JP3699867B2 - Laser equipment - Google Patents

Description

本実施形態の波長に当てはめると、以下の式２となる。
【００３２】
【数２】

また、本実施形態では、２つの異なる波長の光の和周波光を得たが、差周波光を得るようにすることもできる。この場合の計算式は、以下の式３となる（λ₄は和周波を示す）。
【００３３】
【数３】

なお、本実施形態では、光の波長によって透過と反射とを区別して行う特性を持つダイクロイックミラー（ＤＭ１５ａ〜１５ｃ）を使用したが、その代わりに光の偏光方向によって透過と反射とを区別して行う特性を持つ偏光ビームスプリッタを使用してもよい。この場合は、光の偏光方向を変える偏光板を適宜光路中に配置する。
【００３４】
また、図５に示すように、ユニット３０ａ，３０ｂの代りに、ＮＬＣ１３ａ，１３ｂとＨＲ１４ｂ，１４ｄによって構成されたユニット３０ｄを使用し、５３２ｎｍのレーザ光と６５９ｎｍのレーザ光とを同時に出射できるようにしてもよい（もちろん別々に出射することも可能である）。
【００３５】
さらに、図６及び図７に示すように、２つのロッド１１ａ，１１ｂを非線形結晶の片側に配置して、２つの光を位相整合するようにしてもよい。図６は５８９ｎｍのレーザ光を出射する場合を示し、ＮＬＣ１３ｃ、ＨＲ１４ｇ及びＤＭ１５ｇによって構成された波長変換ユニット３１ｃが移動装置１７によって切換え配置される。図７（ａ）は５３２ｎｍのレーザ光を出射する場合を示し、ＮＬＣ１３ａ、ＨＲ１４ｂ及びＤＭ１５ｅによって構成された波長変換ユニット３１ａが移動装置１７によって切換え配置される。図７（ｂ）は６５９ｎｍのレーザ光を出射する場合を示し、ＮＬＣ１３ｂ、ＨＲ１４ｄ及びＤＭ１５ｆによって構成された波長変換ユニット３１ｂが移動装置１７によって切換え配置される。得られた５３２ｎｍ，６５９ｎｍ，５８９ｎｍのレーザ光は、それぞれミラー１６ｄによって反射され、ファイバ５へ導光される。そして、スリットランプ４の照射口から患者眼に向けて照射される。
【００３６】
なお、ＨＲ１４ｇは１０６４ｎｍ、１３１９ｎｍ及び５８９ｎｍに対して全反射の特性を持つ。また、ＤＭ１５ｄは１０６４ｎｍを透過して１３１９ｎｍを反射し、ＤＭ１５ｅは１０６４ｎｍを反射して５３２ｎｍを透過し、ＤＭ１５ｆは１３１９ｎｍを反射して６５９ｎｍを透過し、ＤＭ１５ｇは１０６４ｎｍ及び１３１９ｎｍを反射して５８９ｎｍを透過する特性をそれぞれ持つ。
【００３７】
また、本実施形態では、固体レーザ媒質としてＮｄ：ＹＡＧ結晶を使用したが、これに限定されるものではなく、周知の固体レーザ媒質（結晶）を使用することができる。もちろん、別々の種類の固体レーザ媒質（結晶）をそれぞれ使用してもよい。
【００３８】
さらにまた、本実施形態は眼科用のレーザ治療装置に限るものではなく、医療（形成外科を含む）用や産業（測定等）用など様々な用途のレーザ装置に適用することができる。
【００３９】
【発明の効果】
以上説明したように、本発明によれば、コストを抑えつつ、効率良く複数の異なる波長のレーザ光を出射させることができる。
【図面の簡単な説明】
【図１】本実施形態の装置の外観図である。
【図２】本実施形態の装置の光学系及び制御系概略図である。
【図３】本実施形態の装置の一部光学系及び一部制御系概略図である。
【図４】Ｎｄ：ＹＡＧロッドの発振線の種類を示す図である。
【図５】本実施形態の装置の光学系の一部変容例である。
【図６】本実施形態の装置の光学系及び制御系の変容例である。
【図７】変容例の装置の一部光学系及び一部制御系概略図である。
【符号の説明】
２ コントロール部
４ スリットランプ
１０ レーザ発振器
１１ａ，１１ｂ Ｎｄ：ＹＡＧロッド
１２ａ，１２ｂ 半導体レーザ
１３ａ〜１３ｃ 非線形結晶
１４ａ〜１４ｇ 全反射ミラー
１５ａ〜１５ｇ ダイクロイックミラー
１６ａ〜１６ｄ ミラー
１７ 移動装置
２０ 制御部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser apparatus capable of emitting a plurality of laser beams having different wavelengths.
[0002]
[Prior art]
As a laser apparatus capable of emitting a plurality of laser beams having different wavelengths, an argon die laser in which the wavelength of the laser beam is variable, a multi-wavelength krypton laser, and the like are known. These are used in various fields such as a medical field such as ophthalmic surgery in which a suitable wavelength varies depending on an affected part and a therapeutic purpose. For example, in ophthalmic surgery, different diseases (affected areas) are treated with differences in wavelength (color) around the visible range, and depending on the disease (affected area), different wavelengths (colors) such as red and green can be used simultaneously or Since it may be used continuously, it is convenient that a single device can emit a plurality of different wavelengths.
[0003]
The wavelength-tunable laser treatment device described above is a gas or a die laser, and there are many problems such as a short life of the laser tube, a great amount of power, and an increase in the size of the device. Laser devices capable of multi-wavelength oscillation have been studied. In such a background, a method for obtaining visible laser light from a solid-state laser that could not obtain visible laser light in the past and a method for obtaining sum frequency light from a plurality of light of different wavelengths have been proposed. .
[0004]
For example, in US Pat. No. 5,345,457 and US Pat. No. 5,528,612, sum frequency light can be obtained by combining light of different wavelengths using one or plural prisms and using a nonlinear crystal. A laser device is disclosed. In the US Patent No. 5,345,457 laser device, a laser beam of 589 nm, which is a sum frequency light, can be emitted from the light of 1064 nm and the light of 1318 nm by the Nd: YAG rod. Furthermore, in the laser apparatus of US Patent No. 5,528,612, laser beams of a plurality of wavelengths can be emitted individually, and can be emitted as a sum frequency light in combination. Thereby, for example, in the case of emitting laser beams of three different wavelengths, it can be performed with two laser rods and an excitation light source for exciting them, and can be reduced by one each compared to the conventional case. .
