180 



RADIATION BIOLOGY 



100 



80 



2 60 



> 



< 40 

 _j 

 u 

 a: 



20 



BLUE 



GREEN GOLD PINK r,i^n 



~.-l^-..-^ 1-.^- 



250 300 350 400 450 500 550 600 



WAVE LENGTH, (D/x 



650 



700 



750 



800 



250 



£ 200 



150 

 5 100 



5 50 



STANDARD ^ 

 WARM WHITE / 

 / 



DELUXE 

 WARM WHITE 



DAYLIGHT 



500 W 



GENERAL SERVICE 



INCANDESCENT LAMP 



250 



300 



350 



400 



650 



700 



750 



800 



4 50 500 550 600 

 WAVE LENGTH, m/t 



Fig. 3-15. Spectral emission of fluorescent lamps. The data include only the fluores- 

 cence spectra from the middle part of the tube. The weak line spectra from the 

 mercury discharge and the infrared radiated by the filaments are not included in the 

 curves. The relative intensities of the mercury lines are indicated by the black bars 

 on the upper graph. {Data by courtesy of General Electric Company.) 



LUMINOUS EFFICIENCY 



The luminous efficiency of the radiant energy of the phosphors of the 

 standard commercial "white" fluorescent lamp is over 300 lumens \v~\ 

 which is nearly half the theoretical efficiency of a yellow-green source 

 with all its energy at 555 ran. This high efficiency implies that the phos- 

 phor radiant energy is confined largely to the visible and that relatively 

 Uttle is radiated in the infrared and ultraviolet. However, in the com- 

 plete lamp, infrared from the electrodes and the warm tube reduces the 

 luminous efficiency to about 150 lumens w~^ The fluorescent lamp has 

 been consequently characterized as a "cool" source. A 40-w fluorescent 

 lamp converts about 20 per cent of the input electrical power into the 

 visible and over 25 per cent into the infrared (Table 3-13). Most of the 

 remaining power is dissipated as heat to the surrounding air by con- 

 duction and convection. By contrast, the incandescent lamp radiates 

 over 90 per cent of the input electrical power. 



