JPH08256988A - Tv relay lens unit for ophthalmologic photographing - Google Patents

Abstract

PURPOSE: To enable correcting optical path difference in a TV relay lens unit by providing optical element for correcting the optical path between field lens and imaging device. CONSTITUTION: TV relay lens unit 21 consists of field lenses 38, 38', a reflection mirror 39, a TV relay lens 40, a detachable light quantity adjusting ND filter 54 in the optical path between the TV relay lens 40 and the reflection mirror 39, a planar glass 55 as an optical element for optical path length correction, and a correction lens 56. In a rearward position of the TV relay lens 40, a single plate-type CCD camera 42' with an imaging device is fitted. The field lenses 38, 38' are positioned to be conjugated with the eye to be examined 32 in the photographing system 20b. Also, the ND filter 54 and the planar glass 55 are inserted in the cases of color photographing and visible fluorescent photographg, respectively. The correction lens 56 is inserted in the case of infrared fluorescent photographing and corrects the optical path difference from the field lenses 38, 38' to the image reception plane 47 of the CCD camera 42'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TV relay lens unit for ophthalmic photographing which is mounted on an ophthalmic photographing apparatus main body having a photographing optical system and guides an eye image from the ophthalmic photographing apparatus main body to a TV camera. .

[0002]

2. Description of the Related Art In an ophthalmologic photographing apparatus such as a fundus camera, an exciter filter and a barrier filter can be replaced according to the type of photographing such as color photographing, infrared fluorescent photographing and visible fluorescent photographing. Widely known.

Further, in this type of ophthalmic photographing apparatus, there is one that corrects an optical path difference of a photographing optical system due to different wavelengths of infrared light and visible light by switching barrier filters having different thicknesses. As such,
For example, there is one described in JP-A-2-149246.

On the other hand, a photographing means such as a 35 mm camera or a TV camera is attached to the fundus camera or the like according to the purpose.

Generally, as shown in FIG. 7, the 35 mm camera K1 is permanently mounted on the first mount T1 and is mounted on the TV camera K1.
2 is connected to the apparatus main body H via the TV relay lens unit 100 mounted on the second mount T2.

This TV relay lens unit 100 is
As shown in FIG. 8, it has a field lens 101, a reflection mirror 102, and a TV relay lens 103, and an eye image from the apparatus main body H passes through the TV relay lens 103 from these field lenses 101. T
It is guided to the image pickup device of the V camera K2.

[0007]

By the way, when it is attempted to use light having different wavelengths (for example, infrared light and visible light) for photographing, in the conventional TV relay lens unit 100, the field lens 101 to the TV camera K2 are used. Up to the image pickup element (not shown), an optical path difference due to the wavelength difference occurs. Therefore, when the TV relay lens unit 100 is used, there is a problem that it is not possible to appropriately perform shooting using lights having different wavelengths.

The present invention has been made under such circumstances, and an object of the present invention is to provide a TV relay lens unit for ophthalmic photography capable of correcting an optical path difference in the TV relay lens unit. Is.

[0009]

In order to achieve this object, the invention according to claim 1 is attachable to and detachable from an ophthalmologic photographing apparatus main body having a photographing optical system, and an eye image to be inspected from the ophthalmic photographing apparatus main body. A field relay lens unit for guiding ophthalmology to a TV camera, the field lens being arranged in a position conjugate with the eye to be inspected with respect to the imaging optical system in a state of being attached to the ophthalmic imaging apparatus body. It is arranged in the optical path from the field lens to the image pickup device and the TV relay lens for re-forming the image of the eye to be inspected, which is once formed on the field lens, on the image pickup device of the TV camera, and is used for photographing. An optical element for correcting an optical path length for correcting an optical path difference due to a difference in wavelength of light is provided.

According to a second aspect of the present invention, the optical element for correcting the optical path length is arranged at the entrance pupil position of the TV relay lens or at a position close to the entrance pupil.

[0011]

According to the first aspect of the invention, since the optical element for correcting the optical path length is arranged in the optical path from the field lens to the image pickup element, the optical path difference due to the difference in the wavelength of the light used for photographing occurs. , Is corrected in the TV relay lens unit. Therefore, it is possible to perform shooting using lights having different wavelengths, and it is possible to cope with TV cameras having different image pickup device systems without replacing the TV relay lens.

