The space coronagraph optical bench (SCoOB): 4. Vacuum performance of a high contrast imaging testbed

The Space Coronagraph Optical Bench (SCoOB) is a high-contrast imaging testbed built to demonstrate starlight suppression techniques at visible wavelengths in a space-like vacuum environment. The testbed is designed to achieve <10-8 contrast from 3 - 10 lambda/D in a one-sided dark hole using a liquid crystal vector vortex wave-plate and a 952-actuator Kilo-C deformable mirror (DM) from Boston Micromachines (BMC). We have recently expanded the testbed to include a field stop for mitigation of stray/scattered light, a precision-fabricated pin-hole in the source simulator, a Minus K passive vibration isolation table for jitter reduction, and a low-noise vacuum-compatible CMOS sensor. We report the latest contrast performance achieved using implicit electric field conjugation (iEFC) at a vacuum of similar to 10(-6) Torr and over arange of b and passes with central wavelengths from 500 to 650nm and bandwidths (BW) from << 1% to 15%. Our jitter in vacuum is < 3 x 10(-3)lambda/D, and the best contrast performance to-date in a half-sided D-shaped dark hole is 2.2 x 10(-9) in a << 1% BW, 4 x 10(-9) in a 2% BW, and 2.5 x 10(-8) in a 15% BW.