JPH04303412A - Ophthalmologic camera - Google Patents

Abstract

PURPOSE:To provide an ophthalmologic camera which can dissolve a change in the focusing condition based on a difference between F numbers of a photoelectric picture taking optical system and photographic optical system and ensure the focusing of the other optical system by the focusing of a specified optical system. CONSTITUTION:An objective lens 5 for conducting beams reflected from an eye E to be inspected, a half-mirror 9 for separating and conducting the reflected beams to a TV camera 13 and film 16, a magnification varying lens system 7 provided between the objective lens 5 and half mirror 9 to vary the photographic magnification, a variable diaphragm 11 provided in a position conjugate with the pupil of the eye E at least in either one of the photographic optical systems to vary the focal depth of the corresponding optical system are provided. A variable field optical system 10 provided between the half-mirror 9 and variable diaphragm 11 to vary a focal length according to the magnification selection of the magnification varying lens system 8 and maintain the fixed position conjugate with the pupil shall be a special feature of this device.

Description

[Detailed description of the invention]

0001

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

0002

2. Description of the Related Art Conventionally, fundus cameras have been used to take photographs of 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.

[0003]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 or a television 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.

By the way, focusing of the fundus camera is performed by moving a focusing lens provided in a common portion of each of the above-mentioned optical systems in the optical axis direction.

[0005]

[Problem to be Solved by the Invention] However, in general, in a fundus camera, the photoelectric photographing optical system and the photographic optical system have different magnifications, so the depth of focus at the image receiving part also differs due to the difference in F number. There is.

That is, the depth of focus is generally proportional to the F number of the optical system, so if the entrance pupil diameter is the same, the smaller the magnification (focal length), the shallower the depth of focus.

Therefore, even if a specific optical system is brought into focus by moving the common focusing lens, it is not necessarily guaranteed that other optical systems will be in focus.

Generally, at present, a photoelectric photographing optical system has a smaller magnification than a photographic optical system, and therefore has a shallower depth of focus.

[0009]

[Purpose of the Invention] The present invention has been made in view of the above-mentioned problems, and aims to eliminate the change in focus state due to the difference in F number between a photoelectric photographic optical system and a photographic optical system, and to An object of the present invention is to provide an ophthalmologic photographing device that can guarantee the focus of other optical systems by focusing an optical system.

0010

[Means for Solving the Problems] In order to achieve the above object, the ophthalmological photographing device according to the present invention has a variable aperture at a position conjugate to the pupil of at least one of the photoelectric photographing optical system and the photographing optical system. is provided to change the depth of focus of the photographing optical system.

[0011] Note that in order for the above-mentioned diaphragm to function as an aperture diaphragm, it must be set at a conjugate position of the pupil of the eye to be examined. Therefore, in the ophthalmological imaging device of the present invention, the focal length is adjusted according to the magnification selection of the variable magnification optical system so that the variable aperture does not deviate from the position conjugate with the pupil even when the variable magnification optical system is operated to change the magnification. A variable field optical system is provided for changing the position of the pupil and keeping the position conjugate with the pupil constant.

0012

[Function] According to the above configuration, the depth of focus can be changed by adjusting the aperture, and both photographing optical systems can be brought into focus at the same time.Moreover, there is no need to change the position of the aperture due to zooming, and the aperture diaphragm There is no change in its function.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings.

[0014]

Embodiment 1 FIG. 1 shows Embodiment 1 of the present invention.

[0015] This fundus camera is equipped with an illumination system and an observation and photographing system. The observation and photography system includes a photoelectric photography optical system, a photography optical system, and an observation optical system.

The illumination optical system includes a light source 1, a mirror 2, a condenser lens 3, a perforated mirror 4, and an objective lens 5. The illumination light from the illumination light source 1 is condensed by the condenser lens 3, reflected by the perforated mirror 4, and illuminates the fundus Ef of the eye E to be examined via the objective lens 5.

The observation and photographing optical system has an objective lens 5, a perforated mirror 4, an observation aperture 6, a variable magnification lens system 7, and a focusing lens system 8 as common parts.

The variable magnification lens system 7 can change the magnification of the optical system in stages by inserting one lens system selected from a plurality of lens systems into the optical path, and which magnification is selected can be changed in stages. The information on whether the
Detected by

The focusing lens system 8 focuses the photographing optical system by moving it in the optical axis direction.

The reflected light from the fundus Ef is separated by a half mirror 9 as an optical path separation means, and the reflected light is transmitted through a variable field optical system 10, a variable aperture 11, and a relay lens 12.
, the transmitted light enters a photoelectric photographing optical system consisting of a television camera 13, and the transmitted light enters a photographing optical system consisting of a relay lens 14, a quick return mirror 15, and a film 16.

Since the same fundus image is formed on the television camera 13 and the film 16, by displaying the image taken by the television camera on a television monitor (not shown), it is possible to determine whether the photographing was successful without developing the film. It is possible to judge whether or not.

The quick return mirror 15 of the photography optical system is positioned in the optical path as shown by the solid line during normal observation and guides the reflected light from the fundus to the observer's eye, and during photography it is positioned in the optical path as shown by the broken line in the figure. The film 16 momentarily rotates to the desired position and guides the reflected light to the film 16.

