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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
photon noise fundamental noise due to the quantum nature of light; a statistical variation in optical intensity due to measurements of discrete number of photons. photopic formally, a description of luminances under which human cone cells are active. Informally, describing daylight luminances. photorefractive beam fanning a photorefractive phenomenon in which a beam of coherent light is scattered into a fanned pattern by a photorefractive crystal (e.g., barium titanate, lithium niobate). When a laser beam passes through a photorefractive crystal, significant scattering often occurs. The scattered light appears to be asymmetrical with respect to the beam except for propagation along the c-axis. For laser beams of moderate power, the scattered light appears to develop slowly in time and eventually reaches a steady-state scattering pattern. This is known as photorefractive beam fanning. The beam fanning originates from an initial scattering due to crystal imperfections. The initially scattered light is amplified due to the physical overlap and the energy coupling between the incident beam and the scattered beam. Beam fanning often occurs in highly efficient photorefractive media, even if the material is near-perfect. Photorefractive beam fanning plays an important role in the initiation of many phase conjugators and resonators, even through the fanning itself can be a source of noise in many experimental measurements. photorefractive crystal crystalline solids that exhibit photorefractive effect. The photorefractive effect is observed in many electro-optic crystals, including BaTiO3 , KNbO3 , LiNbO3 , Sr1-x Bax xNb2 O6 (SBN), Ba2-x Srx K1-y Na y
Optical Sources and Detectors
Published in Z. Ghassemlooy, W. Popoola, S. Rajbhandari, Optical Wireless Communications, 2019
Z. Ghassemlooy, W. Popoola, S. Rajbhandari
For an ideal PD, the only significant noise that affects its performance is that associated with the quantum nature of light itself, where the by-product is that the number of photons emitted by a coherent optical source in a given time is never constant. Although for a constant-power optical source the mean number of photons generated per second is constant, the actual number of photons per second follows the Poisson distribution. This results in photon fluctuation or quantum noise. The quantum noise (also termed photon noise) is a shot noise, which is present in all photon detectors due to the random arrival rate of photons from the data-carrying optical source and the background radiation.
Fundamental Detector Performance Limits
Published in Antoni Rogalski, 2D Materials for Infrared and Terahertz Detectors, 2020
The ultimate performance of infrared detectors is reached when the detector and amplifier noise are low, compared with the photon noise. The photon noise is fundamental in the sense that it arises, not from any imperfection in the detector or its associated electronics, but rather from the detection process itself, as a result of the discrete nature of the radiation field. The radiation falling on the detector is a composite of that from the target and that from the background. The practical operating limit for most infrared detectors is not the signal fluctuation limit but the background fluctuation limit, also known as the background-limited infrared photodetector (BLIP) limit.
Improved and Robust Spectral Reflectance Estimation
Published in LEUKOS, 2021
Jingjing Zhang, Youri Meuret, Xiangguo Wang, Kevin A. G. Smet
In real imaging systems, photon noise, shot noise, read noise, and analog-to-digital converter noise contribute in varying proportions at different signal levels, leading to an overall signal noise that is dependent on scene brightness (Hasinoff 2014). Though read noise and analog-to-digital converter noise can be accounted for by signal-independent Gaussian additive noise, photon noise, whose variation is linearly proportional to the signal, is the most prominent in a system with high brightness (Healey and Kondepudy 1994; Jiang and Gu 2012; Prucnal and Saleh 1981). In practice, photon noise is often modeled using a Poisson distribution or a Gaussian distribution with variance equal to the mean (Foi et al. 2008; C. Liu et al. 2008). In this study, photon noise has been added to the pixel output signals to simulate real-world camera operation.
Noise classification and automatic restoration system using non-local regularization frameworks
Published in The Imaging Science Journal, 2018
I. P. Febin, P. Jidesh, A. A. Bini
Gaussian noise can be considered as the statistical noise which processes a probability density function (pdf) equal to that of the Normal distribution. Sensor noise owing to poor illumination or high temperature is an example of Gaussian noise [18]. These are the additive noises, which means they get added to the intensity values. Poisson noise or Photon noise is based on the quantized nature of light, and it can form based on the uncertainty in detecting photons. An individual photon detection is an independent event, hence it can be modelled with the Poisson distribution [19]. Emission tomography (PET, SPECT), microscopy or astronomy images always gets impacted by Poisson noise [20].
Visible imaging characteristics of space targets oriented to on-orbit observation
Published in Journal of Modern Optics, 2018
Qing-yu Hou, Yi-hui Wang, Fan-jiao Tan, Yu-jia Huo, Peng Wu, Zhi-peng Wang
The photon noise is a shot noise of the detector sensor, which is mainly caused by the fluctuations of the number of arriving particles such as photons and electrons per time unit to the detector. The equivalent quantity of electrons of the photon noise is (16) (3) Detection system noise