According to the second aspect of the present invention, since the optical element for correcting the optical path length is located at or near the entrance pupil position, the outer diameter of the optical element for correcting the optical path can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in the drawings.

As shown in FIG. 1, since the TV relay lens unit 21 according to the present invention is used by being attached to the body 20 of the ophthalmologic photographing apparatus such as a fundus camera, for convenience of explanation, the TV relay lens unit 21 The present invention will be described together with the configuration.

First Embodiment As shown in FIG. 1, an ophthalmologic photographing apparatus main body 20 is mainly composed of an illumination optical system 20A and a photographing optical system 20B.

The illumination optical system 20A mainly comprises a concave mirror 22, a halogen lamp 23 for observation illumination, a relay lens 24, a xenon tube 25 for photographing illumination, a condenser lens 26,
It is composed of a reflection mirror 27, a ring-shaped slit 28, and a relay lens 29, and guides illumination light to a fundus 33 of an eye 32 to be examined through a perforated mirror 30 and an objective lens 31.
The fundus 33 is configured to illuminate. An exciter filter 48 for visible fluorescence and an exciter filter 49 for infrared fluorescence can be inserted and removed between the reflection mirror 27 and the condenser lens 26 of the illumination optical system 20A.

The photographing optical system 20B includes an objective lens 31, a perforated mirror 30, optical path length correcting optical elements 50 and 52, a visible fluorescent barrier filter 51, an infrared fluorescent barrier filter 53, and a focusing lens 34. It has an imaging lens 35, a variable power lens 36, and a quick return mirror 37. The optical element 50 for correcting the optical path length and the like can be inserted and removed between the perforated mirror 30 and the focusing lens 34.

The perforated mirror 30 and the objective lens 31 are
It is shared by the illumination optical system 20A and the photographing optical system 20B, and the quick return 37 is adapted to be retracted from the optical path of the photographing optical system 20B when a fundus image is formed on the film 41 '.

The variable power lens 36 is inserted in the optical path of the photographing optical system 20B when 20 ° is selected as the angle of view.

The field lens 38 has an angle of view of 45.
When the degree is selected, it is inserted into the optical path of the TV relay lens unit 21, and when the field lens 38 'is selected as the angle of view, the field lens 38' is used.
Is inserted in the optical path of.

As described above, this ophthalmologic photographing apparatus constitutes an optical system having a relay lens having at least two or more image forming points between the object and the final image forming point.

The optical path length correcting optical element 50 and the like are inserted into the photographing optical path of the photographing optical system 20B in accordance with the wavelength used for photographing, and the optical path length correcting optical element 50 is used for visible color photographing or , The barrier filter 51 for visible fluorescence is inserted in the photographing optical path at the time of monochrome photographing, and the barrier filter 51 for visible fluorescence is inserted in the photographing optical path at the time of visible fluorescence photographing, and the optical element 52 for optical path length correction
Is inserted into the photographing optical path during infrared non-fluorescent photographing, and the infrared fluorescent barrier filter 53 is inserted into the photographing optical path during infrared fluorescent photographing.

Since the optical path length correcting optical element 50 and the like have different thicknesses corresponding to the wavelength of the photographing light, the eye 3 to be inspected.
It serves to correct the optical path difference from the second fundus 33 to the field lenses 38 and 38 '.

The TV relay lens unit 21 according to the present invention includes the field lenses 38 and 38 'and the reflection mirror 3.
9, TV relay lens 40, field lens 38, 3
It is composed of an ND filter 54 for adjusting the amount of light that can be inserted into and removed from the optical path between 8'and the reflection mirror 39, a flat glass 55 as an optical element for correcting the optical path, and a correction lens 56.

The T of the TV relay lens unit 21
Behind the V relay lens 40, a mount (not shown) to which a single plate type CCD camera 42 'having an image pickup device is attached is provided.

The field lenses 38 and 38 'are arranged at positions conjugate with the subject's eye 32 with respect to the photographing optical system 20B in a state where the TV relay lens unit 21 is attached to the ophthalmologic photographing apparatus main body 20.

