CHARACTERIZATION OF MODIFIED FEL QUARTZ-HALOGEN LAMPS FOR PHOTOMETRICSTANDARDS

The stability of luminous intensity and colour temperature of modified FEL-type, 1000W quartz-halogen lamps has been tested at various colou r temperatures to investigate the suitability of these lamps for use a s photometric transfer standards. During 60 h of operation at 2856 K, after seasoning for 100 h, the changes of luminous intensity of these lamps were 0,2 % to 0,6 %, and the changes of colour temperature were less than 2 K. The changes in relative spectral power distributions (n ormalized at 550 nm) over the 60 h of operation were within 0,5 % in t he visible region. The FEL-type lamps operated at 2856 K showed satisf actory stability within the limited duration of these tests. Character istics of the lamps have also been investigated for operation at 2000 K to 3100 K, for reversed polarity, and for long-term storage.