Maintaining a stable and high quality laser wavefront is pivotal for efficient laser communications in deep space networks. In this presentation, we describe the design and expected optical and structural performance of the afocal beam expanding telescope for the NASA DSOC mission. This 22 cm aperture, 11x magnification telescope must survive the stresses of launch and maintain alignment through solar illumination, laser irradiance, thermal transients, and temperature extremes during the DSOC mission life from Earth to Mars. Structural-Thermal-OPtical (STOP) analysis predict very stable downlink wavefront error (< 122 nm RMS) and beam divergence (< 14.5 microradians). Furthermore, we present additional telescope link loss contributions that will be minimized through particulate contamination control, high spectral throughput, and polarization purity. Successful performance of this telescope will support NASA’s ongoing efforts to extended high data rate communications into deep space.
Satellite laser communication hardware design that supports space-based optical communications, and successful hardware demonstrations, are presented for Low Earth Orbit (LEO) terminals. For inter-satellite links (ISL), the design of an optical module has been optimized to support satellite-to-satellite relays. Providing optical line-of-sight (LOS) stabilization, the Optical Bench Assembly (OBA) is the modular component that includes the LOS jitter rejection control loop system, which stabilizes the transmit (Tx) and receive (Rx) data channels. The jitter rejection system design of the OBA is described. The demonstrated performance is reported for the nested control loop rejecting the host platform’s on-orbit vibration profile.
The backend optical assembly module for a space-based, laser communication terminal is presented. The backend optical assembly utilizes voice coil-fast steering mirror technology embedded into a control loop that both provides terminal-level pointing capability, and maintains receive channel fiber coupling. The fast steering mirror technology presents a technical solution for operating within the space environment, while simultaneously meeting the bandwidth requirements for characteristic satellite vibration profiles. The system’s architecture design meets the demands of onplatform, jitter-rejection performance to establish and maintain a communication link.
High-contrast imaging techniques now make possible both imaging and spectroscopy of planets around nearby stars. We present the optical design for the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS), a lenslet-based, cryogenic integral field spectrograph (IFS) for imaging exoplanets on the Subaru telescope. The IFS will provide spectral information for 138 × 138 spatial elements over a 2.07 arcsec × 2.07 arcsec field of view (FOV). CHARIS will operate in the near infrared (λ = 1.15 - 2.5μm) and will feature two spectral resolution modes of R ~ 18 (low-res mode) and R ~ 73 (high-res mode). Taking advantage of the Subaru telescope adaptive optics systems and coronagraphs (AO188 and SCExAO), CHARIS will provide sufficient contrast to obtain spectra of young self-luminous Jupiter-mass exoplanets. CHARIS will undergo CDR in October 2013 and is projected to have first light by the end of 2015. We report here on the current optical design of CHARIS and its unique innovations.
The COMPACT Airborne Spectral Sensor (COMPASS) design is intended to demonstrate a new design concept for solar reflective hyper spectral systems for the Government. Capitalizing from recent focal plane developments, the COMPASS system utilizes a single FPA to cover the 0.4-2.35micrometers spectral region. This system also utilizes an Offner spectrometer design as well as an electron etched lithography curved grating technology pioneered by NASA/JPL. This paper also discusses the technical trades, which drove the design selection of COMPASS. When completed, the core COMPASS spectrometer design could be used in a large variety of configurations on a variety of aircraft.
We designed an electro-optical relay system to perform nonmechanical beam switching in the mid-infrared waveband and built a proof-of-concept prototype to verify the system performance. The prototype is a scalable building block that can be used to fabricate a two-dimensional system to scan a large field of regard at high resolution, low power, and high speed. We designed, fabricated, and tested the major components and then assembled the components into the electro- optical relay system, which demonstrated 8 kHz switching between two fields of view. In order to implement the system, we fabricated mid-wave infrared polarizing beamsplitter cubes that provided excellent polarization separation over a 600 nm waveband and a range of angles of incidence. Additionally, we demonstrated 90 degree polarization rotation in the mid-wave infrared waveband using ferroelectric liquid crystals.