Latency in augmented vision systems can be defined as the total delay imposed on information propagating through a device with respect to a direct path. Latency is critically important in vision systems as it imposes a delay on reaction time. With the emergence of headborne augmented vision systems for dismounted soldiers and widespread usage of embedded digital processing in vision systems, latency becomes most critical in dynamic operational scenarios. As consequence, latency has been characterized in the recent years for various technologies including AR headsets, VR headsets and pilot helmets with integrated symbology overlay and night vision. These efforts have led to latency requirements that vary according to the application. However, as there is no standardized definition and testing methodology for latency in vision devices, it is difficult to compare latency values across devices and as stated by different manufacturers. We propose that latency be characterized as a set and not as a single value.
Testing of Night Vision Devices (NVD) and I2 tubes are regulated by a long series of US Defense standards (often called military standards or MIL standards). These standards set mandatory testing conditions to be fulfilled. Among others, the radiation source used in the tests shall be a tungsten filament lamp operated at a color temperature of 2856 kelvins (K), ±50 K. In recent years, we have noticed that those tungsten filament lamp with a sufficient spectral shape accuracy and stability have been harder to procure. In this paper, we present our characterization efforts to determine if a commercially available LED-based light source is suitable to replace a tungsten filament lamp for NVDs and I2 tubes testing. A LED-based light source is compared to a 2856 K filament lamp in terms of spectral shape, output power linearity, dynamic range and relative intensity noise (RIN). We also present the pros and cons of the two sources in a perspective of evaluating NVD performance in a controlled environment emulating different representative night sky irradiances in support of military and law enforcement operations.
Modern thermal imaging systems are widely used because of their broad military and commercial application range. The performance of the first generations of thermal imagers was limited by resolution and thermal sensitivity. Brightness and contrast adjustments were also the crux of the image quality. From a military user perspective, the amount of details and the interpretation of a scene depends, among others, on the experience of the user and on the time available to complete those adjustments. Modern imagers now feature embedded digital processing that can automatically adjust the device parameters in order to optimize the image quality. With the combined improvements in microprocessor power and microfabrication processes, digital processing enhanced the thermal imagers’ performance until they eventually became limited by their ability to react to different operational scenarios. That brings the need for testing the reaction of digital processing in such operational scenarios. Meanwhile, there were no significant modification in testing methodologies and metrics used for the assessment of thermal imagers. In this paper, we present DRDC-Valcartier Research Centre’s efforts to develop a test bench to measure the efficiency of the digital processing embedded in thermal imagers. The purpose of the testing methodology is to provide reliable, repeatable and user-independent metrics. Outputs quantitatively highlight the impact of digital processing for various operational situations and allow the performance of devices to be compared.
The last decades have brought significant improvements in materials, microfabrication, manufacturing processes, microelectronic fabrication, optical design tools and microprocessing power. It has allowed the development of novel types and designs of electro-optical (EO) military systems having, among others, the following added capabilities: wide field of view, extended spectral response, multifunction devices, image fusion and embedded image processing. Meanwhile, the international standards that regulate the testing and evaluation of EO systems, developed in the 1990s, have not been updated to include those new capabilities that are important on the battlefield. As a result, those standards are often no longer suitable to characterize current state-of-art EO systems and to support major military EO systems acquisition projects. In this paper, we present an overview of some novel testing capabilities developed over the last decade at DRDCValcartier Research Centre that aim at comparing, in a controlled environment, the performance and limitations of EO military systems under different representative operational conditions. Those novel testing capabilities do not aim at replacing standard testing procedures, but rather at complementing them. Methodologies developed to test thermal imagers, wide-field-of-view night vision google, image intensifier tubes and lasers are described.
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