This PDF file contains the front matter associated with SPIE Proceedings Volume 11830, including the Title Page, Copyright Information, and Table of Contents.

Precise time and ultra-stable optical frequency transfers over fiber networks are deployed relatively often these days. When size of such infrastructure for precise time and frequency bidirectional transmission is becoming significant, aspects associated with infrastructure operational cost and time needed for deployment of time and frequency transmission must be considered. First can be decreased via fiber sharing with telecommunication traffic, however spectral allocation must be considered carefully to avoid mutual disturbance of time and frequency transmission versus data and allow future accommodation of growing demands. In text, we show and discuss alternative spectral bands to be used for time and frequency transmission. Time to deployment can be quite excessive especially when transmission must be established via multiple networks or network domains, also there is a chance of blocking. In case of precise time and optical radio frequency transmission it is possible to use conversion from optical to electrical and back to optical domain with wavelength change. This possibility removes danger of blocking and improves time to deployment for such services. We also address possibility to change wavelength or just extend reach by using simple re-amplify and reshape approach.

A 3X3 plastic optical fiber (POF) twisted coupler has been fabricated as a compact sensor of multiple variables. The POFs are twisted into a combined body and the clad was removed by chemical method. Three LEDs of red, green, and blue colors can be used to shape a broad spectrum. Each led was connected at a different input port of the coupler. Since the twisted coupler makes the coupling of light from the input ports, we have a wide spectrum at each one output port. We develop a different sensor at each one output coupler: mass concentration (At the output-1), and curvature (At the output-2). The multi-sensing proposed in this work can increase the number of sensors as increase the number of output ports, and the bandwidth increase as increase the colors of light sources. On the other hand, we can use a wide spectrum lamp in a single input port and in the same way make multiple sensors in the output ports. The variation is evident in all wavelengths of the spectrum for measurements of sugar concentrations and fiber curvature. However, we can directly associate the sugar concentration variations with the spectrum in a range from 570 to 600 nm; and across the full spectrum for curvature measurements.

The infrared Absolute Radiance Interferometer (ARI) instrument - developed at University of Wisconsin-Madison, Space Science and Engineering Center (SSEC) - measures absolute spectrally resolved infrared radiance (200-2000 cm^-1 or 5-50 μm at 0.5 cm^-1 resolution) with ultra-high accuracy (< 0.1 K 3-sigma brightness temperature at scene temperature). The ARI prototype instrument was deployed for field measurements of clear-sky far infrared (FIR) surface emissivity and radiances on the SSEC rooftop. Currently there are very few measurements available in the FIR spectral region. Our targeted samples include snow and ice surfaces which are important for radiative cooling in the polar regions. We will demonstrate the ARI instrument configuration, capability for ground-based measurements in the FIR region, and the retrieval of infrared emissivity spectra. The ARI ground-based FIR measurements would support scientific applications that involve FIR studies, such as the PREFIRE (Polar Radiant Energy in the Far InfraRed Experiment) and the European FORUM (Far-infrared-outgoing Radiation Understating and Monitoring) missions.

In recent years deep learning has proved its ability to both extract object features and classifies them. Diffraction patterns from an aperture on screens play a central role on physical optics. Fourier transform of an aperture represents its diffraction pattern in the far-field. In this proposal we consider far-field diffraction patterns of non-symmetric apertures as objects to be recognized. For this purpose, we consider the MNIST dataset as apertures on a screen. Here the diffraction pattern of each aperture varies due to the variations of the digits in the data set. We present a model based on convolutional neural networks to classify far-field diffraction patterns whose accuracy is above 90%.

Commercial Infrared and Terahertz imaging systems have a focal plane array made of bolometric elements which form the pixels in the imaging system. Bolometers have the disadvantage of being slow and require a bias voltage to operate, which increases the power required to operate the infrared imaging system. The current trend is to transition to small size, weight, and power (SWaP) imaging systems. Seebeck nanoantennas are resonant elements made of two dissimilar thermoelectric materials tuned at a particular wavelength, when this wavelength is incident on the nanoantenna it induces a current that increases the temperature at the feed of the nanaontenna generating a temperature difference that produces a Seebeck voltage. Due to the small size of the antenna and its low thermal mass it makes Seebeck nanoantennas considerably faster than tradition bolometers. Also, since the thermoelectric elements provide an output voltage no bias is needed for operation, reducing the power required by the FPA. In this work an infrared pixel is designed and optimized for detection in the 8-12μm wavelength range, and its thermoelectric voltage is calculated using numerical simulations for different pixel pitch sizes.

