Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2000-09-06
2001-10-30
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06309070
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an integrated ophthalmic illumination method and system and more particularly, to an illuminating device providing both white and laser light sources, to be used as needed. The inventive device has in its illumination path a color filter plate that is divided into a plurality of filter sections for producing a high resolution color image using a monochromatic camera, making it capable of monochromatic imaging and excitation of fluorescent dyes.
BACKGROUND OF THE INVENTION
Currently, many color images are produced for various medical purposes using either single chip color video cameras or color cameras with 3 charge-coupled devices (CCDs), each of the CCDs being monochromatic and representing one of the primary colors R (red), G (green), and B (blue). The method of use of a single chip color camera is limited in resolution, since each pixel is dedicated to only one of the colors. The resolution obtained, therefore, would be significant lower.
Three-chip CCD cameras may be used for the production of monochrome as well as color images. However, prices for such a camera are significantly high, thus precluding the production of images with resolutions above 512×512 pixels.
In order to maximize resolution, a different method is used in which an illuminating means sequentially irradiates light of the three primary colors to illuminate the eye. The imaging signals are read in synchronism with the TV camera frame integration cycle for each color and are processed by a computer to display the image in color. This sequential color imaging has the advantage that it produces an image with high resolution, using a relatively inexpensive monochromatic single chip camera.
However, some procedures (e.g. fundus examination with indocyanine green (ICG)) require stronger light than that provided by a conventional light source, such as a non-coherent light. Prior art devices use flash pulse photography to get single frame photographs of the image desired. This often results in low-resolution images when an inadequate intensity of pulse is applied. Also, there are many cases where dynamic imaging is necessary and cannot be obtained with flash pulse photography.
A laser light could provide a continuous light source, however, the light intensity of a laser is undesirable for some uses because of its strength and the heat which it generates which raise safety issues regarding direct application to the eye. Therefore, it is necessary to decollimate the laser light. An infrared fundus video angiography system is provided in U.S. Pat. No. 5,400,791 to Schlier et al. having a decollimated laser light, however no monitoring is provided for ascertaining the safety of the light intensity passing through the system.
Thus, it would be desirable to provide a cost-efficient illumination system for high resolution monochrome or color-imaging in optical diagnostic equipment, integrating both conventional incandescent and laser light sources, both sources being monitored by a computer feedback system for precise and safe operation for a variety of uses.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to overcome the disadvantages associated with conventional illumination systems for optical diagnostic equipment, and provide a high resolution imaging system with alternative illumination sources.
In accordance with a preferred embodiment of the present invention there is provided a method for integrated ophthalmic illumination comprising the steps of:
providing a light source producing a light beam;
separating red, green and blue components of said light beam;
sequentially illuminating the eye with said separated red, green and blue components at a rate of one component per frame;
imaging said sequentially illuminated subject;
processing said sequential color images such that said separated red, green and blue components are combined so as to obtain a high resolution color image.
There is also provided an integrated ophthalmic illumination system comprising:
a first light source, said first light source being a lamp;
first collimating optics, to provide a collimated light beam from said first light source;
a first light intensity monitor for monitoring said collimated light beam;
a second light source, said second light source being a coherent light source;
second collimating optics, to provide a collimated coherent light beam from said second light source;
a second light intensity monitor for monitoring said collimated coherent light beam;
a separation unit for separating red, green and blue components of said collimated light beam, so as to produce sequential color images;
a computer processor; and
an electronic image capturing sensor,
said computer processor taking said sequential color images obtained using one of said first and said second light sources and forming therefrom at least one of a high resolution color and monochromatic image.
In the preferred embodiment of the invention, there is provided an illumination system having two integrated light sources, a lamp (including but not limited to a tungsten, metal halide or halogen lamp or any type of filament or gas lamp) and a coherent light beam such as an infrared (IR) diode laser. In a preferred embodiment, color images are provided using an RGBT (red-green-blue-transparent) filter wheel. The filter wheel is divided into four sections or arc sections around the periphery of the wheel. Three of the four partitioned sections are larger and equal sections that comprise the three optical R, G and B filter sections. The fourth section is a transparent, or empty, narrow section that is used for transferring the full original content of the white beam when a monochromatic or chromatic image is desired. The RGBT wheel rotates at a speed of one third of the frame rate of a CCD camera, producing a sequence of definite R, G and B spectral light bursts. These light bursts illuminate the interior of the eye, enabling a whole image of the eye fundus to be reflected out and detected by the image capturing sensor. These R, G and B illuminated images are later composed by a computer into a single colored picture.
In an alternative embodiment, similar color splitting is accomplished by means of an X-cube splitter used to divide the white light into its R, G and B components. In yet another preferred embodiment, a series of three 45° tilted beam splitters or dichroic spectral beam splitters are used to divide the light into three channels, and then the desired wavelengths are filtered from each channel.
A second filter wheel is provided with several spaced filters mounted around a disc which allow for use in monochromatic illumination and excitation with angiographic agents. The filter wheel locks in certain positions where one of the interchangeable filters overlaps the entire beam cross section, thus isolating a certain spectral window from the full “white” content of the beam. This filter wheel is provided with a transparent section to allow full spectral content of said collimated light beam to pass through when a filter is not needed.
Other features and advantages of the invention will become apparent from the following drawings and description.
REFERENCES:
patent: 4781453 (1988-11-01), Kobayashi
patent: 5997141 (1999-12-01), Heacock
patent: 6099127 (2000-08-01), Manivannan et al.
Peled Shimon
Svetliza Eduardo
Wigderson Oded
Langer, Pat. Atty. Edward
Manuel George
Medibell Medical Vision Technologies Ltd.
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