This PDF file contains the front matter associated with SPIE Proceedings Volume 12686, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The Thermal Infrared Sensor (TIRS) instruments on board Landsat 8 and Landsat 9 provide routine thermal band image measurements of the Earth for the Landsat program. Although these observatories are specifically designed for mapping the Earth’s surface from their 705-km altitude orbits, they were recently utilized to image the Moon during the total lunar eclipse of May 2022. The full Moon is frequently used as a calibration target for Landsat. However, the imaging of the lunar eclipse provided a unique opportunity to gather accurate temporal thermal band data over the full lunar disc as solar illumination is removed. This campaign required a large effort by the Landsat Flight Operations teams to coordinate acquisitions and technical constraints on both observatories to capture the long temporal extent of the eclipse. The result of this effort was a series of resolved thermal images of the Moon at discrete times as the Earth’s shadow swept across the lunar surface through the start, partial, and total phases of the eclipse. This sequence of images showed an overall drop in surface temperature from approximately 370 K to 180 K in about 300 minutes as solar insolation was removed. Furthermore, the spatial distribution of cooling rates from this unique event provided information about different material properties (density and thermal inertia) across the lunar surface and showed a clear distinction among mare, highlands, and impact craters.

The Landsat program has consistently provided high quality Earth imagery for over five decades. The Thermal Infrared Sensor (TIRS) on Landsat 8 and on Landsat 9, launched in Feb 2013 and Sept 2021 respectively, are nearly identical 2-band (10.9 and 12 micron) push-broom sensors extending the legacy of Landsat thermal measurements. Both Landsat 8 TIRS and Landsat 9 TIRS were built at NASA Goddard Space Flight Center. The pre-launch testing of both TIRS characterized the radiometric, spectral and spatial performance using essentially the same calibration ground support equipment system as well as analysis methodologies and techniques. Landsat 9 TIRS benefited from lessons learned from the original Landsat 8 TIRS so overall has better performance. Once on-orbit, it is challenging to evaluate the spatial calibration performance of a sensor. One technique is to use ocean coastlines in desert regions as a high contrast edge target. This paper focuses on the spatial characterization assessment of both sensors while on-orbit in terms of edge spread function, point spread function and modulation transfer function. It is shown that both Landsat 8 TIRS and Landsat 9 TIRS demonstrate consistent spatial performance over their respective mission lifetime and no significant change from the prelaunch derived estimates.

In the ever-advancing realm of modern technology, the demand for unparalleled precision and stability in timekeeping and frequency control has surged to unprecedented heights. As our interconnected world rellies more than ever on intricate synchronization and seamless communication, the development of cutting-edge optical infrastructure has emerged as a cornerstone in meeting these exacting demands. There has been obvious increased continuous focus on precise time and frequency transmission dissemination at a national and international level recently. We would like to present the situation in the Czech Republic, our strategy, approach, and our experience with a non-commercial, costeffective solution that utilizes optical networks shared with other traffic. The presented solution provides accurate time and stable frequency at a lower operational cost, using the shared spectrum of the CESNET3 network infrastructure.

Recently selected Venus missions, such as NASA's VERITAS, ESA's EnVision, and DAVINCI, are all equipped with instruments that focus on the 1 μm region in their payloads. Specifically, VERITAS and EnVision utilize the Venus Emissivity Mapper (VEM) as a multi-spectral imaging system. VEM is designed to provide global mapping of Venus's surface in all available spectral windows. Meanwhile, DAVINCI has a descent imager that obtains images of the surface around 1 μm. To support these missions, the Planetary Spectroscopy Laboratory (PSL) at DLR has a Venus spectroscopy setup consisting of a Bruker VERTEX 80V FTIR spectrometers with an attached vacuum chamber equipped with an induction heating system. PSL can measure emissivity spectra of Venus analogues at temperatures up to 1000K in the spectral range from 0.8 to 1.2 μm. Additionally, PSL has two hemispherical reflectance units available that can be mounted in the internal chamber of the Bruker VERTEX 80V spectrometer. PSL has already measured the emissivity of over 300 rock samples at Venus surface temperatures for calibration and verification efforts for VEM on VERITAS and the VenSpec-M channel on the EnVision mission. Hemispherical reflectance measurements are also taken for each sample. These data will be used for the basic and enhanced calibration datasets for the missions as well as all other Venus missions carrying similar instrumentation. Coordination and cross-calibration of the missions' instruments are crucial. Team members from VERITAS, EnVision, and DAVINCI are collaborating to establish a good cross-calibration between the missions. The data obtained by these missions will provide unique insights into the coupled surface-atmosphere system of Venus.

