Prisms are blocks of optical material with flat polished sides arranged at precisely controlled angles to each other, which deflect, deviate and rotate beams of light as well as dispersing their wavelengths.There are many types of prisms,each having a particular geometry to achieve the reflections necessary to perform a specific imaging task. Reflecting prisms may invert, rotate, deviate or displace a beam. Dispersing prisms produce spectral separation for spectroscopic applications or for tuning a laser output.