Crossfaded Externally Dispersed Interferometer Testbed for 1000x Improved Doppler Spectrograph Stability

Crossfading - combining two signal components using frequency dependent weights - can stabilize a grating spectrograph against uncontrolled wavelength drifts by using an external interferometer (EDI). This creates moiré patterns, which are processed into wavelets. The system reduces wavelength drifts by ~1000x, and can sharpen the instrument profile, doubling or more the spectrograph resolution. We demonstrate stabilization on star light data and simulations. We report new focal blur diagnostic work using interferometer combs on the Keck Planet Finder spectrograph (KPF)