Abstract
Blue and ultraviolet radiation is well known to be associated with cataract formation and visual damage. These days children and teenagers have increasing exposure to blue light and electromagnetic radiation with even shorter wavelengths, which may cause damage to vision, due to their frequent use of electronic display devices and participation in disco parties and concerts with illumination by UV light. We developed a Fe:Pd/ZnSe Schottky barrier photodetector that detects blue and UV light with an excellent long-wavelength rejection power for green and red light of 4.24 and 5.65 orders respectively. Its Schottky-barrier height and built-in potential are determined to be 2.48 eV and 1.17 eV respectively. Together with the help of a lux meter, this simple and robust photodetector successfully detects the blue light to UV content of different LED light bulbs with an accuracy comparable to the much more sophisticated and expensive spectrometer. This compact and efficient blue to UV light detector can help increase the awareness of over-exposure to vision damaging radiation. We have studied another potential application of our developed photodetector, which is the detection of black objects. The results of our scattering experiments via shining blue and red laser light on a piece of A-Tech black paper reveal that the ratio of percentages of blue to red light scattered is 1.476 confirming the superiority of using blue light in detecting black objects over the use of red light and its larger detection angle range. Via the use of AFM imaging, the RMS roughness of the fine structure of the black paper is revealed, which indeed provides a reasonably good fit between the theory based on the total integrated scatter concept and our experimental data. It is also found that the logarithmic percentage of scattered light power is higher for lower angle of scattering and falls gently from 0 to 75 degrees and sharply from 75 to 90 degrees.