JPH0482531A - Ophthalmological camera - Google Patents

Abstract

PURPOSE:To adjust a quantity of light by an easy means for various photographing systems varied in required quantity of light by a method wherein an emission value of a stroboscope is adjusted according to the required quantity of light and a dimmer means such as filter, stop or the like is inserted automatically into an optical path between a light source and a photographing means to attenuate the quantity of light reaching the photographing means in a photographing with limited required quantity of light. CONSTITUTION:An inspecting person adjusts an emission value with an emission value adjusting circuit 20 of a stroboscope by combining the selection of photographing systems while a filter driver is controlled with a controller to make an adjustment so that quantities of light appropriate to various photographings are obtained. An ND filter 9 used in this example, is 15% in transmissivity and is inserted into an optical path in a color photographing of a still video and retreated from the optical path in other photographings. Therefore, in the color photographing of the still video, an eye to be inspected is lighted by a puantity of light 3% as much as that in a fluorescent photography.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to an ophthalmological device having a photoelectric photographing optical system that displays the fundus image of the eye to be examined on a television monitor, and a photographing optical system that images the fundus image on a film. This invention relates to improvement of photographic equipment.

[Prior Art] Fundus cameras have been used to photograph fundus images in order to observe the condition of the fundus.

The simplest fundus camera is equipped with a photographic optical system for taking photographs and an observation optical system for visual recognition by the operator.

Recently, there has been an increasing trend in the number of fundus cameras equipped with a photoelectric photographing optical system equipped with an image receiving element such as an image pickup tube and a CCD camera. The photoelectric photographing optical system is used to take photographs and store the fundus image as an electrical signal, or to display the fundus image on a television monitor in real time for alignment and observation.

Note that observation using an observation optical system or a television monitor is mainly used for specifying and focusing the imaged region, and still images taken by strobe light are used for diagnosis.

It is better to keep the amount of strobe light as low as possible considering the burden on the examinee, but from the viewpoint of the resolution of the photographic film, it is possible to use less sensitive film as long as it does not place a heavy burden on the examinee. There is a demand to make it as large as possible. This is because the lower the sensitivity of a photographic film, the finer the grains and the higher the resolution. Film sensitivity and strobe light emission amount are determined by taking into account the balance between these conflicting requirements.

For example, in the case of color photography, the film sensitivity is l5O8
A film of about 4-100 mm is used, and the light output of the xenon lamp, which is the light source for the strobe, is about 18.25.36 mm. In addition, in visible fluorescence photography, the amount of light from the fundus is much smaller than in color photography, so l5
It is necessary to use a film with a high sensitivity of about O400, and the emission output of a strobe for excitation is about 200W.

By the way, conventional CCD cameras had a much lower resolution than photographic film due to the small number of pixels, but recently the number of pixels has increased and the resolution has improved, making it easier to obtain still images. It has become sufficiently practical as a means of.

When taking still images with a CCD camera,
Since the sensitivity of a CCD camera is higher than that of film, the amount of light required is considerably smaller than that required for photographing film.

Specifically, in the case of visible fluorescence photography, 50W is sufficient, and in the case of color photography, theoretically 3% of that amount, that is, 1.511W is sufficient.

In conventional ophthalmological photographing apparatuses, the light emission output of the strobe was manually changed according to the above-mentioned photographing method or photographing means.6 Note that, theoretically, it is also possible to perform still video photographing using an observation light source. However, since observation is mainly performed in preparation for photographing, it is common for the examiner to reduce the amount of light from the observation light source in order to reduce the burden on the examinee as much as possible. For this reason, the light intensity of the observation light source generally varies depending on the examiner, and is not preferable as a light source for obtaining still images.

[Problems to be Solved by the Invention] When the range of change in required strobe light output due to differences in photographing methods and photographic means is scattered over a wide range as described above,
1.5 for switching by one output setting means
The adjustment range from w to 200H is too wide and difficult to set.

[Object of the invention] This invention was made in view of the above problems, and
It is an object of the present invention to provide an ophthalmologic imaging device that can adjust the amount of light by a simple means for various imaging methods that require different amounts of light.

[Means for Solving the Problems] In order to achieve the above object, the ophthalmological imaging device according to the present invention adjusts the amount of light emitted by the strobe according to the required amount of light, and also adjusts the amount of light emitted by the light source when performing photography with a small amount of required light. The present invention is characterized in that a light attenuating means such as a filter or diaphragm is automatically inserted into the optical path between the image capturing means and the image capturing means to attenuate the amount of light reaching the image capturing means.

[Function] According to the above configuration, in addition to adjusting the strobe light emission amount, adjustment by the dimming means can be used in combination, so that the range of light emission amount adjustment can be narrowed.

[Embodiment] The present invention will be explained below based on the drawings. Figure 1 shows
1 shows an embodiment of an ophthalmologic photographing apparatus according to the present invention.

This fundus camera includes an illumination system and an observation/photography system. The illumination system has an observation illumination optical system and a photography illumination optical system, and the observation photography system has a photoelectric photography optical system, a photography optical system, and an observation optical system.

The observation illumination optical system includes optical members such as an observation light source 1, an observation condenser lens 2, a half mirror 3, an illumination relay lens 4, a perforated mirror 5, and an objective lens 6. The illumination light from the observation illumination light source 1 is transmitted through the condenser lens 2.
The light is focused by the apertured mirror 5 via the half mirror 3 and the relay lens 4, and illuminates the fundus Ef of the eye E by the objective lens 6.

The photographing illumination optical system includes a strobe tube 7 and a photographing condenser lens 8, and shares an optical path with the observation illumination system after the half mirror 3. The flash light from the strobe tube 7 illuminates the fundus Ef through optical members from the photographing condenser lens 8 to the objective lens 6. The amount of light emitted by the strobe tube 70 can be adjusted by a light amount adjustment circuit 20.

