Abstract:
A laser treatment apparatus for irradiating an affected part of a patient with a treatment laser beam to treat the affected part is disclosed. The apparatus includes a treatment laser beam irradiation system for emitting and delivering the treatment laser beam of a wavelength in a visible region to irradiate the affected part; an observation system provided with an observation optical system for observing the affected part; a protective filter disposed in an optical path of the observation optical system, for intercepting the treatment beam; a first aiming beam irradiation system for emitting and delivering a first aiming beam of about the same wavelength as the wavelength of the treatment beam to irradiate the affected part; a second aiming beam irradiation system for emitting and delivering a second aiming beam of a different wavelength in a visible region from the wavelength of the treatment beam to irradiate the affected part; and an aiming beam switching system for switching between irradiation of the first aiming beam and irradiation of the second aiming beam.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a laser treatment apparatus for irradiating an affected part of a patient with a treatment laser beam to treat the affected part. 
     2. Description of Related Art 
     There have been used laser treatment apparatus such as a photocoagulation device for irradiating an affected part of an eye fundus of a patient with a treatment laser beam (hereinafter simply referred to as a treatment beam) to coagulate the affected part by heat for treatment. In irradiation of the treatment beam to the eye fundus, such the apparatus is operated by an operator, who observes the patient&#39;s eye with a slit lamp, to perform sighting (aiming) of the treatment beam to a desired site on the affected part by utilizing an aiming laser beam (hereinafter simply referred to as an aiming beam) made coaxial with the treatment beam. When the aiming beam and the treatment beam are different in color (wavelength), which causes refraction and dispersion differences based on the wavelength differences, the difference may possibly occur in reaching conditions to the eye fundus between the beams of different colors (wavelengths). For preventing this problem, it is preferable to use the aiming beam of the same color as the color of the treatment beam. 
     In the laser treatment apparatus, normally, a protective filter is interposed in an optical path for observation in the slit lamp in order to cut or intercept the treatment beam reflected by the patient&#39;s eye and others to protect the eyes of an operator during the treatment beam irradiation. Accordingly, if the aiming beam of the same color as that of the treatment beam is used, the aiming beam is also cut or intercepted by the protective filter, so that the aiming beam becomes invisible. As a result, the irradiation site of the aiming beam, namely, of the treatment beam could not be visually recognized by the operator during the treatment beam irradiation. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a laser treatment apparatus which enables an operator to recognize an irradiation site with a treatment beam during irradiation even if using an aiming beam having the same color (wavelength) as that of the treatment beam. 
     Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     To achieve the purpose of the invention, there is provided a laser treatment apparatus for irradiating an affected part of a patient with a treatment laser beam to treat the affected part, the apparatus including: treatment laser beam irradiation means for emitting and delivering the treatment laser beam of a wavelength in a visible region to irradiate the affected part; observation means provided with an observation optical system for observing the affected part; a protective filter disposed in an optical path of the observation optical system, for intercepting the treatment beam; first aiming beam irradiation means for emitting and delivering a first aiming beam of about the same wavelength as the wavelength of the treatment beam to irradiate the affected part; second aiming beam irradiation means for emitting and delivering a second aiming beam of a different wavelength in a visible region from the wavelength of the treatment beam to irradiate the affected part; and aiming beam switching means for switching between irradiation of the first aiming beam and irradiation of the second aiming beam. 
     Preferably, the laser treatment apparatus further includes trigger means for generating a trigger signal to instruct irradiation of the treatment beam, wherein the aiming beam switching means switches between irradiation of the first aiming beam and irradiation of the second aiming beam in accordance with a presence or absence of the trigger signal from the trigger means. 
     Preferably, the laser treatment apparatus further including filter detection means for detecting whether the protective filter is in the optical path of the observation optical system, wherein the aiming beam switching means switches between irradiation of the first aiming beam and irradiation of the second aiming beam in accordance with a detection result of the filter detection means. 
     Preferably the laser treatment apparatus further including: trigger means for generating a trigger signal to instruct irradiation of the treatment beam; filter moving means for inserting or retracting the protective filter in or from the optical path of the observation optical system; and control means for controlling the filter moving means in accordance with a presence or absence of the trigger signal from the trigger means. 
     In the laser treatment apparatus, preferably, the aiming beam switching means switches between irradiation of the first aiming beam and irradiation of the second aiming beam in accordance with a type of an insertion/retraction driving mechanism of the protective filter. 
     In the laser treatment apparatus, preferably, the first aiming beam irradiation means includes attenuation means for attenuating output power of the treatment laser beam, the treatment laser beam with the attenuated output power being irradiated as the first aiming beam to the affected part. 
     In the laser treatment apparatus, preferably, the attenuation means includes a filter for attenuating the output power of the treatment beam to 1/100 to 1/1000. 