[0005]
[Problems to be solved by the invention]
However, when combining different wavelengths depending on the prism, especially when using Nd: YAG crystal as a laser rod and combining relatively close wavelengths over the near infrared region such as 1064 nm and 1318 nm, the difference in the incident angle to the prism is very large. Because it is small, a wide space is required. Further, since each wavelength is guided onto the same optical axis using the prism, the loss in the resonator becomes relatively large, and the conversion efficiency from the excitation light to the laser light is lowered. Furthermore, high accuracy is required for the prism itself and its arrangement position.
[0006]
US Pat. No. 5,345,457 also proposes a method of obtaining sum frequency light using a polarizer instead of a prism, but in either case, only 589 nm laser light, which is sum frequency light, can be emitted.
[0007]
On the other hand, US Patent No. 5,528,612 uses a single nonlinear crystal and can cope with various wavelength conversions by changing the temperature. However, it is not easy to adjust the temperature in detail, and there is a limit to the wavelength conversion that can be handled by one nonlinear crystal.
[0008]
In view of the above-described problems, it is an object of the present invention to provide a laser device that can emit a plurality of laser beams with different wavelengths efficiently while suppressing cost.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is characterized by having the following configuration.
[0010]
(1) In a laser apparatus capable of selectively emitting a plurality of laser beams having different wavelengths, the first laser beam obtained by exciting the first solid-state laser medium is a first harmonic that is a second harmonic by a nonlinear crystal. A first resonance optical system that obtains a wavelength laser beam, and a second resonance optical that obtains a second wavelength laser beam that is a second harmonic from the second laser beam obtained by exciting the second solid-state laser medium using a nonlinear crystal. And a switching optical unit that selectively switches and arranges a switching optical unit in a shared optical path of the first resonance optical system and the second resonance optical system , the nonlinear optical crystal constituting the first resonance optical system as the switching optical unit and a first switching換光Science unit having a resonance mirror, and a second switching換光Science unit with a non-linear crystal and cavity mirror constituting the second resonance optical system, the first laser beam and the second laser beam by phase matching Characterized by comprising a switching means for chromatic and third switching換光Science unit with a non-linear crystal and a resonant mirror and the three-wavelength laser beam, which is the sum frequency light.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external view of an ophthalmic laser photocoagulation apparatus using a slit lamp. 2 and 3 are schematic diagrams of an optical system and a control system of the apparatus. Reference numeral 1 denotes a laser apparatus body. A laser oscillator 10 to be described later, a light guide optical for guiding and irradiating a laser beam to an affected part of a patient's eye. A part of the system, the control unit 20 and the like are accommodated. Reference numeral 2 denotes a control unit of the apparatus, which is provided with a wavelength selection switch 2a for selecting the wavelength of the laser beam and various switches for setting and inputting laser irradiation conditions. Reference numeral 3 denotes a foot switch for transmitting a trigger signal for laser irradiation.
