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Description  |
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BACKGROUND OF THE INVENTION
The present invention relates to an optical apparatus used for a laser
device for operation.
A laser knife for medical use condenses rays of laser of high output, for
example, such as rays of CO.sub.2 laser, and, by utilization of high
temperatures then produced, vaporizes or solidifies a composition composed
of protein or the like to effect operation. Since such laser knife for
medical use possesses several advantages noted below, it is now
increasingly used in field of surgical treatment.
(1) It offers styptic effects.
(2) Micro-surgery can be effected.
(3) Influence on those other than the affected part is minimal.
(4) Non-contact surgery can be effected.
In view of further advantages such that the diameter of the condensed beam
of laser is very small and that the rays of laser may be introduced by the
optical system into a deep part in a state of non-contact, micro-surgery
laser operating apparatus, which is safety and easy in handling, has been
demanded in the fields of cranial nerve surgery, otorhynoloaryngologist,
and obstetrician, who must operate the deep part of the body.
To fulfill such demands, a few processes have been proposed lately. A first
process is that rays of laser condensed by an infrared ray transmission
lens are introduced to the affected part by a plane reflector fixed
frontwardly of an objective lens of the microscope, and the sight of the
laser beam is adjusted by moving the entire microscope up and down, right
and left, and back and forth.
A second process is that rays of laser condensed by an infrared ray
transmission lens are introduced to the affected part by a light
introducing 45.degree. reflector, which is designed so that it can be
moved slightly in front of an objective lens of the microscope, and the
sight of the laser beam is adjusted by varying an angle of the 45.degree.
reflector. This process is described in detail in Japanese Patent
Laid-Open No. 8085/1974, entitled "Stereoscopic Laser Endoscope".
However, according to the above-described two processes, the rays of laser
are commonly condensed by the lens and therefore, they are unavoidably
sufferred from out-of-focus of the condensed spot resulting from a slight
transmission loss of the rays of laser and spherical aberration. Also, in
the first process, in which the entire microscope is moved, there poses
problems such that it is difficult to effect fine or slight movement if
manual operation is employed, and that a large apparatus must be used if
power operation is employed. Even in the second process, in spite of the
fact that a mechanism, by which the angle of the introducing 45.degree.
reflector positioned in front of the objective lens is varied without
impairing the range of field through an eyepiece, becomes complicated, it
was impossible to allow the 45.degree. reflector to effect its elevation
movement and horizontal rotation in a completely independent manner when
the reflector is shaked thereabout. This means that the sight of a laser
spot cannot smoothly be adjusted to the target position by operating a
single stick (a maneuvering lever). For example, it poses a problem such
that even when the stick is moved laterally, the laser spot will move not
only laterally but vertically.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a laser
optical apparatus for operation under a microscope which can minimize loss
of rays of laser, produce no put-of-focus of the condensed spot, and
afford a good maneuverability.
This and other objects have been attained by the laser optical apparatus
for operation under a microscope according to the present invention, which
comprises a laser beam introducing 45.degree. reflector arranged between
two optical axes so as not to impair the range of vision frontwardly of a
binocular telescope for operation, a parabolic mirror with a surface
displaced from an axis for condensing introduced beams of laser and
serving as an objective lens of the microscope, a plane reflector driven
by motors to direct the condensed beams of laser and an optical axis of
the microscope, and a maneuvering mechanism including a stick for
operating said motors.
In accordance with the laser optical apparatus for operation under a
microscope of the present invention, the introduced laser beams are
condensed by the parabolic mirror with a surface displaced from an axis,
and for this reason, the loss of rays of laser can be minimized and the
out-of-focus of the condensed laser beam and the optical axis of the
microscope may be directed towards the target by means of the plane
reflector driven by the motors through the operation of the operating
stick, and hence, the laser optical apparatus for operation under a
microscope, which is excellent in maneuverability, may be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing one embodiment of a laser optical
apparatus for operation under a microscope in accordance with the present
invention;
FIG. 2 is a side view in section of the apparatus shown in FIG. 1;
FIG. 3 is a plan view in section of the apparatus shown in FIG. 1; and
FIG. 4 is a circuit representation showing one embodiment of a
servo-control for moving a plane reflector used in the apparatus shown in
FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention will now be described in detail with
reference to the accompanying drawings.
