(U) Remote Ultra-Low Light Imaging (RULLI) is a Los AlamosNational Laboratory (LANL) project in sensor technology development. The key application for environmental monitoring is nighttime 3-D cloud imaging. A limitation of current imagers is that they depend on a light source. Sunlight is required for daytime images, and moonlight is required for "nighttime" images. Use of selected IR channels can provide high-quality imagery near sunrise and sunset, but no capability currently exists to obtain imagery in complete darkness. RULLI is a visible imager that can operate under complete darkness. While this concept can be used on aircraft in a tactical "reconnaissance" mode, it should eventually transition to space.
(U) The core of the technology is a single-photon counting system with high spatial and very high time resolution. While intensified imaging techniques have been developed and used for many years, typically for night vision and low-light detection applications, RULLI technology brings the capability to measure, accurately and simultaneously, the position and absolute time of arrival for each detected photon. This opens up many new possibilities for the exploitation of data that is literally three dimensional. This Los Alamos project is funded by the Office of Nonproliferation and National Security of the US Department of Energy.
(U) The RULLI technology consists of three primary components: the MicroChannel Plate/Crossed Delay Line (MCP/CDL) detector, the Pulse Absolute Timing (PAT) electronics, and associated photon event construction and data processing.
(U) The MCP/CDL detector is a hermetically sealed vacuum tube which contains the light sensing material (photocathode) on the backside of the transparent window, a Z-stack of three microchannel plates, and a crossed delay line readout. It offers a high signal read-out rate and good spatial resolution. To date, we have implemented a series of detectors each using a 40 mm diameter MCP (which defines the detector's active area) and an S-20 photocathode.
(U) The PAT electronics is a fast and accurate timing technology with heritage from the nuclear test program at Los Alamos. The PAT system measures the absolute arrival time of individual electrical pulses with an accuracy better than 20 picoseconds.
(U) The combination of MCP/CDL and PAT allows us to acquire data with unique characteristics. Following a special technique, we can reconstruct each detected photon's position and absolute arrival time. Spatial resolution at the detector's active surface is projected to be 30 microns or better, and the abslute timing accuracy achieved to date is 200 picoseconds. A full-blown system can achieve a random count rate of 5 million counts/sec. Coupled with a pulsed illumination source, optimized data procesing, and sophisticated information extraction algorithms, this technology offers breakthroughs in many application arenas.
(U) The MCP/CDL/PAT offers a unique way to remotely probe cloud properties in detail. Traditionally, remote probing of the cloud has been done with either one dimensional time-domain light intensity sensor which records returned laser light with no spatial information, or two dimensional imager which averages over time. The intricate relations between the spatial and timing information of the probe are lost in these measurements. The 3D information offered by the MCP/CDL/PAT system allows us to acquire space-time correlated data which will be a powerful tool to diagnose cloud property and aid in developing realistic cloud models.
|Space-Based Sensors||Space Based Sensors|
|ENVIRONMENTAL MONITORING||SPACE FORCE ENHANCEMENT: ENVIRONMENTAL MONITORING|
|RULLI (LANL) Home Page|
Los Alamos National Lab.
(U) Dr. R. Clayton Smith, Los Alamos National Lab, Open Phone: (505) 667-7931.
(U) 15 May 1998
(U) Road Map Production Date: 23 June 2001