The JWST NIRCam dichroics split light in the optical path by reflecting short wavelengths (0.6–2.3 µm) and transmitting long wavelengths (2.4–5.0 µm). This splitting enables simultaneous observations in the short and long wavelength channels.

There is one dichroic in each module, positioned in the optical path after the coronagraphic occulting masks and before the pupil and filter wheels and detectors.