KEYWORDS: Sensors, Cameras, Signal to noise ratio, Signal detection, Fiber optic gyroscopes, Head, Enhanced vision, Nonuniformity corrections, Temperature metrology, Erbium
This paper presents the improvements integrated into the second generation of Enhanced Vision System (EVS) or the Enhanced Flight Vision System (EFVS) (in comparison with the first generation). These improvements are based on the experience and knowledge accumulated during the last 3.5 years of observing more than 300 planes operating with the EVS system. Among the main improvements incorporated into the second-generation product are: - Higher probability of detection for runway lights and flashers, during bad atmospheric conditions. - Extended algorithm for ambient temperature compensation, eliminating the requirement for optics and dewar head temperature stabilization. - The sealed-off system that constitutes the second generation, not requiring any air flow supply or temperature stabilization. (The EVS first generation requires an air flow of 7 liters/second at 23° C with a relative humidity not higher than 30%. The airflow prevents water condensation on the optical parts and also enables stabilizing the optics and dewar head temperatures.) - Improved algorithm for the replacement of clusters of bad pixels. - Reduced size, weight, and power consumption.
KEYWORDS: Sensors, Temperature metrology, Cameras, Nonuniformity corrections, Microbolometers, Signal detection, Signal processing, Modulation transfer functions, Mathematical modeling, Video
This paper concludes the large effort sustained by OPGAL in designing a radiometer instrument based on the uncooled microbolometer detector. A detailed description of the design considerations, temperature drift model and the expected accuracy is presented. The idea is to enable temperature measurement at a relatively high accuracy for any uncooled microbolometer based FLIR, even if the detector is not a radiometric one, by using the NUC flag as an extremely low frequency chopper.
KEYWORDS: Signal to noise ratio, Cameras, Modulation transfer functions, Sensors, Video, Digital signal processing, Microbolometers, Linear filtering, Optical filters, Signal processing
This paper analyzes the various factors contributing to the performances of the FLIR, and describes a series of solutions to control its transfer function and improve its performance. The paper describes the camera concept, elaborating on its behavior and associated control functions in the time domain, on the two dimensional image domain, and on the signal model translation to standard video signal. The camera contains the following blocks :
A. Time domain low pass filter that is controlled in real time according to the velocity of the objects observed
B. Two dimensional high pass filter that is controlled in real time according to SNR of the input video signal,
C. Supplementary filter that removes the 1/f noise, controlled according to the SNR of the input video signal,
D. An automatic controlled dynamic range compression mechanism.
KEYWORDS: Signal to noise ratio, Cameras, Modulation transfer functions, Sensors, Optical filters, Digital signal processing, Signal processing, Forward looking infrared, Video, Signal detection
The adaptive transfer function concept analyzes the various factors contributing to the uncooled microbolometer FLIR camera performances, and describes a series of solutions to control in real time its transfer function for optimal performances. The paper describes the entire camera concept, elaborating in more details the following subjects: 1. The time domain filter used to improve the SNR and its control function, 2. The two dimensional filter used to remove the DC and the low frequencies components, 3. The supplementary filter used to reduce one over f law power noise on vertical direction, 4. The dynamic range compression and its control function.
This paper describes the results of a long, intensive research and development effort related to the subject of nonuniformity correction (NUC). The study has been performed in order to increase the performances of cooled and uncooled FLIR's. The causes of NUC instability have been investigated in parallel with a general approach used for a very high dynamic range, and for very low noise FLIR performances. The results of this research have been implemented on a special design, enhanced vision system (EVS), camera for lending applications, and on ucooled camera FLIR's. This paper contains measured data on optics temperature influence on FLIR performance and theoretical models to explain the measured data.
This paper describes the Enhanced Video System (EVS) camera, built by OPGAL as subcontractor of Kollsman Inc. The EVS contains a Head up Display built by Honeywell, a special design camera for landing applications, and the external window installed on the plane together with the electronic control box built by Kollsman. The special design camera for lending applications is the subject of this paper. The entire system was installed on a Gulfstream V plane and passed the FAA proof of concept during August and September 2000.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.