We are studying the feasibility of using a rotational shearing interferometer to detect a planet in a nearby solar system. In this paper, we describe the status of our work. We built a rotationally shearing interferometer and demonstrated that a simulated star indeed produces a field without fringes. The faint simulated planet provokes appearance of faint fringes. Their density and slope may be changed upon changing the shear angle when the planet is present.

The planet detection challenges have been formulated based on the radiometric, distance, and technology issues as a signal detection problem, under very unfavorable conditions. We would like to find a simplest solar system defined as having one star, similar or identical to our sun, and one planet, likewise similar or identical to our biggest planet, Jupiter. We define the simplest signal-to-noise ratio to determine the optimal wavelength interval for extra-solar planet detection. For a solar system similar to our own, we calculate the signal-to-noise ratio to be one hundred times smaller than that estimated previously. We propose the planet detection in a spectral interval around 0.3 mm (900 GHz) where high-altitude observatories report atmospheric transmission of about 0.4.

Venus is one of the less well studied planets in the inner solar system. Despite its mass being comparable to that of Earth, the development of its environmental conditions followed a completely different evolutionary path. Today's dense CO₂ dominated atmosphere is characterized by extreme surface conditions of 92 bar and 735 K at the mean altitude of the planet's surface and a cloud layer enriched with sulfuric acid aerosols, which makes observations of the daytime surface in the visual spectral range impossible. This circumstance led to a long standstill for further space programs to Venus after the first space-based explorations of this planet in the 1970s through the mid-1990s, which was not broken until the launch of ESA's Venus Express (VEX) mission in 2005. Missions such as VEX, Akatsuki (JAXA), and BepiColombo (ESA; MERTIS, first Venus flyby) have made new VIS-IR spectroscopic measurements of Venus in recent years, contributing to the study of its atmosphere and surface. We report here selected results of these investigations and their comparison with earlier data. We derive from these discussion scientific and instrumental requirements for VIS-IR spectroscopic spaceborne measurements with focus to currently selected and future space missions such as EnVision (ESA) and VERITAS (NASA), and discuss their capabilities and limitations for atmospheric and surface studies.

The ESA-JAXA BepiColombo Mercury mission was launched in October 2018. It performed successful flybys of the Earth-Moon system on April 10, 2020 and of Venus on October 15, 2020 during which the MERTIS instrument operated. MERTIS obtained a total of 1.2 million spectra during the Moon flyby from a distance of more than 700000km. Venus observations started at a distance of more than 1.3 Mio km recording more than 3 million spectra. For reference at Mercury MERTIS will observe the planet from a distance of less than 1500km. These data and the Near-Earth commissioning show that MERTIS performance exceeds requirements.

The MErcury Radiometer and Thermal Infrared Spectrometer (MERTIS) is an instrument to study the mineralogy and temperature distribution of Mercury's surface in unprecedented detail. During the nominal mission, MERTIS will map the whole surface at 500 m scale, combining a push-broom IR grating spectrometer (TIS) with a radiometer (TIR) sharing the same optics, instrument electronics, and in- ight calibration components for the wavelength range of 7-14 μm (TIS) and 7-40 μm (TIR). MERTIS observed the Moon in April 2020 and Venus in October 2020 under conditions different from nominal operation and performed surprisingly well. MERTIS returned several hundreds of thousands scientifically useful spectra from the two campaigns. MERTIS archival data are stored in Planetary Data System v4 format (PDS4), that describes 2 physical formats for each MERTIS channel. Each channel will is stored in Flexible Image Transport System (FITS) and in pure ASCII, to maximize both machine and human readability.

A Dual differential absorption LIDAR (DIAL) based on two stage tandem OPO midinfrared (IR) tunable Optical Parametric Oscillator (OPO) has been developed and characterized. The first OPO stage, built around a nonlinear KTP crystal in an unstable resonator, produces 40 mJ of 1.57 μm radiation when pumped by a Q-switched Nd:YAG laser. Silver gallium selenide (AgGaSe2) crystal forms the OPO second stage which generates 0.9 mJ of Idler peak energies within 5.0 to 11.0 μm tuning region with typical spectral bandwidth values of the mid-IR radiation of 7-8 cm^-1 which is well-matched with many complex molecules in the atmosphere which have bandwidths larger than 15 cm^-1. The receiver is composed of a gold-plated primary mirror of a 300 mm forms the Cassegrain telescope, two channel detection system and control and amplifying electronics. Preliminary path-averaged ammonia concentration measurements are presented and analyzed.

