TMAP is a high spatial resolution thermal imager, optimized for observing Io, derived from BepiColombo’s Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS). TMAP has three detectors with a beam split at image plane level: a multispectral imager using an uncooled microbolometer and two radiometer line detectors provide greater precision than the imager for background temperatures (80–150 K) as well as a precise temperatures measurement of active lava flows at 2μm. The TMAP microbolometer and radiometer operate primarily in a pushbroom imaging configuration. The optical design of TMAP is simplified from MERTIS, replacing the spectrometer with simple stripe filters on the microbolometer. Minor modifications of the three-mirror anastigmat (TMA) telescope optics and updating the microbolometer improve the spatial resolution by over 5x. TMAP has a fully reflective, gold-coated F/2.5 TMA optical path with 135-mm focal length. A flip-panel in the optical path between the detectors and mirror 3 serves as a calibration target and follows the standard design used in a wide range of flight instruments. TMAP will measure thermal infrared emission of SO2-free areas of silicate to characterize spectral shape and locate the Christiansen feature emissivity maximum with 8 stripe filters spanning 4.5–16 μm. TMAP will classify eruptions over a significant portion of Io using a 2μm filter on the radiometer and two 5μm bands of the bolometer. TMAP will measure the surface radiance both with the microbolometer between 5 and 16 μm and with the radiometer at wavelength ≥18μm.

In June 2020 NASA has selected the VERTIAS Discovery mission to Venus for flight. The Venus Emissivity Mapper (VEM) provided by DLR together with the VISAR radar system provided by JPL are the core payload of the mission. VEM is the first flight instrument designed with a focus on mapping the surface of Venus using atmospheric windows around 1 μm wavelength. It will provide a global map of surface composition by observing with six narrow band filters from 0.86 to 1.18 μm. Continuous observation of Venus’ thermal emission will place tight constraints on current day volcanic activity. Eight additional channels provide measurements of atmospheric water vapor abundance as well as cloud microphysics and dynamics and permit accurate correction of atmospheric interference on the surface data. Combining VEM with a high-resolution radar mapper on the NASA VERITAS and ESA EnVision missions will provide key insights in the divergent evolution of Venus. After several years of pre-development including the setup of a laboratory prototype the implementation for flight has started with the qualification of the flight detectors, the review of all requirements flowdowns as well as the finalizing of spacecraft interfaces.

The BepiColombo spacecraft (ESA) on its way to Mercury has performed two flybys at Venus in October 2020 (FB1) and August 2021 (FB2). The pushbroom IR grating spectrometer (TIS) of the MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) instrument has recorded a large number of planetary radiation spectra of Venus in the spectral range 7-14 μm (715 - 1430 cm-1). MERTIS mid infrared spectra are the first spectrally resolved observations of Venus in the thermal spectral range longward of 5 μm since the Venera-15 Fourier spectrometer experiment FS-1/4 (PMV) in 1983. We report on the results of both flybys showing average radiance and brightness temperature spectra. Basing on a multi-channel radiative transfer simulation and retrieval algorithm we extract atmospheric temperature profiles and cloud parameters of Venus’ lower mesosphere (60-75 km). These results are compared to the former PMV studies.

DESTINY⁺ is a science and technology demonstration mission to asteroid Phaethon, the parent body of the Geminids meteor shower. It will explore the asteroid during a flyby for observations of cosmic dust, which is a source of the organic matter on Earth. In-situ analysis of interplanetary and interstellar dust will be carried out. It is planned to be launched in fiscal year 2024. Model-based development process using a bread board model of an onboard mission data processor is employed prior to system level integration test to follow the tight development schedule. Hybrid and reconfigurable computers are exploited as ground-based models to pursue digital development process. Dynamically reconfigurable devices are used as the central processing unit, and extensive simulation is performed by a hardware-in-the-loop simulator.

The first Doppler Wind and Temperature Sensor (DWTS) using the Doppler Scanning with a Gas Filter (DSGF) measurement technique has been constructed. It is now ready for performance testing in a Virginia Tech Laboratory. The DSGF approach promises extraordinary signal-to-noise and spatial resolution by simultaneously modulating the emission from an entire spectral band. The modulation is measured over typically 100 seconds without affecting spatial resolution. The port or starboard measurement resolution is characteristic of an Earth limb imager: 2km in the vertical (potentially continuous from 20 to 250 km), 10 km along-track and 150 km in the observed limb direction.

