gas cell 70 is the same as the gas cell 70 described with reference to FIG. 3, and is characterized in that a gas outlet 77 is further provided on one side of the body of the chamber 71.

The gas outlet 77 is provided at one side of the body of the chamber 71 to be spaced apart from the gas inlet 75 so as to discharge the gas filled in the chamber 71. In this case, the gas inlet 75 is connected to a gas supply source at the time of filling the gas into the gas cell 70, and the chamber 71 is connected to the gas outlet 77 so as to have a predetermined degree of vacuum. (71) draw out the air. The gas cell 70 can then be easily made by allowing gas to be supplied from the gas supply source.

On the other hand, when forming the gas cell 70 as described above can be injected while discharging a portion of the gas to the gas outlet 77, it is easy to adjust the pressure of the gas in the chamber 71. At this time, the gas discharge port 77 is also provided to be blocked to prevent gas from entering and exiting the gas inlet 75.

Here, the accommodation lens housing the focusing lens 50 and the collimating lens 80 at both ends of the barrel constituting the chamber 71, the focusing lens 50 and collimating lens 80 is a gas cell 70 It can be installed integrally to the. In addition, the windows 72 and 73 may be removed at both ends of the chamber 71, and the focusing lens 50 and the collimating lens 80 may be directly installed. In this case, the focusing lens 50 and the collimating lens 80 are installed to seal the inside of the chamber 71.

The focusing lens 50 is disposed between the pumping laser 10 and one end of the gas cell 70 to emit a pumping laser light in the form of a pulse which is emitted from the pumping laser 10 and is incident in the chamber 71. Focus on location

As shown in FIG. 2, the focusing lens 50 has a first surface 61a facing the pumping laser 10 and a second surface 61b facing the gas cell 70. It is preferable to provide the flat convex lens 61 which is a convex surface.

In this case, the first surface 61a transmits most of light having a wavelength of 1.064 mu m ′ incident from the pumping laser 10, and the Raman transformed wavelength 1.54 by induction scattering described later in the gas cell 70. Preferably, mu m` light is a dichroic reflective coating surface 61c intended to reflect mostly.

The second surface 61b is a convex surface and is antireflectively coated with respect to light having the wavelengths of 1.064 mu m ′ and 1.54 mu m ′, and refracts the light transmitted and / or reflected at the first surface 61a so that the gas is refracted. Focusing is at the focal position within the cell 70.

On the other hand, when the intensity of the pumping laser light at the focusing position, that is, the focus position, of the pumping laser light by the focusing lens 50 as described above is greater than or equal to the threshold value, the pumping laser light and the gas and Induced Raman scattering is caused by the interaction of. Here, the induced scattering is characterized in that the scattered light has the same coherence as the pumped laser light, and in particular, the stimulated Raman scattering has a high wavelength transition and a high conversion efficiency, so that the laser has a new wavelength. It is widely used as a method for generating light.

In addition, as the pressure of the gas and the intensity of the pumped laser light increase, nonlinear optical effects, particularly stimulated brillouin scattering, occur in addition to the induced Raman scattering. The induced Brillouin scattering is a phenomenon in which the pumping laser light is scattered by the acoustic wave generated in the gas cell 70 by the pump laser light, and the phase conjugation characteristic and the back scattering propagating in the opposite direction to the pumping laser light. Has characteristics.

Therefore, this induced Brillouin scattering forms the phase conjugate reflector 55 at the focusing position of the pumping laser light. Therefore, a laser resonator for guided Raman scattered light according to the present invention is formed between the phase conjugate reflector 55 formed by guided Brillouin scattering and the first surface 61a of the focusing lens 50 as described above.

Therefore, the light of 1.54 mu m ′ generated by the Stokes process in which backscattering of the induced Raman scattered light and the frequency of the scattered light is smaller than the frequency of the incident light, that is, the pumped laser light, is in phase with the first surface 61a. The laser oscillation is amplified in the resonator formed by the conjugate reflector 55.

The light passing through the phase conjugated reflector 55 of the laser oscillated 1.54 mu m ′ wavelength light is converted into parallel light by the collimating lens 80 and emitted. On the other hand, further comprising a filter 90 for transmitting only the light of 1.54 mu m 'wavelength after the collimating lens 80, the light emitted from the laser device according to the present invention as described above has a wavelength of 1.54 mu m' In-pulse laser light is obtained.