The Venus Emissivity Mapper (VEM) and the VenSpec-M on the NASA VERITAS and ESA EnVision missions, respectively, are multi-spectral imaging systems designed specifically for mapping the surface of Venus using near-infrared atmospheric windows around 1 μm. VEM/VenSpec- M will provide the first global map of rock types on the surface of Venus as well as constant monitoring for volcanic activity at global (VERITAS) and regional/local (EnVision) scales. The VEM/VenSpec- M verification plan ensures accurate performance and science return of the instrument and includes on-ground and in-flight instrument calibrations as well as supporting laboratory measurements for calibration and scientific data analysis. Pre-flight calibrations encompass geometric, spectral, and radiometric calibrations based on the MERTIS (on BepiColombo) calibration campaign and pipeline. Laboratory work involves the creation of spectral libraries of increasing complexity by measuring the emissivity of Venus analogs under Venus surface conditions. These data will distinguish between basalt and felsic rock types on the Venus surface and may enable the identification of intermediate compositions based on iron content. Data analysis uses machine learning models for classification between basalt and felsic rocks and regression to predict FeO content using laboratory calibration data. The data verification plan outlined here not only provides fundamental data needed for VEM/VenSpec-M, but can also be adapted to create data products suitable for calibration of the VenDi (Venus Descent Imager) instrument on the DAVINCI mission. Such use of an integrated calibration plan will benefit all three missions and produce coordinated results that can be directly compared.

The Venus Emissivity Mapper (VEM) as part of NASAs Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy mission (VERITAS) is designed for mapping the surface of Venus within dedicated atmospheric spectral windows. The instrument will provide global coverage for detection of thermal emissions like volcanic activity, surface rock composition, water abundance and cloud formation as well as dynamics by observing 15 narrow filter bands in the near infrared to short wavelength infrared (NIR, SWIR) range of 862 nm to 1510 nm. An almost identical instrument will be part of ESAs EnVision mission to Venus, the VenSpec-M in the Venus Spectroscopy Suite (VenSpec). The utilized photodetector is an InGaAs type imaging sensor with integrated thermoelectric (TE) cooling. It comprises a 640x512 pixel array with 20 μm pixel pitch. Following the mission requirements we irradiated the detector with a set of ions of various stopping powers and range distributions from lower energy Argon (Ar) to higher energy Xenon (Xe). Therefore, exploiting the mentioned ions and proper tilt angles during irradiation, our data covers a Linear Energy Transfer (LET) range of 7 to 75 MeVcm²/mg which fulfills NASA/JPL led space qualification standards (up to 75 MeVcm²/mg) as well as ESA space qualification standards (up to 60 MeVcm²/mg) for heavy-ion irradiation. Our electrical setup consists of a dedicated over-current protection detecting high-current states occurring during irradiation steps and immediate power cycling to prevent physical damage of the device. From the event rates seen during the test we calculated the specific cross-sections and therefore can estimate the expected event rates at Venus during the mission. The detector showed saturated cross-sections below 1E-3 cm² at 10°C with acceptable event rates for the highest LETs and our applications.

Measurements made by MERTIS (MErcury Radiometer and Thermal Infrared Spectrometer) during the BepiColombo mission's first and second close flybys of Venus in October 2020 (FB1) and August 2021 (FB2) have provided a new and solid data base for the study of the planet's mesosphere at near equatorial latitudes. During the two FBs, the Pushbroom IR grating spectrometer (TIS) of the MERTIS instrument recorded a large number of spectra of planetary radiation from Venus in the 7-14 μm spectral range (715 - 1430 cm^-1) for the first time since the Venera-15 Fourier spectrometer experiment FS-1/4 (PMV) in 1983. The MERTIS instrument was designed to study the hot surface of Mercury. Despite the much lower intensity of radiation from the Venusian mesosphere, it was able to demonstrate its suitability for studying the mesospheric temperature profile and various aspects of the mesospheric composition. In this paper, we demonstrate the capability of the MERTIS technology for the study of the Venusian atmosphere. We report on our technical and calibration approach and the main results of the two flybys. Our results on atmospheric temperature profiles and cloud parameters of the upper troposphere and mesosphere (60-75 km) of Venus are presented. We draw conclusions on the applicability and prospects of the developed technology for future targeted explorations of the Venusian mesosphere.

