JP3810109B2 - Laser treatment device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser treatment apparatus for performing treatment by irradiating a patient's eye with therapeutic laser light.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a laser treatment apparatus that performs treatment such as coagulation by irradiating a therapeutic laser beam to a patient's eye is known. In this type of apparatus, there is an apparatus in which the wavelength of the laser beam is made variable, such as an argon dilaser or a multi-wavelength krypton laser. The wavelength of the laser light is selected and used in consideration of the light absorption characteristics of the site to be treated.
[0003]
[Problems to be solved by the invention]
However, since these devices are gas or liquid lasers, the life of a laser tube that performs laser oscillation is relatively short. The laser tube is at the end of its life and it is expensive to replace it.
In addition, a device using a gas laser or a liquid laser has extremely poor conversion efficiency from a power source, and a relatively long laser tube is required to obtain a laser output necessary for treatment. In addition, a great deal of power is required. For this reason, there is a limit to reducing the size and weight of the apparatus.
Furthermore, there was a problem with the stability of the laser output.
[0004]
In view of the above-described drawbacks of the conventional apparatus, the present invention provides a laser treatment apparatus capable of selecting the wavelength of laser light and capable of improving the small size, light weight, and reliability of the apparatus. Let it be an issue.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is characterized by having the following configuration.
(1) In a laser treatment apparatus including a light guide optical system for guiding laser light to an affected area, treatment light selection means for selecting the type of treatment light, and excitation light to a solid laser medium to irradiate a plurality of oscillation lines Oscillating means for emitting light, and harmonic conversion means for selectively obtaining treatment light converted from light of a plurality of oscillation lines into harmonics of a plurality of wavelengths, each wavelength from light of the plurality of oscillation lines A wavelength selector that selects light of a specific oscillation line corresponding to the treatment light and a dedicated wavelength light for the selected oscillation line are prepared, and the wavelength of the selected oscillation line is set to a harmonic. Non-linear crystal to be converted and output mirror prepared exclusively for each oscillation line, an output that transmits most of the wavelength converted harmonic light and reflects the light before wavelength conversion Harmonic conversion optics having a mirror According to the selection by the harmonic conversion means obtained through the system and the treatment light selection means, the wavelength selector is moved so as to select the light of the corresponding oscillation line, and prepared for the selected oscillation line. And a control means for controlling the operation of the harmonic conversion means so as to move the nonlinear crystal and the output mirror on the optical path .
[0013]
[Example 1]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an external view of a laser photocoagulator using a slit lamp. Reference numeral 1 denotes a laser apparatus main body in which a solid-state laser oscillator, a power supply unit, and the like which will be described later are accommodated. Reference numeral 3 denotes a control unit of the apparatus, which is provided with switches for selecting the wavelength of laser light used for coagulation and various switches for setting laser irradiation conditions. Reference numeral 4 denotes an irradiation switch for sending a laser irradiation trigger signal.
[0014]
Reference numeral 5 denotes a slit lamp, which includes an observation optical system for observing the patient's eye and a light guide optical system for guiding the laser light to the affected area, and laser light from the laser apparatus main body 1 for irradiation. Is guided to the optical system of the slit lamp 5 through the fiber 2. Reference numeral 6 denotes a frame for moving the slit lamp delivery 5 up and down.
[0015]
FIG. 2 is a diagram for explaining an optical system and a control system of the apparatus.
(Optical system)
Reference numeral 10 denotes a laser oscillator. The laser oscillator 10 includes an Nd: YAG rod 11 that is a laser medium of a solid laser, an excitation light source 12, a grating 13 that is a wavelength selector, a mirror 14, and a nonlinear crystal 15 that is a wavelength converter. A condenser lens 16, a collimator lens 17 and an output mirror 18 are provided.
[0016]
The Nd: YAG rod 11 emits light having a plurality of oscillation lines in the infrared region by the excitation light from the excitation light source 12 (see FIG. 3). Of the oscillation lines shown in Fig. 3, those whose second harmonics can be used as green lasers are 1052nm, 1061nm, 1064nm and 1078nm, and those which can be used as yellow lasers are 1112nm, 1159nm and 1122nm. Lines that can be used as red lasers are 1318 nm and 1338 nm oscillation lines. The light emitted from the Nd: YAG rod 11 is reflected only in the axial direction by the diffraction of the grating 13, and is amplified by passing through the laser medium. Since the tilt angle of the grating 13 with respect to the optical axis and the reflected wavelength are in a known relationship, it is possible to select light of the desired wavelength by changing the tilt angle of the grating 13 by the driving device 34. it can. The mirror 14 is for efficiently returning the light reflected off the axial direction by the grating 13, and its angle can be changed in conjunction with the grating 13.