The ND filter 54 is inserted during color photographing, and the flat glass 55 is inserted during visible fluorescence photographing. The correction lens 56 is inserted at the time of infrared fluorescence photography, and the field lenses 38, 38 'to C
It plays a role of correcting the optical path difference to the image receiving surface 47 of the CD camera 42 '.

The thickness of the flat glass 55 is the same as that of the ND filter 5.
The same as the thickness of 4. The power of the correction lens 56 is set to a value with which the optical path length is corrected. Further, the plane glass 55 and the correction lens 56 are, as described later, the entrance pupil 4 as an image of the aperture stop with respect to the TV relay lens 40.
9 (see FIGS. 2 and 3) are arranged as close as possible.

Next, the operation of the TV relay lens unit 21 having the above-mentioned structure will be described together with the operation of the ophthalmologic photographing apparatus.

This ophthalmologic photographing apparatus can be simplified by a schematic view as shown in FIGS.

FIG. 2 shows a chief ray when the fundus 33 is photographed at an angle of view of 45 degrees. The fundus 33 is once formed as a first fundus image 42 at the first image forming point 41 by the objective lens 31. It is imaged.

The chief ray forming the first fundus image 42 is
The focusing lens 34 and the imaging lens 35 pass through the center 43 ′ of the hole 43 of the perforated mirror 30 that functions as an aperture stop.
To the second imaging point 4 in front of the field lens 38.
At 4, the second fundus image 45 is formed again.

The chief ray that forms the second fundus image 45 and is guided to the CCD camera 42 'is parallel to the photographing optical axis 46 by the TV relay lens 40.
P2, that is, the image side telecentric on the CCD camera 42 'side, and the third fundus image 48 is formed on the image receiving surface 47 of the CCD camera 42' as the final image forming point.

Further, the entrance pupil 49 as an image of the aperture stop with respect to the TV relay lens 40 has a field lens 38.
And a TV relay lens 40 'at a point M.

On the other hand, in the case of photographing the fundus 33 with the angle of view of 20 degrees, as shown in FIG. 3, when the variable magnification lens 36 is inserted in the optical path of the photographing optical system 20B, the position of the entrance pupil 49 is set to the point M. However, the position of the entrance pupil 49 is kept at the point M in accordance with the insertion of the variable power lens 36 into the optical path of the ophthalmic imaging apparatus main body 20. , A field lens 38 ′ having a focal length different from that of the field lens 38 is inserted into the optical path of the ophthalmic photographing apparatus main body 20.

As described above, the incident condition on the TV relay lens 40 does not change even if the magnification of the ophthalmic photographing apparatus main body 20 is changed. Therefore, the TV relay lens 40
The diameter of can be reduced.

Further, as described above, since the position of the entrance pupil 49 is held so as to be telecentric on the image side, the color separation optical system is provided in the CCD camera 42 'provided behind the TV relay lens 40. Even if there is, the color shading phenomenon can be optically avoided (see Japanese Patent Application No. 3627 of 1991).

On the other hand, as described above, for example, when switching from color photography to infrared fluorescence photography, by removing the ND filter 54 and inserting the correction lens 56,
The optical path difference from the field lenses 38, 38 'to the image receiving surface 47 of the CCD camera 42' caused by the difference in the wavelength of light used for photographing is corrected. In this way, the ND filter 54 and the flat glass 5 are used depending on the type of light used for shooting.
5. By switching the correction lens 56, it is possible to timely perform shooting using lights having different wavelengths.

Furthermore, since the ND filter 54, the flat glass 55, and the correction lens 56 are brought close to the entrance pupil 49, the outer diameters of the flat glass 55 and the correction lens 56 can be reduced.

Second Embodiment In this embodiment, as shown in FIG. 4, a three-plate CCD camera is used for color photography, and a single-plate CCD camera is used for visible fluorescence photography and infrared fluorescence photography. I decided to use the CCD camera 42 'of the TV relay lens unit 2
1, an ND filter 54, a parallel glass 55, and an optical element 56 for correcting an optical path length are detachably provided.