A space-based far-infrared interferometer could work synergistically with the James Webb Space Telescope (JWST) and the Atacama Large Millimeter Array (ALMA) to revolutionize our understanding of the astrophysical processes leading to the formation of habitable planets and the co-evolution of galaxies and their central supermassive black holes. Key to these advances are measurements of water in its frozen and gaseous states, observations of astronomical objects in the spectral range where most of their light is emitted, and access to critical diagnostic spectral lines, all of which point to the need for a far-infrared observatory in space. The objects of interest – circumstellar disks and distant galaxies – typically appear in the sky at sub-arcsecond scales, which rendered all but a few of them unresolvable with the successful and now-defunct 3.5-m Herschel Space Observatory, the largest far-infrared telescope flown to date. A far-infrared interferometer with maximum baseline length in the tens of meters would match the angular resolution of JWST at 10x longer wavelengths and observe water ice and water-vapor emission, which ALMA can barely do through the Earth’s atmosphere. Such a facility was conceived and studied two decades ago. Here we revisit the science case for a space-based far-infrared interferometer in the era of JWST and ALMA and summarize the measurement capabilities that will enable the interferometer to achieve a set of compelling scientific objectives. Common to all the science themes we consider is a need for sub-arcsecond image resolution.

Exploring the outer solar system is a priority, with upcoming missions including ESA JUICE and NASA Lucy. There is high demand for laboratory spectra of analog materials obtained at low pressure or in vacuum at cryogenic temperatures. To meet this demand, PSL has added a compact low-temperature vacuum chamber for angle dependent bi-directional reflectance measurements that attaches directly to an existing spectrometer. The system allows for measurements from UV to far infrared for up to 4 samples at temperatures lower than -150°C under vacuum down to 10-6hPa. The samples are prepared in a glovebox under dry air and controlled temperature conditions down to -50°C and are directly transferred to the vacuum chamber via an airlock.

In this work, we presented a phase demodulation technique for fringe analysis in fringe projection profilometry based on digital moiré and the co-phase technique. The approach involves the use of stereo illumination and the simultaneous projection and acquisition of two π-shifted sinusoidal patterns from each projector. By taking advantage of color multiplexing, we code the sinusoidal patterns in the red and blue channels of the RGB images, so we need to project and acquire one image for each digital light projector. The phase demodulation consists of two steps: first, digitally generating the moiré pattern for each RGB image utilizing the spatial phase carrier; second, computing the analytic signals for the two moiré patterns via a third-order, low-pass Butterworth filter in the frequency domain; third, calculate the final phase by merging the two analytic signals using the co-phasing technique.

In classical physics, the detection of any physical quantity is accompanied by noise, including the classical noise of the system and quantum noise, which limits the detection accuracy. Among them, the classical noise mainly comes from technical defects, the advantages and disadvantages of instruments and other factors. With the development of science and technology, the classical noise of the system is greatly reduced and can often be ignored. Therefore, quantum noise determined by quantum mechanical properties gradually becomes the main source of noise. The squeezed light source has the quantum property that a certain orthogonal component can be lower than the shot noise limit, which breaks through the standard quantum noise limit and further improves the detection accuracy. As a kind of non-classical light, the squeezed state has great application potential in the field of quantum optics. Based on the stable working squeezed light prepared in the early stage, and combining with the theory, experiment and key technology of Professor Bi over 20 years, we have developed a set of instrumentized short-range quantum infrared detector. Special design is made in light source, detection system, pattern matching, phase locking, structure design and packaging, which can effectively improve detection accuracy and imaging quality in the range of 0.5m-9m, and then used in light source correction such as transverse displacement and tilt measurement of light beam and various detection under special conditions such as weak light.

