Instrument for optically measuring soft contact lens parameters
AssigneeAmerican Optical Corporation
InventorC. Hermas Swope
Life of this patent
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Abstract
Apparatus is disclosed for determining, with improved accuracy, the back vertex power of a hydrated soft contact lens. The increased accuracy is determined by sequentially using several optical modes to provide additional information needed to accurately calculate back vertex power. Lens thickness, sagittal height and posterior radius values are also accurately obtained with the apparatus. Optionally, a mode for determining lens radius and thickness is also disclosed.
Claims11
An optical system having a center line for accurately measuring parameters of a soft contact lens supported on a pedestal and submerged in a liquid which comprises,
- a source of collimated light,
- means for directing light from said source toward one side of the lens along a first path parallel to and spaced from the center line,
- first objective means for imaging light on said center line, said first objective means being selectively positionable on the center line between said means and the lens,
- second objective means for imaging light on the center line, said second objective means being located on the other side of said lens,
- reflection means for reflecting light received from said second objective means along a second path, a plane common to said first path, said second path and the center line, and said center line being located between said first and second paths, a portion of said second path being parallel to said center line, and
- detection means for determining when said portion is spaced from said center line the same as said first path.
Dependencies are inferred from the claim text.