Importance

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Abstract

A field tester wherein a patient's tested eye is located at the center of an interior hemisphere defining a projection surface and wherein a light spot is projected onto said surface from an eccentric location is disclosed. Optics in common with the projector assure that the off-center projected light is of constant intensity and diameter as selected for each test sequence according to test criteria. Specifically, a filament light source is projected to a collimating lens. The light source is re-imaged to a system lens stop. There is a movable aperture between the collimating lens and the first lens of telescopic optics for projecting the image of the aperture onto the projection surface of the sphere. By using a coordinate transform to predict the distance from the point of light source projection to the projection surface of the sphere, the movable aperture is registered to a conjugate distance with respect to the telescope optics. Aperture registration insures projection of a constant image of the aperture to any point along sphere surface. There results a field testing spot of constant diameter and intensity, according to selected image criteria, in spite of a continuously changing distance between the point of projection and projecting surface on the inside projection hemisphere. An apertured finder for centering of the patient's eye is also disclosed wherein relay optics projecting a real image of the patient's eye as viewed through a peep hole assure a wide angle view of the eye being tested. The eye is viewed through an aperture having a sight that does not significantly interfere with the test being conducted.

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First Claim