Spatial structuring of light for undergraduate laboratories

Abstract

In recent times, spatial light modulators have become a common tool in optics laboratories as well as industrial environments for shaping the spatial structure of a light beam. Although these devices are often easy to use, their high cost has limited their use in many undergraduate laboratories. However, in recent years the progress in developing more cost-effective projectors has led to affordable spatial light modulators in the form of so-called Digital Micromirror Devices (DMD). This reduction in price, as well as their simple employment, make such devices increasingly suitable for use in undergraduate instructional laboratories to demonstrate optical effects and the shaping of light fields. Here, we show one of the most cost-effective ways to make a DMD available, namely, turning a projector evaluation module into a computer-controlled spatial light modulator. We explain the underlying functioning and how this low-cost spatial light modulator can be used in undergraduate laboratories. We further characterize the efficiency of the device for the most commonly used laser wavelengths and demonstrate various exemplary optics experiments suitable for undergraduate laboratories ranging from single and multi-slit diffraction to optical Fourier transformations. Finally, we show that by using amplitude holography, the device can generate transverse spatial modes, e.g., Laguerre-Gaussian beam, which are one of the most commonly used spatially structured beams.