A sturdy student instrument for simultaneously showing the spectra of two gas discharge spectrum tubes against a common back-lighted scale that reads in nanometers.
This unit may also be used to observe other light sources, such as halide, fluorescent and sodium vapor lamps. It uses a fine grade replica transmission grating of 600 lines per mm to create a virtual image of the two spectra one above the other.
The scale, which is about 75 mm in actual length, is illuminated only when the push-button at the end of the cord is held closed. Calibrations are from 380 to 760 nm.
Strong spring wire clips hold the spectrum tubes securely. The adjustable slit is controlled by small side knob. The cast aluminum housing is finished with light gray polyurethane paint. The weight is well-balanced on the stainless steel post and wide-span tripod base.
A long-life 9 volt alkaline battery is included.
Spectrum tubes are to be mounted as shown, but are not included. Spectrum tubes with a wide selection of gases and elements are readily available online.