JP2740514B2 - Laser scan fundus camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system of a laser scanning fundus camera that scans and illuminates a fundus of a subject's eye with laser light.

(Related Art) In general, in a fundus camera, when observing and photographing the fundus of the eye to be inspected, the entire fundus of the eye to be inspected is evenly illuminated. In this case, since the fundus of the subject's eye is illuminated with relatively strong light, it places a burden on the subject and is not very desirable.

In recent years, as a fundus camera that can reduce such a burden,
The fundus of the eye to be inspected is scanned and illuminated with a laser beam having a constant spot diameter to detect the amount of reflected light from the fundus of the eye to be examined at intervals of the spot diameter of the laser beam, and the detected spot light information is applied to a monitor television. An optometry fundus image is constructed.

Such a fundus camera is disclosed, for example, in Japanese Patent Application Laid-Open No. 60-13 / 1985.
Japanese Patent Application Publication No. 2536 and Japanese Patent Application Laid-Open No. Sho 62-117524 are known. This fundus camera uses an optical scanning device for both an illumination optical system for irradiating laser light and a light receiving optical system for guiding reflected light or fluorescence from the fundus to a light receiver in order to improve image contrast. I am doing it.

In these fundus cameras, by arranging a pinhole (aperture) at a position conjugate with the fundus in the light receiving optical system, the size of the light beam projected on the fundus with the diameter of this pinhole,
That is, the resolution is determined by defining the size of each pixel of the image.

In other words, in the light receiving optical system of these fundus cameras, since only the light reflected from the portion of the projected image to the fundus passes through the pinhole, for example, the illumination light spot is Even if the distance is large, the reflected light from the outside of the projected image does not pass through the pinhole. Therefore, the resolution of the image is defined by the pinhole image projected on the fundus. Thus, in the device having such a configuration, the resolution is determined by the optical system that projects the pinhole, that is, the performance of the light receiving optical system.

(Problems to be Solved by the Invention) By the way, in such a fundus camera, the diameter of the laser beam of the illumination optical system is increased in order to make the light receiving unit receive as much reflected light from the fundus as possible and improve the resolution. It is preferable that the pupil diameter of the light receiving optical system be made as large as possible, while changing the pupil diameter according to the scanning magnification to the fundus of the optometry.

However, although the resolution improves when the pupil diameter of the light receiving optical system is large, the depth of field becomes shallow, and the entire fundus of the subject's eye with irregularities becomes out of focus. However, there is a problem that they are shifted.

Therefore, the present invention provides a laser scanning fundus camera that can obtain a clear fundus image of the eye to be examined even if there are individual differences in the condition of the subject such as the age of the subject or the examination of the subject and the structure of the fundus. The purpose is to do so.

(Means for Solving the Problems) In order to achieve this object, a laser scanning fundus camera according to the present invention includes: an illumination optical system that projects laser light from a light source as spot light onto a fundus by an optical scanning device; And a light receiving optical system that guides the reflected light beam to a light receiving unit by an optical scanning device and causes the light receiving unit to receive the light beam through a pinhole at a position conjugate with the fundus. Light beam diameter adjusting means for variably adjusting the diameter of light is provided.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 to 3 show a first embodiment of the present invention.

The first view, fundus camera shown in FIG. 2, by projecting a laser beam onto the fundus E _f of the eye E, and an illumination optical system for scanning illumination of the fundus E _f, from the fundus E _f And a light receiving optical system for guiding the reflected light to the light receiving unit.

The illumination optical system includes a laser oscillator 1, a lens 2, a beam splitter 3, a polygon mirror 4 as a horizontal scanning member, variable power lenses 5, 6, a galvanometer mirror 7, a vertical scanning member, a relay lens 8, a focus lens 9, and a reflection lens. It has a mirror 10 and an objective lens 11 in this order. The optical components from the polygon mirror 4 to the galvanometer mirror 7 constitute an optical scanning device A. In the figure, P is shows the pupil E _{p (P o)} and a position conjugate of the eye E, R represents a fundus E _f (R _o) position conjugate with the eye to be examined E.

