JPH02268734A - Ophthalmic imaging apparatus - Google Patents

Abstract

PURPOSE:To obtain an image in focus at all regions by selecting the optimum region reduced in image blur from all of images using the images taken at a plurality of focus positions in a depth direction to synthesize an image. CONSTITUTION:The image of the eyeground obtained when a lattice part 6a and a transparent part 6b are inserted in a light path at the first and second positions of the focusing lens 10 focused on the eyeground is taken in a microprocessor 13. When the lattice part 6a is inserted, lattice images L1, L2..., are looked in the image of the eyeground and, with respect to the vertical directions m1, m2... of the lattice images L1, L2..., when the blur states at the first and second positions ar a compared, the blur state of the image of the eyeground can be compared. Blur positions are different between the first and second positions of the focusing lens 10. The images of the same region at a non-blur position are extracted from a frame memory 16 or 18 and a frame memory 17 or 19 in the microprocessor 13 to be stored in a frame memory 20. When image taking-in, comparing and memory operations are repeated, an image in focus is obtained and can be also observed on a television monitor 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fundus imaging device for photographing the fundus of an eye to be examined, for example, in an eye clinic or the like.

[Prior Art] Conventionally, when taking a fundus image of the subject's eye using an optical imaging means, only a specific part of the uneven fundus is focused in the depth direction, and the focused range is the field of view. Since it is limited by the depth of field, in order to increase the depth of field and focus, the F number must be increased.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, since the fundus has irregularities, when focusing on the fundus in the depth direction, other parts become out of focus. Also,
If the F number is increased to increase the depth of field, the fundus image will become darker, so there is a limit to the size of the F number. Furthermore, if the imaging aperture diameter is determined in advance for fundus imaging, there is a drawback that it is impossible to focus on any part.

An object of the present invention is to solve the above-mentioned drawbacks of the conventional example, and to provide a method for determining the depth of all parts from multiple captured images when photographing the fundus, which has unevenness and cannot be focused in the depth direction on all parts at once. An object of the present invention is to provide a fundus imaging device that synthesizes images that are directionally focused.

[Means for Solving the Problems J] In order to achieve the above object, the fundus imaging device according to the present invention includes an illumination optical system having an index that is selectively projected onto the fundus of the eye to be examined, and a fundus of the eye to be examined. - an imaging means for imaging the fundus of the eye to be examined; a focus adjustment means for adjusting the focus on the fundus surface while holding the index and the imaging means conjugate with respect to the fundus of the eye to be examined; and a plurality of focal points set by the focus adjustment means. a comparing means for partially comparing the focus state from the image when the index is projected at each position; a synthesizing means for selectively capturing the images at each comparison position and synthesizing a fundus image;
The apparatus is characterized by comprising a display means for displaying the fundus image synthesized by the synthesis means.

[Operation] The fundus imaging device having the above-mentioned configuration can obtain an image in which all parts are in focus in the depth direction when capturing an uneven fundus image.

[Example] The present invention will be explained in detail based on illustrated embodiments.

Fig. 1 shows a configuration diagram, where ■ is a light source, and along the optical path from the light source 1, there is a condenser lens 2, a reflecting mirror 3, a ring slit plate 4, a relay lens 5, and a movable index plate that rotates around the axis O. 6, a relay lens 7 and a perforated mirror 8 are arranged, and an objective lens 9 is arranged along the reflected optical path of the perforated mirror 8. Behind the hole of the perforated mirror 8.

2 orcasing lens 10. Photographic lens 11, two-dimensional C
Imaging means 12 consisting of an OD or the like is arranged. The output of the imaging means 12 is connected to a television monitor 14 and an A/D converter 15 via a microprocessor 13.
The output of converter 15 is connected to five frame memories 16-20.

The movable index plate 6, which uses a glass plate, is provided with a grid section 6a and a transparent section 6b as shown in FIG. The grid section 6a or the transparent section 6b can be selected and introduced into the illumination optical path. The grid chart Li on the grid section 6a
The imaging surface L2a of the imaging means 12 is always conjugate with the fundus Ef in conjunction with the focusing lens 10, so that focusing in the depth direction can be achieved.

The light from light source 1 passes through condenser lens 2 and reflection mirror 3.
．． The light beam passes through the ring slit plate 4, becomes a ring-shaped light beam, and further passes through the relay lens 5, movable index plate 6, and relay lens 7, and forms an image around the hole of the perforated mirror 8. The light flux that enters the perforated mirror 8 from the above-mentioned illumination optical system is reflected by the perforated mirror 8 in the direction of the eye E to be examined, and then passes through the objective lens 9.
It reaches the fundus Ef of the eye E to be examined. The light irradiating the fundus E' returns along the original optical path, passes through the hole in the perforated mirror 8, passes through the focusing lens 10 and the photographic lens 11, and forms an image on the imaging surface 12a on the imaging means 12.Imaging surface 1
The image of the fundus Ef formed on 2a is captured into the microprocessor 13, and its output is stored in one of the frame memories 16-20 after passing through the A/D converter 15.

