JPH0523305A - Ophthalmologic camera - Google Patents

Abstract

PURPOSE:To obtain an ophthalmologic camera which enables the obtaining a proper exposure value accurately for an eye to be inspected. CONSTITUTION:An illumination luminous flux extraction optical member 30 is provided in the course of an illumination light optical system 1 having light sources 3 and 5 for lighting an eye to be inspected to extract a part of an illumination luminous flux for observation and a reflected illumination flux extraction optical member 40 is provided in a photographing optical system 2 to extract the reflected flux of the illumination luminous flux for observation from an eye to be inspected. An arithmetic means 44 is arranged to determine a reflection factor as ratio to a quantity of light of the reflected luminous flux for observation based on the quantity of light of the illumination luminous flux for observation extracted with the illumination luminous flux extraction optical member 30 by computation and a quantity of emission of a photographing light source 5 is controlled by the reflection factor determined by the arithmetic means 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmic photographing apparatus capable of automatically adjusting the amount of illumination light to an eye to be inspected to adjust the amount of exposure.

[0002]

2. Description of the Related Art Conventionally, in an ophthalmic photographing apparatus, when the amount of light reflected from the eye to be examined by the photographing illumination light having a constant emission intensity is detected and the appropriate exposure amount is reached, the light emitted from the photographing light source is emitted. There is known a configuration in which the exposure is stopped to obtain an appropriate exposure amount.

[0003]

By the way, in this type of ophthalmic photographing apparatus, when the photographing region of the eye to be examined is excessively bright, the amount of reflected light becomes excessive, so that an appropriate exposure amount is obtained within an extremely short time. When the imaged region of the subject's eye is too dark, the amount of reflected light becomes too small, so the reflected light flux reaches the appropriate exposure amount in a relatively long time, and the amount of reflected light from the imaged region of the subject's eye. Directly affects the exposure amount, so that when the amount of reflected light from the subject's eye changes during imaging, for example, when the amount of reflected light from the fundus changes due to involuntary eye movement, an appropriate amount of exposure can be obtained. difficult.

Therefore, an object of the present invention is to provide an ophthalmologic photographing apparatus which can more reliably obtain an appropriate exposure amount for an eye to be examined.

[0005]

In order to solve the above-mentioned problems, the ophthalmic photographing apparatus according to claim 1 of the present invention has an illumination for observation in the middle of an illumination optical system having a light source for illumination of the eye to be examined. An illumination light flux extraction optical member that extracts a part of the light flux is provided, and a reflected light flux extraction optical member that extracts a reflected light flux of the illumination light flux for observation from the eye to be inspected is provided in the photographing optical system. The calculation means for calculating the reflectance, which is the ratio to the light quantity of the reflected light flux for observation, based on the light quantity of the illumination light flux for observation extracted by It is characterized in that the photographing illumination light amount is set to an appropriate light amount by being controlled by the rate.

According to a third aspect of the present invention, in the ophthalmic photographing apparatus, an index projection optical system for projecting an index for focusing on an eye to be inspected is provided in the illumination optical system, and the photographing optical system is provided. It is characterized in that a light shielding means is provided for shielding the index at least while detecting the reflectance.

[0007]

According to the ophthalmic photographing apparatus of the first aspect of the present invention, the illumination light flux extracting optical member extracts a part of the illumination light flux for observation. The reflected light flux extraction optical member extracts a reflected light flux of the illumination light flux for observation from the eye to be inspected into the photographing optical system. The calculating means calculates the reflectance, which is a ratio with the light quantity of the illuminating light flux for observation extracted by the illuminating light flux extracting optical member, as a reference. The amount of light emitted from the photographing light source is controlled by the reflectance obtained by the calculation means, thereby controlling the amount of photographing illumination light.

Further, according to the ophthalmic photographing apparatus of the third aspect, the index of the index projection optical system is shielded at least while the reflectance is being detected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an ophthalmologic image taking apparatus according to the present invention will be described below with reference to the drawings in which an eye fundus camera is applied.

In FIG. 1, reference numeral 1 denotes an illumination optical system, and 2
Is a photographing optical system.

The illumination optical system 1 comprises an observation light source 3, a condenser lens 4, a photographing light source 5, a condenser lens 6, a ring diaphragm 7, a relay lens 8, a mirror 9 and a relay lens 10. The photographing optical system 2 includes an objective lens 12 facing the eye 11 to be inspected, a perforated mirror 13, a focusing lens 14, and an imaging lens.
It is equipped with 15, quick return mirror 16, shutter 17, and film 18. The ring-shaped diaphragm 7 is provided with respect to the relay lenses 8 and 10 and the objective lens 12 at a position substantially conjugate with the pupil of the eye to be inspected.

