Surgical microscope

A surgical microscope arranging, so as to be insertable into and removable from an illuminating optical path for observation, a semi-transparent mirror capable of introducing illuminating light for photographing in a coaxial relation into illuminating light for observation or a totally reflecting mirror having such size as not to entirely interrupt the illuminating light for observation, in order to make it possible that compact size and low cost are attained, the amounts of illuminating light for observation and photographing are sufficiently secured, both the illuminating light are conducted along a common optical axis, and the illuminating light for observation is not interrupted even for a moment in photographing.

BACKGROUND OF THE INVENTION 
1. Field of the invention 
The present invention relates to a surgical microscope and more 
particularly to a light source apparatus for surgical microscopes. 
2. Description of the prior art 
Recently, what is called microsurgery in which a delicate surgical 
operation is performed while a part to be operated upon is magnified and 
observed under a microscope, has been largely adopted. According to the 
microsurgery, from the fact that a delicate surgical operation is 
performed with accuracy, many favorable results have been achieved not 
only in ophthalmology, cerebral nerve surgery and otorhinology but also in 
various fields. Also in such microsurgery, it is necessary to photograph a 
part to be operated and an operating technique for education and study, as 
in other operations, and magnification photographing relying on a surgical 
microscope often brings about inevitably the lack of a sufficient amount 
of light. As a result, an Xe flash lamp (stroboscopic lamp) is used as an 
auxiliary light source for photographing and, in the past, various 
stroboscopic devices for surgical microscopes have been designed. Of these 
devices, the commonest one has a system that the Xe flash lamp is attached 
adjacent to a tube of the surgical microscope as illustrated in FIG. 1. 
That is to say, in FIG. 1, reference numeral 1 represents an objective 
tube section of the surgical microscope, in which an illuminating optical 
system for observation, an observing optical system and driving devices 
for these systems, not shown, are incorporated. Then, a light beam, 
incident on the objective tube 1, coming from a part to be operated is 
divided by a beam splitter, not shown, incorporated likewise in the 
objective tube 1 and an operation is performed in a such state that the 
one of the light beam travels to a photographing device 4 for 
photographing, while the other travels to an eyepiece 2 to be observed 
with an operator's eye 3. Reference numeral 7 indicated in broken lines 
represents, in an illustrating manner, an eye to be operated. For such an 
operation of the eye in ophthalmology, an illuminating device 5 including 
an optical axis B intersecting obliquely with an optical axis A of an 
objective lens 9 is mounted to the objective tube 1. The illuminating 
device 5 for illuminating the part to be operated has an Xe flash tube 5a 
as a light source for illumination and a lens 5b for condensing light 
emitted from the Xe flash tube 5a at the part to be operated. 
In such an illuminating device 5 arranged obliquely in respect of the 
optical axis A, there has been a defect that, when an affected part to be 
operated which is narrow and deep in aperture, like an affected part 8a to 
be operated in otorhinology and cerebral nerve surgery shown in solid 
lines, is illuminated, illuminating light cannot completely reach the 
affected part 8a due to its oblique illumination and an illuminating 
effect is not brought about. To solve this problem, in the past, a method 
has been adopted that a direct suspension type illuminating device 6 is 
attached to the objective tube 1 in close vicinity to the objective lens 9 
and the affected part 8a is illuminated, through the aperture of a cranium 
8, by an Xe tube 6a placed in the direct suspension type illuminating 
device 6 and an objective lens 6b for illumination to condense light from 
the Xe tube 6a at the affected part. Also in the use of the direct 
suspension type illuminating device 6, however, it is necessary to extend 
its illuminating section in the vicinity of the optical axis A of the 
objective lens 9 and, as a result, a visual field for observing directly 
the part to be operated with the operator's naked eye has been obstructed. 
Further, it is limited to set the illuminating section near the optical 
axis A and, in fact, even the direct suspension type illuminating device 6 
emits somewhat obliquely the illuminating light, with the result that the 
affected part 8a with a deep region is inevitably subjected to uneven 
illumination. Because the oblique illuminating device or the direct 
suspension type illuminating device is attached, in either case, to the 
outside of the objective tube 1 as mentioned above, a space necessary for 
an operator in the surgical operation would be blocked. Originally, a 
microscope for an assistant and other apparatus for operation are provided 
in the objective tube 1 of the surgical microscope, so that the operating 
space is made narrow, further by mounting the illuminating device for 
photographing, and the operator's operation would be disturbed. 
