Mercury spectrum using slit and grating, includes UV lines.

Light from a mercury lamp passes through a slit, a 10" achromat lens and then a 750 lpmm transmission diffraction grating, creating a mercury line spectrum on a projection screen about 10' away. If the adjustable slit is narrowed to a small separation, the main clearly visible lines are a purple line, a green line, and two yellow lines (although several other dim lines are visible if one is standing close to the screen.) A zinc sulphide screen is used to show the UV lines. Note to setup people: The slit is positioned as close as possible to the Hg lamp. The lens must be fine adjusted to focus the lines on the screen. An iris should be inserted in the setup between the lens and grating. A mask (not shown) should be inserted between the slit and the lens. Mercury spectrum using slit and grating, includes UV lines.