In this article an introduction to the dynamical behavior of a beam within a ring phase-conjugated optical resonator is presented and modeled using two-dimensional iterative maps. Four well known iterative maps are described: Duffing, Tinkerbell, Hénon, and Standard and are applied to the description of optical resonators. It is explicitly shown how the difference equations of these maps can be used to describe the dynamic behavior of what we call Tinkerbell, Duffing, Hénon, Standard and Ikeda beams i.e. beams that behave according to these maps. The matrix of a map-generating device is found in terms of the specific map parameters, the state variables and the resonator parameters for each of the four named maps.

We present recent work on III-V semiconductor mid-infrared light emitters and detectors. The employed type-II broken bandgap alignment between InAs and Ga_xIn_1-xSb allows for widely tunable emission and absorption wavelengths with energies below the individual material bandgaps. We demonstrate room temperature operation of GaSb-based interband cascade lasers (ICLs) emitting between 6.1 and 6.9 μm. Furthermore, we investigate ideal growth conditions for InAs/GaSb type-II superlattices (T2SL) for the implementation in interband cascade detectors (ICDs) with cut-off wavelengths up to 7.5 μm at room temperature. We focus on strain balancing different SL compositions for different cutoff wavelengths via Sb-soak and sub-monolayer (SML) growth of InSb. An ideal growth temperature of T_Sub=430 °C is found by comparing the quality of different sets of samples by means of high-resolution X-ray diffractometry (HRXRD) and room temperature photoluminescence (PL) measurements.

The graphical method we develop is presented for scanners with two rotational Risley prisms, in an analysis that considers all system parameters: angles, refractive indexes, and apertures of the prisms, rotational speeds, distance between prisms, as well as from the scanner to the target plane. Marshall’s parameters are also used: k, ratio of the angles of the prisms; M, ratio of the rotational speeds. The scan patterns of the different systems are simulated using a mechanical design program, CATIA V5R20 and basic prisms equations. The advantages of the method are: exact scan patterns are obtained, in contrast with approximative methods (e.g., using the paraxial approximation); the method is simple, fast, and easy-to-use, in contrast to (rather complicated) analytic approaches. Rules-of-thumb to design such scanners are extracted from the analysis. Experimental validation and a discussion on perspectives of Risley prisms conclude the study.

MIRS (MMX InfraRed Spectrometer) is an imaging spectrometer onboard of MMX (Martian Moon eXploration) mission. MMX is a JAXA sample return mission that will be launched in September 2024 to Martian system, to bring back to Earth sample from Phobos, to observe in detail Phobos and Deimos and to monitor Mars’s atmosphere with observations of dust storm, clouds, and distributions of total amount of water vapor. The main objectives of the mission are to understand the origin of Martian moons, to constrain the processes for planetary formation and to understand the evolutionary processes of the Martian system. MIRS is a push-broom imaging spectrometer working in the range from 0.9 to 3.6 micron.

We propose a polarizing Michelson interferometer coupled to a pixelated polarizing camera to visualize dynamic phase objects. Considering the capabilities of the polarizing camera, we employed a temporal phase unwrapping algorithm to process information. Experimental results are presented showing the capabilities of our proposal.

Air pollution depends on various factors including: the economic activities of specified geographic region, the transport and mobility infrastructure, as well as the physiographic characteristics of the region. In general, in urban areas the main air pollutants are gasses and particles emitted by factories and cars, including PM10 and PM2.5 particles, and gases like SO₂ , NO_x, CO, VOC, NH₃ affecting the quality of the air. In this work, a remote sensing system is proposed to monitoring of air quality, which is mounted on unmanned aerial vehicle, UAV and developed as wireless sensor networks WSN. The electronic instrumentation consists of a wireless communication interface based in LoRaWAN protocol and an array of sensors to measure the concentration of carbon monoxide (CO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), Ammonia (NH₃) and suspended particles PM2.5 and PM10. The optimal design of the sensing system has been development under the constrain: a low weight, a compacted design and a low power consumption. The system will be used to monitor the air quality in Torreon, Mexico. In particular, we are interesting in measure the pollution concentration a function of height from 10 to 150 m, at specified areas. For example, near to factories.

