The JWST tunable filter imager (TFI)

The Fine Guidance Sensor (FGS) of the James Webb Space Telescope (JWST) features a tunable filter imager (TFI) module covering the wavelength range from 1.6 to 4.9 μm at a resolving power of ~100 over a field of view of 2.2’x2.2’. TFI also features a set of 4 occulting spots for coronagraphy. A review of the current design and development status of TFI is presented along with two key TFI science programs: the detection of first light, high-redshift Lyα emitters and the detection/characterization of exoplanets.