Photonics/Optics

Laser Diode Driver

The laser diode drivers iC-NZN and iC-NZP from iCHaus Corp. (Bodenheim, Germany) operate laser diodes in both CW and spike-free pulse mode, with up to 155 MHz. The devices allow either the optical output power (APC) or laser diode current (ACC) to be controlled. Blue laser diodes can also be operated with iC-NZN. The maximum available laser diode current is 300mA, and the devices have an adjustable current limit. When the current limit is reached, it is signaled as an error message output which also indicates undervoltage and overtemperature. There is a safety shutdown function for the output stage in the event of overtemperature. The device can also be driven by either LVDS or TTL pulse signals. iC-NZN and iC-NZP have a standby mode with a low current consumption of < 50 μA.

Posted in: Products, Products, ptb catchall, Photonics

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Single-Photon Counter

AUREA Technology (Besancon, France) has introduced the SPD_B, a single-photon counting module used for short near infrared wavelengths [1,000 to 1,350 nm]. The SPD_B is an ultra-low-noise, highquantum- efficiency, and low-timing-jitter near-infrared single photon counter. The SPD_B includes a Geiger-mode InGaAs avalanche photodiode and thermoelectric coolers that ensure high detection efficiency up to 30%, a very low dark count rate of < 5.10-6 per ns gate, and a low timing jitter of < 180ps. The SPD_B comes with a graphical user interface compatible with LabView and C++.

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Hybrid Sensor

OSRAM Opto Semiconductors (Sunnyvale, CA) has released a “3 in 1” SFH 7773 digital sensor that combines an IR LED emitter and detector chips together, eliminating the need to install a separate IR emitter to enable the proximity sensor function. Apertures are integrated into the package to reduce crosstalk. The SFH 7773 detects objects up to a distance of 15cm (5.9 in.) while simultaneously measuring the intensity of the ambient light. Its power consumption is a maximum of 5μA in standby mode and 300μA in operational mode. The integration time of the detector and, thus, the detection range of the proximity sensor, can be selected via the I2C interface. The 5.3mm x 2.5mm x 1.2mm sensor can also be adjusted to the transparency of the smart phone cover. A variety of sensitivity levels is available, ranging from 3 to approximately 65.500 lux and 0.03 to 655 lux.

Posted in: Products, Products, ptb catchall, Photonics

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2011 Products of the Year

The votes are in and the winners of the 2011 Photonics Tech Briefs Readers’ Choice Product of the Year Awards have been selected. The three PTB Products of the Year awards will be presented to each company in person.

Posted in: Products, Products, ptb catchall, Photonics

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Multiple-Event, Single-Photon Counting Imaging Sensor

This sensor has applications in high-energy physics and medical and biological imaging systems. The single-photon counting imaging sensor is typically an array of silicon Geiger-mode avalanche photodiodes that are monolithically integrated with CMOS (complementary metal oxide semiconductor) readout, signal processing, and addressing circuits located in each pixel and the peripheral area of the chip. The major problem is its “single-event” method for photon count number registration. A single-event single-photon counting imaging array only allows registration of up to one photon count in each of its pixels during a frame time, i.e., the interval between two successive pixel reset operations. Since the frame time can’t be too short, this will lead to very low dynamic range and make the sensor merely useful for very low flux environments. The second problem of the prior technique is a limited fill factor resulting from consumption of chip area by the monolithically integrated CMOS readout in pixels. The resulting low photon collection efficiency will substantially ruin any benefit gained from the very sensitive single-photon counting detection.

Posted in: Photonics, Briefs, TSP, ptb catchall, Tech Briefs, Photonics

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Qualification of Fiber Optic Cables for Martian Extreme Temperature Environments

Means have been developed for enabling fiber optic cables of the Laser Induced Breakdown Spectrometer instrument to survive ground operations plus the nominal 670 Martian conditions that include Martian summer and winter seasons. The purpose of this development was to validate the use of the rover external fiber optic cabling of ChemCam for space applications under the extreme thermal environments to be encountered during the Mars Science Laboratory (MSL) mission.

Posted in: Photonics, Briefs, ptb catchall, Tech Briefs, Photonics

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Transverse Pupil Shifts for Adaptive Optics Non-Common Path Calibration

A simple new way of obtaining absolute wavefront measurements with a laboratory Fizeau interferometer was recently devised. In that case, the observed wavefront map is the difference of two cavity surfaces, those of the mirror under test and of an unknown reference surface on the Fizeau’s transmission flat. The absolute surface of each can be determined by applying standard wavefront reconstruction techniques to two grids of absolute surface height differences of the mirror under test, obtained from pairs of measurements made with slight transverse shifts in X and Y.Adaptive optics systems typically provide an actuated periscope between wavefront sensor (WFS) and common-mode optics, used for lateral registration of deformable mirror (DM) to WFS. This periscope permits independent adjustment of either pupil or focal spot incident on the WFS. It would be used to give the required lateral pupil motion between common and non-common segments, analogous to the lateral shifts of the two phase contributions in the lab Fizeau.

Posted in: Photonics, Briefs, TSP, ptb catchall, Tech Briefs, Photonics

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