     According to another aspect of the present invention, there is provided a laser treatment apparatus for irradiating an affected part of a patient with a treatment laser beam to treat the affected part, the apparatus including: a treatment beam irradiation optical system provided with a first laser source for emitting the treatment laser beam of a wavelength in a visible region, for delivering the treatment beam to irradiate the affected part; an observation optical system for observing the affected part; a protective filter disposed in an optical path of the observation optical system, for intercepting the treatment beam; a first aiming beam irradiation optical system for emitting and delivering a first aiming beam of about the same wavelength as that of the treatment beam to irradiate the affected part; a second aiming beam irradiation optical system provided with a second laser source for emitting a second aiming beam of a different wavelength in the visible region from the wavelength of the treatment beam, for delivering the second aiming beam to irradiate the affected part; and a control unit for switching between irradiation of the first aiming beam and irradiation of the second aiming beam. 
     In the laser treatment apparatus, preferably, the first aiming beam irradiation optical system includes attenuation means for attenuating output power of the treatment laser beam emitted from the first laser source, and the attenuated treatment laser beam being used as the first aiming beam. 
     In the laser treatment apparatus, preferably, the attenuation means includes a filter for attenuating the output power of the treatment laser beam to 1/100 to 1/1000. 
     In the laser treatment apparatus, preferably, the control unit controls the first laser source, the second laser source and the attenuation means individually to switch between irradiation of the first aiming beam and irradiation of the second aiming beam. 
     Preferably, the laser treatment apparatus further including a trigger switch for generating a trigger signal to instruct irradiation of the treatment laser beam, wherein the control unit switches irradiation of the first aiming beam and irradiation of the second aiming beam in accordance with a presence or absence of the trigger signal. 
     Preferably, the laser treatment apparatus further including a sensor for detecting whether the protective filter is in the optical path of the observation optical system, wherein the control unit switches between irradiation of the first aiming beam and irradiation of the second aiming beam in accordance with a detection result of the sensor. 
     Preferably, the laser treatment apparatus further including: a trigger switch for generating a trigger signal to instruct irradiation of the treatment laser beam; and a filter moving unit for inserting/retracting the protective filter in/from the optical path of the observation optical system; wherein the control unit controls the filter moving unit in accordance with a presence or absence of the trigger signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of this specification illustrate an embodiment of the invention and, together with the description, serve to explain the objects, advantages and principles of the invention. 
     In the drawings, 
     FIG. 1 is a schematic perspective view of a laser treatment apparatus in an embodiment according to the present invention; 
     FIG. 2 is a schematic structural view of an optical system of the apparatus in the embodiment; 
     FIG. 3 is a schematic block diagram of a main part of a control system of the apparatus in the embodiment; 
     FIG. 4 is a flowchart of an irradiation control of an aiming beam; and 
     FIG. 5 is a schematic structural view of a modification of a main part of the optical system of the apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A detailed description of a preferred embodiment of a laser treatment apparatus embodying the present invention will now be given referring to the accompanying drawings. 
     FIG. 1 is a schematic perspective view of the laser treatment apparatus in the present embodiment; FIG. 2 is a schematic structural view of an optical system of the apparatus; and FIG. 3 is a schematic block diagram of a main part of a control system of the apparatus. 
     Numeral  1  is a main unit of the laser treatment apparatus. Numeral  2  is a control board for inputting settings such as irradiation conditions of a treatment laser beam (hereinafter simply referred to as a treatment beam) and light quantity of an aiming laser beam (hereinafter simply referred to as an aiming beam), etc. Numeral  3  is a slit lamp delivery internally provided with an illumination optical system  40  and an observation optical system  50 . The slit lamp delivery  3  is provided at its head with an irradiation section  3   a  including an irradiation optical system  30  for delivering the treatment beam and the aiming beam from the main unit  1  to irradiate an eye of a patient. Numeral  4  is an optical fiber cable for delivering the treatment beam and the aiming beam from the main unit  1  to the irradiation section  3   a.    
     Numeral  5  is a multi-conductor cable used for transmission/reception of signals of various kinds between the slit lamp delivery  3  and the main unit  1 . Numeral  6  is a footswitch for generating a trigger signal to start the irradiation of the treatment beam. Numeral  7  is a joystick for moving the slit lamp delivery  3  on a table of a base stand  8 . 
     Numeral  10  is a laser source which emits the treatment beam. 
     In the present embodiment, an Nd:YAG laser capable of oscillating a fundamental wavelength of 1064 nm is used to generate a green light of 532 nm (linearly polarized light) which is double the fundamental wavelength. Numeral  11  is a beam splitter for transmitting most of the treatment beam from the laser source  10  while reflecting a part thereof. The treatment beam reflected by the beam splitter  11  is incident to a power sensor  13  through a diffusing plate  12 . The power sensor  13  detects the output power of the treatment beam emitted from the laser source  10 . 
