Coaxial spatially resolved refractometer

US6000800A · kind A · utility

Assignee

• The Schepens Eye Research Institute, Inc. · US

Inventors

• Robert H. Webb · Lincoln, US
• Stephen Burns · Reading, US
• Carl M. Penney · Saratoga Springs, US

Key dates

• Filing date: Jun 22, 1998
• Grant date: Dec 14, 1999
• Expiry date: Jun 22, 2018

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61B3/1015
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

A refractometer provides a reference path coaxial with a measurement path and thereby simplifies construction by reducing the number of parts and simplifies maintenance by halving the number of optical axes to be aligned. The refractometer includes a reference projector for projecting a reference pattern on a reference pattern position on a detector during a reference interval, a site-selector for selecting a measurement site on an optical system, and a measurement projector for projecting a measurement pattern through this selected measurement site and onto a measurement pattern position on the detector during a measurement interval. The reference projector, the site selector, and the measurement projector are all aligned along the same optical axis. In the case in which the optical system is a human eye, the designated site in typically a site on the cornea and the detector is the retina of the eye. The refractometer provides an aligner for alignining the reference pattern position with a measurement pattern position. The amount by which these two positions are moved in order to achive alignment provides a measure of the optimal wavefront corresponding to the measurement site.