Television – Special applications – Microscope
Reexamination Certificate
1998-08-27
2001-09-18
Le, Vu (Department: 2713)
Television
Special applications
Microscope
C396S432000
Reexamination Certificate
active
06292214
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a microscopic digital photography system. In particular, the present invention relates to a microscopic digital photography system comprising a microscope and an image pickup device for photographing an image of a sample observed by using the microscope and making conversion into an electric signal.
2. Description of Related Art:
A microscopic digital photography system has been hitherto known for photographing and recording an image of a sample observed by using a microscope. In this system, a reflecting member is arranged on an optical axis (optical axis of an objective lens and an imaging lens) of the microscope. The reflecting member is used to divide the optical path into those concerning an observing optical system and an image pickup optical system. A magnified image of the sample, which is formed on an image plane on the side of the observing optical system, is observed through an eyepiece lens. The light flux of the sample image, which is focused on the image plane on the side of the image pickup optical system, is photographed by an image pickup device arranged on the image plane. An obtained image is converted into an electric signal.
The method for dividing the optical path into those concerning the observing optical system and the image pickup optical system includes several systems.
FIGS. 4 and 5
show representative systems with optical paths.
FIG. 4
shows a system in which a half prism
102
is arranged on an optical axis
104
of a microscope between an objective lens
106
and an imaging lens
108
B. In this system, the optical path, through which the light flux (light flux of an image of a sample
110
) coming from the objective lens
106
is transmitted by the aid of the half prism
102
, is utilized as an observing optical path. In this observing optical path, the light flux is focused in the vicinity of a front focal plane of the eyepiece lens
114
through the imaging lens
108
B and a view prism
118
to observe an image
112
. On the other hand, a second imaging lens
108
D is arranged on an optical path for the light flux which comes from the objective lens
106
and which is reflected by the half prism
102
. An image pickup device
116
is arranged on an image formation plane of the second imaging lens
108
D. Thus, the image pickup optical path is constructed. This system is used for an intermediate body tube type beam splitter in which a beam splitter is arranged in an intermediate body tube in a microscope of the type capable of installing an intermediate body tube unit between a main microscope body and an observing body tube. The system is constructed by arranging a digital still camera containing an image pickup device, at an output section of an optical path divided by the beam splitter to obtain a magnified image of a sample. Another intermediate body tube is also known, in which an image pickup device is contained in a housing.
FIG. 5
shows a system in which a view prism
120
is arranged over an imaging lens
122
on an optical axis of a microscope. In this system, a magnified image
124
of a sample is observed, which is formed in the vicinity of a front focal plane
124
of an eyepiece lens
126
disposed on a side of an optical path for a light flux (light flux of the image of the sample
110
) which comes from an objective lens
106
and which is reflected by the view prism
120
. An image pickup device
116
is arranged on an image plane on a light path for a light flux transmitted through the view prism
120
. A magnified image, which is formed on the image plane, is photographed. This system is adopted in many microscopes having a trifurcate body tube provided with a binocular unit for observation and a straight barrel for photographing operation. Such a system is constructed by attaching, to the straight barrel, a digital still camera containing an image pickup device. Another body tube is also used, in which an image pickup device is contained in a housing. In the system constructed as described above, a photographer operates a focusing handle of the microscope while looking into the binocular unit of the body tube so that the focal point is adjusted to the sample.
Besides, a system is also known, in which a digital still camera of the single-lens reflex camera type is used. In this case, the focusing operation is performed for the microscope by making observation through an optical finder of the digital still camera. In other cases, the digital still camera is connected to a computer. A real time image, which is captured by an image pickup device, is displayed on a monitor of the computer. The focusing operation is performed for the microscope while observing of the image.
However, the microscopic digital photography system, which adopts the system shown in
FIGS. 4 and 5
described above, has an inconvenience in that it is impossible to confirm the range of the image projected onto the picture element of the image pickup device during the photographing operation.
When the photographer performs the focusing operation for the microscope while looking into the binocular unit of the body tube so that the focal point is adjusted on a sample, the resolving power for the image, which is obtained by looking into the binocular unit by the photographer, is generally different from the resolving power possessed by the image photographed by the image pickup device of the digital still camera. The resolving power, which is obtained by viewing a photographing range with human eyes, is converted into the number of picture elements of the image pickup device as follows:
((photographing length in longitudinal direction/resolving power of naked eye)×2)×((photographing length in transverse direction/resolving power of naked eye)×2).
It is now assumed, for example, that the field number of a 10×eyepiece lens is 20 mm, and the photographing range is 12 mm×16 mm (diagonal: 20 mm) inscribing the size of the observing field. The resolving power of the human eye is generally 0.14 mm at the distance of distinct vision (250 mm). Therefore, the resolving power is 0.014 mm on the image plane when a sample is viewed through the 10×eyepiece lens. In order to obtain a resolving power approximately equivalent to the resolving power of the human eye, the following number of picture elements is required:
((12/0.014)×2)×((16/0.014)×2)=3918367.
That is, it is necessary to use a number of picture elements of about four millions.
However, the digital still camera, which is provided with an image pickup device having a number of picture elements of four millions, is used for commercial digital photographs, but it is not generally used. Therefore, such an instrument tends to be extremely expensive. In general, a digital still cameral having a number of picture elements of about three hundred thousand is utilized. Therefore, when the entire observing field is photographed by using the general digital still cameral having the number of picture elements of about three hundred thousand, the resolving power of the photographed image is extremely coarse as compared with the image captured by the naked eye observation. As a result, it is impossible to obtain an image expected by the photographer.
Therefore, even when the digital still camera having a small number of picture elements is used, the photographing operation is preferably performed by magnifying and projecting a narrow range of a sample onto the image pickup device plane, not by projecting the entire observing field onto the plane, so as to make it possible to improve the resolving power converted into one concerning the sample dimension corresponding to one picture element, i.e., the dimension of the sample. However, if a sample is magnified and photographed, the photographing range for the sample becomes narrow. Therefore, the photographer is forced to perform the operation such that a test shot is taken in order to obtain a desired image, and the photographing m
Le Vu
Nikon Corporation
Oliff & Berridg,e PLC
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