CO2Image is a satellite demonstration mission, now in Phase B, to be launched in 2026 by the German Aerospace Center (DLR). The satellite will carry a next generation imaging spectrometer for measuring atmospheric column concentrations of Carbon Dioxide (CO2). The instrument concept reconciles compact design with fine ground resolution (50-100 m) with decent spectral resolution (1.0-1.3 nm) in the shortwave infrared spectral range (2000 nm). Thus, CO2Image will enable quantification of point source CO2 emission rates of less than 1 MtCO2/a. This will complement global monitoring missions such as CO2M, which are less sensitive to point sources due to their coarser ground resolution and hyperspectral imagers, which suffer from spectroscopic interference errors that limit the quantification.

Technological progress in uncooled infrared focal plane array sensors has contributed significantly to enlarge the scope of applications of such sensing technique in many domains: Leisure, Manufacturing, Process Survey, Building insulation diagnostic, Civil Engineering, Road works, etc. Different outdoor situations and objects of interest monitored by an in-house designed measurement architecture are presented. Designed instrumentation architectures and measurements correction from varying environmental conditions and geometrical considerations are discussed. A first step toward joint estimation of emissivity and temperature is introduced for outdoor applications. Then moving object detection by an AI approach applied on thermal image sequences is also presented and discussed. Finally conclusion and perspectives are proposed.

We have developed a time-resolved two-dimensional temperature monitoring system using shortwave infrared (SWIR) detection scheme for a nanocrystalline diamond foil under intense hydrogen ion beams with 1.4 MW average power at 1.0 GeV energy in harsh radiation environment. The optical system composed of a light collecting reflective telescope, dichroic and bandpass filters, SWIR and visible CMOS cameras combined with PIN photodiodes and image sampling pinhole mirrors. It receives thermal radiation located at 40 m from the measurement location. The optical design, optical calibration of the system with high temperature blackbody source, measurement results based on two-dimensional temperature mapping and uncertainties will be presented.

A novel snapshot imaging spectrometer has been developed for short wave infrared monitoring. A custom designed fiber bundle remaps an incoming image to create void spaces on the sensor for a prism to disperse each individual fiber cores. This results in 35,000 spatial samples and each spatial sample providing spectral sampling for over 20 channels in the wavelength range of 1100nm to 1300nm. This spectral region spans the vapor sensitive dip of 1130nm and the vapor insensitive peak of 1260nm in the reflect spectrum of land covers, allowing calculation of a vapor index and the potential for monitoring vapor fluctuations in the atmosphere. Laboratory testing confirms the sensitivity can reach about 42 micrometers of precipitable water, due to the absorption coefficient at 1130 nm. Field testing demonstrates the ability to monitor the temporal and spatial fluctuations of vapor from different land covers such as lawn, concrete surfaces. Real time mapping of the vapor variation - index may provide useful information for atmospheric, environmental, agriculture and solar energy research.

Event-based camera (EBC) technology shows promise for efficient capture of spatio-temporal information, producing a sparse data stream and enabling consideration of nontraditional data processing solutions (e.g., new algorithms, neuromorphic processors). Given the fundamental difference in camera architecture, the EBC response and noise behavior differ considerably compared to standard CCD/CMOS framing sensors. These differences necessitate development of new characterization techniques to quantify performance and assess if the EBC technology produces benefits relative to traditional imaging sensors. Here we present progress on development of basic sensor performance modeling and test capabilities for commercial-off-the-shelf visible EBCs. Laboratory characterization techniques include noise level as a function of static scene light level (termed background activity) and EBC temporal contrast response to dynamic signals. Initial environmental tests of the Prophesee PPS3MVCD event-based sensor found several addressable areas of concern but identified no showstoppers that would prevent use of this device in a high-reliability aerospace application. Two independent radiation tolerance test efforts, one for the PPS3MVCD and another for the iniVation DAVIS346 EBC (both based on 180 nm CMOS technology), indicate functional issues for total ionizing dose (TID) of greater than 30 krad(Si), and show background activity increasing with TID. However, no significant change in contrast response was observed. One DAVIS346 exhibited functional failure following final gamma radiation dose from 20 krad(Si) to 50 krad(Si), and the readout saturated during doses dominated by negative-polarity events (by a factor of 10 or greater). A second DAVIS346 locked-up during proton dose but recovered normal operation following a brief rest period and power cycling. DAVIS346 pixels include both change detection (DVS) and standard grayscale frames (APS) functionalities – driven by a single photodiode; results show a 70% increase in dark current and 23% increase in dark event noise after proton exposure to 20 krad(Si). As new versions of EBC technology are developed for infrared wavelengths, we anticipate these characterization techniques will be largely translatable to IR EBCs.

