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 − 10λ/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 s top f or m itigation o f s tray/scattered l ight, a p recision-fabricated pinhole 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 c onjugation (iEFC) a t a v acuum o f ∼ 10⁻⁶ Torr a nd o ver a r ange o f b andpasses w ith c entral wavelengths from 500 to 650nm and bandwidths (BW) from ≪ 1% to 15%. Our jitter in vacuum is < 3 × 10⁻³λ/D, and the best contrast performance to-date in a half-sided D-shaped dark hole is 2.2 × 10⁻⁹ in a ≪ 1% BW, 4 × 10⁻⁹ in a 2% BW, and 2.5 × 10⁻⁸ in a 15% BW.