Characterization of Powell lens with a broadband light source input

A Powell lens is a unique optic that projects a line output profile from a collimated laser with its output characteristics dictated by the input beam and geometry of the lens. The goal of this work was to demonstrate that a Powell lens can be used to shape the output of the broadband source to be complimentary to the input of a passive line scanning hyperspectral spectrometer. In this paper the use of a Powell lens with a broadband white light source is demonstrated to produce a similar output when compared to a monochromatic source. Output from a tungsten halogen lamp was collimated and transmitted through a Powell lens with input diameters ranging from 400 to 5000 μm. The output from the lens was characterized by a fiber spectrometer at three distances from the lens creating a profile of the output beam. Complementary experiments were then performed with a 532 nm laser to provide a direct comparison to the broadband source and mimic typical usage of the lens. The results show that while the resultant output does produce a line of white light, the intensity of the output is reduced when compared to the source. In addition, the input diameter of the source can be greater than specified limit of the lens, depending on the application as imperfections in the lens surface can cause aberrations in the output.