Topic
Signal beam
About: Signal beam is a research topic. Over the lifetime, 1881 publications have been published within this topic receiving 20717 citations.
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Patent•
26 Sep 1986
TL;DR: In this article, a multi-frequency laser beam having different frequencies, splitting one or more of these constituent beams into reference and signal beams, encoding information on the signal beams by frequency modulation and detecting the encoded information by heterodyne techniques.
Abstract: Laser optical communication according to this invention is carried out by producing multi-frequency laser beams having different frequencies, splitting one or more of these constituent beams into reference and signal beams, encoding information on the signal beams by frequency modulation and detecting the encoded information by heterodyne techniques. Much more information can be transmitted over optical paths according to the present invention than with the use of only one path as done previously.
3 citations
Patent•
27 Aug 2013TL;DR: In this article, a phase mask is used to modulate a phase of different portions of incident light, such that a different optical phase delay, in a range between 0 and 2π is imparted to different parts of the incident light.
Abstract: A phase mask includes a phase modulation layer that modulates a phase of different portions of incident light, differently, such that a different optical phase delay, in a range between 0 and 2π is imparted to different portions of the incident light. A hologram recording apparatus includes a light source; a signal beam optical system that divides a beam emitted from the light source into a reference beam and a signal beam, modulates the signal beam according to hologram pixel information, and radiates the signal beam onto a hologram recording medium. The signal beam optical system includes the phase mask. The hologram recording apparatus also includes a reference beam optical system that radiates the reference beam onto the hologram recording medium.
3 citations
18 Oct 2006
TL;DR: In this paper, a controllable photon source is proposed for high-accuracy optical characterisation of photometric devices at the ultra-low intensities, which can also serve as a standard in testing of optical image intensifiers, night vision devices and in the accurate measurement of spectral distribution of transmission and absorption in optical materials.
Abstract: We have developed our pervious experimental setup using correlated photon pairs (to the calibration of photo detectors) to realize a controllable photon source. For the generation of such photon pairs we use the non-linear process of parametric down conversion. When a photon of the pump beam is incident to a nonlinear crystal with phase matching condition, a pair of photons (signal and idler) is created at the same time with certain probability. We detect the photons in the signal beam with a single photon counting module (SPCM), while delaying those in the idler beam. Recently we have developed a fast electronic unit to control an optical shutter (a Pockels cell) placed to the optical output of the idler beam. When we detect a signal photon with the controlling electronic unit we are also able to open or close the fast optical shutter. Thus we can control which idler photons can propagate through the Pockels cell. So with this photon source we are able to program the number of photons in a certain time window. This controllable photon source that is able to generate a known number of photons with specified wavelength, direction, and polarization could be useful for applications in high-accuracy optical characterisation of photometric devices at the ultra-low intensities. This light source can also serve as a standard in testing of optical image intensifiers, night vision devices, and in the accurate measurement of spectral distribution of transmission and absorption in optical materials.
3 citations
TL;DR: In this article, the sensitivity of the adaptive photo-electromotive-force (photo-EMF) detectors arranged in the conventional transverse configuration and optimized for laser ultrasonic applications is analyzed.
Abstract: The sensitivity of the adaptive photoelectromotive-force (photo-EMF) detectors arranged in the conventional transverse configuration and optimized for laser ultrasonic applications is analyzed It is shown that for the devices based on bipolar photoconductors operating under typical conditions, ie with approximately {\rm 10 \times 10} pixels in the detected speckle-like signal wave, the amplifier input noise current {\rm \approx 1 \hspace{0167em} pA/\sqrt {Hz},} and the probe beam wavelength of \mgreek{l} \approx 08 \hspace{0167em} \mgreek{m} m; the optimal matching with the preamplifier can be achieved with a detected signal beam power P S greater than ≈01 mW The limit on the sensitivity of these optimized photo-EMF detectors (with the inter-electrode spacing equal to 5 optimal fringe periods) found to be determined by the noise of the detector itself and is approximately a factor of 14 below the fundamental limit set by the shot noise of the detected signal power In particular, for P_{S} \approx
3 citations
Patent•
03 Aug 1990TL;DR: In this paper, an all-optical, continuous-time, recurrent neural network is presented which is capable of executing a broad class of energy-minimizing neural net algorithms.
Abstract: An all-optical, continuous-time, recurrent neural network is disclosed which is capable of executing a broad class of energy-minimizing neural net algorithms. The network is a resonator which contains a saturable, two-beam amplifier; two volume holograms; and a linear, two-beam amplifier. The saturable amplifier permits, through the use of a spatially patterned signal beam, the realization of a two-dimensional optical neuron array; the two volume holograms provide adaptive, global network interconnectivity; and the linear amplifier supplies sufficient resonator gain to permit convergent operation of the network.
3 citations