The laser light emitted from the laser oscillator 1 of such an illumination optical system passes through the lens 2 and the beam splitter 3,
The light enters the polygon mirror 4. This polygon mirror 4
Scans the incident laser beam at high speed.
The scanned laser light is applied to the variable power lenses 5, 6, galvanometer mirror 7, relay lens 8, focus lens 9, reflection mirror
Guided in the order of 10, the fundus of the eye E from the objective lens 11
Projected to E _f . At this time, the galvanomirror 7 is rotated by a predetermined angle every horizontal scanning of the laser light by the polygon mirror 4 to move the horizontal scanning position of the laser light in the vertical direction. By such scanning, the fundus oculi E _{f of the} eye E to be inspected is obtained.
To form a scanning surface.

The light receiving optical system includes an optical system from the above-described beam splitter 3 to the objective lens 11, a beam expander 12 as a light beam diameter adjusting means, a condenser lens 13, a pinhole plate 14, and a photodiode 15 as a light receiving unit. ing. And
The reflected light flux reflected by the fundus E _f is the objective lens 11, reflecting mirror 10, focusing lens 9, a relay lens 8, the galvano mirror 7, the variable magnifying lens 6,5 is guided by the order of the polygon mirror 4 to the beam splitter 3 The light enters and is reflected by the beam splitter 3 toward the beam expander 12. After the diameter of the reflected light beam is changed and adjusted by the beam expander 12, the condensing lens 13
Of the photodiode 1
It is incident on 5.

At this time, the pupil diameter of the light receiving optical system for receiving the reflected light flux is defined by the effective diameter of the beam expander 12 when the scanning device A and the lens have no vignetting. Therefore,
If several beam magnifications having different magnifications are prepared in the beam expander 12, the pupil diameter can be converted by converting them.

Here, the pinhole plate 14 immediately before the photodiode 15
When the pin hole 14a of are geometrically projected onto the fundus E _f through the light receiving optical system, when the magnification pinhole 14a is projected onto the fundus E _f by the diffraction of the light receiving optical system and the projection magnification, resolution Changes as follows by adjusting the beam expander 12. That is, when the pupil diameter of the light receiving optical system is increased by the beam expander 12, the projection magnification to the fundus oculi Ef with respect to the pinhole diameter 14a of the pinhole plate 14 immediately before the photodiode 15 is reduced, and the resolution is improved. The depth becomes shallower. Conversely, when the pupil diameter of the light receiving optical system is reduced by the beam expander 12, the projection magnification to the fundus oculi Ef with respect to the pinhole diameter 14a of the pinhole plate 14 immediately before the photodiode 15 increases, and the resolving power decreases. The depth of field increases.

Therefore, the examiner can use this property to select the pupil diameter by the examinee or by the observation magnification, and observe the eye E in the method that is the easiest to observe. In addition, since the amount of received light changes due to the change in the pupil diameter, it is preferable to link the adjustment of the amount of illumination light for correcting the amount of received light.

FIG. 3 schematically shows the fundus camera shown in FIGS. 1 and 2. The optical scanning device A shown in FIG. 3 is an optical scanning device from the polygon mirror 4 to the galvanometer mirror 7 as described above. With parts. In FIG. 3, the illustration of the optical components from the relay lens 8 to the objective lens 11 is omitted.

In the embodiment described above, an example is shown in which the beam expander 12 is provided as a light beam diameter adjusting means, but the present invention is not necessarily limited to this. For example, as shown in FIG. 4, a stepped diaphragm plate 16 in which a large number of diaphragm holes 16a having different diameters are formed in the circumferential direction is disposed between the beam splitter 3 and the lens 13, and The aperture plate 16 may be used as a beam diameter adjusting means.

FIGS. 5 to 8 show a fundus camera having a configuration in which one optical scanning device A is disposed in a common optical path of an illumination optical system and a light receiving optical system, as in the first embodiment, as a beam diameter adjusting means. 2 shows an example of the arrangement of the beam expander 12 of FIG. In these embodiments, the optical components from the relay lens 8 to the objective lens 11 are not shown.

FIG. 5 shows an example in which the beam expander 12 between the beam splitter 3 and the condenser lens 13 is omitted, and the beam expander 12 'is arranged between the beam splitter 3 and the optical scanning device A. is there. In this embodiment, the laser beam spot diameter projected from the laser oscillator 1 to the fundus E _f, and, both of the light flux diameter of the light reflected from the fundus E _f can be adjusted by the beam expander 12 '.