On the other hand, the focusing lens 50 may be provided with a meniscus lens 66 as shown in FIG. The meniscus lens 66 is disposed such that its center of curvature is directed toward the gas cell 70, and the S_1 ′ surface facing the pumping laser 10 receives the pumping laser light incident from the pumping laser 10. It is refracted to focus in the gas cell 70.

The S_2` surface facing the gas cell 70 transmits the pumped laser light having a wavelength of 1.064 mu m`, and the dichroic reflective coating surface reflects light having a Raman converted wavelength of 1.54 mu m` by induction scattering. It is preferable that it is (66a).

At this time, if the center of curvature of the S_2` plane is provided to coincide with the focal position f of the focusing lens 50, the back-scattered light may return back to the focal position irrespective of wavelength conversion. It is possible to form a concentric resonator.

6 is a schematic view showing an optical arrangement of a laser device according to another embodiment of the present invention. Here, the laser device shown is substantially the same as the laser device described with reference to FIG. 2, and is characterized in that the first surface 61a of the focusing lens 60 serves as the second reflecting mirror 17. have.

At this time, the first surface 61a is substantially the same as the embodiment of the present invention described with reference to FIG. 2, and in this embodiment, the pumping laser having the wavelength of the first surface 61a is 1.064 mu m ′. Most of the light is transmitted, but a small amount is used to reflect it. Here, the first surface 61a together with the first reflector 13 constitutes a resonator of the pumping laser 10.

As such, when the focusing lens 60 is provided to serve as the second reflecting mirror 17 of FIG. 2, the number of optical elements constituting the laser device can be reduced, thereby simplifying the structure.

In the laser device according to the present invention as described above, 1.54 mu m` wavelength of induced Raman scattering is induced by the interaction of methane gas filled at a proper pressure in the gas cell with a pulsed pumping laser beam having a wavelength of 1.064 mu m`. Light is generated, and the light having a wavelength of 1.54 mu m` is amplified by a resonator composed of a phase conjugate reflector formed by one side of the focusing lens and a focused conjugated lens at the focal position of the focusing lens to form a pulsed laser beam. It is emitted.

Therefore, the laser device according to the present invention generates a laser light having a wavelength of 1.4 μm or longer, that is, 1.54 μm, which can be used for distance measurement and the like without damaging the eye.

Claims (10)

A pumping laser for generating a pumping laser light of a first wavelength in pulse form; An oscillator which is pumped by a pumping laser light input from the pumping laser to generate a long wavelength laser light, comprising: The oscillator is provided to be sealed, and a gas cell filled therein; A focusing lens installed between the pumping laser and the gas cell to focus the pumping laser light emitted from the pumping laser into the gas cell so that induced scattering may occur by interaction between the pumping laser light and the gas. , And induced raman scattering by interaction between the pumping laser light focused by the focusing lens and a gas, thereby converting light of a first wavelength into light of a second wavelength and outputting the light. The laser device according to claim 1, wherein the light of the first wavelength has a wavelength of 1.064 mu m`, and the light of the second wavelength has a wavelength of 1.54 mu m`. The laser apparatus as claimed in claim 1, wherein the gas cell is filled with methane gas. The convex lens of claim 1, wherein the focusing lens is a flat convex lens in which a first surface facing the pumping laser is flat and a second surface facing the gas cell is convex. A laser having a phase conjugate reflector formed by guided Brillouin scattering at a focal position of the focusing lens and a first surface formed with a resonator to amplify and output light of a second wavelength generated by guided Raman scattering in the gas cell; Device. The method of claim 4, wherein the first surface transmits the pumping laser light of the first wavelength incident from the pumping laser, and reflects the light of the second wavelength generated by the induced Raman scattering in the gas cell. Laser device characterized in that the dichroic reflective coating surface. 5. The laser apparatus as claimed in claim 4, wherein the first surface is a reflector of a pumping laser resonator for causing the pumping laser to oscillate a pumping laser light having a first wavelength. The method of claim 1, wherein the gas cell, A chamber forming a sealed space for accommodating the gas; And a gas injection hole provided at one side of the body of the chamber to inject gas into the chamber. 8. The laser apparatus as claimed in claim 7, wherein the gas cell further comprises a gas discharge port provided at the other side of the body spaced apart from the gas injection port to discharge the gas in the chamber. The laser apparatus according to claim 1, further comprising a collimating lens installed at one end of the gas cell to convert the focused light of the second wavelength generated by the induced Raman scattering into parallel light. The laser apparatus as claimed in claim 1, further comprising a filter for transmitting only light having a second wavelength among the light output from the oscillator.

Images