[0020]
Reference numeral 4 denotes a slit lamp, which includes an observation optical system for observing a patient's eye and a part of a light guide optical system. Reference numeral 5 denotes a fiber for guiding laser light from the main body 1 to the slit lamp 4. Reference numeral 6 denotes a frame for moving the slit lamp 4 up and down.
[0021]
A laser oscillator 10 includes Nd: YAG crystals (hereinafter also simply referred to as rods) 11a and 11b, which are solid laser media (laser rods), and semiconductor lasers (hereinafter simply LD (Laser Diode)), which are excitation light sources. 12a, 12b, nonlinear crystals (hereinafter also simply referred to as NLC (Non Linear Crystal)) 13a to 13c, total reflection mirrors (hereinafter also simply referred to as HR (High Reflector)) 14a to 14f, Dichroic mirrors (hereinafter also simply referred to as DM (Dicroic Mirror)) 15a to 15c and mirrors 16a to 16c are provided. As the nonlinear crystal, a KTP crystal, an LBO crystal, a BBO crystal, a CLBO crystal, or the like can be used. In this embodiment, a KTP crystal is used.
[0022]
The NLC 13a and the HR 14b constitute a wavelength conversion unit 30a, the NLC 13b and the HR 14d constitute a wavelength conversion unit 30b, and the NLC 13c, the HR 14e and the HR 14f constitute a wavelength conversion unit 30c. These wavelength conversion units can be switched and moved by the moving device 17. The moving device 17 may be a well-known device such as a device that rotates and switches each housing in which the units 30a, 30b, and 30c are housed, or a device that switches by sliding.
[0023]
The Nd: YAG crystal emits light having a plurality of oscillation lines in the near infrared region by excitation light from the excitation light source (see FIG. 4). Therefore, in the apparatus of the present embodiment, about 1064 (1064.1) nm and about 1319 (1318.8) nm, which have high output among a plurality of oscillation lines and can be converted into different colors, are used, and about 532 nm (green). , Laser beams of three colors of about 589 nm (yellow) and about 659 nm (red) are emitted. In this embodiment, the resonator on the rod 11a side oscillates 1064 nm light, and the resonator on the rod 11b side oscillates 1319 nm light (details will be described later).
[0024]
HR14a is totally reflected for 1064 nm, HR14b is totally reflected for 1064 nm and 532 nm, HR14c is totally reflected for 1319 nm, HR14d is totally reflected for 1319 nm and 659 nm, and HR14e is for 1064 nm and 589 nm. Total reflection and total transmission with respect to 1319 nm, and HR14f have total reflection with respect to 1319 nm and total transmission with respect to 1064 nm and 589 nm. DM15a reflects 1064 nm and transmits 532 nm and 589 nm, DM15b reflects 1319 nm and transmits 659 nm, and DM15c reflects 532 nm and 589 nm and transmits 659 nm.
[0025]
Reference numerals 18a and 18b denote drive circuits for the LDs 12a and 12b, respectively. Reference numeral 19 denotes a drive circuit for the moving device 17 that switches and arranges the units 30a, 30b, and 30c. A control unit 20 controls each unit of the apparatus based on signals from the control unit 2 and the foot switch 3.
[0026]
Next, a method for emitting a plurality of laser beams having different wavelengths will be described based on the above configuration.
[0027]
<Method of emitting laser beam of 532 nm>
