280 INSTRUMENTATION IN SCIENTIFIC RESEARCH [Chap. 5 



bolometers are "at best 2 to 3 times better than the Golay pneumatic 

 detector 1 and 10 to 20 times better than the best thermopiles and 

 room-temperature bolometers." 2 



Comparison of different bolometers is very difficult. A consider- 

 able number of parameters enter in the performance characteristics 

 of bolometers as they do in other light transducers, as has been 

 pointed out by Jones, 3 so that data on the sensitivity or the input 

 or output characteristics have very limited value and are omitted 

 here. Comparative studies made by Fuson 4 are tabulated in Table 

 16; others made by Billings, Barr, and Hyde 5 in Table 17. The 



Table 16. Comparison of Thermal-radiation Receivers* 



Type 



Shortest response 

 time, msec 



AJ , watts | 



Superconducting bolometer 



Platinum strip bolometer 



Evaporated nickel bolometer 



Semiconducting bolometer 



Thermocouple 



Golay (pneumatic) detector 



x 10" 10 



* N. Fuson, J. Opt. Soc. Am., 38, 845 (1948). 



t AJ is that value of steady incident radiation power which produces a 

 steady output equal to the rms Johnson noise. 



Table 17. Comparison or Thermal Receivers* 



Type 



Response time 



Calc. threshold, 

 watts 



Metal bolometer 

 Thermistor bolometer 

 Dielectric bolometer 

 Thermocouple 



4.0 msec 

 3.0 msec 

 3.5 sec 

 0.2 sec 



3.3 x 10~ 8 



7.2 x 10" 8 



2.3 x 10~ 4 

 3.0 x 10~ 6 



* B. H. Billings, E. E. Barr, and W. L. Hyde, J. Opt. Soc. Am., 37, 123 (1947). 



comparison in the originals of these tables is made under certain 

 standardized conditions. Variations of these conditions may change 

 the relative merit of these bolometers by orders of magnitudes. 



1 M. J. E. Golay, Rev. Sci. Instr., 18, 357 (1947). 



2 N. Fuson, loc. cit. 



3 R. C. Jones, Rev. Sci. Instr., 24, 1035 (1953). 



4 Fuson, loc. cit. 



5 B. H. Billings, E. E. Barr, and W. L. Hyde, J. Opt. Soc. Am., 37, 123 (1947). 



