Infrared and terahertz are two imaging technologies that differ fundamentally in numerous aspects. Infrared imaging is
an efficient passive technology whereas terahertz technology is an active technology requiring some kind of illumination
to be efficient. What's more, the detectors are also different and yield differences in the fundamental physics when
integrated in a complete system. One of these differences lies in the size of the detectors. Infrared detectors are typically
larger than the infrared wavelengths whereas terahertz detectors are typically smaller than the wavelength of
illumination. This results in different constraints when designing these systems, constraints that are imposed by the
resolution capabilities of the system.
In the past INO has developed an infrared imaging camera core of 1024×768 pixels and tested some microscanning
devices to improve its sampling frequency and ultimately its resolution. INO has also engineered detectors and camera
cores specifically designed for active terahertz imaging with smaller dimensions (160×120 pixels). In this paper the
evaluation of the resolution capabilities of a terahertz imager at the pixel level is performed. The resolution capabilities
for the THz are evaluated in the sub-wavelength range, which is not actually possible in the infrared wavebands. Based
on this evaluation, the comparison between the resolution limits of infrared detectors and the terahertz detectors at the
pixel level is performed highlighting the differences between the wavebands and their impact on system design.
In various military, space and civilian infrared applications, there is an important need for fast prototyping. For example,
detectors with small pitch compared to the diffraction limited spot radius are now available and their specificities must
be studied to optimize the design of the next imaging systems. At the very heart stands a requirement for flexible camera
modules that provide a multitude of output formats as well as fast adaptability. Based on this concept, INO has
developed an advanced compact camera module IRXCAM that can provide both raw data as well as fully processed
images under a variety of outputs: NTSC, DVI, VGA, GigE and Camera Link. This tool can be used to perform a rapid
demonstration of concept for a specific application. IRXCAM now supports the bolometric detectors INO IRM160A
(160 x 120 52 μm pitch pixels, LWIR and THz), Ulis 04 17 1 (640 x 480 25 μpitch pixels, LWIR) and Ulis 05 25 1
(1024 x 768 17 μm pitch pixels).
Reduction of the pixel pitch is a way to improve the compromise between the spatial resolution and the dimensions of an
imaging system, mainly by reducing the required optical focal length with constant numerical aperture. Microscanning is
another way that provides excellent results in terms of spatial resolution for pixel pitches as small as 25 μm in the LWIR
range for F/1 optics. Microscanning also preserves the field of view without increasing the number of pixels of the
detector. Finally, microscanning is an efficient way to reduce the aliasing effect of a non unity filling factor, a parameter
that becomes increasingly important for small pixels. This paper presents the IRXCAM-1024 camera module, its
performances, and its use for microscanning with 17 μm pitch pixels and commercial F/1 and F/0.86 refractive optical
While anecdotal reports suggest that Night Vision Goggles influence spatial navigation and wayfinding (Braithwaite, Douglass, Durnford, and Lucas, 1998), few studies have systematically characterized the nature of these effects. To address this issue, the current study examined the impact of NVGs on navigation and wayfinding performance. One group of participants were required to navigate a walking maze and retrieve target objects while wearing NVGs (experimental condition), while a second control group navigated the maze without NVGs. We measured several performance metrics of navigation and wayfinding. Our results show that navigation and wayfinding with NVGs (experimental group) appeared to be harder, with longer navigation durations and more navigational errors compared to not using NVGs (control group). However, a significant decrease in navigation duration over the course of the wayfinding trials occurred earlier with NVGs, in addition to significant decreases in navigational steps compared to the control group. These results support the notion that NVGs directly affect spatial navigation and wayfinding performance. These degradations in performance should be considered in operational planning and NVG training programs. Further research is necessary to expand our understanding of the impact of NVGs on spatial cognition.
Proc. SPIE. 5800, Helmet- and Head-Mounted Displays X: Technologies and Applications
KEYWORDS: Defense and security, Goggles, Light sources, Visualization, Night vision, Light sources and illumination, Modulation transfer functions, Psychophysics, Night vision goggles, Standards development
Several methodologies have been used to determine resolution acuity through Night Vision Goggles. The present study compared NVG acuity estimates derived from the Hoffman ANV-126 and a standard psychophysical grating acuity task. For the grating acuity task, observers were required to discriminate between horizontal and vertical gratings according to a method of constant stimuli. Psychometric functions were generated from the performance data, and acuity thresholds were interpolated at a performance level of 70% correct. Acuity estimates were established at three different illumination levels (0.06-5X10-4 lux) for both procedures. These estimates were then converted to an equivalent Snellen value. The data indicate that grating acuity estimates were consistently better (i.e. lower scores) than acuity measures obtained from the Hoffman ANV-126. Furthermore significant differences in estimated acuity were observed using different tube technologies. In keeping with previous acuity investigations, although the Hoffman ANV-126 provides a rapid operational assessment of tube acuity, it is suggested that more rigorous psychophysical procedures such as the grating task described here be used to assess the real behavioural resolution of tube technologies.