Onboard sensor electronics of satellites are hard real-time systems and exploit high performance of heterogeneous computing. This paper describes sensor electronics design framework with heterogeneous computing edge nodes based on onboard demonstration records of satellites. Dedicated functional processing elements (PEs) for specific purposes implemented on Field Programmable Gate Arrays (FPGAs) and Application Specific Integration Circuit (ASIC) are used in addition to conventional Micro-Processing Units (MPUs). Many core processors like General Purpose Graphics Processing Units (GPGPUs) are also used for signal processing of sensor electronics in these days. Semiconductor process shrink is accelerating this technological trend. Because it reduces power consumption, size and mass while maintaining high processing performance. The applications of artificial intelligence, such as image recognition, became common for onboard sensor electronics. Dedicated PEs for image recognition implemented on FPGAs enables wire rate processing. Sensor signals are processed without interrupting data flow, and in-situ measurement results can be used for other purposes such as optical guidance and navigation. Heterogeneous computing edge nodes are often realized with distributed memory system. In addition to that the semantic gap between hardware and application software is widening. Despite these complexities, changes to the operation scripts of onboard sensor electronics are often needed on orbit. We have found that the layered architecture of heterogeneous PEs and the middle-out approach of system integration design are practical enough for onboard operation to aim at realizing user-centric command operation scripts. The design scheme is explained in this paper.

We report on the design of a new laboratory setup for testing the performance of optical and thermal sensors at temperatures ranging from 50 K to 350 K and pressures ranging from ambient atmospheric pressures down to 10^-5 mbar. The system will be built around a closed-cycle cooled cryostat which houses the device under test. Optical stimuli will be provided by a calibrated selectable light source which provides collimated light from an integrating sphere or a cavity blackbody. Bandpass filters as well as imaging targets can be selected for determining the spectral response and modular transfer function. Data acquisition from the device under test will be accomplished using an automated test bench based on a custom-made FPGA interface adaption board.

A two-color imaging pyrometer was developed to investigate two-dimensional thermal behavior of micrometer thick nanocrystalline diamond foils with microsecond temporal resolution. The optical system composed of an on-axis Cassegrain telescope, dichroic and bandpass filters, two high-sensitivity SWIR cameras combined with two PIN photodiodes and an image sampling pinhole mirror. The imaging pyrometer is calibrated with a high temperature blackbody source and compared to a commercially available infrared camera. The design has achieved high imaging quality and the system measures absolute temperatures of diamond foils with surface roughness and emissivity variation under high intensity hydrogen ion beams up to 1.6 MW average power. The results obtained shows that the two-color imaging pyrometer developed can measure the temperatures with accuracy better than 1.0 % over the range of 1000 K to 2000 K.

In this work, we will present two techniques for extracting the wavefront and polarization structure of optical fields. The first being a digital analogy to Stokes polarimetry involving only four measurements, as opposed to the usual six. Here, we implement static polarisation optics, such as a Polarization Grating (PG) to project a mode into left- and right-circular states, which are subsequently directed to a Digital Micro-mirror Device (DMD) to impart a phase retardance for full phase and polarisation reconstruction. The second approach uses the transport-of-intensity which harnesses the connection between observed energy flow in optical fields and their wavefronts. We present a simple scheme using a DMD to perform angular spectrum propagation and extract the wavefront of optical fields. Finally, we demonstrate these approaches by spatially resolving complex polarization structures such as metasurfaces, liquid crystal devices and chiral materials.

One of the main objectives of the NASA's VERITAS and the ESA's EnVision missions is to characterize the composition and origin of the major geologic terrains on Venus. Both missions carry the Venus Emissivity Mapper (VEM) – a multispectral imager - which will be able to observe the surface of Venus through five atmospheric windows with six bands, around the 1μm spectral range. This will enable the spectral characterization of the Venusian surface, as well as deduce the type of lava and likely alteration processes, providing new insights into the evolution of Venus. To improve our knowledge of the mineralogical information obtained from the 1μm spectral range, we are developing a series of "VEM emulator" (aka VEMulator). The first one was based on a commercial Raspberry PI HQ 12MP camera, containing the Sony IMX477 sensor, with a 35mm lens. Four filters with wavelengths of 860, 910, 990, 1100 nm could be attached in front of the lens similar to four of the six VEM mineralogy spectral bands. This instrument was deployed in summer 2022 on the Vulcano island in southern Italy as Venus analog site. Vulcano rocks display a diverse compositional variation from basaltic to rhyolitic, which makes this site an attractive analog to Venus. Currently, a new version of the VEMulator is being developed using the SCD Cardinal 1280 InGaAs detector – similar to the detector used in the VEM flight model. This VEMulator 2.0 will be used in Iceland, in 2023, for a VERITAS field campaign.

