The housing of the optical system should minimize any possibility of errors due to stray light; this is particularly relevant in the short-wave region of the spectrum.
CONTROL OF WAVELENGTHS Verify the wavelength scale using the absorption maxima of Holmium Perchlorate Solution, the line of a hydrogen or deuterium di lamp or the lines of a mercury vapour are shown below. The permitted tolerance is 1 nm for the range 200 to 400 nm and nm for the range 400 to 600 nm