Design and development of low noise transimpedance amplifier for low intensity light level detection applications for UV range

In this work the concept of using a single partitioned pixel amplifier with variable topology for both low light level operation and Wide Dynamic Range (WDR) for CMOS imagers is presented. Low light level imaging is based on the Active Reset (AR) technique combined with the Active Column Sensor (ACS) readout technique for low noise operation. WDR for high light level detection is achieved by utilizing multiple resets via real-time feedback where each pixel in the field of view is independent and can automatically set an exposure time according to its illumination. Due to the commonalities in the low and high light level readout techniques, and the fact that they occur in staggered instances of time, we propose the use of a single column level partitioned pixel amplifier which can be configured in various modes of operation to satisfy the conditions for the suggested techniques. We also propose a Conditional Active Reset (CAR) scheme in which an AR is employed for every reset in the multiple-reset WDR algorithm, thereby reducing the overall noise involved in the technique. The advantages of the proposed column level partitioned pixel amplifier are simplicity in the analog readout path, reduced chip size and less power consumption. The Variable Topology Amplifier was designed and simulated in a mixed signal 0.18 um CMOS technology. Its design is discussed and simulation results are presented.

We examine the low light level performance of a four-channel polarimeter with a single photon counting sensor associated with each channel. Specifically, we investigate how the detectionnoise propagates through the polarimeter calibration matrix and influences the estimation of I and 12, the intensities in two orthogonal polarization states and, 8, the phase delay betweenthe two orthogonal states. The error in estimating the phase delay is first derived in the smallangle approximation for low light levels. The approximation is removed by deriving a general formalism valid for arbitrary light levels including very low light levels. A specific polarimeterdesign is examined and quantitative examples are shown and discussed for that polarimeter.Keywords: polarized light , polarimetry, Mueller calculus, statistical optics. 1 INTRODUCTION The polarization properties of light can be completely described by the four Stokes polarization parameters.1 Polarizing elements can be represented as a 4 x 4 matrix operator that operateson the Stokes vector. A matrix of this type is called a Mueller matrix. Any optical device thatchanges the polarization state can be represented as a Mueller matrix .

WITHDRAWN: Design and implementation of CMOS transimpedance amplifier as a photodetector

A high and low light imager (HALLI) developed in a CMOS process is presented. The HALLI utilizes a single column parallel partitioned pixel amplifier with variable topology for the detection of both high and low light levels in the same frame. For high light level detection, a wide dynamic range algorithm is utilized in which multiple resets via real-time feedback are employed. Each pixel in the field of view is independent and can automatically set its exposure time according to its illumination. For low light level detection, two noise reduction techniques are employed, active reset and active column sensor readout technique. Due to the commonalities in the high and low light level readout techniques, and the fact that they occur in staggered instances of time, a single partitioned pixel amplifier which can be configured in various modes of operation is used. The advantages of using a single column parallel partitioned pixel amplifier are simplicity in the analog readout path, reduced chip size, and lower power consumption than using individual dedicated blocks for each technique. The CMOS imager was designed and fabricated in a mixed signal 0.18 μm CMOS technology. System architecture, operation and results are presented.

Low noise and low Power transimpedance amplifiers (TIA) are essential module for optical sensor based systems. But low power and low noise TIAs are still a challenge for the scientists despite of rapid advances in complementary metal oxide semiconductor (CMOS) technology. This paper proposes a three-stage nested miller compensated (NMC) based design of low noise low power transimpedance amplifier for stable wideband operation. The circuit is designed in the 0.18μm CMOS technology by using Mentor Graphics environment. The simulation results show that the proposed TIA can operate at frequency 20 KHz and produces an output of 1.4265V for ±1.2 V input voltages dissipating only 2.9206 mW power at 27°C temperature. The complete layout of the TIA is only 0.005 μm2. This shunt-feedback TIA can be a better choice for high-resolution, low-to mid frequency applications.

Silicon photomultipliers are novel solid state photodetectors that recently became commerciallyavailable. The goal of this paper was to investigate their suitability for low light level detectionin miniaturized functional near-infrared spectroscopy instruments. Two measurement modules with afootprint of 26×26 mm2 were built, and the signal-to-noise ratio was assessed forvariable source-detector separations between 25 and 65 mm on phantoms with similar opticalproperties to those of a human head. These measurements revealed that the signal-to-noise ratio ofthe raw signal was superior to an empirically derived design requirement for source-detectorseparations up to 50 mm. An arterial arm occlusion was also performed on one of the authorsin vivo, to induce reproducible hemodynamic changes which confirmed the validity ofthe measured signals. The proposed use of silicon photomultipliers in functional near-infraredspectroscopy bears large potential for future development of precise, yet compact and modularinstruments, and affords improvements of the source-detector separation by 67% compared tothe commonly used 30 mm.

Bioluminescent indicators have found many uses in, for example, the detection of ATP and free calcium levels. However, such probes often emit only very low levels of light and it is important to optimize the efficiency of the system used to detect this light. We describe some of the problems encountered in using photomultiplier tubes for detecting low levels of light, and some ways of overcoming these problems. We have developed a versatile photomultiplier light detection system which is both efficient and physically small. This system is described and details of its fabrication are given.