The TV relay lens has a reference numeral 40,
There are two types, i.e., 65, and they can be replaced according to the type of TV camera used for shooting. Thereby, the optical path difference between the TV relay lens 40 and the image pickup element due to the difference in TV camera is corrected.

Here, the optical element 56 for correcting the optical path length is composed of a convex lens. These ND filters 54
The parallel glass 55 and the convex lens 56 play a role of correcting an optical path difference to the image pickup element caused by a difference in light type.

Further, reference numeral 57 in the drawing denotes a color separation optical system, and this color separation optical system 57 includes color separation prisms 57A to 57A.
57C, and when performing color photography, the ND filter 54 is inserted and the TV relay lens 40 is inserted.

When performing visible fluorescence photography, the parallel glass 55 is inserted between the TV relay lens 65 and the reflection mirror 39, and the TV relay lens 65 is inserted.
Furthermore, when performing infrared fluorescence photography, the convex lens 56 is inserted and the TV relay lens 65 is inserted.

Next, the operation of the TV relay lens unit 21 having such a structure will be described together with the operation of the ophthalmologic photographing apparatus.

This ophthalmologic photographing apparatus can be simplified by a schematic view as shown in FIGS.

FIG. 5 shows chief rays when the fundus 33 is photographed with an angle of view of 45 degrees.

The fundus 33 is once formed as an aerial image 42 by the objective lens 31, and the chief ray forming the aerial image 42 passes through the center 43 'of the hole 43 of the perforated mirror 30. The chief ray passing through this center 43 ′ is the focusing lens 3
4. The aerial image 45 is formed again before the field lens 38 by being guided to the imaging lens 35.

A light flux forming the aerial image 45,
The chief rays guided to the peripheral portions of the CCDs 58, 59, 60 are
The TV relay lens 40 makes the light flux parallel to the photographing optical axis 46. That is, the CCD 58, 59, 60 side (the color separation optical system 57 side) becomes telecentric,
It is guided to the color separation optical system 57. And its chief ray is
Passing through the interference films 61 and 62 in parallel with the photographing optical axis 46,
You will be led to D58, 59, 60. Therefore, the color shading phenomenon can be avoided.

When the fundus 33 is photographed with an angle of view of 20 degrees, a lens 36 for changing the magnification is inserted in the optical path of the photographing optical system 20B as shown in FIG.

At this time, the field lens 38 is T
A field lens 38 ′ having a focal length different from that of the field lens 38 is retracted from the optical path of the V relay lens unit 21 and is inserted into the optical path of the TV relay lens unit 21. As a result, the luminous flux entering the color separation optical system 57 becomes telecentric.

On the other hand, for example, when switching from color photography to visible fluorescence photography, the ND filter 54 and the TV are used.
The relay lens 40 is removed from the TV relay lens unit 21, and the parallel glass 55 and the TV relay lens 65 are removed.
Is inserted into the TV relay lens unit 21. As a result, as described above, the optical path difference to the image pickup element caused by the difference between the three-plate type having the color separation optical system 57 and the single-plate type not having the color separation optical system 57 is corrected.

As described above, the optical path difference due to the difference in the image pickup device system of the CCD camera is corrected by inserting the ND filter 54, the parallel glass 55, and the convex lens 56, and exchanging the TV relay lenses 40 and 65. Because
It is possible to support CCD cameras having different image pickup device systems without replacing the entire TV relay lens unit 21.

In the modification of the second embodiment, the TV relay lens unit 21 is provided with an ND filter 54, an optical element for correcting the optical path length 63, and a parallel glass 64 so that the optical element can be inserted and removed. 63 is a concave lens.

The difference from the second embodiment is that the optical element 63 for correcting the optical path length is used for visible fluorescence photography, the parallel glass 64 is used for infrared fluorescence photography, and the TV relay lens 65 is used. This is a point inserted between the reflection mirror 39 and the reflection mirror 39.

Although the embodiments of the present invention have been described above, the present invention is not limited to such a TV relay lens unit 21 and the following ones are also included in the present invention.

