We evaluated the morphology of ultra-thin a-Se photodeposited nano-structures obtained by direct deposition of a-Se on glass substrates. Photodeposition (PD) from solutions has been used for realizing various thin film patterns, of sub-microscopic thicknesses i.e., 5-500 (nm) to produce various spatially distributed components for optical applications. During PD nanometer particles appear on the irradiated zones of any transparent substrates, such as glass used in this investigation. In this work, CW Photodeposition from a-Se colloid solutions onto glass substrates a Xenon UV-Visible lamp has been employed. A new technique based on capturing the evanescent light leaking image, named Differential Evanescent Light Intensity (DELI), is used to get the information about the photodeposited a-Se nanostructures profiles in the deposited zone on glass substrates serving as waveguides. The deposited particles observed on the substrates have diameters typically in the range of 100-300 nm as obtained by other microscopy methods. The morphology of the nano-structures observed by DELI during this work conditions consist of a random array of individual particles adsorbed onto the surface. The deposited material morphological profile was observed for fluences in excess of F > Fth ∼ 25 J/cm2 for the particular experimental conditions of this work for a-Se. The highest merits found for the DELI technique are the fast and ease of measurements, comparable z-resolution to SEM and capability of large areas profiling and mean thickness measurements. We obtained that deposition fluences of about F ≈ 300 J/cm2 were enough to produce layers up to about 340 nm thickness, similar to values needed for CW Ar+ ion laser PD deposition at λ = 498 nm reported in previous investigations.