The interferometer mirror of a Fourier transform infrared spectrophotometer travels 61 cm.

(a) How many centimeters is the maximum retardation, D?
(b) State what is meant by resolution.
(c) What is the approximate resolution (cm^-1) of the instrument?
(d) At what retardation interval, d, must the interferogram be sampled (converted into digital form) to cover a spectral range of 0 to 2000 cm^-1?