<P> To correct the bluish tinge, many mercury vapor lamps are coated on the inside of the outer bulb with a phosphor that converts some portion of the ultraviolet emissions into red light . This helps to fill in the otherwise very - deficient red end of the electromagnetic spectrum . These lamps are generally called "color corrected" lamps . Most modern mercury vapor lamps have this coating . One of the original complaints against mercury lights was they tended to make people look like "bloodless corpses" because of the lack of light from the red end of the spectrum . A common method of correcting this problem before phosphors were used was to operate the mercury lamp in conjunction with an incandescent lamp . There is also an increase in red color (e.g., due to the continuous radiation) in ultra-high - pressure mercury vapor lamps (usually greater than 200 atm .), which has found application in modern compact projection devices . When outside, coated or color corrected lamps can usually be identified by a blue "halo" around the light being given off . </P> <P> The strongest peaks of the emission line spectrum are </P> <Table> <Tr> <Th> Wavelength (nm) </Th> <Th> Name (see photoresist) </Th> <Th> Color </Th> </Tr> <Tr> <Td> 184.45 </Td> <Td> </Td> <Td> ultraviolet (UVC) </Td> </Tr> <Tr> <Td> 253.7 </Td> <Td> </Td> <Td> ultraviolet (UVC) </Td> </Tr> <Tr> <Td> 365.4 </Td> <Td> I - line </Td> <Td> ultraviolet (UVA) </Td> </Tr> <Tr> <Td> 404.7 </Td> <Td> H - line </Td> <Td> violet </Td> </Tr> <Tr> <Td> 435.8 </Td> <Td> G - line </Td> <Td> blue </Td> </Tr> <Tr> <Td> 546.1 </Td> <Td> </Td> <Td> green </Td> </Tr> <Tr> <Td> 578.2 </Td> <Td> </Td> <Td> yellow - orange </Td> </Tr> </Table> <Tr> <Th> Wavelength (nm) </Th> <Th> Name (see photoresist) </Th> <Th> Color </Th> </Tr>

Difference between mercury vapour lamp and sodium vapour lamp