Dynamic range

About: Dynamic range is a research topic. Over the lifetime, 7576 publications have been published within this topic receiving 101739 citations. The topic is also known as: DNR & DR.

Imaging of radionuclide emissions with a low-noise charge-coupled device

Abstract: Film-based autoradiography provides excellent spatial resolution, but presents some problems with regard to sensitivity, dynamic range, and quantitation. The authors are investigating the adaptation of a cooled charge-coupled device (CCD) for some autoradiographic applications which may alleviate some of the problems encountered with film. The proposed approach uses a scientific-grade CCD which is optically coupled via a lens to scintillator without intermediate amplification. On the basis of the experience with the lens coupling, the performance of the CCD is investigated with the option of a fiber-optic coupling between the scintillator and CCD. The performance attainable by operating the CCD in the charge integration mode is explored experimentally, and computations are presented in order to predict the performance of a modified imaging system operating in the counting pulse-height mode for energy discrimination. >

Performance of Subsampled Analog Optical Links

Abstract: We analyze the operation and performance of subsampled analog optical links. These links downconvert microwave signals by optically sampling at a rate much lower than the RF carrier frequency. Expressions for conversion gain, noise figure, and spurious-free dynamic range are derived for intensity modulation and direct detection. The impact of pulse width on link performance is revealed and quantified. Also, in order to characterize noise in a subsampled link, the influence of timing jitter in the periodic optical source is considered. Timing jitter and pulse width are found to be two important factors which limit the noise figure and dynamic range in subsampled links.

Optical fiber three-axis accelerometer based on lasers locked to π phase-shifted Bragg gratings

Abstract: We report on a high-bandwidth, three-axis accelerometer developed with π phase-shifted fiber Bragg gratings. The gratings are inserted into a cantilever system and interrogated by three separate telecom distributed-feedback diode lasers. The lasers are frequency locked to the sensors using a radio-frequency Pound–Drever–Hall technique. This scheme reduces the effect of laser amplitude noise and allows for real-time measurements with a dynamic range greater than 50 g. An operation bandwidth of about 1000 Hz is demonstrated with minimum detectable accelerations in the order of 10 µgrms Hz−1/2 for frequencies above 10 Hz, only limited by the interrogating lasers frequency noise.

A Fifth-Order G $_{\rm m}$ –C Continuous-Time $\Delta\Sigma$ Modulator With Process-Insensitive Input Linear Range

Abstract: Continuous-time ?? modulators (CT-DSMs) that use transistor-based Gm-C integrators are simple but sensitive to process and temperature variations. Their performance depends heavily on the input linear range that varies widely. A CT-DSM is implemented using a triode Gm-C integrator and a tri-level switched-capacitor digital-to-analog converter (SCDAC). A self-scaling SCDAC keeps the input signal range constant, and an adaptive input common-mode bias control enables the triode Gm cell to operate always with its constant input linear range. The proposed Gm cell exhibits a tuning range of ± 15% while maintaining its linear range over the temperature variation from -30°C to 85°C. A 2-MHz bandwidth, fifth-order CT-DSM in 0.18 ?m CMOS samples at 128 MS/s with an over-sampling ratio of 32 (OSR = 32), occupies an active area of 0.4 mm2, and consumes 11 mW at 1.8 V. With a -3 dB input of the full scale (400 mV), the measured dynamic range, second harmonic distortion (HD2), and third harmonic distortion (HD3) are 71, -86, and -91 dB, respectively.

Shack-Hartmann wavefront sensor with large dynamic range by adaptive spot search method.

Abstract: A Shack-Hartmann wavefront sensor (SHWFS) that consists of a microlens array and an image sensor has been used to measure the wavefront aberrations of human eyes. However, a conventional SHWFS has finite dynamic range depending on the diameter of the each microlens. The dynamic range cannot be easily expanded without a decrease of the spatial resolution. In this study, an adaptive spot search method to expand the dynamic range of an SHWFS is proposed. In the proposed method, spots are searched with the help of their approximate displacements measured with low spatial resolution and large dynamic range. By the proposed method, a wavefront can be correctly measured even if the spot is beyond the detection area. The adaptive spot search method is realized by using the special microlens array that generates both spots and discriminable patterns. The proposed method enables expanding the dynamic range of an SHWFS with a single shot and short processing time. The performance of the proposed method is compared with that of a conventional SHWFS by optical experiments. Furthermore, the dynamic range of the proposed method is quantitatively evaluated by numerical simulations.