FIG. 1 is a perspective view showing one embodiment of a laser optical
apparatus for operation under a microscope in accordance with the present
invention; FIG. 2 is a side view in section thereof, and FIG. 3 is a plan
view in section of the same. Rays of laser 10 generated by a laser
generator (not shown) enter a housing 14 through a laser ray introducing
portion 12 and are reflected by a 45.degree. reflector 16 and then
condensed by a parabolic mirror 18 with a surface displaced from an axis,
and the rays are then reflected by a plane mirror 20 towards the outside
and incident on the affected part P'. Visible rays of light 22 from the
affected part P' are reflected by the plane mirror 20 and formed into
parallel rays of light by the parabolic mirror 18, and the rays of light
pass by the opposite sides of the 45.degree. reflector 16 into a
magnification varying optical system 24. In a prism system 26, an inverted
image is formed into an erect image and the affected part is observed by
an eyepiece 28. The magnification varying optical system 24 serves to vary
the magnification of the microscope while maintaining a working distance
in constant.
The parabolic mirror 18 with a surface displaced from an axis is a mirror
of which reflection surface is a partial surface displaced from main axis
(axis-Y) of parabolic surface formed when a parabola taking an original
point O with a focal point at P in the X-Y plane in FIG. 2 is rotated
about the axis-Y.
Such a parabolic mirror has already been used for an astronomical telescope
or the like, which is easily available. The parabolic mirror 18 reflectes
rays of light incident in parallel to the main axis and condenses them at
the focal point with no-aberration. Since the rule of reflection is
established irrespective of wavelength of light, no aberration is produced
with respect both to rays of CO.sub.2 laser having the wavelength of 10.6
.mu. and to visible rays of light for observation.
A condenser lens used in an optical system, which requires exact
registration of the focal position of the observation optical system with
the focal position of rays of CO.sub.2 laser as in the present apparatus,
need to have an accurate focal distance as specified in design. However,
since conventional focal distance measuring apparatus by means of visual
light cannot be used for infrared ray of 10.6 .mu., it is impossible to
verify and correct the focal distance in the stage of polishing step. It
was therefore, necessary to produce several different lenses to select one
closest to the specification for user or to incorporate a complicated lens
fine movement focus control mechanism into the apparatus. It is noted that
parabolic mirror with a surface displaced from an axis in preferably
utilized to provide a laser optical apparatus for operation under a
microscope, which is safety and simple in construction.
Rays of CO.sub.2 laser introduced from the outside advance parallel to the
main axis with the aid of the 45.degree. reflector, which is positioned in
the midst of a binocular optical system and secured to a position not to
shut off rays of visible light for observation as described previously,
are reflected and condensed by the parabolic mirror 18 and reflected by
the plane reflector 20, and then condensed at pont P' which is in surface
symmetry with the original focal point P. As a consequence, even if the
plane reflector 20 is shaked, only the point P' will move whereas the
focal point P will not change its position. Therefore, the rays of light
from the moving point P' is always incident on the parabolic mirror 18 as
if it comes out of the fixed point P. When the parabolic mirror 18 is
moved to move the condensed point P' of beams of CO.sub.2 laser, the
condition where the beams of CO.sub.2 laser are allowed to make incidence
thereof parallel to the main axis fails to be satisfied to produce an
aberration in the focal point of the laser beam and the observed image. In
the laser optical apparatus for operation under a microscope according to
the present invention, it is designed so that the parabolic mirror 18 with
a surface displaced from an axis is fixed but the plan reflector 20 is
movable, whereby the disadvantages noted above may be eliminated.
In accordance with one embodiment of the present invention, the plane
reflector 20 is mounted on a rotational shaft of a servo-motor 32 mounted
on a vertical member of an L-shaped supporting bed 44, which has a
horizontal member mounted on a rotational shaft of a servo-motor 30. A
stick 34, which controls signals to the servo-motors, may be maneuvered to
rotate the plane reflector 20 about the vertical axis by means of the
servo-motor 30 and about the horizontal axis by means of the servo-motor
32.