[0017]
The light whose wavelength is selected by the grating 13 is increased in energy density by the condenser lens 16 and enters the nonlinear crystal 15. When the wavelength-selected and amplified light passes through the nonlinear crystal 15, a part thereof is converted into a harmonic. In this embodiment, in order to obtain laser light for photocoagulation for fundus treatment, a nonlinear wave such as KTP, BBO, or LBO that can convert the fundamental wave in the infrared region of Nd: YAG into the second harmonic wave in the visible region. Crystals are arranged. Since the crystal direction with respect to the optical axis in order to efficiently convert a certain fundamental wave to the second harmonic is in a known relationship, the tilt angle of the nonlinear crystal 15 is changed by a driving device to be described later in accordance with the selected wavelength. The second harmonic can be obtained.
[0018]
The light that has passed through the nonlinear crystal 15 is collimated by the collimator lens 17 and travels to the output mirror 18. The output mirror 18 transmits most of the light in the wavelength range converted into the second harmonic, and has the characteristic of substantially totally reflecting the light in the fundamental wavelength range of Nd: YAG. The reflected fundamental wavelength light resonates and amplifies in the laser oscillator 10, and the light transmitted through the output mirror 18 is used as therapeutic light. That is, the laser oscillator 10 emits laser light that is wavelength-selected by the grating 13 and converted to the second harmonic by the nonlinear crystal 15.
[0019]
The laser light emitted from the laser oscillator 10 is divided by the beam splitter 19, and a part of the laser light enters the light receiving element 20. The light receiving element 20 detects the output of the laser light based on the amount of light received.
[0020]
A safety shutter 21 is inserted into the optical path in a predetermined case to block the laser light. The therapeutic laser beam that has passed through the beam splitter 18 passes through the dichroic mirror 22 and is then coaxially superimposed on the aiming beam emitted from the semiconductor laser light source 23. These laser lights are incident on the fiber 2 by the condenser lens 24. Thereafter, the laser light emitted from the fiber 2 is irradiated to the fundus of the patient's eye E by the contact lens 28 through the collimator lens 25, the focusing lens 26 and the mirror 27 provided in the slit lamp 5. The
Reference numeral 29 denotes a microscope portion of the slit lamp 5, and 30 denotes an operator's eye.
[0021]
(Control system)
The detection processing circuit 31 performs detection processing on the laser output signal detected by the light receiving element 20, and the signal is input to the control unit 32 and used for laser output control. A power supply unit 33 supplies power to the excitation light source 12 and changes the power supplied under the control of the control unit 32.
[0022]
Reference numeral 34 denotes a driving device for adjusting the angles of the grating 13 and the mirror 14, and reference numeral 35 denotes a driving device for adjusting the angle of the nonlinear crystal 15. The driving devices 34 and 35 are composed of a pulse motor, a driving circuit, and the like. The
36 is a solenoid for inserting / removing the safety shutter 21 into / from the optical path, and 37 is a drive circuit thereof. Reference numeral 38 denotes a drive circuit for the semiconductor laser 23.
[0023]
The operation of the apparatus configured as described above will be described.
After starting the apparatus, the operator operates the switch of the control unit 3 to select a laser wavelength corresponding to the treatment content, and to set other coagulation conditions such as laser output and coagulation time. In response to the wavelength selection signal from the control unit 3, the control unit 32 operates the driving device 34 to place the grating 13 and the mirror 14 at a predetermined inclination angle, and operates the driving device 35 to operate the nonlinear crystal 15. Is set to an inclination angle corresponding to the selected wavelength. In addition, the control unit 32 controls the power that the power supply unit 33 applies to the excitation light source for laser output control by the wavelength selection and laser output setting signals. This power control is performed based on the relationship between each fundamental wavelength and the oscillation intensity shown in FIG. 3 (the oscillation intensity of each fundamental wavelength in FIG. 3 is shown as a relative degree when 1064 nm is 100). That is, laser light having a set output is emitted from the laser oscillator 10 by applying strong excitation power at a wavelength with weak oscillation, and conversely with weak excitation power at a strong oscillation. Further, the control unit 32 inputs an adjustment signal to the power supply unit 33 based on the detection signal from the light receiving element 20, and stabilizes the output of the laser light at a set value.
[0024]
Next, the operator adjusts the spot size and the like while aiming the aiming light from the semiconductor laser 23 to the affected area while observing the patient's eye E with the observation optical system of the slit lamp 5. When the aiming is completed and the irradiation switch 4 is pressed, the safety shutter 21 is retracted out of the optical path, and the emitted laser light is irradiated to the patient's eye E through the optical system of the fiber 2 and the slit lamp 5. As a result, photocoagulation with a desired wavelength is performed.
