An apparatus suitable for receiving a sample for optimetric analysis includes a sample cell comprising an opaque hollow tube. Several apertures are defined in the wall of the tubing and a lens barrel which extends beyond to opposite surfaces of the wall is supported within at least one of the apertures. A housing is provided with one channel for receiving the sample cell and a series of channels extending from the exterior housing to the sample cell apertures. A filter element is housed in each of these latter channels. These channels slidingly receive an excitation light source for a photodetector cell to permit selective focusing. A sample cell containing at least three apertures in the walls can be mounted for rotation relative to a light source or photoconduction means for simultaneous or alternative optimetric determination of the components of a single sample. The sample cell is fabricated by supporting a lens barrel within the aperture. A molten portion of glass is deposited in the lens barrel and cooled while in a horizontal position to form a lens having an acceptable angle