The first position of the focusing lens lO focuses on a part of the fundus Ef, and the focusing lens 1 moves the focus position of the fundus El and refocuses it.
0 and the second position, the fundus images obtained when the grating section 6a is inserted into the illumination optical path and immediately after that, the transparent section 6b is inserted into the optical path are respectively taken into the microprocessor 13, Furthermore, via the A/D converter 15, the fundus image when the grating section 6a and the transparent section 6b are inserted at the first position is stored in the frame memory 18. A fundus image obtained when the unit 6b is inserted is stored in the frame memories 18 and 19. .

When the lattice portion 6a is inserted as shown in FIG. 3, the lattice images L1, L2, . . . are seen in the fundus image, so these lattice images L1, L2, By comparing the blur states at the first position and the second position for vertical shoulders 1 and 12, fist φ-11, and 3, it is possible to compare the same blur states in the fundus images. m of Li lattice image
A/D at the first and second positions for position i
Letting the output values of the converter 15 be Ai and ai, respectively,
Since the fundus E has irregularities, the position of blurring is different between the first position and the second position of the focusing lens 10, as shown in FIG.
Ai is compared with ai, and an image of the same part at a less blurred position is stored in the frame memory 16 or 18.
, and is extracted from the frame memory 17 or 19 and stored in a separate frame memory 20. All lattice images Li
and all 11, m2. By comparing the blurred states of No.-mi, . be able to.

Similarly, the lattice portion 6a and the transparent portion 6 at the third position of the focusing lens lO after moving the focus position on the fundus Ef.
The fundus image when b is inserted is stored in the frame memory 16.17 from which the image has been erased, and the fundus image is stored in the frame memory 18.1.
The microprocessor 13 compares the blurred state with the image No. 9, and stores the more focused image in the frame memory 20.
Replace with the image above.

By repeating the above focusing, image capture, comparison, and storage operations, you can finally obtain an image that is well focused in the depth direction on the metal part of the screen, and display it on the TV monitor 14 to display the image. You can also observe it.

In the above embodiment, the same frame memory is used multiple times by repeating erasing and writing, but it is also possible to prepare frame memories necessary for the number of operations in advance and store images independently.

Further, as another embodiment, a rotation index plate 6'' as shown in FIG. 5 may be inserted into the illumination optical path. A chart 6a'' is provided, and if the 0 rotation indicator plate 6' rotating around axis 0 is rotated by a fixed angle and the blur state on the chart 6a' is compared as in the above embodiment, , a new in-focus image can be constructed.

Although the light source is not specified in the above embodiments, a strobe light source may be attached to the light source 1 to emit strobe light when capturing one image, or a telecentric optical system may be used for the light beam projected onto the focusing lens 10. if,
This is further advantageous because the image height remains unchanged even if the focus moves.

[Effects of the Invention] As explained above, the fundus imaging device according to the present invention compares the blur state of each part of the image using captured images at a plurality of focus positions in the depth direction, and selects the optimal part with small blur. Since the images are selected from all images and combined, it is possible to obtain an image in which all parts of the eye are in focus, even if the fundus is uneven.

[Brief explanation of drawings]

The drawings show an embodiment of the fundus imaging device according to the present invention.
The figure is a configuration diagram, Figure 2 is a front view of the movable index plate, Figure 3 is a fundus photographed image with a grid image projected, Figure 4 is an explanatory diagram of blur state comparison, and Figure 5 is a rotation of another embodiment. It is a front view of an index board. Reference numeral 1 is a light source, 2 is a condenser, 4 is a ring slit plate, 5 and 7 are relay lenses, 6 and 6° are rotary index plates, 8 is a perforated mirror, 9 is an objective lens, 1O is a focusing lens, and 11 is a photographing lens. lens, 12 is an imaging means, 13 is a microprocessor, 14 is a television monitor, 15 is an A/D
converter. 16 to 20 are frame memories. Patent applicant Canon Co., Ltd. Figure 2! Figure 4

Claims (1)

[Claims] 1. An illumination optical system having an index selectively projected onto the fundus of the eye to be examined, an imaging means for taking an image of the fundus of the eye to be examined, and the index and the imaging means held in a conjugate state with respect to the fundus of the eye to be examined. a focus adjustment means for adjusting the focus with respect to the fundus surface; a comparison means for partially comparing the focus state from the image when the index is projected at a plurality of focus positions set by the focus adjustment means; 1. A fundus imaging device comprising: a composition means for selectively capturing images and composition of a fundus image; and a display means for displaying a fundus image composed by the composition means.