FIG. 6 shows an example in which beam expanders 12, 12 'are provided between the beam splitter 3 and the condenser lens 13 and between the beam splitter 3 and the lens 2, respectively. According to the present embodiment, the fundus E _f
Can be adjusted separately from the spot diameter of the laser light projected onto the _reticle and the luminous flux diameter of the reflected light from the fundus oculi Ef.

FIG. 7 shows a beam splitter of the configuration of FIG.
3 shows an example in which a condenser lens 13, a pinhole plate 14, and a photodiode 15 are arranged between the optical scanning device A and the eye E to be inspected. In this case, the reflection mirror 10 shown in FIG. 1 may be replaced with the beam splitter 3.

FIG. 8 shows an example in which the beam expander 12 between the beam splitter 3 and the condenser lens 13 in FIG. 6 is omitted.

9 to 11 show the arrangement of the beam splitter 3 between the relay lens 8 and the subject's eye E shown in FIG. 2, the space between the beam splitter 3 and the lens 2, and the arrangement of the beam splitter 3 and the lens 13. In a fundus camera provided with optical scanning devices A and A 'between
It shows an example in which the arrangement of 12 is changed. In these embodiments, the optical components from the relay lens 8 to the objective lens 11 are not shown. In these cases, the reflection mirror 10 shown in FIG. 1 may be replaced with the beam splitter 3.

FIG. 9 shows an example in which a beam expander 12 'is disposed between the optical scanning device A and the lens 2, and the beam expander 12 is disposed between the optical scanning device A' and the condenser lens 13. Things.

FIG. 10 shows an example in which the beam expander 12 'of FIG. 9 is omitted.

FIG. 11 shows an example in which the beam expander 12 of FIG. 9 is omitted.

(Effects of the Invention) As described above, the present invention provides an illumination optical system that projects laser light from a light source as spot light onto a fundus by an optical scanning device, and a light receiving unit that reflects light flux reflected from the fundus by an optical scanning device. And a light receiving optical system for receiving light through a pinhole at a position conjugate with the fundus, in a laser scanning fundus camera, wherein the light receiving optical system variably adjusts the diameter of the reflected light beam. The pupil diameter of the light-receiving optical system can be adjusted by adjusting the pupil diameter of the subject even if there are individual differences in the conditions such as the age of the subject or the subject's examination and the structure of the fundus. Can be easily adjusted to adjust the resolution of the eye to be inspected and the focus of the entire eye fundus of the eye with irregularities, so that a clear fundus image of the eye to be inspected can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing an optical system of a laser scanning fundus camera according to the present invention. FIG. 2 is a layout view of a part of the optical system of FIG. 1 as viewed from the side. FIG. 3 is a schematic explanatory view of the optical system shown in FIG. 1 and FIG. FIG. 4 is an explanatory view showing another example of the light beam diameter adjusting means shown in FIG. 5 to 11 are schematic explanatory views showing another example of the optical system of the laser scanning fundus camera according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Laser oscillator (light source) 2 ... Lens 3 ... Beam splitter 4 ... Polygon mirror (optical scanning device) 5, 6 ... Magnifying lens (optical scanning device) 7 ... Galvano mirror (optical scanning device) 8 Relay lens 9 Focus lens 10 Reflective mirror 11 Objective lens 12, 12 'Beam expander (beam diameter adjusting means) 13 Lens 14 Pinhole plate 15 Photodiode ( Light-receiving part) 16 Aperture plate (beam diameter adjusting means) A, A '... Optical scanning device E ... Eye to be examined E _f ... Fundus

Claims (1)

(57) [Claims] An illumination optical system for projecting a laser beam from a light source onto an eye fundus as a spot light by an optical scanning device, and a light beam reflected from the fundus is guided to a light receiving unit by an optical scanning device, and a light beam is conjugated with the fundus. A laser scanning fundus camera comprising: a light receiving optical system that causes a light receiving unit to receive light via a pinhole; wherein the light receiving optical system is provided with a light beam diameter adjusting unit that variably adjusts the diameter of the reflected light beam. Scan fundus camera.