The aim of this study was to investigate the effects of light intensity and enhanced nitrogen supply on the growth and photosynthesis of the green-tide macroalga, Ulva prolifera. Thalli of U. prolifera were grown in natural or NH (4) (+) -enriched seawater under two different light intensities for 7 days, and then the growth rate, pigmentation, and photosynthetic performance of the thalli were evaluated. The results show that the relative growth rate (RGR) was markedly higher under the high light level than under the low light level. Enrichment with NH (4) (+) enhanced the RGR under high light intensity, but did not affect RGR under low light intensity. In low light conditions, NH (4) (+) -enrichment resulted in a marked decrease in the maximal photosynthetic rate (P (m)) and the maximum carbon fixation rate (V (max)), but it did not affect the half saturation constant for carbon (K (0.5)) or the ratio of V (max) to K (0.5), which reflects the carbon acquisition efficiency. In high light conditions, P (m), K (0.5), and the dark respiration rate (R (d)) increased under NH (4) (+) enrichment, but V (max) and the V (max) / K (0.5) ratio decreased. Regardless of the light intensity, NH (4) (+) -enrichment did not affect the apparent photosynthetic efficiency (alpha), which reflects the ability of the alga to use light energy at low light levels. Under both low and high light intensities, the chlorophyll a (Chl a), chlorophyll b (Chl b), and carotenoids (Car) contents in thalli were higher in NH (4) (+) -enriched than in natural seawater, except that there was a decrease in the Chl b content of thalli in NH (4) (+) -enriched seawater under low light intensity. Therefore, NH (4) (+) enrichment improved the growth and photosynthetic performance of U. prolifera under high light intensity, but not under low light intensity. We discuss the possible mechanisms underlying these physiological responses.

Current low-level light detection technologies for biomedical applications such as DNA microarray sensors use charge-coupled devices or photomultiplier tubes which cannot be easily integrated with electronic circuits on a chip. Complementary metal-oxide semiconductor (CMOS) image sensors do allow for the integration of photosensitive and signal processing elements on the same chip. However, more research is required if optimized low-level light detectors in standard CMOS technologies are to be developed. In this research, we have investigated different photosensitive devices, including vertical, lateral, and avalanche photodiodes and two floating gate-well-tied phototransistors with different gate oxide thicknesses. The photodetectors were fabricated in a commercial 0.18μm CMOS technology, and their optoelectronic characteristics were measured to determine the optimum configuration for low-level light detection.

In this paper, an equivalent circuit modeling method of photodetector is proposed, and the equivalent circuit model of quantum dots photodetector is established. Experimental results show that the simulation curves and parameters agree very well with the measured results. The 10 picowatts power focused laser is readout based on readout circuits and low light level detection system at 77 K temperature. The 7 mV response voltage is achievable under 29 μs integration time and −3.1 V bias voltage. The voltage responsivity has reached 7 × 108 V/W.

An interdigital SiPM with coincidence measurement for rejection of dark noise

Time-Correlated Raman and Fluorescence Spectroscopy Based on a Silicon Photomultiplier and Time-Correlated Single Photon Counting Technique

Benefiting from close to ideal amplification properties (high gain, low dark current, and low excess noise factor), HgCdTe electron initiated avalanche photodiode (e-APD) technology exhibits state of the art sensitivity, thus being especially relevant for applications relying on low light level detection, such as LIDAR (Light Detection And Ranging). In addition, the tunable gap of the Hg1-xCdxTe alloy enables coverage of the short wavelength infrared (SWIR) and especially the 2μm spectral range. For these two reasons, a HgCdTe e-APD based detector is a promising candidate for future differential absorption LIDAR missions targeting greenhouse gas absorption bands in SWIR. In this study, we report on the design and evaluation of such a HgCdTe e-APD based detector. The first part focuses on detector architecture and performance. Key figures of merit are: 2.8μm cutoff wavelength, 200μm diameter almost circular sensitive area, 185K operating temperature (thermo-electric cooling), 22 APD gain (at 12V reverse bias), 360 kΩ transimpedance gain, and 60 fWHz-0.5 noise equivalent power (at 12V reverse bias). The second part presents an analysis of atmospheric LIDAR signals obtained by mounting the HgCdTe e-APD based detector on the 2μm differential absorption LIDAR developed at the Laboratoire de Météorologie Dynamique and dedicated to CO2 monitoring. Discussion emphasizes random and systematic errors in LIDAR measurements regarding breadboard detector characterization. In particular, we investigate the influence of parasitic tails in detector impulse response on short range DIAL measurements.

The effects of light and ammonium levels on net production, fluorescence parameters and non-structural carbohydrates of the seagrass Zostera noltii under different phosphate conditions were studied. A fully factorial design was used with light (low/high levels), ammonium supply and phosphate preculture conditions of the plants as the experimental variables. Both ammonium supply and low light caused negative and synergistic effects on net production, while ammonium toxicity was more severe at high light levels; in this case, it was independent of the non-structural carbohydrate (sucrose and starch) content. Preculturing of plant with added phosphate alleviated the ammonium toxicity, and also attenuated the negative production balance of plants grown at low light levels. The results indicated that phosphate preculture ameliorated the plant’s short-term response against the assayed stressors (low light, high ammonium) significantly. An overall consumption of non-structural carbohydrates in response to environmental stressors was recorded throughout the experiment, indicating the importance of carbon and phosphorus reserves to cope with adverse conditions. In addition, phosphate deficiency increased the vulnerability of plants, which could have negative ecological consequences for seagrass species thriving under phosphate deficiency conditions, or in developing seagrass transplantation programs.

Exciting work is being done in quantum information theory and the detection of low light levels.