National time and frequency dissemination networks are being developed in many countries; also international connections are being established. In the contribution we present Czech Infrastructure for Time and Frequency as a non-commercial, open activity focused on the transfer of accurate time and very stable frequency using optical networks. The national optical infrastructure for time and frequency transfer is operated on top of the CESNET network infrastructure, to have operational cost under control. We also address actually running and planned upgrades and future development plans regarding wavelength bands and considered geographic extensions. We will also focus on creation of bidirectional dark channels on different wavebands within shared fibers together with bidirectional compensation of fiber losses. Single path bidirectional amplification utilizing lumped optical amplifiers is sensitive to feedback from fiber line like back scattering and reflections and in case of increased feedback can produce unwanted oscillations, which potentially interfere with parallel data transmissions. We will also briefly mention the CLONETS-DS project working on design study for coherent Pan-European time and frequency dissemination network, which would connect national networks and provide different services based on time and frequency for a wide range of users.

A calibration system is described for the scanning and staring time-of-flight lidars under development for 3D imaging for autonomous driving and similar applications. These lidars must provide distances to objects in the scene with accuracies of a few centimeters while the received light energies span five orders of magnitude. They must operate reliably when exposed to temperature extremes. They must monitor at several dozen frames per second a wide field of view. To fulfill these requirements many lidar designs must incorporate non-linear electronic and optical systems that introduce systematic range-to-target errors that must be compensated by calibration. The calibration system’s alignment stages couple the transmitted laser pulses into a fiber loop which simulates laser propagation in free space for up to one kilometer while retaining a compact, practical device. Optical switches and a variable optical attenuator vary the simulated distance to target and the received pulse amplitude. High stability and repeatability are achieved. Tests of the calibration system will be described that measure the distortion of the laser pulse produced by propagating the laser beam through its fiber optic cables. The ability of the system to calibrate over temperature variations will be discussed.

We discuss state-of-the-art mid-infrared light emitters and detectors based on the so-called 6.1 Å family of semiconductors, i.e. InAs, GaSb, and AlSb. Via epitaxial design routines, heterostructures composed of their binary, ternary or quaternary alloys allow unique features such as optically active type-II superlattices enabling light emitters and detectors suitable for the mid-infrared wavelength region. Here we compare and discuss the design differences between interband cascade infrared detectors employing Ga free Type II superlattices and resonant tunneling diodes (RTD) employing the quaternary alloy GaInAsSb. We show that by substituting the standard InAs/GaSb superlattice for a Ga-free superlattice, i.e. InAs/InAsSb, one requires an inverted carrier extraction path. Here it is needed to form a hole-ladder in the electron-barrier, instead of an electron-ladder in the hole-barrier. At elevated temperatures, we observe seven negative-differential-conductance (NDC) regions due to electrons tunnelling through the electron barriers of the seven cascade stages. The detector operates in photovoltaic mode with a cut-off wavelength of 8.5 μm. The RTD photodetector on the other hand utilizes GaInAsSb absorbers that allow efficient operation in the 2-4 μm range with significant electrical responsivity of 0.97 A/W at 2 μm. Contrary to interband cascade infrared detectors, RTD PD operate only at finite voltages and hence these devices are Shot noise limited.

The synthesis of Newtonian concept of corpuscles during emission with Huygens’ concept of secondary-wavelets during propagation implies that all EM radiations from quantized atoms and molecules are released as discrete amount of energies. However, they propagate out as time-finite Maxwellian light pulses. Huygens also underscored that his secondary wavelets keep propagating as independent pulses in the absence of any interacting medium, or until intercepted by an interface with a medium or a detector. Then we use the Superposition Principle and the coherence theory to derive Einstein’s photoelectric equation by summing innumerable random time-finite pulses. This process driven approach should yield the characteristic statistical variations of photoelectron current pulses, as generated by photodetectors for different kinds of light sources. Lamb & Scully originally proposed this semiclassical approach without assuming that light actually consists of time finite pulses. The quantumness remains confined within the excitation and de-excitations processes in the material particles.

Optical and laser scanning is an essential technology for Remote Sensing. We present our one decade works on one of the most common scanning systems, galvanometer-based. These results can be extended to other scanners such as MEMS with oscillatory mirrors or 2D systems with a polygon mirror (PM) plus a galvanometer scanner (GS). The advantages and limitations of 1D GSs are discussed. Theoretical and experimental analyses and optimizations were performed for the three most common input signals: sinusoidal, triangular, and sawtooth. The trade-off between scan frequency and amplitude (i.e., between scan speed and Field-of-View (FOV)) was studied. Effective versus theoretical duty cycle was determined, in a multi-parameter analysis. Optimal linear plus parabolic custom-made input signals were demonstrated, in contrast to literature, where linear plus sinusoidal input signals were considered to produce the highest possible duty cycle. Further on, 2D GSs were approached for raster scanning modalities. Thus, for the slow scan axis, we demonstrated that step-by-step scanning is the best option, while constant speed scan requires electromechanical impulses (in the system) that should be avoided. Finally, optimal scanning laws are deduced for 2D GSs. Perspectives of laser scanning modalities are discussed.