(1) The optical path length correction optical elements 54, 55, 56 of the TV relay lens unit 21 are interlocked with each other in accordance with the respective photographing modes of color photographing, visible fluorescent photographing, and infrared fluorescent photographing to take a photographing optical path. The structure is such that it can be inserted into and removed from Further, in the second embodiment, the TV relay lens and the TV camera are linked.

(2) In the first and second embodiments, a convex lens is used as the optical path length correction member 56 of the TV relay lens unit 21, and in the modification of the second embodiment, the optical path length correction optics is used. Although a concave lens is used as the element 63, the optical path difference is corrected using parallel plane plates having different thicknesses.

(3) In both of the above embodiments, the optical elements 54, 55 and 56 for correcting the optical path length are the reflecting mirror 39 and the T.
Although it is configured to be inserted between the V relay lens 40 and T
It is arranged between the V relay lens 40 and the image receiving surface of the CCD camera.

(4) In the above-described embodiment, during color photographing,
Although the ND filter 54 is used, an ND filter may be inserted in the illumination system or the light amount of the light source itself may be reduced.

[0061]

As described above, according to the first aspect of the invention, since the optical element for correcting the optical path length is arranged in the optical path from the field lens to the image pickup element, the light used for photographing is The optical path difference due to the difference in the wavelength is corrected in the TV relay lens unit. Therefore, it is possible to perform shooting using light with different wavelengths,
It is possible to support TV cameras with different image sensor systems without replacing the TV relay lens.

According to the second aspect of the invention, since the optical path length correcting optical element is located at or near the entrance pupil position, the outer diameter of the optical path length correcting optical element can be reduced.

[Brief description of drawings]

FIG. 1 is an optical diagram showing a state in which a TV relay lens unit according to a first embodiment of the present invention is attached to an ophthalmologic photographing apparatus main body.

FIG. 2 is a schematic diagram showing an optical path of a chief ray of a field of view of 45 degrees of the ophthalmic photographing optical system in FIG.

FIG. 3 is a schematic diagram showing an optical path of a chief ray of the ophthalmic imaging optical system in FIG. 1 with a visual field of 20 degrees.

FIG. 4 is an optical diagram showing a state in which the TV relay lens unit according to the second embodiment of the present invention is attached to the ophthalmologic photographing apparatus main body.

5 is a schematic diagram showing an optical path of a chief ray with a field of view of 45 degrees of the ophthalmic photographing optical system in FIG.

6 is a schematic diagram showing an optical path of a chief ray with a visual field of 20 degrees of the ophthalmic photographing optical system in FIG.

FIG. 7 is a perspective view showing a fundus camera to which a 35 mm camera and a TV camera are attached.

FIG. 8 is a sectional view showing a conventional TV relay lens unit.

[Explanation of symbols]

 20 Ophthalmic Imaging Apparatus Main Body 20A Illumination Optical System 20B Imaging Optical System 21 TV Relay Lens Unit 31 Objective Lens 32 Eye to Be Tested 35 Imaging Lens 38 Field Lens 40, 65 TV Relay Lens 42 'CCD Camera 50, 52 Optical Path Length Correction Optical Element 51 Barrier Filter for Visible Fluorescence 53 Barrier Filter for Infrared Fluorescence 54 to 56 Optical Element for Optical Path Length Correction

Claims (2)

[Claims] 1. An ophthalmic image taking device main body having an image taking optical system, which is attachable to and detachable from the ophthalmic image taking device main body.
A field relay lens unit for ophthalmology photography that leads to a V camera, the field lens being arranged in a position conjugate with the eye to be examined with respect to the imaging optical system in a state of being mounted on the body of the ophthalmology photography apparatus. A TV relay lens for re-imaging the image of the eye to be inspected, which is once formed on the field lens, on the image pickup device of the TV camera, and a light used for photographing, which is arranged in the optical path from the field lens to the image pickup device. A TV relay lens unit for ophthalmic photography, which includes an optical element for correcting an optical path length that corrects an optical path difference due to a difference in wavelength. 2. The optical element for correcting the optical path length is provided in the TV.
The TV relay lens unit for ophthalmology according to claim 1, wherein the TV relay lens unit is arranged at the entrance pupil position of the relay lens or at a position close to the entrance pupil.