A low pressure mercury lamp is one of the most popular discharge lamps in lab, frequently used for wavelength calibration of optical measuring instruments and disinfection. Their comparatively efficiency, good color rendition, very long lifetime make this type of traditional lamp ideal source for various applications even now.
Low pressure mercury lamp use mercury in an excited state to produce light. The arc discharge is generally confined to a little fused quartz tube mounted within a larger borosilicate glass bulb. As the main arc strikes and the gas heats up and increases in pressure, the light becomes visible and then appears more white.