Note that an ND filter 9 serving as a light attenuating means is installed between the photography condenser lens 8 and the nof mirror 3 so that it can be inserted into and removed from the optical path. This can be done using the drive motor 9a+2. The filter drive motor 9a is connected to a controller 30 that selects the type of observation and photography as described later.
automatically controlled by

The observation photographing optical system includes an objective lens 6, a perforated mirror 5, an observation aperture 10, and a focusing lens system 11.The zero-focusing lens system 11 is moved in the optical axis direction.
Adjust the focus of the observation and photography optical system.

The reflected light from the fundus Ef is a half mirror (12 cm) J
The reflected light is separated by a variable aperture 13, a relay lens 14,
The transmitted light enters a photoelectric photographing optical system consisting of a CCD camera 15, and the transmitted light enters a photographing optical system consisting of a relay lens 16, a quick return mirror 17, and a film 18.

The quick return mirror 17 of the photography optical system is positioned in the optical path as shown by the solid line during observation and guides the reflected light from the fundus to the observer's eye, and momentarily moves to the position shown by the broken line in the figure during photography. It rotates to guide the reflected light from the fundus to the film 18.

The variable aperture 13 of the photoelectric photographic optical system is controlled by an aperture drive motor 1.
3a to change the aperture diameter, change the depth of focus of this photographic optical system, and adjust the amount of light.

Since the same fundus image is formed by the CCD camera 15 and the film 18, by displaying the imaging results by the CCD camera on a TV monitor (not shown), it is possible to check whether or not the imaging was successful without developing the film. can be judged.

Next, the operation of the ophthalmological photographing apparatus configured as described above will be explained.

The examiner adjusts the focusing lens system 11 to focus on the fundus while observing the eye to be examined using the observation optical system.

At this time, since the photographing optical system has the same lens system as the observation optical system, focusing is guaranteed by the focusing of the observation optical system. However, the photoelectric imaging optical system has a different lens system from the observation optical system and generally has a shallower depth of focus than the observation optical system, so even if the observation optical system focuses on the fundus while observing, There is a possibility that the fundus image formed on the CCD camera 16 may be out of focus. Therefore, the aperture drive motor 13a is controlled, and the variable aperture 13 is adjusted to change the aperture diameter of the optical system so that the depth of focus of the photoelectric photographing optical system matches that of the observation optical system. With this adjustment, the in-focus state of the photoelectric photographing optical system can be guaranteed by checking the in-focus state with the observation optical system.

The selection of the shooting method is performed by the controller 30. The controller 30 allows selection of observation shooting methods such as shooting with photographic film, shooting still images with a CCD camera (still video), and observing with a CCD camera (TV movie). , it is possible to select between color photography and fluorescence photography as the photography method.

The examiner adjusts the amount of light emitted by the strobe light amount adjustment circuit 20 in combination with the selection of the photographing method, and also controls the filter drive device using the controller, so as to obtain an appropriate amount of light for each photograph.

The strobe light output is 18.25.3 for color photography using film with a sensitivity of about 15O64-100.
In the case of visible fluorescence photography using a film of about 15O400, it is set to about 200W, in the case of still video fluorescence photography, it is set to 50W, and in the case of still video color photography, it is set to IOW.

The ND filter 9 used in this example has a transmittance of 15%, and is inserted into the optical path when shooting color still videos.
During other shooting, it is moved out of the optical path. Therefore, when color still video photography is performed, the subject's eye is illuminated with a light intensity of 3z as in the case of fluorescence photography.

The transmittance of the ND filter and the light emission output of the strobe are not necessarily limited to the above examples, and are ultimately determined by the film or C.
As long as the amount of light reaching the CD camera is the same as above, the combination of filter transmittance and light emission output is arbitrary. In addition, in the above example, the light intensity is adjusted by inserting and removing one filter, but the light intensity can be adjusted by providing multiple filters and inserting them selectively or simultaneously into the optical path. Good too.

With this configuration, in addition to controlling the strobe's light output, it is also possible to adjust the light intensity by inserting and removing the filter, which narrows the adjustment range for strobe light output, and also allows the subject's eye to adjust as needed. Since it is illuminated with only the minimum amount of light, there is less burden on the subject.

Note that the position where the ND filter as a light attenuation means is provided is not necessarily in the same position as the photographing condenser lens 8 as in the above example.
It is not necessary to provide it between the half mirror 12 and the half mirror 9, and it may be provided between the half mirror 12 and the CCD camera 15.

In addition, a variable aperture 13 provided for adjusting the depth of focus
It can also be used as a means for adjusting the amount of light.

[Effects] As explained above, according to the ophthalmological imaging device of the present invention, the amount of light reaching the camera is adjusted not only by the flash output of the strobe but also by using the dimming means. Can be narrowed. Further, since the light reduction means is automatically inserted, it is possible to eliminate photographing errors such as overexposure.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of an ophthalmologic photographing apparatus according to the present invention. E...Eye to be examined 7...Strobe light source 20...Emission amount adjustment means 9...ND filter (light reduction means)

Claims (1)

[Scope of Claims] Photography control means for selecting a combination of a plurality of photographing optical systems having different sensitivities and a plurality of photographing methods having different required amounts of light, and a strobe for emitting a flash for still image photographing toward the subject's eye. A light source, a light emission amount adjusting means for controlling the light emission amount of the strobe light source, and a light reduction means for suppressing the amount of light reaching a highly sensitive photographing optical system based on the combination selected by the photographing control means. Features of ophthalmology imaging equipment.