Abstract:
A shutter mechanism for employment in an ophthalmic laser treatment system mounts between the binoculars and a slit lamp or operating microscope. The shutter mechanism provides a filter movable into the optical viewing path when the laser is under selected power during treatment to prevent damage to the operator&#39;s eyes from the laser beam and uncovers the viewing paths when said treatment site is being viewed in conjunction with laser beam alignment and similar pre-operational procedures.

Description:
DESCRIPTION 
     1. Technical Field 
     The invention relates generally to shutters for opening and closing light paths and more specifically to an optical shutter for use in a laser system associated with a slit lamp or an operating microscope for ophthalmic procedures to protect the user&#39;s eyes from harmful laser light. 
     2. Background Art 
     Laser systems associated with a slit lamp for ophthalmic procedures carried out in a doctor&#39;s office or associated with an operating microscope for ophthalmic procedures carried out in hospital surgery are known. As part of such procedures, the doctor typically views the operating site through binoculars while using a relatively low power laser aiming beam. At the time the laser is actually employed for the operating procedure at a higher power, it is necessary to protect the doctor&#39;s eyes from the laser beam. Therefore, various types of optical shutters have been devised for this purpose. Typically, the shutter is positioned by a solenoid drive mechanism which has the disadvantage of relatively slow speed and the further disadvantage of requiring substantial power relative to the power required by a motor drive as with the present invention. In other respects, the conventional optical shutters have employed plural lenses and mechanism for positioning such plural lenses between shielding and non-shielding positions. 
     With the mentioned prior art practices in mind, the object of the present invention is to provide an optical shutter mechanism employing a relatively fast motor drive, a self-latching mechaism and a single shutter lens for uncovering and covering dual light paths associated with binoculars and means for operating the lens with the motor so as to minimize the power required during the shutter operation. Other objects will become apparent as the description proceeds. 
     DESCRIPTION OF THE INVENTION 
     The invention is directed to providing a shutter mechanism comprising an assembly adapted to be installed between binoculars and either a slit lamp or operating microscope used in conjunction with a laser for ophthalmic procedures. Two light paths through the shutter mechanism correspond to the viewing paths of the binocular eye pieces. A single lens member is operatively associated with a motor-driven crank arm such that when the motor is energized, the lens can be quickly positioned to block both lights paths immediately prior to use of a high power laser beam and to assume a self-latching mode. Binoculars are secured on one side of the invention assembly and a slit lamp or operating microscope is secured on the opposite side of the invention assembly. The drive motor is powered through a foot switch such that when the foot switch is operated, the shutter moves into position to block both light paths and thereby protect the eyes of the operator, i.e., the doctor or surgeon performing the ophthalmic procedure. As the shutter rotates to its shielding position, a position sensitive switch is actuated which enables laser power to be applied to the operation site at a selected high level and for a brief interval of time. Release of the foot switch serves to reverse the direction of operation of the motor and to restore the shutter to its non-blocking position prior to which the laser power level will have been restored to a level that will not be harmful to the operator or patient. 
    
    
     DESCRIPTION OF DRAWINGS 
     FIG. 1 is a cross section of the invention shutter mechanism assembly and illustrating how the slit lamp or operating microscope fitting and the binoculars are clamped to opposite ends of the invention assembly. 
     FIG. 2 is a left end view of the assembly of FIG. 1. 
     FIG. 3 is a right end view of the assembly of FIG. 1. 
     FIG. 4 is a section view taken along line 4--4 of FIG. 1. 
     FIG. 5 is a section view taken along line 5--5 of FIG. 1. 
     FIG. 6 is a left end view of the shutter core. 
     FIG. 7 is a right end view of the shutter core. 
     FIG. 8 is a section view taken along line 8--8 of FIG. 6. 
     FIG. 9 is an end view of a core cover. 
     FIG. 10 is a side view of a core cover. 
     FIG. 11 is a left end view of the shutter mounting shaft. 
     FIG. 12 is a right end view of the shutter mounting shaft. 
     FIG. 13 is a cross section of the shutter mounting shaft. 
     FIG. 14 is a side view of the filter crank. 
     FIG. 15 is an end view of the filter crank. 
     FIG. 16 is an outer end view of the male shutter flange which is adapted to fit a slit lamp or operating microscope fitting. 
     FIG. 17 is a section view taken along line 17--17 of FIG. 16 of the male shutter flange. 
     FIG. 18 is a side view of the shutter housing. 
     FIG. 19 is a left end view of the shutter housing. 
     FIG. 20 is a section view taken along line 20--20 of FIG. 19. 
     FIG. 21 is a right end view of the shutter housing. 
     FIG. 22 is a side view of the shutter filter. 
     FIG. 23 is a section view taken along line 23--23 of FIG. 22. 
     FIG. 24 is an outer end view of the female shutter flange which is adapted to accept the binoculars. 
     FIG. 25 is a section view taken along line 24--24 of FIG. 24. 
     FIG. 26 is a simplified schematic diagram of a system incorporating the shutter mechanism of the invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Referring initially to FIG. 1, the shutter mechanism 35 of the invention is adapted to be installed in an ophthalmic laser system between binoculars 36 and a slit lamp or operating microscope fitting 37 as indicated in FIG. 1. The description will first describe the electromechanical construction of the invention shutter mechanism 35 and will then discuss its operating features. 
