Apparatus for measuring the refractive power of an optical system
US5428414A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 30, 1993 |
| Grant date | Jun 27, 1995 |
| Priority date | — |
| Expiry date | Nov 30, 2013 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B3/103
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A compact, low-cost apparatus for measuring the refractive index of an eye utilizes a chopper which forms and scans two orthogonal fringes. In a light-receiving unit, at least three light-receiving elements are arranged not to be aligned in a line. With these light-receiving elements, time differences when the fringes pass light-receiving elements in each of two pairs are measured. A control & arithmetic unit calculates the spherical power, the cylindrical power, and the cylindrical axis degree by performing predetermined calculations using the measurement data. The apparatus requires no image rotator, and hence, a compact, low-cost apparatus can be realized. Also, the measurement time can be shortened.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.