In order to solve the above-mentioned problem, such a device as shown in 
FIG. 2 is thus disclosed in Japanese Utility Model Preliminary Publication 
No. Sho 60-31691, for example. That is to say, a microscopic tube 12 is 
coupled to a microscopic base arm (not shown) by a support arm 11. In the 
tube 12, a replaceable objective lens 22 is provided to change a focal 
distance depending on an operating manner or the depth of the affected 
part to be operated. Further, in the tube 12 is incorporated a light guide 
18 comprising an optical fiber for supplying illuminating light for 
observation which continues to illuminate the affected part to be operated 
during the surgical operation and the illuminating light emitted from the 
light guide 18 is condensed by the objective lens 22 to illuminate the 
affected part. Reflecting light coming from the affected part to be 
operated traverses again the objective lens 22 and after passing through a 
magnification optical system 19 of a Galileo type binocular microscope 
optical system, is incident on a beam splitter 14. The light incident on 
the beam splitter 14 is reflected by a half transmitting surface 14b, is 
further reflected by a reflecting surface 14a and then is formed as an 
image on a film 13b through an image forming lens 13a of a photographing 
device 13 for photographing. On the other hand, light transmitting the 
half transmitting surface 14b of the beam splitter 14 is reflected from a 
reflecting surface 14c, is further reflected from a reflecting surface 15a 
of a reflecting optical member 15 of an eyepiece section and is last 
reflected by a reflecting surface 16a of another reflecting optical member 
16 so as to enable the operator to observe the affected part to be 
operated through an eyepiece system 17. Also, the tube 12 incorporates an 
illuminating device 21 for photographing in a space between a driving 
device 20 of the magnification optical system 19 the objective lens 22. 
The illuminating device 21 for photographing comprises a socket 21a and a 
lamp house 21c which has an Xe lamp 21d and which is coupled to the socket 
21a by a plug 21b and electric power for trigger and electric power for 
illumination are supplied from the socket 21a through the plug 21b. A 
shading plate 23 is interposed between the illuminating device 21 for 
photographing and the magnification optical system 19 so that light is not 
incident on the magnification optical system 19 from the Xe lamp 21d. 
Also, in a retinal camera, it is a known system that the Xe lamp is 
arranged at a position optically conjugate with a light source for 
observation in an illuminating optical system for observation so that an 
illuminating optical axis for observation may coincide with an 
illuminating optical axis for photographing. In other words, as shown in 
FIG. 3, the system is such that a filament image of a light source lamp 34 
for observation is formed at the center of an Xe lamp 33 through an 
illuminating optical system 36a and a field of operation is illuminated by 
an illuminating optical system 36b and an objective lens 32. Also, 
reference numeral 31 denotes a microscopic tube and 35 a magnification 
optical system. 
In the device described in Japanese Utility Model Preliminary Publication 
No. Sho 60-31691, however, what is used as a measure for condensing a 
light beam from the Xe lamp 21d is only the objective lens 22. In 
addition, since the light beam emitted from the Xe lamp 21d is diverged 
and the focal distance of the objective lens 22 is 150-300 mm, whereas the 
Xe lamp 21d is placed at a distance of several tens of millimeters from 
the objective lens 22, its illuminating field is much widely enlarged as 
compared with a photographing region and consequently the amount of light 
reaching the photographing region is nothing but several percents of the 
total amount of light obtained from the Xe lamp 21d. Further, the 
illuminating field is more largely covered with the reduction of 
illumination as the focal distance of the objective lens 22 becomes longer 
and, at the same time, the numerical aperture of the observing optical 
system is reduced as the focal distance of the objective lens 22 becomes 
larger, so that the amount of light reaching a film surface becomes 
extremely small when the focal distance of the objective lens 22 is long. 
Since it is therefore required that the Xe lamp 21d has light-emitting 
energy of several hundreds of joules to secure the amount of light 
sufficient for photographing, there has been a problem that both the Xe 
lamp 21d and the light source section are inevitably used in large size 
and, as a result, the body of the microscope housing the Xe lamp 21d is 
also increased in size. Also, if the luminous intensity of the Xe lamp 21d 
is automatically controlled for the simplification of photographing, 
electric power to be supplied into the Xe lamp 21d becomes very high. In 
addition, with the surgical microscope, the distance between the objective 
lens and the affected part to be operated is widely different depending on 
a region to be operated and magnification for observation needs to be 
largely changed in accordance with the purpose of operation, so that the 
control of the luminous intensity with very high degree of accuracy is 
required, and there has been a problem that such a control circuit is 
substantially difficult to be realized. Furthermore, there is an 
indication of a problem that, since the optical axis of the Xe lamp is 
different from that of the illuminating light for observation, when the 
operation of a deep region is performed through a narrow aperture, the 
illuminating light for observation reaches the affected part to be 
operated, while on the other hand, the light of the lamp cannot pass 
through the aperture and therefore it may be impossible to take a 
photograph. 
