Abstract: A method and apparatus are disclosed for detecting sample fluid on an analysis slide of the type which is used to perform quantitative analyses. The apparatus comprises means for projecting radiation comprising wavelengths absorbed by water onto the slide and means for measuring the intensity of radiation received from the slide, both before fluid is metered on the slide and after fluid has been metered thereon. The difference between radiation received from a wet slide and from a dry slide is compared with known values to determine if the slide contains sufficient fluid for a suitable test result.

Abstract: An objective lens comprising a front positive meniscus element, a middle negative biconcave element and a rear positive biconvex element. Improved optical performance at a relative aperture of f/1.70 is achieved by the incorporation of an asphere on the rear surfaces of the first and second elements.