     As seen in FIG. 1, the shutter mechanism 35 comprises the shutter core 38 formed of black coated aluminum and as best seen in FIGS. 6, 7 and 8 includes a pair of laterally-spaced, horizontally-oriented apertures or bores 40, 42 which align with the binocular sight paths, an aperture-recess formation 44 for mounting the filter drive motor 45 (FIGS. 1 and 4), a hole 46 between and on the horizontal centerline of holes 40, 42 for mounting the shutter mounting shaft taken along line 13--13 of FIG. 11 48 and a rib portion 50. Motor 45 drives the end 53 of filter crank 52 through gear 54 on the motor shaft and gear 58 on crank end 53. The outer crank end 55 slides in a slot 56 formed in the shutter filter 60. Filter 60 is formed of thin, e.g. 0.125 inch, amber-tinted, transparent &#34;Plexiglas&#34; sheet material. Filter 60 is in turn secured by bolt 62 on one end of mounting shaft 48 and is formed with outwardly-extending filter lens sections 65, 66 which can be brought into the binocular sight paths, i.e., to cover holes 40, 42, as in the dashed line position of FIG. 4 or in a position to uncover such light paths as in the solid line position of FIG. 4. Radially-oriented slot 56 is formed alongside section 66. Adjustable stops 70, 72 are utilized to respectively limit the counterclockwise and clockwise directions of travel of the shutter filter 60 as viewed in FIG. 4. 
     Core 38 mounts in the aluminum-formed shutter housing 75 which provides a hollow interior and wire entryway 74 and is secured by set screw 76. An aluminum-formed male shutter flange 77 retains a thin, metal plate core cover 82 with holes 40&#39;, 42&#39; aligned with holes 40, 42. Flange 77 is secured by screws 78 to one side of housing 75 for receiving the previously-mentioned slit lamp or operating microscope fitting 37 utilizing thumb screw 73. An aluminum-formed female shutter flange 80 retains another core cover 82 and is secured by screw 81 to the opposite end of housing 75. The female shutter flange 80 is adapted to receive the binoculars 36 and secure such binoculars by means of a thumb screw 83 inserted in the threaded hole 84 (FIG. 1). Flanges 77 and 80 may, if desired, be formed integrally with respective core covers 82. 
     Drive motor 45 comprises a microsize, reversible DC motor energized through a pair of leads 79 which in turn are fed from the shutter mechanism 35 through a grommet 85 (FIG. 5) which also receives another pair of leads 86 connected to a microswitch 88. Contacts 90, 92 are opened and closed by means of a cam 94 which contacts switch actuator 96 (FIG. 5). Cam 94 on the end of the shutter mounting shaft 48 engages switch actuator 96 whenever the shutter filter 60 is in the shielding position as indicated in dashed lines in FIG. 4. Thus, switch 88 is normally employed as a means to signal and allow the laser source to produce a laser pulse and to deenergize drive motor 45 through appropriate control circuitry when the filter shutter 60 is in the filtering position. Also, through appropriate controls the laser is then pulsed at selected power without danger to the operator&#39;s eyes. 
     In the general system diagram illustrated in FIG. 26, operation of foot switch 90 is coordinated with the application of the briefly pulsed laser beam under selected operating power such that when the foot switch 90 is depressed, a pulse of power is applied to drive motor 45 to move the shutter filter 60 to the closed or filtering position and when the operator removes his foot from the foot switch 90, a pulse of power is applied to drive motor 45 so as to cause the filter crank 52 to rotate the shutter filter 60 to the nonfiltering position as indicated in the solid line position of filter 60 in FIG. 4. Appropriate controls apply such power pulses and in correct polarity relation for the desired direction of rotation. The foot switch 90 as indicated in FIG. 26 is linked electrically to the laser source and thus the selected pulse of laser power can be applied after the usual preliminary aiming and aligning procedure has been accomplished. The adjustable stops 70, 72 limit the travel of shutter filter 60. A cylindrical rubber bumper 57 secured to filter 60 extends into slot 56 of shutter filter 60 to absorb any shock induced by crank overtravel. Also to be noted is that crank 52 and slot 56 are oriented operationally such that when filter crank 52 drives the shutter filter 60 into either the nonfiltering position as in solid lines in FIG. 4 or in the filtering position as in dashed lines in FIG. 4, the filter crank 52 assumes a self-latching position. By this is meant that when the shutter filter 60 is in either the nonfiltering or filtering position, it cannot be rotated from such position except by energizing drive motor 45 by a short power pulse of suitable duration and polarity for the appropriate direction of rotation to drive filter crank 52 accordingly. 
     Of particular significance is the relation of the filter crank 52 to the shutter filter 60. In this regard, slot 56 (FIG. 4) is oriented with respect to filter crank 52 such that when motor 45 is initially energized by a power pulse to move shutter filter 60 to the blocking position, indicated in dashed lines in FIG. 4, filter crank 52 can actually rotate and move approximately 15° to 20° before any load is transferred to drive motor 45. Thus, when a load is initially placed on motor 45, the motor is operating at near maximum power output and is thus at or near-peak efficiency. This allows the shutter filter to be moved to blocking position very rapidly, e.g., in 40 to 50 milliseconds and with minimum power requirement. In one embodiment an extremely small Micromo Series 1516 motor was employed with satisfactory results. 
     Since shutter filter 60 is of a single-piece, thin, plastic plate construction and includes slot 56, filter crank 52 can be connected directly to shutter filter 60 without intermediate linkage. Further, the described tinted, Plexiglas thin-plate filter construction eliminates the need for plural ground glass blocking lenses as in prior art devices and provides an extremely lightweight and easily rotated filtering lens.