We present a novel laser-pulsed shutter constructed by combining a solid-state pulsed high-voltage gas pre-ionizer and a CO₂-TEA laser beam self-generated plasma. This cascaded electro-optical modulator produces 60 ns laser output pulses with less than 7 ns jitter leading to high output energy stability. No pulse recovery occurs after the laser pulse is clipped. The high voltage pulse-based pre-ionization module also has the advantage of being automatically integrated into the pulse-forming network of the laser discharge circuit.

It is a generally accepted belief that a shearing interferometer finds a derivative of the wavefront along the direction of the shear. A shear could be implemented in a form of a linear displacement along an axis, a vector displacement along an arbitrarily chosen direction, a small rotation, and the radial magnification, to list the most popular ones. The shearing function implemented in the interferometer as a device that finds a specific derivative is valid only for a small amount of shear. In fact, in the mathematical definition of a derivative, we arrive at the concept of the derivative of the function, by requiring that that the small change should approach to zero. We examine the range of validity of the shearing-induced change as a derivative of the aberration polynomial in a rotationally sharing interferometer. Furthermore, we propose steps to decrease the errors in the determination of the magnitude of individual aberrations.

The 2020 fire season includes the single largest fire in California’s history, the August Complex Fire. Ash and soot contained in wildfire smoke have a low albedo and can absorb incoming UV radiation. As a result, one would hypothesize that at a local level the surface UV irradiance dosage would change in areas leeward of large fires. To test this hypothesis, the direct and diffused UV irradiance recorded east of the August Complex Fire at the UVMRP station in Davis, CA were compared between 2020 and 2016. Direct and diffused UV irradiance levels at local noon of an entire year were compared between these two years, trying to identify how wildfire impacts surface UV. Using satellite imagery to determine when smoke was present in the skies over Davis, CA, this study investigated how UV irradiance changes during those time periods.

For infrared imaging systems the most used detectors are microbolometers. The trend is to create focal plane array (FPA) sensors composed of smaller and smaller infrared pixels, but this reduction decreases the efficiency of traditional bolometers. Optical antennas have been studied as an option to replace traditional bolometers, but they require a bias voltage and a rectification system. Recently, nanoantennas with thermoelectric elements have been incorporated to provide a continuous output voltage, reducing part of the energy of the entire infrared imaging system. In this work, Seebeck nanoantennas are modeled as an infrared pixel for FPA, and their response and effectiveness are calculated using finite element simulation.

The moisture content of forest fuel on the forest floor is a determining factor in assessing the ignition and spread of fire. The measurement of moisture content through indirect methods benefits obtaining and visualizing results immediately. Some indirect methods are based on the measurement of environmental variables, but they require calibration for specific tree data. In this work, we examine the diffuse reflectance spectra of the leaves of different tree species in two spectral bands, obtaining a relationship with the measurement of the moisture content of the leaves through the indirect method based on meteorological factors. This relationship contributes to the characterization of remote sensing devices implemented in measuring moisture content in biomass dry on the forest floor, improving measurement accuracy.

The signal-to-noise ratio compares the power of a signal with information of interest against an undesired signal considered noise. In a lab experiment, we measured the signal-to-noise ratio of two intensity patterns in a Rotational Shearing Interferometer based on a Mach-Zehnder configuration with a dove prism in one arm of the interferometer. One signal represents the faint radiation of a planet, and another means the high radiation from a star. The proper rotation of the dove prism eliminates the intensity pattern produced by the star, but the intensity pattern due to the planet prevails. The rotation of the dove prism improves the extremely small SNR of these signals. This improvement helps the planet detection near a star by interferometric methods.

In this paper, we show the results and feasibility of a designed software for obtaining and graphing aberrations in 2D, and the post-processing necessary for the detection of the centroids. This software is designed to be used in low-cost and highly affordable commercial devices such as Raspberry pi and Raspberry pi HQ Camera. Preliminary results will also be presented.

This PDF file contains the front matter associated with SPIE Proceedings Volume 12233 including the Title Page, Copyright information, Table of Contents, and Conference Committee Page.