Colorimeter using interchangeable meter face members

Claim 1

Colorimetry apparatus for performing any selected ones of a plurality of different qualitative assays of biologic materials and to provide, according to a selected assay, quantitative date based on the light absorption characteristics of a test sample, containing a biologic material and prepared for such assay, which apparatus comprises in combination a housing; a circuit including a power connection and an unscaled meter having an indicator carried on the housing; a block carried within the housing and providing a testwell; a light source to provide a plurality of paths of light emanation through the block and across the test well, said light source comprising a lamp and a plurality of fiber optics elements, each fiber optic element having a predetermined number of individual fibers depending upon the quantum of light required for a particular assay, the distal end of each element being held in a wall defining the testwell, all of such fiber optic elements joined in a proximal common end which receives light emanation from the lamp; a plurality of photocells carried in the wall defining the testwell, each photocell being opposite a corresponding distal end of a fiber optic element and being particularly responsive to light within a respectively different wave band, and arranged to be includable in the circuit; at least the selected one of a plurality of dial members, each such dial member providing a scale for different assay, adapted to be emplaced in and removed from readable assocIation with the indicator, and having respectively distinguishing selector means; and switch means on the housing responsive to the selector means of the selected dial member to include in the circuit one of the photocells, so that when the selected dial member is emplaced in readable association with the indicator, and power is supplied to the circuit, and a test sample is placed in the testwell across the light path to the in-circuit photocell, the light transmitted to the in-circuit photocell influences the meter, and the indicator is caused to show in the scale, the reading for the test sample.