Photography – Eye tracking
Reexamination Certificate
1999-08-03
2001-01-23
Gray, David M. (Department: 2851)
Photography
Eye tracking
C396S232000, C396S432000
Reexamination Certificate
active
06178294
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a photographing unit for a microscope.
2. Related Background Art
FIG. 12
is a view for explaining optical paths of a microscopic unit which is provided with a conventional photographing unit for a microscope, while
FIG. 13
is a view taken along the line XIII—XIII in FIG.
12
.
A microscopic unit
100
is provided with an objective lens
101
, a projection lens
102
, a photographing unit
110
for a microscope, and a camera
130
.
The camera
130
is mounted on the photographing unit
110
for a microscope, in which a film
131
is loaded.
The photographing unit
110
is provided with prism
111
which divides light from a sample
103
which is guided by the objective lens
101
, into an optical path A of a photographing system, an optical path B of an observation system and an optical path C of a photometric system.
A shutter
112
is disposed between the camera
130
on the optical path A of the photographing system and the prism
111
. This shutter
112
controls an exposure time onto the film
131
of an image of the sample
103
which is formed on a primary image plane
101
a
of the objective lens
101
and enlarged by the projection lens
102
.
On the optical path B of the observation system there are provided a reduction lens
114
which incorporates an angle of view of the film
131
into the field of view of a viewfinder eyepiece
113
, and a reticle
115
which has double cross lines serving as an index for a photographing range frame or a focusing operation. The viewfinder eyepiece
113
is used to observe the reticle
115
and an image
115
a
formed on the reticle
115
.
On the optical path C of the photometric system there is provided a photometric detector
123
which measures the brightness of the image from the sample
103
.
An operation of the above-mentioned photographing unit for a microscope will be described below.
The prism
111
is located at a-1 position in
FIG. 13
at a time other than the time of exposure. A light reflected on an optical path dividing plane RF
1
is guided to the viewfinder optical path B, and the light passing through this optical path dividing plane RF
1
is reflected on an optical path dividing plane RF
2
and is guided to the optical path C of the photometric system.
A photographer adjusts the position of the eyepiece
113
in the direction of the optical axis with respect to the reticle
115
in accordance with a diopter, adjusts the focus on the double cross lines on the reticle
115
, and at the same time, moves a stage
104
on which the sample
103
is mounted in the direction of the optical axis so that the double cross lines of the reticle
115
and the image of the sample
103
can be seen clearly.
In the photographing unit
110
for a microscope, an amount of the light which is guided by RF
2
to the optical path C of the photometric system is measured by the photometric detector
123
, and an exposure time is calculated from this measured value, and a film sensitivity and an exposure correction value which are previously determined.
During exposure, the prism
111
is moved from the position on the solid line in
FIG. 13
to the a-2 position shown as the double-dotted line, as indicated by the arrow a, so as to be removed from the optical path B of the observation system and the optical path C of the photometric system. Thus, all of the light from the sample
103
is guided to the optical path A of the photographing system. Then, the shutter
112
is opened only for the exposure time which is determined by the arithmetic calculation, so that the image is projected to the film
131
.
Since the photographing for a microscope is usually conducted by enlarging a small portion so that, it is susceptible to vibration. As a result, an obtained photograph may be blurred in some cases due to an instantaneous vibration which is caused when the shutter
112
inside the photographing unit
110
is actuated. In order to avoid the influence of this vibration, the illumination light onto the sample
103
may be darkened, so that, out of the overall exposure time a time period after the mitigation of the vibration is prolonged as compared with a time period in which the operation is under the influence of the initial vibration.
However, when the exposure time is too long, the obtained photograph tends to be underexposed owing to the reciprocity law failure characteristic of the film
131
or to lack a color balance. In such cases, it is necessary to make exposure correction, dispose a filter for color correction in an illumination optical path of the microscope, or take some other counter steps. It is also necessary to retake photographs several times or take a lot of photographs under different conditions, in order to determine appropriate exposure correction or color correction.
Accordingly, in photographing for a microscope, when the exposure time is too short, the photographing is susceptible to vibration. On the other hand, if the exposure time is too long, an obtained photograph is underexposed or lacks a color balance. As a result, in order to obtain an excellent photograph, it is necessary to set such exposure time which can avoid the influence of the vibration of the shutter
112
or the reciprocity law failure characteristic of the film
131
.
However, in the conventional photographing unit
110
for a microscope, even when an appropriate value as can avoid the influence of the vibration of the shutter
112
or the reciprocity law failure characteristic of the film
131
is set for the exposure time, if a ratio of division of the prism
111
toward the optical path B of the observation system is set to be small, an image of a viewfinder VF is dark when the sample
103
is dark. On the otherhand, if the ratio of division of the prism
111
toward the optical path B of the observation system is set to be large, the image of the viewfinder VF is too bright so as to be dazzling when the sample
103
is bright.
When the film
131
to be used is of high sensitivity, the exposure time is appropriate with a dark photographed image so that an image of the viewfinder VF at that time becomes dark. When the film
131
to be used is of low sensitivity, since the exposure time does not become appropriate unless a photographed image is bright, the image of the viewfinder VF becomes too bright so as to be dazzling.
Microscope manufacturers have set a ratio of division of the prism
111
in such a manner that an image of the viewfinder VF has reasonable brightness when the exposure time is set to be proper based on a film sensitivity which is most frequently used in general.
However, since a ratio of sensitivity of a low sensitivity film to a high sensitivity film comes to one to several hundreds, if the microscope makers use a film
131
having a sensitivity widely different from the film sensitivity used for determining the ratio of division of the prism
111
, the image of the viewfinder VF may be too bright or too dark even when a proper value is set for the exposure time. Thus, the image becomes difficult to observe for the photographer.
For this reason, it is required for the photographer to first adjust an illumination light of the microscope, confirm a photographing range, and conduct focusing for the purpose of obtaining a proper light amount for the viewfinder VF, then to adjust an amount of the illumination light of the microscope for the second time for the purpose of obtaining a proper value for the exposure time. These procedures are troublesome for the photographer.
When light from the sample
103
is weak and it is bright outside the microscope, an amount of a light intruding from the optical path B of the observation system is relatively larger than an amount of the light from the sample
103
, so that the photometric detector
123
can no longer conduct a correct photometric operation of the sample
103
. As a result, when a photograph is taken with an exposure time which is calculated based on this photometric value, the obtained photograp
Iko Chikaya
Matsuno Jun
Otaki Tatsuro
Sakano Hitoshi
Gray David M.
Nikon Corporation
Vorys Sater Seymour and Pease LLP
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