     Numeral  14  is a filter for largely attenuating the power of the green light (treatment beam) emitted from the laser source  10  so that the attenuated light is used as the aiming beam having the same color (wavelength) (hereinafter referred to as the same-color aiming beam) as that of the treatment beam. When the filter  14  is moved out of the optical path by means of a filter driving device  14   b , the green light (treatment beam) emitted from the laser source  10  without attenuation is used for the treatment beam. It is to be noted that a sensor  14   a  detects the open/close (insertion/retraction) state of the filter  14 . 
     Numeral  18  is a laser source which emits an aiming beam. In the present embodiment, the laser source  18  is a laser diode capable of emitting a red light having a wavelength of 630 nm. It is to be noted that the aiming beam is not limited to the red light of 630 nm. Any light may be adopted if only it differs in color (wavelength) from the treatment beam emitted from the laser source  10  and it is not intercepted by an operator protective filter  57  (mentioned later) disposed in the observation optical system  50 . The aiming beam (hereinafter referred to as the different-color aiming beam) emitted from the laser source  18  passes through a collimator lens  19  and it is made coaxial with the treatment beam by a dichroic mirror  20 . 
     Numeral  21  is a safety shutter which is inserted in or retracted from the optical path by a shutter driving device  21   b . The open/close (insertion/retraction) state of this shutter  21  is detected by a sensor  21   a . Numeral  22  is a condensing lens for condensing the treatment beam and the aiming beam into an entrance end  4   a  of the fiber  4 . The laser beams are delivered through the fiber  4  to the irradiation optical system  30  of the slit lamp delivery  3 . 
     The irradiation optical system  30  is constructed of a collimator lens  31 , a group of variable magnification lenses  32 , an objective lens  33 , and a driven mirror  34 . The variable magnification lens  32  is moved along the optical axis with the turn of a knob not shown to thereby change each spot diameter of the laser beams. The driven mirror  34  can freely change its reflecting angle with the control of a manipulator not shown by the operator. 
     The illumination optical system  40  is provided with a light source  41  which emits a visible illumination light, a condensing lens  42 , a variable circular aperture  43 , a variable slit plate  44 , a filter  45 , a projection lens  46 , a correcting lens  47 , and splitting mirrors  48   a  and  48   b . The aperture  43  and the slit plate  44  are used for determining the height and width of the illumination light to form luminous flux in a slit form. Numeral  49  is a contact lens for laser treatment, which is placed on a patient&#39;s eye E in the treatment. 
     The observation optical system  50  is constructed of an objective lens  51  used in common between a right and left observation optical paths and two sets each including a group of variable magnification lenses  52 , an image forming lens  53 , an erect prism  54 , a field diaphragm  55 , a group of eyepiece lenses  56 , and a protective filter  57  used for protecting the eyes of the operator from the treatment beam reflected by the patient&#39;s eye E and the contact lens  49 . Each set of the components  52 - 57  is disposed on the right and left optical paths respectively. 
     As the protective filter  57 , there are for example a fixed type which is always placed on the observation optical path, a hand-operated type which is manually inserted in or retracted from the observation optical path, and an electrically operated type which is automatically inserted in or retracted from the observation optical path in response to the trigger signal from the footswitch  6 . In the present embodiment, the protective filter  57  is of an electrically operated type which is automatically inserted in or retracted from the observation optical path by means of a filter driving device  61  which is filter moving means of the present invention. The protective filters  57  are placed out of the respective observation optical paths during observation of the eye E. Upon receipt of the trigger signal from the footswitch  6  acting as a trigger of the treatment beam irradiation, a controller  60  drives the filter driving device  61  to insert the protective filters  57  in the respective optical paths. Alternatively, a switch for inserting or retracting the protective filters  57  may be provided. In this case, the filter driving device  61  is driven in response to the signal from the switch. 
     Operation of the apparatus constructed as above will be explained below, referring to FIG.  4 . 
     Upon power-on of the main unit  1 , the controller  60  determines the type of an insertion/retraction driving mechanism of the protective filter  57  among the fixed type, the hand-operated type, or the electrically-operated type, based on an identifying signal from the slit lamp delivery  3  side. In the present embodiment, the protective filter  57  is of the electrically operated type. 
