Patent ID: 7758190

Claim:
An apparatus for measuring the thickness of the lipid layer on the surface of a patient's eye after distribution of the lipid layer subsequent to blinking comprising: an illuminator that directs light to the lipid layer of a patient's eye, the illuminator comprising a broad spectrum light source in the visible region being a lambertian emitter such that the rays from the light source are specularly reflected from the lipid layer and undergo constructive and destructive interference in the lipid layer, wherein said illuminator further includes a plurality of spaced apart light emitting diodes adapted to emit light in the visible region; an imaging device for observing the specularly reflected light such that the interference patterns on the tear film lipid layer are observable; and a diffuser for diffusing the light emitted by the respective light emitting diodes positioned between said light emitting diodes and the surface of the eye, wherein the diffuser is arcuate such that the light rays emitted therefrom strike the surface of the eye such that Snell's law is satisfied with respect to the acceptance angle of said imaging device so as to produce an observable area of interference on the eye.