Photonics/Optics

Near-Infrared Photon Counter

The id220-FR-SMF from id Quantique (Carouge, Switzerland) provides a cost-effective tool for applications that require asynchronous photon detection. The cooled InGaAs/InP avalanche photodiode and associated electronics achieve low dark count and afterpulsing rates in free-running mode. The module operates at two detection probability levels of 10% and 20%, with a deadtime that can be set between 600ns and 25ms. Arrival time of photons is reflected by a 100ns TTL pulse available at the SMA connector; the timing resolution is as low as 250ps at 20% efficiency. A USB interface allows users to set the efficiency level and the deadtime. A standard FC/PC connector followed by a single mode fiber is provided as optical input.

Posted in: Products, Products, Photonics

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InGaAs Camera

FLIR Systems (Portland, OR) has announced its SC2600 near infrared (NIR) camera. The device features a 640 × 512 InGaAs sensor. The SC2600 combines a spectral sensitivity range of 0.9-1.7μm and small 25μm pixels. Other features include independent analog and digital (gigabit Ethernet) video outputs, external frame synchronization, video windowing, and independent data streams.

Posted in: Products, Products, Photonics

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Ensuring Safe Operation and Accurate Characterization of Laser Diodes

Laser diodes are very sensitive to electrostatic discharge (ESD), current/ voltage transients, and temperature changes, and extra care must be taken to ensure the laser diode is protected during all operating conditions. Unlike general-purpose power supplies or current supplies, laser diode drivers, mounts, and cables greatly improve the protection of laser diodes and allow low noise operation. A temperature controller helps stabilize the temperature of the laser diode packages, which provides for safe operation and wavelength stability of the laser. For fast and reliable characterization, an optical power meter and integrating sphere-based photodiode detectors are often employed where a good understanding of optical measurements is required.

Posted in: Articles, Features, Photonics

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Comparing Apples to Oranges: Self-Service Scales With USB Cameras Auto-Detect Fruits and Vegetables

From apples to oranges, from avocado to zucchini — the fruit and vegetable departments of large supermarkets offer an overwhelming choice of fresh products. Consumers benefit from this broad selection, as most fruits are now available year round. Another advantage of self-service supermarkets is that consumers can check and choose the fruit and vegetables themselves. Difficulties start, however, when you reach the self-service scale — how to find the right button among dozens of different types of produce. The vast choice can quickly turn into an ordeal when it takes ages to locate the papaya or peppers button. But there might finally be a solution. A compact, integrated USB camera helps self-service scales automatically recognize individual products.

Posted in: Application Briefs, Applications, Photonics

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885-nm Pumped Ceramic Nd:YAG Master Oscillator Power Amplifier Laser System

Reduced thermal load results in a higher-performance laser.The performance of a traditional diode pumped solid-state laser that is typically pumped with 808-nm laser diode array (LDA) and crystalline Nd:YAG was improved by using 885-nm LDAs and ceramic Nd:YAG. The advantage is lower quantum defect, which will improve the thermal loading on laser gain medium, resulting in a higher-performance laser. The use of ceramic Nd:YAG allows a higher Nd dopant level that will make up the lower absorption at the 885-nm wavelength on Nd:YAG.

Posted in: Briefs, Tech Briefs, Photonics

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Terahertz Quantum Cascade Laser With Efficient Coupling and Beam Profile

High-power QCLs can be used in medical instruments, security screening equipment, and illicit material detection. Quantum cascade lasers (QCLs) are unipolar semiconductor lasers, where the wavelength of emitted radiation is determined by the engineering of quantum states within the conduction band in coupled multiple-quantum-well heterostructures to have the desired energy separation. The recent development of terahertz QCLs has provided a new generation of solid-state sources for radiation in the terahertz frequency range. Terahertz QCLs have been demonstrated from 0.84 to 5.0 THz both in pulsed mode and continuous wave mode (CW mode).

Posted in: Briefs, Tech Briefs, Photonics

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Measurement Via Optical Near-Nulling and Subaperture Stitching

This simple and universal technique uses adjustable corrective optics. A subaperture stitching interferometer system provides near-nulling of a subaperture wavefront reflected from an object of interest over a portion of a surface of the object. A variable optical element located in the radiation path adjustably provides near-nulling to facilitate stitching of subaperture interferograms, creating an interferogram representative of the entire surface of interest. This enables testing of aspheric surfaces without null optics customized for each surface prescription.

Posted in: Briefs, TSP, Tech Briefs, Photonics, Physical Sciences, Measurements, Optics

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