The variable aperture 11 of the photoelectric photographing optical system is driven by an aperture drive motor 11a to change its aperture diameter, thereby changing the depth of focus of the photographing optical system and adjusting the amount of light. Note that this diaphragm may have a structure in which the aperture diameter can be continuously adjusted as described above, or may have a structure in which a plurality of fixed apertures with different aperture diameters are selectively inserted into the optical path.

In this example, the aperture for adjusting the focal depth balance of each photographic optical system is provided only in the photoelectric photographic optical system. This is because photoelectric photographic optical systems generally have lower magnification and shallower depth of focus than photographic optical systems.
This is because even if the depth of focus of this photoelectric photographing optical system can be adjusted only in the direction of increasing it, the function of adjusting the depth of focus balance can be achieved.

The variable field optical system 10 of the photoelectric photographing optical system is driven by a field lens drive motor 10a, and changes the focal length in steps by selecting one lens system from a plurality of lens systems. be able to.

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

The examiner adjusts the focusing lens system 8 to focus on the fundus Ef while observing the eye to be examined using the observation optical system.

At this time, since the photographing optical system has a common lens system with the observation optical system, focusing is guaranteed by the focusing of the observation optical system.

On the other hand, a photoelectric imaging optical system has a lens system different from that of the observation optical system, and generally has a shallower depth of focus than the observation optical system, so it is difficult to focus on the fundus while observing with the observation optical system. Even if this is done, there is a possibility that the fundus image formed on the television camera 13 may be out of focus.

Therefore, the aperture drive motor 11a is controlled,
The variable aperture 11 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.

[0031] When changing the magnification for observation and photography,
The lens of the variable power lens system 7 is replaced. At this time, in each optical system, the position conjugate with the fundus of the eye does not change, but the position conjugate with the pupil changes. The variable diaphragm 11 can function as an aperture diaphragm by providing it at a position conjugate to the pupil where the chief ray is most focused, so it is not preferable for the conjugate position of the pupil to move.

Therefore, by changing the lens of the variable field lens system 10 and changing its focal length in accordance with the exchange of the variable magnification lens, the change in the conjugate position of the pupil due to the selected magnification of the variable magnification lens system 7 can be prevented. Let them cancel each other out. Thereby, even when the magnification changes, the conjugate position of the pupil is fixed at the position of the variable aperture, and the light amount and depth of focus can be adjusted without moving the aperture.

[0033]

[Embodiment 2] FIG. 2 shows a second embodiment of the present invention.

Although television cameras and films each have their own appropriate exposure amounts, changes in the amount of light due to aperture adjustment may disrupt the appropriate balance of exposure amounts. If no corrective measures are taken here, a situation will occur in which, for example, even if the amount of light reaching the television camera is sufficient, the amount of light reaching the film will be insufficient.

Therefore, in the apparatus shown in Example 2, a plurality of ND filters 1 having different transmittances are installed in the photoelectric photographing optical system.
7, 18, etc. are provided to be replaceable, thereby eliminating the influence of the change in light amount due to the above-mentioned aperture adjustment. Filter replacement is performed by a filter drive motor 20.

The configuration other than the filter is the same as that of the device of Example 1.

[0037] In addition to correcting changes in light amount due to aperture adjustment, filter selection is performed depending on the type of photographing. That is, in this device, the controller 30 controls flow (fluorescence) photography, color photography, and red free (red,
It is possible to select each shooting mode of (excluding infrared) shooting and anterior segment shooting, and depending on this selection, the filter drive motor 20 is controlled to automatically adjust the filter so that the amount of light suitable for each shooting mode is obtained. exchange. The amount of light required varies greatly depending on the shooting mode, but by automatically replacing filters and adjusting the amount of light, a single color television camera can perform color photography and fluorescence photography.

[0038]

[Effects of the Invention] As explained above, according to the present invention, by adjusting the aperture provided in the photographing optical system,
The depth of focus of the optical system can be adjusted, and the depth of focus balance of the plurality of photographing optical systems can be adjusted to match. Therefore, by focusing one optical system, the in-focus state of the other optical systems can also be guaranteed.

Furthermore, even when the magnification is changed using the variable magnification optical system, by changing the focal length of the field optical system, the conjugate position of the pupil and the position of the variable aperture can be matched without moving the variable aperture. can be done.

Furthermore, if these filters are configured to be automatically selected depending on the type of photography, it is possible to guide the light beam with the optimum amount and wavelength to the light receiving means depending on the type of photography.

[Brief explanation of drawings]

[Fig. 1] Example 1 of an ophthalmological imaging device according to the present invention
FIG.

FIG. 2 is an explanatory diagram showing Example 2.

[Explanation of symbols]

E... Eye to be examined Ef...fundus 5...Objective lens 10...Variable field optical system 11...Variable aperture 13...TV camera 16...Film

Claims (1)

[Claims] Claim 1: An objective lens that guides reflected light from an eye to be examined;
an optical path separating means that separates the reflected light and guides it to a photoelectric photographing optical system and a photographing optical system; a variable magnification optical system that is provided between the objective lens and the optical path separating means and changes the photographing magnification; A variable diaphragm that is provided in at least one of the photographing optical systems at a position conjugate with the pupil of the subject's eye and that changes the depth of focus of the photographic optical system, and a variable diaphragm that is provided between the optical path separation means and the variable diaphragm. 1. An ophthalmologic photographing apparatus comprising: a variable field optical system that changes a focal length according to a selection of a magnification of the variable magnification optical system and maintains a constant position conjugate with the pupil.