Lidar (laser radar) offers advantages over conventional radar in terms of higher resolution, greater anti-interference capability and ultra-low altitude detection performance. However, Lidar has now reached a bottleneck in terms of detection range and is no longer able to correctly identify targets beyond 500 meters, thus failing to meet the requirements for detection, measurement and imaging. To break this bottleneck, we have developed a Quantum Lidar with a detection range of up to one kilometre, which is based on a quantum vacuum squeezed laser and can compress the photon fluctuation by 5.6dB in the vacuum state through quasi-phase matching in non-linear crystals, reducing the quantum noise of laser which accounts for 73% of the lidar, thus reducing the overall noise of the quantum lidar by 3.27dB and improves the phase stability of the laser (from 10 minutes to more than 120 minutes) to achieve higher accuracy measurements, with a Signal-Noise Ratio (SNR) twice that of conventional lidar, and therefore a sensitivity twice as high. The basic technical implementation is to use a 20W power 1064nm wavelength continuous wave laser (CW, M² less than or equal to 1.05) to irradiate a target located one kilometre away. By detecting a very weak reflected laser (power=10μW ± 5μW) which is exponentially attenuated by distance, We use noiseless amplification by a quantum vacuum-squeezed laser with the same power magnitude to obtain a higher power (7dB amplification) and higher signal-noise ratio (4.77dB SNR improvement). A reflective lens set (250mm aperture) of our design is used to receive the laser diffusion due to the 4mrad transmission angle of one kilometre. In the squeezed laser system, the resonant cavity locking efficiency is improved to 99.7%, and the re-locking time is less than 0.3s, it is directly switchable with the balance homodyne detection system. The mode cleaner improves the transverse mode quality(the mode bandwidth is reduced by 67%) while filtering high-frequency noise. The quantum lidar imaging system has been developed, and the experimental results show that the resolution of the laboratory-simulated long-range decay experiment is 3 times higher than that of traditional lidar is a promising development. This means that the system can detect and image smaller objects and features with greater accuracy and precision. The use of a self-developed quantum enhancement algorithm to obtain a 5 times higher contrast lidar image is also a significant improvement, and the use of a quantum denoising algorithm to reduce graphic distortion and image scatter caused by atmospheric pollution and environmental interference is a critical development. These issues can significantly degrade the quality of lidar images, so being able to mitigate their effects is a significant step forward. Through a self-developed LiDAR 3D reconstruction algorithm, the reconstruction efficiency is increased by 3 times and the resolution is increased by 2.5 times, which means that the reconstructed 3D model is faster, more detailed and accurate. In the future, based on one kilometre's work, achieving a quantum lidar with a detection distance of 10, 20 or even 50 kilometres with much clearer images would require advancements by steadily improving the resolution, improving the signal-noise ratio of the system, improving the laser power and optimising the algorithm.

We propose a new derivation for two-plane wavefronts incident in a rotational shearing interferometer. We introduce a displacement in the optical path of the Rational Shearing Interferometer and therefore modify the spatial frequency. We obtain an approximate formulation for the total incidence for two independent signals. We use a 4f optical processor and interferometric cancellation to recover the weakest signal. We also use a cancellation signal’s advantage to improve the interest signal’s signal-to-noise ratio (SNR). The proposed method works efficiently for computer simulation, the next step uses the same procedure to eliminate frequencies for a laboratory interferogram. We simulate a Star-Planet system, and this process will help in exoplanet detection.

