Correcting spurious apodization effects in digital holographic microscopy using a simple Fourier transform spectrometer

The use of quasi-monochromatic light in digital holographic microscopy can lead to spurious apodization effects. The resulting image degradation can be corrected by compensating for this effect if the spectrum of the light source is known. Here, we present a simple Fourier-transform spectrometer that accurately measures the spectrum of a quasi-monochromatic light source. We will present measured spectra, obtained with this FT spectrometer, and we will show how these spectra can be used to computationally correct for spurious apodization effects. The resulting improvement of image quality is especially of interest for optical metrology applications that require high-quality imaging performance like overlay metrology.