  Knowledge of the intensity and phase profiles of spectral components in a
coherent optical field is critical for a wide range of high-precision optical
applications. One of these is interferometric gravitational wave detectors,
which rely on such fields for precise control of the experiment. Here we
demonstrate a new device, an \textit{optical lock-in camera}, and highlight how
they can be used within a gravitational wave interferometer to directly image
fields at a higher spatial and temporal resolution than previously possible.
This improvement is achieved using a Pockels cell as a fast optical switch
which transforms each pixel on a sCMOS array into an optical lock-in amplifier.
We demonstrate that the optical lock-in camera can image fields with 2~Mpx
resolution at 10~Hz with a sensitivity of -62~dBc when averaged over 2s.
