Jan. 25, 2025
Remote Sensing
Intensifying environmental challenges globally are placing heightened focus on advanced detection and monitoring technologies. In the optics and photonics realm, solutions characterized by both precision and adaptability are establishing new levels of performance, as well as enabling new applications. Optical remote sensing solutions shine in environments that are remote, hazardous or otherwise extreme. From the component level, and the humble photodiode - a fundamental component that enables precise and rapid data collection across diverse scales - to advanced systems such as lidars, spectrometers, and hyperspectral imagers, optical remote sensing remains characterized by longstanding themes such as device miniaturization. Now, with an era of AI integration upon us, these themes are set to ensure with new influences ready to establish new performance benchmarks.
Key Technologies: remote sensing, water quality detections and monitoring, Photodiodes (silicon and InGaAs/UV, IR, NIR), environmental lidar, multi-wavelength (SWIR,MWIR) LEDs, gas emissions monitoring, NIR spectroscopy, hyperspectral imaging/detection, colorimetry, CMOS and CCD Sensors, fluorophores, navigation sensing
CMOS Image Sensors
CMOS sensors, initially developed for visible light and later adapted for infrared applications, are gaining prominence in the UV spectrum (between 200 and 400 nm). CMOS technology excels in the imaging field due to its cost-effectiveness, integration capabilities, and low power consumption compared to CCD sensors. Despite the short wavelength of UV light, which results in lower penetration depth in silicon, UV CMOS sensors have significant applications across various fields. In industrial inspection, UV light’s propensity for scattering and its ability to reveal minute defects enable the production of highly detailed images. And in research, UV CMOS sensors are utilized in astronomy for the study of celestial bodies and in medicine for detecting DNA damage. In an era of increasing ecological awareness, UV CMOS technology offers solutions from plastic sorting in recycling processes to the detection of noxious gases (e.g., SO2, NO2) using UV absorption spectroscopy. In this article, First Light Imaging examines the physics underlying UV CMOS sensors, reviewing recent advancements and challenges in their development and exploring new and emerging applications.
Key Technologies: CMOS image sensors (for UV applications including industrial inspections; material sorting; forensics; semiconductor materials inspection; Nondestructive testing; machine vision inspections; atmospheric sensing/imaging; astrophysics; gas spectroscopy [gas sensing]; agriculture; material science.
Directed Energy Optics
In the past several years, the directed energy space has seen a ramp-up in the build of high-power lasers, and multiple successful tests of these systems. Military/governmental agencies and Tier-1s have invested in, and advanced the viability and performance of these systems, hitting new power thresholds/benchmarks. Accordingly, the "real-world" deployment of these systems seems to be drawing closer. At the same time, harnessing the incredible power of these systems in a way that optimizes their functionality and minimizes damage to non-targets in an ongoing challenge. Beam control and optimization optics hold the key, with several distinct technologies such as diffractive elements and adaptive optics central to the conversation. Contributing editor Michael Eisenstein draws a link between extremely high power systems and the need to maximize their effectiveness using high-power, durable, and scalable optics, and how this relationship manifests in/on the current directed energy roadmap with plenty of opportunity for small and medium-size suppliers in addition to the Tier-1s.
Key Technologies: Adaptive optics, high-energy optics, directed energy, DOEs (DE context), optics manufacturing, large optics, beam control (DE context), beam shaping (DE contxt),
Photodiodes
Detecting and measuring NIR radiation with high sensitivity is essential for various defense and security applications. These applications also demand rapid photodetection speeds to promptly respond to sudden changes in light signals. Therefore, photodetectors designed for NIR applications must achieve both high responsivity and fast rise times within the NIR wavelength range—a challenging feat to accomplish simultaneously. This article explores the challenges associated with NIR detection using conventional silicon photodiodes, focusing on the inherent trade-off between responsivity and rise time. The different factors affecting the photodiode performance for selected applications in the NIR region, including YAG laser (1064 nm) guidance and laser beam tracking/alignment by using 4-quadrant photodetectors, plus solutions for how to tackle those challenges., are explored. Particular focus will be on improving photodetector responsivity through effective anti-reflection techniques. Nanostructured black silicon surfaces, which exhibit unique properties that enhance NIR performance by increasing the effective optical path length and reducing surface reflections, are an essential technology here.
Key Technologies: NIR detection, silicon photodiodes, photodetection, Nd:YAG lasers, III-V materials, industrial inspections
Photonics at Work: Laser Welding
Laser oscillation welding is becoming increasingly popular in large-scale industrial production. Extensive studies have been carried out on the welding of aluminum and steel with oscillating laser beams at frequencies of 100 Hz - 200 Hz, and offer strong evidence for the better controllability, reduction in weld defects, shallower heat-affected zones, and other discernible advantages offered by the technique. The improved weld quality in terms of weld morphology, mechanical, electrical and thermal properties is the prerequisite for the series production of battery systems. However, the control of laser penetration at different combinations of welding conditions (laser power, welding speed, oscillation frequency and welded material) is still an open issue aimed at evaluating the overall weld quality. This is crucial if an uncontrolled penetration of the laser beam during the joining process poses a safety risk when the welded workpiece is in operation. In a case study, Lessmüller Lasertchnik GmbH identifies and details an approach that uses high-dynamic OCT to ensures effective production, as well as high throughput and optimum performance of the manufactured parts.
Key Technologies: Laser welding, OCT, beam diagnostics, scanning mirrors, scanning lenses, EV battery manufacturing
Photonic Fundamentals: Surface Mount Optics/Optical Assembly
The lighting technology of surface mount optics (SMO) offer several advantages in optical assembly. The technology uses optical silicones on a printed circuit board, and located alongside the electronics, to enable users to avoid "post-reflow" steps. This article identifies and examines SMO technology, and considers the distinct advantages that optical silicones deliver to a user/application compared to conventional thermoplastics. The development and manufacture of the technology, as it accommodates the evolving optical assembly, is explored: SMO have been on the market only a few years and continue to evolve as applications develop for environments not suitable for glass or thermoplastic optics and for cost reduction in assembly.
Key Technologies: Surface-mount optics, optical silicones, optical assembly/lighting, LEDs, machine vision lighting, optics commercialization/manufacturing
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