MCP detectors: overview, advances, and prospects for Habitable Worlds Observatory

A future ultraviolet (UV) large strategic mission will require a capable and qualified far-UV detector. Microchannel plate (MCP) detectors provide unique capabilities for space-based astrophysics and have extensive flight heritage. MCPs can be obtained in large geometric form factors (up to 20×20 cm2). They have operational characteristics that include: a broad input energy bandwidth, further tailorable by photocathode selection, large global and local photon-counting dynamic range capabilities, an intrinsically low dark count rate, and support high spatial and temporal resolution. The initialization of an MCP event is purely photoemissive and is agnostic to readout architecture, so the backend event handling is adaptable. This flexibility allows the technology to support a diverse set of mission requirements. Implementations can vary widely from supporting low-power, long-lifetime, planetary missions to large area, high spatial resolution, low background Earth-orbiting sensors, as well as low-cost access capabilities—rugged rocket flights and CubeSats. The backend sensing element of the imaging device is typically achieved by one of several means: cross delay line (XDL) anodes, image intensifiers (phosphor screens), cross strip (XS) anodes, or a pixelated charge sensing complementary metal-oxide-semiconductor (CMOS) approach. MCP detector technology has improved over the years when compared with a previous UV flagship mission [e.g., Hubble Space Telescope – Cosmic Origins Spectrograph (HST-COS)]. Improvements in MCP background, lifetime, and gain stability have been enabled by atomic layer deposited (ALD) resistive and secondary emissive layers. XS and pixelated backend readout approaches allow for lower gain operation which further improves the detector’s local and global rate capability as well as detector lifetime. In addition, these backend approaches require less power to operate while also allowing for higher dynamic event capture and improved spatial and temporal resolving power. These sensor properties are achieved without cooling, or out-of-band filtering, and constitute a high signal-to-noise (S/N) photon-counting and imaging detector capability well suited for prospective National Aeronautics and Space Administration missions.