The present invention relates to the testing, appraisal, and comparison of endoscopes by using an array of targets including a grid of evenly spaced pinholes to measure at least the image quality, field of view, distortion, and depth of field of an endoscope, a diffuse but translucent white target, a single pinhole target and a detector for measuring luminous flux.
The heart of an endoscopic system is in its endoscope. There are two optical typesxe2x80x94those which utilize lenses for image forwarding and formation, and those which utilize fiber optic bundles for forwarding the image. The former is usually referred to as a xe2x80x9crigidxe2x80x9d endoscope, and the latter as a xe2x80x9cflexiblexe2x80x9d endoscope. In all cases, the elements of the endoscope are carefully installed and aligned by the manufacturer so as to present the best image to the ocular piece, or to the camera, as possible.
The performance characteristics of the individual endoscope are of immediate and very intimate importance to the surgeon. Thus, the surgeon is to be aware, before the procedure, that the endoscope can inherently deliver the quality of image he requires, and that if it inherently has such quality, the instrument is in good enough condition that it can deliver that quality.
Depending on the inherent design of the endoscope, the specific instrument might not provide the magnification, clarity, depth of field and resolution which would be required, even if it appears undamaged from a cursory inspection.
Then it is an unfortunate fact that actions apart from its actual use in the patient such as handling, transporting and cleaning, the endoscope may have become misaligned or otherwise damaged. A resulting inability to resolve an area of the field should not first be discovered by the surgeon while the endoscope is inserted in the patient during an endoscopic procedure, as this may result in adverse consequences including additional surgery costs, surgery cancellations and increased risk to the patient.
What is desired, therefore, is an apparatus for evaluating the optical performance of an endoscope that utilizes a minimal number of measuring devices for performing a wide variety of optical tests. Also desirable is an apparatus for evaluating the optical performance of an endoscope that utilizes a grid of evenly spaced pinholes to measure the image quality, field of view, distortion, and depth of field of an endoscope. Providing an apparatus for automatically evaluating the optical performance utilizing a bifurcated fiber optic cable to precisely measure transmission of illumination fibers without manual intervention during a test is also desirable is also desirable. A method for automatically performing a series of tests on an endoscope and for comparing the results of these tests with a set of standardized parameters is also desirable, as is an apparatus for visually displaying the results of this comparison.
An apparatus and method according to the invention achieve it by generating beams of light which are transmitted through a distal end of an endoscope towards a proximal end of the endoscope. As a result, output signals indicative of one or more performance characteristics measured by a variety of tests are generated in response to signals corresponding to one or more of the conducted tests.
Particularly, a combination of a grid target, a diffuse but translucent white target, a single pinhole target and a detector for measuring luminous flux is capable of performing a variety of tests. This variety of tests includes measuring a field of view, geometrical distortion, angle of view, image quality at single and various object distances, percentage light transmission through illumination fibers, relative light transmission and illumination intensity across the field of view.
According to one aspect of the invention, a grid target has a plurality of pinholes and is utilized to measure the image quality, field of view, distortion, and depth of field of an endoscope to be tested. Thus, utilizing a single target which is provided with a plurality of evenly spaced pinholes, each having a uniform size, can make a variety of measurements.
In accordance with another aspect of the invention, a bifurcated fiber optic light guide attached to a light source is utilized to measure illumination transmission efficiency. The light guide is specifically designed so that it the output of one of the bifurcated ends end is known, then so it the output of the other. Thus, measuring the power out of the one unattached bifurcated end of this guide light and measuring the power out of the endoscope to which the other bifurcated end is attached one can calculate the transmission of the scope.
A number of tests can be automatically selected by utilizing a control system of the inventive device which allows a user to bypass any of the regular tests. The control system includes a central processing unit regulating the sequence of operations leading to performing any of or all of the regular optical tests. Images of the results can appear on a monitor and be compared to the standardized results stored in the system""s database. Some of the images can be color-coded to assist a user in easy identification of the optical performance of the tested scope.
The apparatus in accordance with the invention allows a user to test an endoscope by comparing its optical performance with a standard endoscope whose parameters are stored in database. Alternatively, an endoscope can be tested without being compared with the standard one. Also, a set of new parameters of an endoscope to be tested can be added to database of the apparatus.
Accordingly, it is an object of the invention to provide a method and apparatus for evaluating the optical performance characteristics of a fiber optic endoscope.
Still another object of the invention is to provide an apparatus for measuring the mage quality, field of view, distortion, and depth of field of an endoscope by utilizing a single target having a plurality of pinholes.
Yet another object of the invention is to provide a method and apparatus for measuring illumination transmission of an endoscope by utilizing a bifurcated fiber optic light guide.
It is a further object of the invention to provide a method for operating an apparatus for evaluating the optical performance of an endoscope in a variety of automatic and manual modes.
It is still another object of the invention to provide a method for operating an apparatus for evaluating the optical performance of an endoscope to assist a user in conducting the evaluation.