Automatic refractor, lensmeter and keratometer utilizing Badal optics
US5208619A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 18, 1991 |
| Grant date | May 4, 1993 |
| Priority date | — |
| Expiry date | Jul 18, 2011 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B3/107
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
Badal optics are disclosed in which an aperture array at an optical system under test is interrogated for the deflection of light between a detector array conjugate with the aperture array of the optical system under test being examined. Excursion is measured in a plane normal to the axis of the Badal optics instead of observing towards and away image focus along the axis of the Badal system. In the case of an objective refractor, the eye is illuminated at the retina with a test spot, preferably light in the infrared. An image of a detector array is relayed by a relay lens through the Badal optics to the cornea of the eye, the lens under test. Light emanating from the test spot on the retina passes through the eye lens at the at the image of the detector array. This light undergoes excursion in accordance with the power of eye lens under test at each aperture of the detector array. The extent of this excursion is determined by a moving boundary locus between the image of the detector array and the detector array itself. This excursion is related directly to the eye prescription.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.