Noise fundamental

Spontaneous Raman spectroscopy has the ability to provide clinically relevant chemical concentration measurements of multiple analytes in biofluids. Blood serum, whole blood, and urine have all been studied. The detection limit (assuming a few hundred seconds of spectral acquisition) appears, based upon fundamental noise considerations, to be around 0.1 mM for most biochemicals this places several important analytes within reach but certainly precludes... 

Fundamental noise or random noise this type of noise is statistically distributed and its amplitude as a function of the frequency can be written as a sum of many sinusoidal functions. This type of noise is related to the corpuscular nature of matter or to the quantization of radiation, respectively, and cannot be completely eliminated. 

Non-fundamental noise also called flicker noise or excess noise . Here the sign or the magnitude can correlate with well-defined phenomena. 

For Kinetic Inductance Detectors the fundamental noise source is the quasiparticle generation-recombination noise (Visser et al. 2012 Baselmans et al. 2008). To integrate this source of noise in the simulation, the first step is to compute the density of quasiparticles per unit volume in a superconductor in thermal equilibrium, this is... 

Fundamental noise due to the statistical nature of light. One standard deviation of the average intensity equals the square root of the total number of photons measured. 

Spontaneous emission The random generation of a photon due to the spontaneous recombination of an electron-hole pair. Spontaneous emission is the fundamental noise-generating process in an optical amplifier. 

Unlike thermal detectors, which sense the power of the absorbed radiation, photon detectors respond to the number of photons arriving per unit time. Photon as well as thermal detectors are incoherent transducers, which means that the detection process is independent of the wave properties of the incident radiation field. Incoherent detectors produce an electrical signal proportional to the intensity of the radiation. In contrast, coherent detectors, such as the nonlinear elements in heterodyne receivers discussed in Section 5.9, register the amplitude and phase of the electric field associated with the absorbed radiation. Due to the simultaneous measurement of amplitude and phase, coherent detection is subject to a fundamental noise limit that has its origin in the quantum mechanical uncertainty principle. Incoherent detectors are free of this particular limit. However, as we shall see, they are subject to othernoise sources. 

Some noise sources are fundamental and cannot be avoided. Some of the sources of these fundamental noises are the following ... 

Some noise components will appear at very specific frequencies. A pump will vibrate a dewar a few times every second, and an AC power line near a critical amplifier will introduce noise at the line rate - 60 cycles per second (see Figure 1.8). The more fundamental noise sources, however, will add some noise more or less uniformly at all frequencies. This is referred to as white noise, by analogy to the fact that white light contains all wavelengths (frequencies) of light. Even if the noise is not quite white. 

A. Thumaim and R. Miller, Fundamentals of Noise Control Engineering, 2nd ed.. The Fairmont Press, Inc., Lilbum, Ga., 1990. 

As femtomolar detection of analytes become more routine, the goal is to achieve attomolar (10 molar) analyte detection, corresponding to the detection of thousands of molecules. Detection sensitivity is enhanced if the noise ia the analytical system can be reduced. System noise consists of two types, extrinsic and intrinsic. Intrinsic aoise, which represents a fundamental limitation linked to the probabiHty of finding the analyte species within the excitation and observation regions of the iastmment, cannot be eliminated. However, extrinsic aoise, which stems from light scatteriag and/or transient electronic sources, can be alleviated. 

Although at the time of his early inventions Dr. Schoop envisaged that an electric arc could be used to produce the molten metal for spraying, forty years passed before the method became commercially important. Then, in Germany, Russia and Japan tools were made based on the arc. Although in Japan alternating current is used, the noise is nearly intolerable and elsewhere direct current from motor generators is employed. The fundamental idea is simple two wires, carefully insulated from each other, are advanced to meet at a point where an arc is formed, immediately in advance of a Jet... 

Hierarchical Structures Huberman and Kerzberg [huber85c] show that 1// noise can result from certain hierarchical structures, the basic idea being that diffusion between different levels of the hierarchy yields a hierarchy of time scales. Since the hierarchical dynamics approach appears to be (on the surface, least) very different from the sandpile CA model, it is an intriguing challenge to see if the two approaches are related on a more fundamental level. 

A simple expression for the signal-to-noise ratio (SNR) of a measurement of visibility amplitude involves several parameters relating to interferometer and source properties. The formula presented here provides the fundamental sensitivity limit. Contrast loss arising from instrumental jitter and seeing are summarised in a common factor system Strehl , which is the ratio of the number of photons which can be used for a coherent measurement to the... 

Abstract Either because observed images are blurred by the instrument and transfer medium or because the collected data (e.g. in radio astronomy) are not in the form of an image, image reconstmction is a key problem in observational astronomy. Understanding the fundamental problems underlying the deconvolution (noise amplification) and the way to solve for them (regularization) is the prototype to cope with other kind of inverse problems. 

Williams, R. R., Fundamental Limitations on the Use and Comparison of Signal-to-Noise Ratios, Anal. Chem. 63, 1991, 1638-1643. 

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