Thyroid cancer is the most common type of neoplasm in the head and neck regions, thermal imaging has been used successfully for medical diagnostic purposes in areas such as breast cancer, wound care, vascular diseases, skin cancer and eye diseases. The thyroid is a richly vascularized gland that is located close to the skin, its hyper or hypo activity modifies the temperature pattern of the neck making thermography a good candidate to evaluate possible pathologies by digital infrared thermography. In this work an Artificial Neural Network based on the Nested U-Net architecture is trained and used to detect thyroid pathologies. Two thermographic databases were used to train the artificial neural network, the dataset was split into 80% for training and 20% for testing, with cross-validation used to evaluate the network's performance. The error between the predicted masks and the actual masks is calculated with the combination of Binary Cross Entropy (BCE) Loss and Dice Loss using Adam algorithm as training rule, with a cosine annealing schedule during 1500 epochs with a learning rate of 0.003 and a batch size of 6. Results show that when calculating the correlation coefficient between these deltas and the results of thyroid ultrasound expressed in the ACR TI-RADS classification, a high degree of correlation is obtained.

Remote sensing used in vegetation monitoring has been a significant study area for decades. With the advent of multispectral and hyperspectral cameras, detecting healthy vegetation in forests and crops were more accessible through the ratio of different spectral bands that resulted in other vegetation indices. However, even with the usefulness and practicality of these methods, they need to be more accurate since they are relative values that depend on several factors of the internal composition of the vegetation. This work proposes the analysis of a spectral bandwidth of a central wavelength of 1 μm, using a conventional CCD camera as a detector with a bandpass filter with a linewidth of 10 nm. This range presents characteristics of water absorption but also reflectance due to the cellulose of the cell walls of the leaves. In this way, using the electro-optical array, the radiation reflected changes by several leaves will be analyzed considering the hydration and deterioration of the leaf.

A laser shock wave is a pressure wave that travels through a material at supersonic speed induced by a high-power laser pulse. Shock waves suddenly change direction as reflected at the physical limits of the medium, producing interference between the wave remnants. The reflected wave reaches the front surface transiting a distance as a function of the thickness and the reflection angle. The time it takes for the shock wave from being induced to reflect toward the front surface of the material can be used to determine the thickness of the propagation medium. A finite element method estimate the propagation of a laser shock wave in four basic geometric shapes of 6061-T6 aluminum alloy. The time it takes to reach the front surface of the geometric shapes is measured. Its controlled the material thickness and spatial coordinate of the induction. The effects of the porosity, absorption and transmission of the medium are ignored. The results demonstrate the feasibility of use the time-of flight as a thickness measurement and a distribution of compression and pressure zones inside the medium generated by the wave interference. Some applications of this method are to determine the thickness of solid materials, the estimation of caverns or aquifers on geophysics, and the determination of the density of a material.

Precise time and stable radio frequency dissemination is becoming standard application in optical networks. The White Rabbit system is commonly used for this purpose to support applications that require precise time and a stable frequency signal. Optical fibers are preferred for distributing the precise time and frequency signal in this system. To achieve best results, i.e. determine absolute offsets, it is necessary to know the asymmetry of the optical transmission path in which the system is deployed. We developed a device based on a MEMS optical switch that measures the delay of the optical path in both the forward and reverse directions. These measurements are used to continuously evaluate changes in the asymmetry of the transmission path, and the resulting asymmetry can be used to calibrate the time transfer system.

The off-axis three-mirror optical system is derived from the classical Cooke triplet or a derivative of the inverse telephoto lens. By properly arranging an internal reimaging mechanism or altering the location of the optical stop, one can create different versions of three-mirror optical systems. They include very compact configurations and wide field of view imagers. Insights into the optical design process, manufacturing, stray light management, and remote sensing applications are presented.

High performance megapixel focal plane arrays with small pixels have been widely used in modern optical remote sensing, astronomical, and surveillance instruments. In the prediction models applied in the traditional instrument performance analysis, the image of a point source is assumed to fall on the center of a detector pixel. A geometrical image of a point source in the realistic optical system may actually fall on any position on the detector pixel because the sensor’s line-of-sight includes pointing errors and jitter. This traditional assumption may lead to an optimistic error, estimated at between 10% and 20%. We present the critical factors that impact the performance estimate in a realistic instrument design based on the prediction for the noise equivalent power (NEP). They are the optical centroid efficiency (OCE) and the ensquared energy, or more precisely, the energy on the rectangular detector pixel (EOD).