Software Digital Lock-in Amplifier in the Application of fNIRS System

Yin, Xu; Xu, Baolei; 王, 志東; Li, Hong Yi; Shi, Gang

doi:10.4028/www.scientific.net/amm.333-335.535

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…The signals with a different frequency from the reference signal were removed, resulting in a direct current (DC) signal containing only the radiation information from the sample. Finally, the DC signal was sent back to the FTIR [15,16]. The commercial software OPUS (7.8, Ettlingen, Germany) was used to help transform the interferogram of the DC signal into an emission spectrum.…”

Section: Methodsmentioning

confidence: 99%

An Apparatus for Spectral Emissivity Measurements of Thermal Control Materials at Low Temperatures

Zhang

et al. 2019

Materials

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Thermal control materials are employed to adjust the temperature of a spacecraft operating in deep space. The spectral emissivity is a crucial factor in evaluating the thermal radiative properties of such materials. An apparatus, composed of a Fourier transform infrared spectrometer (FTIR), a sample cooling chamber and a mechanical modulation system was demonstrated to measure low temperature infrared spectral emissivity under vacuum. The mechanical modulation system, which includes a chopper and a lock-in amplifier, is employed to reduce the interference of background radiation during measurements. The limitation of the Fourier transform frequency on the chopper frequency can be eliminated by setting the FTIR on step-scan mode. The apparatus is separated into two parts and evacuated by different pumps. In this study, a high quality emission spectrum of a sample is measured by the apparatus. The spectral emissivity of thermal control materials are obtained in the wavelength range of 8 to 14 μm at 173 and 213 K. The combined standard uncertainty of the apparatus is 3.30% at 213 K.

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Section: Methodsmentioning

confidence: 99%

An Apparatus for Spectral Emissivity Measurements of Thermal Control Materials at Low Temperatures

Zhang

et al. 2019

Materials

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Ultra-low noise front-end design for smart optical sensors with high sensitivity and wide dynamic range

Wan,

Meng,

Wang

et al. 2024

Review of Scientific Instruments

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Ultra-low noise is a critical component in the design of high-precision sensor front-ends. We introduced differential phase-sensitive detection (d-PSD) to mitigate both multiplicative and additive noise in optical sensors, aiming for an enhanced performance and cost-effectiveness. The d-PSD combines a capacitive transimpedance amplifier (C-TIA), a delta–sigma analog-to-digital converter (ΔΣ-ADC), and a software-based lock-in amplifier (s-LIA). The first two components utilize the DDC112 (a dual current input 20-bit ADC) for a minimal analog channel length, thus reducing noise efficiently, while the latter employs a cost-effective 32-bit microcontroller unit (MCU), the HC32F460. This approach was successfully implemented as the front-end for a smart optical sensor. Testing indicated that the sensor achieved an equivalent current noise level of 0.6 nA/√Hz, primarily attributed to the light source driver rather than the sensor’s front-end circuit. The sensor exhibited an exceptional performance, with a 3σ measurement precision of 5.4 × 10−4 over a 1-second integration time and a dynamic range of 100 dB, leveraging the proposed method and design. Furthermore, the front-end of the sensor boasts a compact size, low power consumption, and affordability, making it an ideal, versatile solution for ultra-high precision, smart optical sensors.

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A Compact THz Quasi TDS System for Mobile Scenarios

Tonder

Kolpatzeck

et al. 2019

2019 Second International Workshop on Mobile Terahertz Systems (IWMTS)

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Software Digital Lock-in Amplifier in the Application of fNIRS System

Cited by 4 publications

References 7 publications

An Apparatus for Spectral Emissivity Measurements of Thermal Control Materials at Low Temperatures

An Apparatus for Spectral Emissivity Measurements of Thermal Control Materials at Low Temperatures

Ultra-low noise front-end design for smart optical sensors with high sensitivity and wide dynamic range

A Compact THz Quasi TDS System for Mobile Scenarios

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