Detection, identification, and quantification of greenhouse gases is essential to ensure compliance with regulatory guidelines and mitigate damage associated with anthropogenic climate change. Passive infrared hyperspectral imaging technology is among the solutions that can detect, identify and quantify multiple greenhouse gases simultaneously. The Telops Hyper-Cam Airborne Platform is an established system for aerial thermal infrared hyperspectral measurements for gas survey applications. In support of the Hypercam, Telops is developing a suite of hyperspectral imaging data processing algorithms that allow for gas detection, identification, and quantification in real-time. In the Fall of 2020, the Hyper-Cam-LW Airborne platform was flown above a validated SF6 gas release system to collect hyperspectral data for gas quantification analysis. This measurement campaign was performed to document performance of the Hyper-Cam gas quantification capabilities against known quantities of released gas. This talk introduces the principles behind the gas detection, identification, and quantification algorithms and presents the motivations and results from the Fall 2020 measurement campaign.
Almost every aspect concerning the design of modern panoramic lenses brings new challenges to optical designers.
Examples of these include ray tracing programs having problems finding the entrance pupil which is moving through the
field of view, production particularities due to the shape of the front lenses, ways of tolerancing these systems having
strong distortion, particular setups required for their characterization and calibration, and algorithms to properly analyze
and make use of the obtained images. To better understand these modern panoramic lenses, the Optical Engineering
Research Laboratory at Laval University has been doing research on them during the past few years. The most
significant results are being presented in this paper.
Controlled distortion, as in commercial panomorph lenses (Immervision), is used to image a specific part of the object
with more pixels than in a normal fisheye lens. This idea is even more useful when a zone of interest vary in time with
dynamically adjustable distortion as in a panoramic locally magnifying imager. Another axis of research is the use of
modern computational techniques such as wavefront coding in wide-angle imaging systems. The particularities of such
techniques when the field of view is large or with anamorphic imagers are considered. Presentation of a novel circular
test bench in our laboratories, required to calibrate and check the image quality of wide-angle imaging system, follows.
Another presented setup uses a laser and diffractive optical elements to compactly calibrate wide-angle lenses. Then, a
discussion of the uniqueness in tolerancing these lenses, especially the front elements due to the large ratio between lens
diameter and entrance pupil diameter, is included. Lastly, particularities with polarization imaging and experiments of
triangle orientation detection tests before and after unwrapping the distorted images are briefly discussed.
The emerging paradigm of imaging systems, known as wavefront coding, which employs joint optimization of both the
optical system and the digital post-processing system, has not only increased the degrees of design freedom but also
brought several significant system-level benefits. The effectiveness of wavefront coding has been demonstrated by
several proof-of-concept systems in the reduction of focus-related aberrations and extension of depth of focus. While
previous research on wavefront coding was mainly targeted at imaging systems having a small or modest field of view
(FOV), we present a preliminary study on wavefront coding applied to panoramic optical systems. Unlike traditional
wavefront coding systems, which only require the constancy of the modulation transfer function (MTF) over an extended
focus range, wavefront-coded panoramic systems particularly emphasize the mitigation of significant off-axis
aberrations such as field curvature, coma, and astigmatism. The restrictions of using a traditional generalized cubic
polynomial pupil phase mask for wide angle systems are studied in this paper. It is shown that a traditional approach can
be used when the variation of the off-axis aberrations remains modest. Consequently, we propose to study how a
distributed wavefront coding approach, where two surfaces are used for encoding the wavefront, can be applied to wide
angle lenses. A few cases designed using Zemax are presented and discussed