[0025]
In the above embodiment, the Nd: YAG rod is used as the laser medium. However, various Nd-doped solid laser media such as Nd: KGW can be used.
The wavelength selector may use an optical element such as a prism, an etalon, or a via flange wavelength plate instead of the grating. In the case of a prism or a via flange wavelength plate, the wavelength can be specified by determining the angle as in the case of the grating. In the case of an etalon, the wavelength can be specified by inserting and removing the etalon corresponding to the wavelength to be specified.
[0026]
[Example 2]
FIG. 4 is a diagram illustrating a main part of the optical system of the apparatus according to the second embodiment. Since the same reference numerals as those in FIG. 2 are the same elements, the description thereof is omitted.
In order to obtain the second harmonics of a plurality of wavelengths, the first embodiment uses one nonlinear crystal and changes the crystal angle with the optical axis, whereas in the second embodiment, for each wavelength to be selected. A plurality of nonlinear crystals having a predetermined crystal direction are used.
In the figure, on a turn table 104, three sets of nonlinear crystal 101, a collimator lens 102 and an output mirror 103 are provided, and a drive device 105 is driven to rotate the turn table 104. Thus, one set is positioned on the optical axis. The three nonlinear crystals have crystal directions that convert, for example, the fundamental waves 1064 nm, 1112 nm, and 1318 nm to the second harmonics (green oscillation, yellow oscillation, and red oscillation) among the oscillation lines of the Nd: YAG rod 11. . Each of the three output mirrors 103 has reflection and transmission characteristics corresponding to the fundamental wave to be selected and light having a wavelength to be converted.
[0027]
With this configuration, it is not necessary to incline the nonlinear crystal with respect to the optical axis, and it is possible to coat the antireflection film corresponding to each wavelength on the nonlinear crystal. In other words, the laser device is less affected by reflection and refraction with respect to incident light and has a high conversion efficiency, and a second harmonic with high accuracy can be obtained.
Further, the output mirror is easy to manufacture because it does not need to expand the wavelength range of reflection and transmission with respect to that of the first embodiment.
[0028]
The arrangement of the plurality of nonlinear crystals and the output mirror on the optical path in the second embodiment can be selectively inserted and removed in various ways such as a slide type in addition to the rotation by the turntable.
Furthermore, by providing a set that does not have a nonlinear crystal, it is possible to emit laser light as a fundamental wave that is not converted into a harmonic.
[0029]
Although the present invention has been described with reference to the first and second embodiments, the present invention is not limited to the examples described as the embodiments, and various modifications of the embodiments are possible. It is included in the invention.
[0030]
【The invention's effect】
As described above, according to the present invention, it is possible to configure a solid-state laser device capable of selecting a wavelength corresponding to a change in treatment method due to a difference in light absorption characteristics. It becomes possible. In addition, the laser output can be stabilized and the lifetime can be increased, so that a device with improved reliability can be realized.
[Brief description of the drawings]
FIG. 1 is an external view of a laser photocoagulation apparatus according to an embodiment.
FIG. 2 is an explanatory diagram of a main configuration of an optical system and a control system of an apparatus that is an embodiment.
FIG. 3 is a diagram showing types of oscillation lines of an Nd: YAG rod.
4 is an explanatory diagram of a main part configuration inside a laser oscillator according to a second embodiment; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser apparatus main body 5 Slit lamp delivery 11 Nd: YAG rod 13 Grading 15,101 Nonlinear crystal | crystallization 18,103 Output mirror
34, 35 Drive device 104 Turntable

Claims (1)

In a laser treatment apparatus equipped with a light guide optical system for guiding laser light to an affected area, treatment light selecting means for selecting the type of treatment light, and emitting light of a plurality of oscillation lines by irradiating the solid laser medium with excitation light Oscillating means, and harmonic conversion means for selectively obtaining treatment light converted from light of a plurality of oscillation lines into harmonics of a plurality of wavelengths, the treatment light having the respective wavelengths from light of the plurality of oscillation lines A wavelength selector that selects light of a specific oscillation line corresponding to the wavelength of the selected oscillation line, and a dedicated wavelength light for the selected oscillation line, and a wavelength converter that converts the light of the selected oscillation line into a harmonic. A linear crystal and an output mirror prepared exclusively for each oscillation line, an output mirror that transmits most of the wavelength-converted harmonic light and reflects the light before wavelength conversion; Via harmonic conversion optics with And a non-linear crystal prepared for the selected oscillation line by moving the wavelength selector to select the light of the corresponding oscillation line according to the selection by the harmonic conversion means obtained by the above and the treatment light selection means And a control means for controlling the operation of the harmonic conversion means so as to move the output mirror on the optical path .

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