Between the relay lens 8 and the ring-shaped diaphragm 7, there is provided a half mirror 20 which constitutes a part of the index projection optical system 19 for focusing. The index projection optical system 19 is the light source 2
1, an index plate 22, split prisms 23, 24. A halogen lamp is used as the light source 21 here. The split prisms 23 and 24 are integrated with the index plate 22.

The fundus camera is provided with a light shielding device 27 having a light shielding plate 26 inserted into the optical path of the index projection optical system 19. The shading device 27 has a rotary solenoid 28,
9'is its axis of rotation. The operation of the light shielding device 27 will be described later.

Between the condenser lens 6 and the ring diaphragm 7, there is provided a reflection mirror 30 which constitutes a part of the extraction optical system 29. The reflection mirror 30 extracts a part of the illumination light flux for observation. The reflection mirror 30 is provided as close as possible to the ring-shaped diaphragm 7 in order to extract light beams other than the fundus illumination light beam. The extraction optical system 29 has a condenser lens 31 for condensing the light flux reflected by the reflection mirror 30, and the light flux is focused on a light receiving element 32.

In the middle of the photographing optical system 2, a perforated mirror 13
A half mirror 33 is provided between the focusing lens 14 and the focusing lens 14. This half mirror 33 is an alignment index projection optical system.
It forms part of 34, and 35 is its light source. An LED, for example, is used for this light source.

The quick return mirror 16 is an eyepiece optical system 36.
Is inserted in the optical path of the photographing optical system 2 during observation, and is retracted from the optical path of the photographing optical system 2 during photographing. The eyepiece optical system 36 has a reflecting mirror 37 and an eyepiece lens 38. A movable mirror 40 is provided between the imaging lens 15 and the quick return mirror 16 as a reflected light beam extraction optical member for extracting a part of the reflected light beam from the fundus 39 of the eye 11 to be inspected. The extraction optical member 40 constitutes a part of the extraction optical member 41, and the extraction optical member 41 includes the condenser lens 42 and the light receiving element.
43, the reflected light flux from the fundus imaging region extracted by the extraction optical member 41 is focused on the light receiving element 43.

At the time of photographing, the alignment index is reflected by the half mirror 33, and the hole portion 13 of the perforated mirror 13 is taken.
The image is projected through the eye a onto the eye 11 to be examined, and the subject aligns the eye 11 with the alignment index.

The illumination luminous flux for observation is once focused on the position of the photographing light source 5 by the condenser lens 4 and diffused again,
The light is condensed by the condenser lens 6, and the ring-shaped diaphragm 7
Be led to. A part of the illumination light flux for observation guided to the ring-shaped diaphragm 7 is reflected by the reflection mirror 30, guided to the condenser lens 31, and focused on the light receiving element 32. Light receiving element 32
The illumination light flux for observation guided to is used as a reference light amount,
The light receiving element 32 outputs a photoelectric signal corresponding to the reference light amount to the reflectance calculation circuit 44.

The illumination light flux for observation that has passed through the ring-shaped diaphragm 7 becomes an annular light flux, and passes through the relay lens 8, the reflecting mirror 9, the relay lens 10, the perforated mirror 13, and the objective lens 12 to the fundus 39 of the eye 11 to be inspected. Illuminate. The illumination light flux for observation is the fundus 39
The reflected light beam is guided to the quick return mirror 16 through the objective lens 12, the hole portion 13a of the perforated mirror 13, the focusing lens 14, and the imaging lens 15, and is reflected by the quick return mirror 16. It is guided to the examiner's eye via the reflection mirror 37 and the eyepiece lens 38.

The pair of indexes of the index projection optical system 19 for focusing are reflected by the half mirror 20, and the relay lens 8,
It is projected onto the fundus 39 of the eye 11 to be examined via the reflection mirror 9, the relay lens 10, the perforated mirror 13, and the objective lens 12, and the reflected light flux is similarly guided to the eyepiece optical system 36. Fundus 39
When the image of (1) appears to be blurred, the pair of indexes are visually recognized separately, and when the image of the fundus 39 is clearly imaged, the pair of indexes are visually recognized to match. Index plate 22 and focusing lens
When the index plate 22 is moved along the optical path of the index projection optical system 19 for focusing, the focusing lens 14 is moved along the optical axis of the photographing optical system 2 along with the movement. Then, the fundus 39 is focused.