A microlens array is a junction of small-sized lenses distributed one-with-other for decreasing the sizes in some sensors or CCD for applications where portability is mandatory. However, working with circular apertures reduces the arrangement efficiency due to the distance between each element. Using several parameters, as spatial distributions, optical apertures, and materials for the microlenses, prevents the light incidence on non- photosensitive areas due to diffraction. The study of these parameters employing the finite element method (FEM) is a complementary tool to arrangement optimization. We present an investigation based on FEM for microlens arrays optimization in two dimensions, where the arrangement, geometry, and materials for the array are changed. The analysis can be useful to estimate the incidence on a non-photosensitive surface due to diffraction of any aperture geometry, or lens material, knowing the focal length and the wavefront transmitted, as the previous step to the final elaboration.

More than 4000 planets beyond our solar system have been confirmed since 1995. Transit, radial velocity, microlensing, imaging, orbital brightness, timing variation, and optical detection are most common for exoplanet detection. Optical detection implies several challenges in selecting the proper wavelength range, the small angular resolution star-planet, and the extremely low SNR of the planet near the star. We propose lab proof-of-concept using a rotationally shearing interferometer. This approach includes enhancing the star-planet SNR by hybrid optical and electronic techniques with simulated planet-star signals. The planet's signal is modulated and then detected by a lock-in amplifier, and the rotational shearing interferometer performance cancels the star's signal.

Pattern recognition techniques are widely used in computer vision, classification of radio signals, and voice recognition. The fractional Fourier transform is used to recognize patterns using binary rings masks and segment images. This technique has the characteristic of being invariant to position and rotation and finally obtaining a one-dimensional signature. On the other hand, Neural Networks are used for pattern recognition based on a deep neural network algorithm. It has the characteristic of training large datasets with millions of images. Artificial Neural Networks(ANNs) are used for several applications such as pattern recognition and classification of input data. In particular, the ANN has been used to evaluate medical images from the brain to assess if the image corresponds to Alzheimer's disease. One disadvantage of the neural network is a large amount of time to learn depending on the number of patterns to be identified or classified and the ability to adapt and recognize patterns. Besides, the fractional Fourier transform cannot analyze a large amount of information. In this work, a comparison between the Artificial Neural Network and the Fractional Fourier Transform is presented to determine which will be the best for recognizing a batch of selected medical images. We propose a reconstruction method using both techniques for precise image recognition and the evaluation of their respective metrics such as accuracy, precision, sensitivity, and specificity. The medical images regarding Alzheimer's disease are no dementia, very mild dementia, mild dementia presenting the best performance regarding the receiver operating characteristics and moderate dementia was the worst classified related to the number of images of the dataset.

3D-profilometry of discontinuous solids by fringe projection is a difficult task due to the problem posed by the phase (profile) unwrapping at sharp borders. To solve this problem, Servin et al. proposed the so-called two-steps temporal unwrapping, in which two consecutive sequences of fringe patterns with different spatial frequencies (a low- and a high-frequency patterns sequence) are projected over a static test surface. As the 3D surface profile is retrieved by phase-shifting techniques, each fringe sequence must have at least three phase–shifted frames, which in principle would preclude the use of temporal unwrapping for measuring moving objects since at least it would be necessary to acquire a total of twelve frames (six frames for the test object plus six more for a reference plane). In the present work we present an improvement to this method, which requires the acquisition of only two color-coded fringe patterns (i.e., two RGBimages) for reconstructing the discontinuous 3D surface of a moving object. The proposed approach is based on the projection of fringes with two different frequencies. Validation experiments are presented.

Chronic ulcers are skin wounds, which have severe repercussions for patients regarding mobility restriction and economic problems. Nowadays, no technique allows to evaluate the evolution of ulcers' healing process in clinical practice consistently. UV fluorescence excitation photography can provide spatial and temporal information on molecular and structural changes, providing an objective means for evaluating the healing process. In this work, the UV intrinsic fluorescence from the reepithelization process was imaged in an in vivo wound animal model. Scan imaging process and imaging misalignments were emulated. We evaluated SURF and RANSAC algorithms for stitching low-intensity and low contrast images. The evaluated algorithms could identify up to 16 common characteristics in contiguous images with a 20% overlap area. The maximum error found in the stitching process in an 18-day healing period was 1.69%.