|Sensitivity Issues in Step-Scan FT-IR Spectrometry
The primary heat source in most infrared
spectrometers is the reference laser which typically produces 7 to 9 watts of waste heat
for its one milliwatt optical output. The heat capacity of air (effectively the same as
that of N2) is approximately 1 Joule/gram-°C, or 1 J/liter-°C. The waste heat
is sufficient to heat 1 liter of air by 9 °C per second! (Remember that the temperature
difference between the two arms of the interferometer should be < 0.01°C). The waste
heat was trapped away from the critical beam paths by foam baffles.