This initial design of the PWS microscope was based on several key components including a critical illumination system via a fixed low-numerical-aperture (, ) objective lens (38-339, Edmund Optics, Barrington, New Jersey), a manual sample stage, and a spectral filtering system using a scanned 10-μm slit spectrometer (SP-2150i, Acton Research, Acton, Massachusetts).16,21 With this system, collimated broadband light from a Xenon lamp (66902 100W, Oriel Instruments, Stratford, Connecticut) was focused on the sample by the low-numerical-aperture objective lens. Backscattered light was collected by the same objective lens, and the magnified image was focused on the slit of the spectrometer, which was mounted on an automated linear stage (T-LA60A, Zaber Technologies, Vancouver, British Columbia), to allow the slit to be scanned across the entire illuminated field (). Images were collected with a CCD camera (Coolsnap HQ, Photometrics, Tucson, Arizona) with 6.45-μm pixels from the output of the spectrometer at each 10-μm step of the automated stage. Each image collected by the camera yielded an image with the -axis representing the spatial -dimension in the image plane and the -axis representing the wavelength of light. By combining all the images collected at each -spatial position, a three-dimensional data cube () was formed representing the diffraction-limited spatial data as well as the sub-diffraction spectral data.