The operator sets the color (wavelength) of the laser beam used for the operation to green (532 nm) by using the wavelength selective switch 2a. The controller 20 applies a current only to the LD 12a via the drive circuit 18a, and excites the rod 11a by the LD 12a. It should be noted that AR (Anti Reflective) coating is applied to both end faces of the Nd: YAG crystal, which is the rod 11a, so as to increase the transmittance with respect to 1064 nm. Further, the control unit 20 drives the moving device 17 via the drive circuit 19, and sets the unit 30a constituted by the NLC 13a and the HR 14b. A resonator 25a is configured by the HR 14a, DM 15a, and HR 14b, and an NLC 13a having AR coatings for 1064 nm and 532 nm on both end faces is disposed immediately before the HR 14b (see FIG. 3A). As a result, light of 1064 nm is oscillated in the resonator 25a and further wavelength-converted into light of 532 nm, which is the second harmonic of 1064 nm, inside the resonator 25a. The obtained 532 nm laser beam is transmitted through the DM 15a and guided to the fiber 5 through the mirrors 16a and DM15c. And it irradiates toward the patient's eyes from the irradiation port of the slit lamp 4.
[0028]
<Method for emitting laser light of 659 nm>
The surgeon changes the color (wavelength) of the laser beam used for the operation to red (659 nm) by using the wavelength selective switch 2a. The controller 20 applies a current only to the LD 12b via the drive circuit 18b, and excites the rod 11b by the LD 12b. Note that the AR coating is applied to both end faces of the Nd: YAG crystal, which is the rod 11b, so as to increase the permeability to 1319 nm. Further, the control unit 20 drives the moving device 17 via the drive circuit 19, and sets the unit 30b constituted by the NLC 13b and the HR 14d. A resonator 25b is configured by the HR 14c, DM 15b, and HR 14d, and an NLC 13b having AR coatings for 1319 nm and 659 nm is disposed on both end faces immediately before the HR 14d (see FIG. 3B). As a result, light of 1319 nm is oscillated in the resonator 25b, and further wavelength-converted into light of 659 nm, which is the second harmonic of 1319 nm, inside the resonator 25b. The obtained 659 nm laser beam is transmitted through the DM 15b and guided to the fiber 5 through the mirrors 16b and 16c and the DM 15c. And it irradiates toward the patient's eyes from the irradiation port of the slit lamp 4.
[0029]
<Method for emitting laser beam of 589 nm>
The surgeon changes the color (wavelength) of the laser beam used for the operation to yellow (589 nm) by using the wavelength selective switch 2a. The controller 20 applies current to the LDs 12a and 12b via the drive circuits 18a and 18b, respectively, and excites the rods 11a and 11b. In addition, the control unit 20 drives the moving device 17 via the drive circuit 19, and sets the unit 30c configured by the NLC 13c, the HR 14e, and the HR 14f. The resonator 25c by HR14a, DM15a, and HR14e and the resonator 25d by HR14c, DM15b, and HR14f are respectively configured, and AR coating for 1064 nm, 1319 nm, and 589 nm is provided between the HR14e and HR14f (substantially in the middle). NLC13c to which is applied is arranged (see FIG. 2). As a result, the 1064 nm light oscillated by the resonator 25c and the 1319 nm light oscillated by the resonator 25d are incident on the NLC 13c, phase-matched, and wavelength-converted to 589 nm light which is a sum frequency light, DM15a is transmitted through the reflection of DM14e and the transmission of DM14f. The obtained 589 nm laser light is reflected by the mirrors 16 a and DM 15 c and guided to the fiber 5. And it irradiates toward the patient's eyes from the irradiation port of the slit lamp 4.
[0030]
The following formula 1 is known as a formula for calculating the sum frequency (λ ₁ and λ ₂ are fundamental wavelengths, and λ ₃ is a sum frequency),
[0031]
[Expression 1]