     Prior to execution of the laser treatment, the operator presses an aiming switch  2   a  provided on the control board  2  to provide the aiming beam, and observes the fundus of the eye E through the observation optical system  50 , the eye E being illuminated by the illumination light from the illumination optical system  40 . At this time, since the protective filter  57  has an electrically driven mechanism in the present embodiment, the controller  60  judges that the same-color aiming beam should be emitted. The controller  60  therefore drives the laser source  10  to emit the treatment beam, whereby to make the treatment beam pass through the filter  14 . By the passage of the treatment beam through the filter  14 , the output power of the treatment beam is attenuated to about 1/100 to 1/1000 of a standard power. The power attenuated treatment beam is used as the aiming beam. Thus the aiming beam of the same color (wavelength) as that of the treatment beam can be provided. When such same-color aiming beam is emitted, the controller  60  controls the shutter driving device  21   b  to move the shutter  21  out of the optical path. 
     The operator observes the same-color aiming beam applied to the eye fundus and controls the joystick  7  and the manipulator not shown to perform the sighting (alignment) to the affected part. Then, the operator inputs the irradiation conditions including the irradiation power and the irradiation time of the treatment beam with the switches on the control board  2 . It is to be noted that the irradiation conditions may be set in advance. 
     After preparation for the irradiation of the treatment beam, the operator operates the manipulator to fine adjust the sighting using the same-color aiming beam to the affected part. After completion of the sighting, the operator depresses the footswitch  6 , thereby starting the irradiation of the treatment beam. 
     The controller  60 , upon receipt of the trigger signal from the footswitch  6 , causes the laser source  18  to emit the different-color aiming beam and, simultaneously, drives the filter driving device  61  to insert the protective filters  57  in the respective optical paths. Subsequently, the controller  60  controls the laser source  10  to emit the treatment beam at the predetermined irradiation power set with the use of the control board  2 . When the sensor  13  detects the predetermined irradiation power, the controller  60  moves the filter  14  to the outside of the optical path. 
     The treatment beam and the different-color aiming beam are delivered through the fiber  4  and the irradiation optical system  30  to the affected part of the eye E to irradiate the affected part of the eye E. This aiming beam being different in color from the treatment beam, the operator can recognize the aiming beam even though the protective filter  57  is disposed in the observation optical path (or even during the irradiation of the treatment beam). Accordingly, the operator can also recognize the irradiation site of the treatment beam. 
     In the above explanation, the ON/OFF state of the footswitch  6  is used for switching between the same-color aiming beam and the different-color aiming beam. Alternatively, a sensor  57   a  for detecting the insertion/retraction of the protective filter  57  in/from the observation optical path may be provided as shown in FIG.  5 . In this case, the switching between the aiming beams differing in color is performed based on a detection result of the sensor  57   a.    
     The electrically operated protective filter  57  is provided in the observation optical system  50  of the slit lamp delivery  3  in the present embodiment. Instead of the electrically operated type, however, there may be cases where the filter  57  of a fixed or hand-operated type is used in a laser treatment apparatus constructed such that the irradiation section  3   a  is incorporated in an existing slit lamp or a binocular inverted-image mirror which is attached on the head of the operator at the time of use. In using such the apparatus (the inverted-image mirror or the slit lamp), the type of the insertion/retraction mechanism of the protective filter  57  can be determined in advance under the filter identifying signal. In the case of the fixed or hand-operated type, therefore, the controller  60  operates to emit the different-color aiming beam from the beginning (see FIG.  4 ), instead of emitting the same-aiming beam. As a result, even if the protective filter  57  is interposed in the observation optical path during the observation as well as during the treatment beam irradiation, the different-color aiming beam not intercepted by the protective filter  57  makes it possible for the operator to recognize the irradiation site of the aiming beam. 
     It is to be noted that in the case of the hand-operated type, the sensor  57   a  shown in FIG. 5 may be used to detect the insertion/retraction, or presence/absence of the protective filter  57 . In this case, at the time when the protective filter  57  is inserted in the optical path, the switching from the same-color aiming beam to the different-color aiming beam is executed. 
     The switching from the irradiation of the same-color aiming beam to the irradiation of the different-color is not limited to the above manners. A special switch for switching between the aiming beams may be provided in the main unit  1 , whereby to permit the switching in accordance with operator&#39;s own judgement. 
     In the above embodiment, the same-color aiming beam is produced as a result of attenuation of the power of the treatment beam emitted from a single laser source. Alternatively, the apparatus may additionally be provided with a laser source specifically designed for emitting an aiming beam of about the same color (wavelength) as that of the treatment beam. 
     As described above, the laser treatment apparatus in the present embodiment is arranged to appropriately use the aiming beam of the same-color (wavelength) as that of the treatment and the other aiming beam of the different-color. Accordingly, the sighting can be performed with the use of the aiming beam of about the same color as that of the treatment beam at the observation (at nonuse of the protective filter  57 ). The irradiation site of the treatment beam can be recognized even during the irradiation of the treatment beam (during use of the protective filter  57 ). 
     The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiment chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.