The Direct-Reading Spectroscope is a replica diffraction grating instrument with an internal scale that shows students the wavelength in nanometers.
It is used for the detection and identification of elements by their characteristic spectral emission lines.
The light source may be from salts in a flame or from electrically excited tubes filled with elemental gases, such as helium or nitrogen. It may also be used to observe the more prominent Fraunhofer lines in the solar spectrum as well as the absorption spectra of solutions such as those that contain chlorophyll or blood.
The grating has 600 lines per mm. The scale reads from 380 to 720nm and has an actual length of approximately 35mm. The entire spectrum can be seen at once.
The slit is adjustable and a reflector is provided to back-light the scale. The housing is a one-piece aluminum casting, finished with light gray polyurethane paint, mounted on a stainless steel post and supported on a cast iron tripod base.