Filters, Prism, and GrismThe element wheel contains the filters, grism, and prism. The filters are made of glass with special coatings that only allow light in carefully chosen wavelength bands to reach the detector array. The grism and prism each contain several custom optics designed to spread the light from cosmic objects into spectra over a wide wavelength range. The Wide Field Instrument will combine imaging using the filters and spectroscopy using the grism and prism to study galaxies and supernovae to help us understand dark energy. Observing stars using the filters will reveal exoplanets via a technique called gravitational microlensing. This observational effect occurs because the presence of mass warps the fabric of space-time. When two stars closely align from our vantage point, the nearer star – and any orbiting planets – can lens light from the farther star, making it briefly brighten.
