Video opto-diagnostic instrument with single-adjustment focus

Abstract

A hand-held ophthalmoscope modified by the removal or augmentation of the focusing wheel and the addition of a manual or automatic focusing lens system. An electronic imager (CCD array or video camera) is placed optically conjugate to a viewing screen such that focus operations performed by the examiner to adjust the image seen by the examiner on the screen also focuses the image on the electronic imager. This is accomplished by an optical system which includes a straight path from the viewing screen to the patient's eye with a beam splitter interposed to cause the image of the patient's eye to be reflected onto the imager. As a result, when the examiner uses the focusing lens system, manual or automatic, positioned between the beam splitter and the patient's eye, to affect the image viewed by the examiner, the focus of the imager is simultaneously affected as well. Alternatively, the image from the imager is sent to a liquid crystal display (LCD) in the instrument's eye piece; when the examiner focuses the image on the LCD, the image on the imager is focused simultaneously. Also provided is an automatic focusing system for the imager that operates independently of the examiner's focusing adjustments. An automatic focusing system for the imager can also be incorporated in the other two embodiments. The output from the electronic imager can be in digital or analog form and can consist of a single frame or a video stream.

We claim:  
     
         1 . Apparatus in an opto-diagnostic instrument used by a medical examiner for simultaneously focusing first and second images of an original image of an area of interest comprising: 
 a mirror for reflecting the original image;    an imager for receiving the original image and forming a first image thereon;    a liquid crystal display (LCD) for receiving the first image from the imager and forming a second image on the LCD for direct observation by the examiner; and    a lens system located between the mirror and the area of interest for focusing the first and second images;    wherein, when the second image on the LCD is focused using the lens system, the first image on the imager is thereby focused simultaneously.    
     
     
         2 . Apparatus in an opto-diagnostic instrument used by a medical examiner for automatically focusing a first image of an original image of an area of interest comprising: 
 a beam splitter for splitting the original image into the first image and simultaneously allowing the examiner to directly observe the patient's eye;    a lens system for receiving and focusing the first image;    a partial reflector for passing the first image and a second image;    an imager for receiving the first image;    a mirror for reflecting the second image;    a lenslet array for receiving the second image and forming a third image;    a linear CCD array for receiving the third image;    an amplifier for receiving the output of the linear CCD array and forming an error signal indicative of the error in focus of the first image; and    a feedback loop for sending the error signal to the lens system, the error signal causing the lens system to automatically focus the first image.    
     
     
         3 . Apparatus in an opto-diagnostic instrument used by a medical examiner for automatically focusing a first image of an original image of an area of interest comprising: 
 a beam splitter for splitting the original image into the first image and simultaneously allowing the examiner to directly observe the patient's eye;    a lens system for receiving and focusing the first image;    an imager for receiving the first image;    an integrated circuit for receiving the output of the imager and deriving a signal indicative of the quality of the first image;    an amplifier for receiving the image quality signal of the integrated circuit and forming an error signal indicative of the error in focus of the first image based upon the received image quality signal; and    a feedback loop for sending the error signal to the lens system, the error signal causing the lens system to automatically focus the first image.