The Air Force Research Laboratory (AFRL) is studying the application and utility of various ground-based and space-based
optical sensors for improving surveillance of space objects in both Low Earth Orbit (LEO) and Geosynchronous
Earth Orbit (GEO). This information can be used to improve our catalog of space objects and will be helpful in the
resolution of satellite anomalies. At present, ground-based optical and radar sensors provide the bulk of remotely sensed
information on satellites and space debris, and will continue to do so into the foreseeable future. However, in recent
years, the Space-Based Visible (SBV) sensor was used to demonstrate that a synthesis of space-based visible data with
ground-based sensor data could provide enhancements to information obtained from any one source in isolation. The
incentives for space-based sensing include improved spatial resolution due to the absence of atmospheric effects and
cloud cover and increased flexibility for observations. Though ground-based optical sensors can use adaptive optics to
somewhat compensate for atmospheric turbulence, cloud cover and absorption are unavoidable. With recent advances in
technology, we are in a far better position to consider what might constitute an ideal system to monitor our surroundings
in space. This work has begun at the AFRL using detailed optical sensor simulations and analysis techniques to explore
the trade space involved in acquiring and processing data from a variety of hypothetical space-based and ground-based
sensor systems. In this paper, we briefly review the phenomenology and trade space aspects of what might be required in
order to use multiple band-passes, sensor characteristics, and observation and illumination geometries to increase our
awareness of objects in space.
In order to understand the phenomenology of optimum data acquisition and analysis and to
develop an understanding of capabilities, field measurements of multiband, polarimetric data can
substantially assist in developing a methodology to collect and to exploit feature signatures.
In 1999, Duggin showed that images obtained with an 8-bit camera used as a polarimeter could
yield additional information to that contained in a radiometric (S0) image. It should be noted that
Walraven and Curran had performed some very fine experiments almost two decades earlier,
using photographic film, and North performed careful polarimetric measurements of the
skydome using a four-lens polarimetric film camera and convex mirror in 1997. There have been
a number of papers dealing with polarimetric field measurements since that time. Recently,
commercial color cameras have become available that have 12-bit depth per channel. Here, we
perform radiometric and chromatic calibrations and examine the possible use of a Nikon D200
10.2 mega pixel, 3 channel, 12-bit per channel camera fitted with a zoom lens as a potential field
imaging polarimeter. We show that there are still difficulties in using off-the-shelf technology for
field applications, but list some reasons why we need to address these challenges, in order to
understand the phenomenology of data collection and analysis metrics for multiple data streams.
In the Advanced Detectors Research Group of the Air Force Research Laboratory's Space Vehicles Directorate, we work to enhance existing detector technologies and develop new detector capabilities for future space-based missions, most often using photonic techniques. To that end, we present some ideas we are presently investigating: (i) tuning the wavelength response of detectors using applied electric or magnetic fields, (ii) detecting the full polarization vector of a signal within a single pixel of a quantum well detector, (iii) monolithic solid-state cooling of a detector using photoluminescence, and (iv) enhancement of weak electromagnetic fields using interactions with plasmons.
With the increasing use of night vision goggles and night missions, new methods to display information in the infrared region is of interest. We have developed both inorganic and organic electroluminescent thin films which emit at wavelengths between 700 nm and 1.8 μm. These thin films have been incorporated into simple devices and the feasibility of a NIR flat panel display has been demonstrated. Both inorganic zinc sulfide and organic polymers doped with rare earth lanthanide ions have been demonstrated. The wavelength of emission can be varied by choosing the appropriate lanthanide ion, such as dysprosium, erbium, thulium or neodymium. Power densities of ~30 μW/cm2 have been achieved with these devices.