When the photographing switch 45 is operated at the time point t1 as shown in FIG. 2A, the rotary solenoid 28 is simultaneously driven at the time point t1 and the light shielding plate 26 is inserted into the optical path of the index projection optical system 19. The index for focusing is shown in Fig. 2.
As shown in (d), light is shielded from time t2 to time t3. Further, the light source 35 of the alignment index projection optical system 34 is turned off at substantially the same time.

Next, the driving means 46 is driven to drive FIG. 2 (b).
At time t4, the extraction optical member 40 is inserted into the optical path of the photographing optical system 2 as shown by, and a part of the reflected light flux reflected by the fundus 39 is guided to the light receiving element 43. The corresponding photoelectric signal is output to the reflectance calculation circuit 44. The reflectance calculation circuit 44 is driven from time t4 to time t5 in FIG. 2B to calculate the reflectance, and its output is input to the light emission amount control circuit 47. Here, the light emission amount control circuit 47 changes the charging voltage with which the capacitor is charged based on the reflectance information.

On the other hand, the shutter 17 is shown in FIG.
As shown in (c), it is driven at time t6, and after a certain time elapses, a sync contact signal is input to the light emission amount control circuit 2 at time t7 as shown in FIG.
Emits a flash as shown in FIG. The photographing light source 5 emits light with a light emission intensity (peak) based on the reflectance information. By changing the light emission intensity, the total light emission amount is changed according to the reflectance. The movable mirror 40 is retracted from the optical path of the photographing optical system 2 at time t5 after measuring the reflectance of the fundus photographing region immediately before photographing.

According to the present embodiment, the light source 35 of the alignment index projection optical system 34 is turned off and the light source 21 with a slow turn-off speed is shielded during the reflectance calculation prior to the detection of the reflectance of the fundus imaging region. Therefore, the reflectance of the fundus imaging part can be accurately measured.

In the above embodiments, the light shield plate 26 is rotated and inserted into the optical path of the index projection optical system 19, but instead of using the light shield plate 26, a liquid crystal shutter is provided in the optical path of the index projection optical system 19. A shutter mechanism such as the above may be provided.

In the embodiment, the index projection optical system for focusing is also used.
I tried to shield 19 indexes from light, but alignment indexes,
The fixation target may also be shielded.

[0027]

As described above, the ophthalmic photographing apparatus according to the first aspect of the present invention obtains the fundus photographing by obtaining the reflectance of the fundus photographing region. The present invention has an effect that the proper exposure amount can be set more accurately than the conventional one in which the proper exposure amount is integrated and set.

Further, according to the ophthalmic photographing apparatus of the third aspect, when the reflectance of the fundus photographing portion is obtained, the index for focusing focused on the fundus of the eye is shielded. The reflectance can be accurately obtained.

[Brief description of drawings]

FIG. 1 is an optical diagram showing an embodiment of a fundus camera as an ophthalmic examination apparatus according to the present invention.

FIG. 2 is a timing chart showing a process from reflectance measurement to a photographing light source of a fundus camera as an ophthalmic examination apparatus according to the present invention.

[Explanation of symbols]

1 Illumination optical system 2 Shooting optical system 7 Ring diaphragm 11 Eye to be examined 26 Light shield 29 Extraction optical system 30 Mirror (illumination light flux extraction optical member) 34 Extraction optical system 40 Movable mirror (optical component for extracting reflected light flux) 44 Reflectance calculation circuit

Claims (3)

[Claims] 1. An illumination light beam extracting optical member for extracting a part of an illumination light beam for observation is provided in the middle of an illumination optical system having a light source for illuminating an eye to be inspected, and an optical system for observation from an eye to be inspected is provided in a photographing optical system. A reflection light flux extraction optical member for extracting a reflection light flux of the illumination light flux is provided, and the reflection is a ratio of the light intensity of the observation illumination light flux extracted by the illumination light flux extraction optical member to the light intensity of the observation reflection light flux. An ophthalmic photographing apparatus comprising: a calculating unit for calculating a ratio, wherein the light emission amount of a photographing light source is controlled by the reflectance calculated by the calculating unit. 2. The illumination light flux extracting optical member is provided in the illumination optical system and illuminates a fundus of the eye to be inspected between a light source and a ring diaphragm that is optically substantially conjugate with a pupil of the eye to be inspected. The ophthalmic photographing apparatus according to claim 1, wherein the ophthalmic photographing apparatus is provided at a location where a luminous flux other than the illumination luminous flux can be extracted. 3. An index projection optical system for projecting an index onto the eye to be inspected is provided in the middle of the illumination optical system, and a light shielding unit is provided for shielding the index of the index projection optical system at least while detecting the reflectance. An ophthalmic imaging device characterized by being provided.