Detector, Single Photon, Infrared
Wednesday, October 11, 2006
Industrial Products
The id201. is a complete photon counting system based on a cooled InGaAs/InP avalanche photodiode (APD). The operation temperature is set to -50°C to optimise the signalto-noise performance. A temperature variation of less than 0.1°C is achieved through a thermoelectric cooler controlled by a PID regulator. The APD is operated in the so-called gated mode.
The id201 offers advanced functionalities, including:
A trigger unit providing the timing signal for the gate generation. The user can choose from external or internal trigger sources:
• The external trigger source can have NIM, TTL and a Var input types. The Var input type lets the user select three parameters: level, slope, load. The id201 accepts external trigger frequencies up to 4 MHz. Larger frequencies can be used, but the id201 will automatically limit the trigger frequency to 4 Mhz.
• An internal trigger source is also available. Trigger frequencies of 1kHz, 10 kHz, 100 kHz and 1 MHz can be selected. The trigger signal is also available on a front panel connector for the synchronization of other devices (e.g. pulsed laser source, such as the id300).
A delay function providing a delay between the trigger and the gate signals. This allows the user to scan the gate and synchronize the gate and the optical signals. Coarse synchronization should be done using cables and optical fibers, while fine adjustment can be obtained with the internal adjustable delay line. The delay can be adjusted from 0 to 25ns in 100ps increments.
A generator unit and a pulser unit produce a gate with the appropriate duration and amplitude. A variable deadtime can be selected to suppress afterpulse occurences. The following parameters can be selected using an intuitive graphical user interface:
Dead Time. At high trigger frequencies, afterpulsing may significantly deteriorate the performance. To suppress detrimental afterpulsing effects, the id201 allows one to set a dead time after a detection. The dead time duration can be chosen between 1μs, 2μs, 5μs or 10μs. When this mode is enabled, the module will ignore trigger signals during a time equal to the deadtime after each registered avalanche event. The unit displays the actual trigger rate.
Gate Width. Five different values of the gate can be set: 2.5ns, 5ns, 20ns, 50ns or 100ns. A user-defined gate duration can also be entered. Gate widths of 2.5ns and 5ns result in an effective gate of typically 500ps and 1.5ns. These short gates provide a very low noise level for applications where the arrival time of the photon is known with high accuracy.
Photon detection probability at 1550nm that can be chosen between 10%, 15%, 20% and 25%, independently of the gate width and trigger frequency. A user-defined detection probability can also be entered. Large detection probability levels allow one to obtain oustanding timing resolution.
An internal counter whose result is displayed on the front panel to monitor the detection and the trigger signals. For each detection, the module also produces electronic pulses (NIM and TTL) available on front panel connectors. These pulses can, for example, be registered by an external counter or sent to a processing unit, such as a time-to-amplitude converter.
An auxiliary counter, which offers the possibility to count external signals. The result of the counter can then be displayed on the LCD screen.
The electronic circuit of the id201 has been designed to reach outstanding timing resolution of less than 300 ps at25% detection probability.
All the user-adjustable parameters can be easily entered from the front panel or when this option is selected from a computer connected to the RS232 port. The graphical user interface offers several display modes: 1) display the internal and auxiliary counters as frequencies, 2) display the number of counts of the internal and auxiliary counters, 3) display the trigger rate and the internal counter as frequencies, 4) display the ratio of the internal counter over the trigger counter as well as the auxiliary counter frequency, and 5) display all the important detector parameters.
For more information regarding this product please contact:
id Quantique SAde la Marbrerie 3
1227 Carouge
Switzerland
Tel: +41(0)22 301 83 71
Fax: +41(0)22 301 83 79
Email: mailto:sales@idquantique.com
posted by JD52 @ 9:21 PM,
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Detector, Single Photon, Visible
Wednesday, October 04, 2006
Industrial Products
Single Photon Detectors in Visible Range by id Quantique SA
id Quantique’s id100 consists of compact and affordable single-photon counting modules with best-in-class timing resolution. Based on a reliable silicon avalanche photodiode sensitive in the visible spectral range, these modules are able to detect weak optical signals down to the single photon level. The includes:
- two free-space versions, the id100-20 and id100-50 with a 20um, respectively a 50um diameter photosensitive area.
-a fiber-coupled version, the id100-MMF50, coming with a standard FC/PC optical Input
The free-space and fiber-coupled modules are easy-to-use, self-contained and can be integrated in every optical setup. With a timing resolution as low as 40ps and a remarkably short dead time of 45ns, these modules outperform existing commercial detectors in all applications requiring single-photon detection with high timing accuracy. Besides an extremely fast IRF (Instrument Response Function), the modules have an excellent timing stability up to count rates of at least 20MHz
The id100 consists of an avalanche photodiode (APD) and an active quenching circuit integrated on the same silicon chip. The chip is mounted on a thermo-electric cooler and packaged in a standard TO5 header with a transparent window cap. A thermistor is used to measure temperature. The APD is operated in Geiger mode, i.e. biased above breakdown voltage. A high voltage supply used to bias the diode is provided by a DC/DC converter . The quenching circuit is supplied with +5V. The module output pulse reflects the arrival of a photon with high timing resolution. The pulse is shaped using a hold-off time circuit and sent to a 50ohm output driver. All internal settings are preset for optimal operation at room temperature. No user adjustment is necessary. In the fiber-coupled version, the TO5 header and the optical fiber are included in the housing. The optical input consists of a FC/PC connector on the front side of the module.
For more information regarding this product please contact:
id Quantique SA
de la Marbrerie 3
1227 Carouge
Switzerland
Tel: +41(0)22 301 83 71
Fax: +41(0)22 301 83 79
Website: http://www.idquantique.com
Email: mailto:msales@idquantique.com
posted by JD52 @ 8:42 PM,
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Viewer, 3D, Stereoscopic
Wednesday, September 20, 2006
A Stereoscope 3-D Viewer has been designed and developed for television sets and computers. It can be viewed without headgear or special glasses. The Viewer uses a camera to track the viewer’s eyes, allowing the Viewer to change position and still maintain 3D imaging.
The Viewer consists of folded focusing optics, two liquid crystal display video projectors mounted behind a partially silvered screen and a reflective screen. The left image and the right image fields of a stereoscopic image are projected and reflected off a pair of 45° retroreflective mirrors at the bottom of the cabinet. The silvered mirror suspended at 45° is in front of a 50-inch rear projection screen. This provides for the passage of 50 percent of the reflected light.
A small TV camera is positioned under the cabinet and tracks the viewers eyes to ensure correct image focus in both eyes. The tracking is updated 25 times per second. This information is used to adjust the position of the projected images automatically keeping the images aligned for 3D viewing.
The two images are spaced at 32 mm, half an eye spacing, to prevent image spillover. The eye tracking system allows both vertical and lateral viewer motion. The internal mirror optics is controlled by a logic servomechanism from information signals analyzed from the TV camera inputs. The projectors move horizontally for viewer lateral movement and the silvered mirrors tilt for viewer vertical movement.
Source: Laser Focus World, 1996
Reference: Xenotech , Perth West, Australia
Industrial Products
posted by JD52 @ 9:01 PM,
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