When applied to the wavelength of the present embodiment, the following Expression 2 is obtained.
[0032]
[Expression 2]

In this embodiment, the sum frequency light of two different wavelengths of light is obtained, but difference frequency light can also be obtained. The calculation formula in this case is the following formula 3 (λ ₄ indicates the sum frequency).
[0033]
[Equation 3]

In this embodiment, the dichroic mirrors (DM15a to 15c) having the characteristic of distinguishing between transmission and reflection according to the wavelength of light are used, but instead, the transmission and reflection are distinguished according to the polarization direction of light. A polarizing beam splitter having characteristics may be used. In this case, a polarizing plate that changes the polarization direction of light is appropriately disposed in the optical path.
[0034]
In addition, as shown in FIG. 5, instead of the units 30a and 30b, a unit 30d constituted by NLCs 13a and 13b and HRs 14b and 14d is used so that 532 nm laser light and 659 nm laser light can be emitted simultaneously. (Of course, it is also possible to emit separately).
[0035]
Further, as shown in FIGS. 6 and 7, two rods 11a and 11b may be arranged on one side of the nonlinear crystal so that the two lights are phase-matched. FIG. 6 shows a case where a laser beam of 589 nm is emitted, and the wavelength conversion unit 31c configured by the NLC 13c, the HR 14g, and the DM 15g is switched by the moving device 17. FIG. 7A shows a case where a laser beam of 532 nm is emitted, and the wavelength conversion unit 31a constituted by the NLC 13a, the HR 14b, and the DM 15e is switched by the moving device 17. FIG. 7B shows a case where a laser beam of 659 nm is emitted, and the wavelength conversion unit 31b constituted by the NLC 13b, the HR 14d, and the DM 15f is switched by the moving device 17. The obtained laser beams of 532 nm, 659 nm, and 589 nm are respectively reflected by the mirror 16 d and guided to the fiber 5. And it irradiates toward the patient's eyes from the irradiation port of the slit lamp 4.
[0036]
HR14g has total reflection characteristics with respect to 1064 nm, 1319 nm, and 589 nm. DM15d transmits 1064 nm and reflects 1319 nm, DM15e reflects 1064 nm and transmits 532 nm, DM15f reflects 1319 nm and transmits 659 nm, and DM15g reflects 1064 nm and 1319 nm and transmits 589 nm. Each has its own characteristics.
[0037]
In this embodiment, the Nd: YAG crystal is used as the solid laser medium. However, the present invention is not limited to this, and a known solid laser medium (crystal) can be used. Of course, different types of solid-state laser media (crystals) may be used.
[0038]
Furthermore, the present embodiment is not limited to an ophthalmic laser treatment apparatus, and can be applied to laser apparatuses for various uses such as medical (including plastic surgery) and industrial (measurement, etc.).
[0039]
【The invention's effect】
As described above, according to the present invention, it is possible to efficiently emit laser beams having a plurality of different wavelengths while suppressing cost.
[Brief description of the drawings]
FIG. 1 is an external view of an apparatus according to an embodiment.
FIG. 2 is a schematic diagram of an optical system and a control system of the apparatus according to the present embodiment.
FIG. 3 is a schematic diagram of a partial optical system and a partial control system of the apparatus according to the present embodiment.
FIG. 4 is a diagram showing types of oscillation lines of an Nd: YAG rod.
FIG. 5 is a partial modification example of the optical system of the apparatus according to the present embodiment.
FIG. 6 is a modification example of an optical system and a control system of the apparatus according to the present embodiment.
FIG. 7 is a schematic diagram of a partial optical system and a partial control system of an apparatus of a modification example.
[Explanation of symbols]
2 Control unit 4 Slit lamp 10 Laser oscillators 11a, 11b Nd: YAG rods 12a, 12b Semiconductor lasers 13a-13c Non-linear crystals 14a-14g Total reflection mirrors 15a-15g Dichroic mirrors 16a-16d Mirror 17 Moving device 20 Control unit

Claims (1)

In a laser apparatus capable of selectively emitting a plurality of laser beams having different wavelengths, the first laser beam obtained by exciting the first solid-state laser medium is converted to a first wavelength laser beam that is a second harmonic by a nonlinear crystal. A second resonance optical system for obtaining a second wavelength laser beam that is a second harmonic from a second laser beam obtained by exciting a second solid-state laser medium with a nonlinear crystal; A means for selectively switching and arranging a switching optical unit in a shared optical path of the first resonance optical system and the second resonance optical system , wherein the switching optical unit is a nonlinear crystal and a resonance mirror constituting the first resonance optical system. a first switching換光Science unit having a second switching換光Science unit with a non-linear crystal and cavity mirror constituting the second resonance optical system, the first laser beam and the sum frequency and the second laser beam is phase-matched Non-linear crystal and a laser device comprising a switching means for chromatic and third switching換光Science unit having a resonance mirror, further comprising a to the third wavelength laser beam is.

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