Also, in the device shown in FIG. 3, the optical axes of the illuminating 
light for observation and the light of the Xe lamp are arranged to be 
completely coaxial and the light from the Xe lamp 33 is condensed through 
the illuminating optical system 36b, with the result that the efficiency 
of the light intensity of the Xe lamp is markedly improved as compared 
with the device described in Japanese Utility Model Preliminary 
Publication No. Sho 60-31691. However, a problem has been encountered 
that, when the light beam of the light source lamp 34 passes through the 
Xe lamp 33, the amount of light is lost due to the surface reflection of 
the lamp 33 and a common amount of light for observation will be lacking. 
Thus, as shown in FIG. 4, it has been devised that a free directional light 
deflecting device is arranged in the illuminating optical system for 
observation so that an optical system provided in the rear of the light 
deflecting device of the illuminating optical system for observation is 
used in common with the illuminating optical system for photographing and 
that the arrangement is made so that only one of both the illuminating 
optical systems is selected by the switching of the light deflecting 
device, the light from a light source for photographing is once converged, 
the optical axis of the illuminating light for observation completely 
coincides with that of the illuminating light for photographing and the 
light from the illuminating light source for observation is not blocked by 
that from the illuminating light source for photographing. That is, in 
FIG. 4, reference numeral 43 represents an Xe flash lamp, 44 a relay lens 
system, 45 a light source lamp, 46 a relay lens system, and 47 a 
leaping-up mirror provided to select either illuminating system relying on 
the light source lamp 45 or the Xe flash lamp 43. When the arrangement is 
made as mentioned above, the illuminating device for photographing 
securing a large amount of light can be constructed by means of the Xe 
flash lamp with low electric power which is substantially the same as a 
stroboscopic lamp for ordinary cameras, without the loss of the amount of 
light of the illuminating device for observation, and as such a 
small-sized and power-saving surgical microscope is available. Moreover, 
the illuminating light for observation is completely in a coaxial relation 
with respect to the illuminating light for photographing, so that it is 
possible to be photographed even in the surgical operation performed 
through a narrow aperture. Also, the electric power may be low even when 
the light intensity of the illuminating device for photographing is 
automatically controlled, and therefore the surgical microscope, which can 
employ a small-sized light intensity controlling device, can be 
materialized with ease and at a low cost. When the optical system is 
arranged as stated above, however, there has been a serious danger that 
since the leaping-up mirror 47 interlocks with the shutter of a camera to 
leap to a position 47' indicated in broken lines followed by the emission 
of light from the Xe flash lamp 43, the illuminating light is interrupted 
for a few seconds and, as a result, not only uneasiness is caused in the 
surgical operator's mind, but also operating time may be prolonged. 
SUMMARY OF THE INVENTION 
In view of the above problems, it is the object of the present invention to 
provide a surgical microscope with small size and a competitive price in 
which the amounts of the illuminating light for observation and 
photographing are sufficiently attained, both the illuminating light are 
introduced along a common optical axis, and the illuminating light for 
observation is not interrupted even for a moment during the photographing. 
This object is accomplished, according to the present invention, by the 
arrangement that a light merging device which is insertable into and 
removable from an illuminating optical system for observation and which 
has a proper light distribution ratio is provided so that an optical 
system provided in the rear of the light merging device of the 
illuminating optical system for observation is used in common with an 
illuminating optical system for photographing and that the illuminating 
optical systems for observation and for photographing are used at the same 
time and either one is selected by the switching of the light merging 
device so that illuminating light for observation is completely in a 
coaxial relation with respect to illuminating light for photographing. 
According to a preferred formation of the present invention, the light 
merging device comprises a rotatable semi-transmissive mirror which 
transmits the illuminating light for observation and reflects the 
illuminating light for photographing. The semi-transmissive mirror can be 
constructed as a leaping-up mirror driven by a rotary solenoid or a rotary 
mirror driven by a motor. This enables the objective tube to be reduced in 
size and photographing to be rapidly carried out. 
According to another preferred formation of the present invention, an 
aperture stop is provided between a relay lens system and a magnification 
lens system in the illuminating optical system for observation, a totally 
reflecting mirror, capable of introducing the illuminating light for 
photographing into an illuminating optical path for observation, having an 
area smaller than the aperture at a position close to the aperture stop is 
provided, and this totally reflecting mirror is used as the light merging 
device. Thereby, a smaller-size objective tube and more rapid 
photographing are available.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In accordance with the embodiments shown in the drawings, the present 
invention will be described in detail below. 
