Define Essential Parts of Photocolorimeter - Sample Cuvettes?

For accurate and precise reading, cuvette must be transparent, clean, devoid of any scratches and there should be no bubble adhering to the inner surface of the filled cuvette. Square or rectangular cuvettes with flat optical surface are most desirable. Optical path in the cuvette is always 1 cm. The capacity may be 3-4 ml or 1 ml depending upon the thickness of the side walls, that is broader or narrower. Glass cuvettes are used for reading in the visible light range while quartz or fused silica cuvettes are used for UV range.