2012 BFY Abstract Detail Page
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||W16 - Using Spatial Light Modulators to Teach Students Experimental Fourier Optics
||A spatial light modulator (SLM) changes the phase and/or amplitude of light incident on the SLM. The SLMs we use alter the phase of the incident light via an array of 1024x768 9x9 µm pixels. What can these computer-controlled devices be used to do?
We use SLMs to teach students Fourier optics and Fourier transforms, experimentally. As an amplitude modulator (with the addition of polarizers), we use SLMs to create objects within a collimated laser beam. These objects can be imaged with a lens, or, by moving the lens, the Fourier transform of the object can be seen. A particularly simple use of SLMs is in a multiple-slit experiment, where the width of single slits, the spacing between slits, and the total number of slits are dynamically controllable. The single-slit diffraction pattern is a particularly simple Fourier transform; a multi-slit diffraction pattern is a nice application of the Array Theorem.
More interestingly, by placing the SLM in the transform plane of a single lens, the Fourier transform of an arbitrary object can be manipulated; a second lens is used to take the inverse transform and display the modified image. Regularly repeating features of an image can be removed - for example, in one lab, students are given the picture of this kitty in a cage (printed onto a transparency), and asked to remove the cage.
In the workshop, we will use SLMs to:
-perform a multi-slit diffraction experiment, with slit width and spacing changeable onthe fly
-perform 2-D crystal diffraction demonstrations, including quasicrystals
-remove the kitty from the cage using spatial filtering
-create computer generated holograms (along the lines of Thad Walker's Holography Without Photography)
Download the Workshop Document