FIG. 4 is a circuit representation showing one embodiment of a
servo-control used in the laser optical apparatus for operation under a
microscope to effect positional control of the plane reflector. In a stick
mechanism 60, guide plates 62 and 64, which are made from metal plates
each formed with an elongated rectangular hole or opening therethrough,
the metal plates being bended into a semi-circular configuration, are
crossed at right angles to each other, one end thereof being rotatably
mounted on a case 66 whereas the other end being mounted on shafts of
potentiometers 50 and 52, respectively, A stick 34 is inserted into a hole
at a point of intersection between the guide plates 62 and 64, and the
lower end thereof is fixed in universal-joint fashion so that the upper
end thereof can be moved freely by hands.
In bridge circuits 36 and 38, when the stick 34 is in the middle position,
resistance values of resistors R1 to R8 are adjusted so that voltages
between a and b and between e and f, respectively, are zero (0). That is,
equations R1.times. R2=R3.times.R4 and R5.times.R6 = R7 .times. R8 are
established. When the stick 34 is displaced from the central position
towards the direction A, the resistor R3 in the potentioneter 52 decreases
to unbalance the bridge 38 and to produce a negative potential at point E.
This negative potential is supplied to an amplifier 40 where it is
amplified and then supplied to the servo-motor 30. When a negative voltage
is applied to the servo-motor 30, the servo-motor 30 rotates rightwardly
rotation of which is reduced in r.p.m. by a gear mechanism enclosed to
slightly rotate the L-shaped supporting bed 44. As a consequence, the
plane reflector 20 is slightly rotated in conjunction with the servo-motor
mounted on the L-shaped supporting bed 44. A potentiometer 46 associated
with the rotational shaft of the servo-motor 30 gradually increases in
resistance R4 as the motor runs, and when the equation R1 .times. R2 = R3
.times. R4 is again to be established, the voltage between e and f assumes
0 to stop the servo-motor 30.
Conversely, when the stick 34 is displaced in the direction of A', the
resistance R3 increases to produce a positive voltage at pont e and as a
result, the servo-motor 30 runs leftwardly. Then, the resistance R4 of the
potentiometer 46 decreases to balance the bridge circuit 38 and at this
time, the servo-motor 30 stops.
When the stick 34 is displaced from the central position to the direction B
or B', the resistance R7 of the potentiometer 50 varies in value and the
servo-motor 30 causes the plane reflector 20 to be slightly rotated about
the axis z rightwardly or leftwardly. When the stick 34 is displaced in a
direction other than the direction A-- A' and B--B', two potentiometers 50
and 52 simultaneously run and the plane reflector 20 receives a combined
motion of two slight rotations about the axes x and z. In this manner,
since the shaking motion of a single stick 34 and the shaking motion of
the plane reflector 20 are in the ratio of 1 : 1, the operator may easily
maneuver the apparatus. In other words, by employment of such an electric
process as described above, it is not only capable of remote-controlling
the apparatus but also of establishing a linear correspondence as
previously mentioned between the shaking angle of the stick and the
shaking angle of the plane reflector. It will further be noted in the
control by means of the electric process that the sensitivity of the
amplifier may be changed over by means of a switch whereby even when the
stick is greatly displaced, the plane reflector is moved only in a small
amount for the performance of precise operation. As is apparent from the
foregoing, since two motors may be driven by a single stick (a maneuvering
lever), operation is not only simple but remote control operation is
possible to be made by extending a cord. For this reason, in the case
where the operator holds operating instruments or the like in his hands,
his assistant, while staying is a position away from the operator
monitoring a television, can adjust the sight of a laser spot to the
target position as instructed by the operator in a condition where
disinfection is not required. Moreover, the present invention employs a
method for moving the plane reflector in order to simultaneously reflect
rays of light for observation and rays of laser, and accordingly, the
range of vision and the laser spot will move at the same time and no
displacement therebetween occurs. It should be noted that a glass plate,
in which a circle of the same size as that of the laser spot is depicted
about a point of crossed lines, may be inserted into the eyepiece system
to thereby clearly indicate the position and the size of the laser spot,
which eliminates the provision of guide light heretofore required.
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