Direct Vision Spectroscope With Wave-Length Scale

A compact visible spectrometer which allows the direct reading of spectral length and employs a prism for dispersion. It is also useful for flame test of basic radicals (sodium , strontium, potassium, copper etc.). There is a single eyepiece and independent focusing tube for the graticule, which carries an index at 590mm, with 'D' marked right below the scale,(corresponding to the wave length of sodium light ) can be calibrated to a known screw.