Field tester
US4561738A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 26, 1982 |
| Grant date | Dec 31, 1985 |
| Priority date | — |
| Expiry date | Oct 26, 2002 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B3/024
- WIPO fieldMedical technology
- WIPO sectorInstruments
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 chan…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.