FIGS. 5 and 6 are basic structural views of the optical system of a first 
embodiment and FIG. 6 shows a side elevation viewed from the right side of 
FIG. 5 from which a photographing device is excluded. An affected part 60 
to be operated is observed through an observing optical system comprising 
an objective lens 61, a magnification optical system for observation 62, a 
beam splitter 63, an observing prism 64 and an eyepiece 65. In such a 
case, the beam splitter 63 separates a photographing optical path from an 
observing optical path, as shown in FIG. 5, and conducts light to a film 
13b through an image forming lens 13a of a photographing device 13. Also, 
as depicted in FIG. 6, an illuminating optical system for observation 
illuminating the affected part 60 to be operated comprises a light source 
lamp 66, a first relay lens 67, an illuminating magnification optical 
system 69, an illuminating prism 70 and the objective lens 61, and light 
emitted from the light source 66 illuminates the affected part 60 to be 
operated through the illuminating optical system for observation. On the 
other hand, an illuminating optical system for photographing includes an 
Xe flash lamp 71, a second relay lens 72, a semi-transmissive mirror 68 
provided to be insertable into and removable from the illuminating optical 
system for observation, the illuminating magnification optical system 69, 
the illuminating prism 70 and the objective lens 61 and, in photographing, 
the semi-transmissive mirror 68 is leapt up to a position 68' indicated in 
a broken line by, for example, a rotary solenoid 68a, so that the light 
emitted by the Xe flash lamp 71 illuminates the affected part 60 through 
the illuminating optical system for photographing. In such an instance, 
the light source 66 and the Xe flash lamp 71 are disposed at optically 
conjugate positions. Further, the relation between the positions of the 
light source 66 and the Xe flash lamp 71 to the semi-transmissive mirror 
68, shown in the drawing, is such that the illuminating light for 
observation is not lost in ordinary observation. Also, it is needless to 
say that the ratio of the reflection to the transmission of the 
semi-transmissive mirror 68 is selected to be fit to a light-emitting 
capacity of the Xe flash lamp 71. 
As mentioned above, this embodiment has advantages that, because the 
illumination of the affected part 60 to be operated is selected from 
either the illumination for observation or the illumination for 
photographing by a leaping-up motion of the semi-transmissive mirror 68, a 
sufficient amount of illuminating light for observation can be secured, 
without any obstruction to the light in observation, the illuminating 
light for photographing which has been condensed forms a coaxial relation 
with the illuminating light for observation in photographing to be able to 
illuminate efficiently the affected part and that, because the 
illuminating light for observation traverses the semi-transmissive mirror 
68 even in photographing, the illumination onto the affected part 60 is 
not blocked even for a moment. In addition, when the surgical microscope 
is used, a front-to-back dimension of the microscope offers little 
obstruction to the surgical operation and the thickness of the objective 
tube may rather cause troubles, so that the embodiment has also an 
advantage that the objective tube, in which the Xe flash lamp is not 
included, can be designed for small size. 
FIG. 7 is a schematic view of the optical system of a second embodiment. 
Since the second embodiment is the improvement of the first embodiment, 
the drawings and explanation relative to the same structure as in the 
optical system of the first embodiment are omitted. The illuminating 
optical system for photographing comprises the Xe flash lamp 71, the 
second relay lens 72, a semi-transmissive mirror 73, the illuminating 
magnification optical system 69, the illuminating prism 70 and the 
objective lens 61 and, in photographing, the semi-transmissive mirror 73 
is rotated to a position 73' indicated in a broken line about a rotary 
shaft 74 by, for example, a motor 75, with the result that the light 
emitted from the Xe flash lamp 71 illuminates the affected part 60 to be 
operated through the illuminating optical system for photographing. When 
the semi-transmissive mirror 73 is rotated about the rotary shaft 74 held 
at a constant angle with respect to the optical axis of the second relay 
lens 72, as in the second embodiment, to be inserted into the illuminating 
optical path for observation, the arrangement makes it possible to 
instantaneously stop the mirror 73 and to emit the light from the Xe flash 
lamp 71 immediately after the stop of the mirror, which will be very 
effective. 
FIG. 8 is a schematic view of the optical system of a third embodiment, in 
which an aperture stop 76 is provided between the first relay lens system 
67 and the illuminating magnification optical system 69 to arrange a 
totally reflecting mirror 77 having an area smaller than the aperture of 
the aperture stop 76 at a position close thereto and the same effect as in 
the first and second embodiments is brought about in such a manner that 
the illuminating light for photographing is introduced into the 
illuminating optical path for observation by means of such a structure as 
in the above embodiments. In this embodiment, there is an advantage that, 
from the fact that the totally reflecting mirror 77 can be constructed 
smaller, its inertia force caused by the shift is smaller as compared with 
the semi-transmissive mirrors 68, 73 of the above embodiments and 
therefore its driving and positioning works are easily carried out.