Apparatus for measuring frontal power of contact lenses

Claim 1

Apparatus for measuring the frontal power of soft corneal contact lenses made of a somewhat hydrophilic material having a predetermined index of refraction, in a liquid having itself a predetermined index of refraction, which comprises a frame and, mounted on this frame, a measuring optical system and a sighting optical system spaced from each other and having a common optical axis extending substantially vertically at least in the gap between said two optical systems, a cup disposed in said gap and filled with said liquid, the cup bottom comprising a fluid-tight window permitting the passage of light beams from said measuring optical system to said sighting optical system, and means for supporting and centering a contact lens of which it is desired to measure the frontal power in said liquid in a substantially horizontal position with the optical axis of the contact lens merging into the vertical optical axis of the apparatus, said sighting optical system extending vertically, and being movably mounted on said frame so that it can selectively be brought to an operative position with its lower end immersed into the liquid contained in said cup and to a clear position away from said cup, to permit the positioning and removal, respectively, of the supporting and centering means with the contact lens to be measured.