We investigate the problem of obtaining minimum-bias spectral estimates under the constraint of finite spectral-window bandwidth. The problem is meaningful for spectral estimation with a coherent optical system in which the power-spectrum estimate, i.e., the Fourier irradiance, is physically available for smoothing. An example that deals with the smoothing of statistically unstable optical data is furnished in connection with the problem of particle-size estimation with an optical-digital computer. We show that the smoothing of the irradiance spectrum prior to particle-size estimation furnishes more satisfactory results than operating with unsmoothed data.
H. Stark, D. Lee, and B. Dimitriadis, "Smoothing of irradiance spectra with finite-bandwidth windows, with application to particle-size analysis," J. Opt. Soc. Am. 65, 1436-1442 (1975)