Low-cost, digital lock-in module with external reference for coating glass transmission/reflection spectrophotometer

Alonso, R.; Villuendas, F.; Borja, Juan; Barragán, L.A.; Salinas, Í.

doi:10.1088/0957-0233/14/5/303

Cited by 25 publications

(16 citation statements)

References 15 publications

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“…The experimental results show that The performance of our DLIA at high temperature is equivalent to the room temperature one in [23,24]. …”

Section: Experimental and Resultsmentioning

confidence: 99%

A Digital Lock-In Amplifier for Use at Temperatures of up to 200 °C

Cheng

et al. 2016

Sensors

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Weak voltage signals cannot be reliably measured using currently available logging tools when these tools are subject to high-temperature (up to 200 °C) environments for prolonged periods. In this paper, we present a digital lock-in amplifier (DLIA) capable of operating at temperatures of up to 200 °C. The DLIA contains a low-noise instrument amplifier and signal acquisition and the corresponding signal processing electronics. The high-temperature stability of the DLIA is achieved by designing system-in-package (SiP) and multi-chip module (MCM) components with low thermal resistances. An effective look-up-table (LUT) method was developed for the lock-in amplifier algorithm, to decrease the complexity of the calculations and generate less heat than the traditional way. The performance of the design was tested by determining the linearity, gain, Q value, and frequency characteristic of the DLIA between 25 and 200 °C. The maximal nonlinear error in the linearity of the DLIA working at 200 °C was about 1.736% when the equivalent input was a sine wave signal with an amplitude of between 94.8 and 1896.0 nV and a frequency of 800 kHz. The tests showed that the DLIA proposed could work effectively in high-temperature environments up to 200 °C.

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“…The experimental results show that The performance of our DLIA at high temperature is equivalent to the room temperature one in [23,24]. …”

Section: Experimental and Resultsmentioning

confidence: 99%

A Digital Lock-In Amplifier for Use at Temperatures of up to 200 °C

Cheng

et al. 2016

Sensors

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“…O amplificador Lock-iné uma excelente ferramenta para medir sinais com pequenas amplitudes em sistemas imersos em ruído [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Neste caso, um Lock-in de 16 bits de resolução recebe um sinal do Chopper como referência e outro sinal do fotodector através do condicionador de sinais.…”

Section: Metodologiaunclassified

Aparato experimental para medidas de atividade óptica da sacarose usando um amplificador Lock-in

Fauth¹,

Batista²

2018

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Resumo: Este trabalho apresenta a montagem de um polarímetro digital para medidas de atividadeóptica em modo pulsado. Em termos de instrumentação científica, foi desenvolvido um circuito eletrônico para medir a intensidade luminosa usando um fotodetector em conjunto com outros componentesópticos e um amplificador Lock-in. Além disso, um porta amostra foi projetado utilizando uma lente de quartzo acoplada em uma tampa e conectada a um tubo de PVC. O desempenho do sistema de medidasé investigado considerando a resolução e o limite de detecção a partir da determinação da rotaçãoóptica específica da sacarose. Este trabalho foi desenvolvido tendo como base o paradigma open source hardware e, portanto, toda a documentação estará disponível para que possa ser utilizada e aprimorada pela comunidade científica.Palavras chave: AtividadeÓptica, Polarímetro, Lock-in, Open Source Hardware. Abstract:This work presents the assembly of a digital polarimeter for measurements of optical activity in pulsed mode.In terms of scientific instrumentation, an electronic circuit was developed to measure light intensity using a photodetector in conjunction with other optical components and a Lock-in amplifier. In addition, a sample port was designed using a quartz lens attached to a cap and connected to a PVC pipe. The performance of the measurement system is investigated considering the resolution and the limit of detection from the determination of the specific optical rotation of sucrose. This work was developed based on the open source hardware paradigm and, therefore, all the documentation will be available so that it can be used and improved by the scientific community.

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“…6 In addition, digital signal processing units have been employed to develop cost-effective lock-in amplifiers. [7][8][9] Nonetheless, the physical dimension and electrical requirements of these devices may be prohibitive when addressing Global Health challenges. It is, therefore, a purpose of this work to provide an alternative to enable portable lock-in detection with digital signals.…”

Section: A Lock-in Circuit Design and Performancementioning

confidence: 99%

Portable digital lock-in instrument to determine chemical constituents with single-color absorption measurements for Global Health Initiatives

Vacas-Jacques

Linnes

Young³

et al. 2014

Review of Scientific Instruments

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Innovations in international health require the use of state-of-the-art technology to enable clinical chemistry for diagnostics of bodily fluids. We propose the implementation of a portable and affordable lock-in amplifier-based instrument that employs digital technology to perform biochemical diagnostics on blood, urine, and other fluids. The digital instrument is composed of light source and optoelectronic sensor, lock-in detection electronics, microcontroller unit, and user interface components working with either power supply or batteries. The instrument performs lock-in detection provided that three conditions are met. First, the optoelectronic signal of interest needs be encoded in the envelope of an amplitude-modulated waveform. Second, the reference signal required in the demodulation channel has to be frequency and phase locked with respect to the optoelectronic carrier signal. Third, the reference signal should be conditioned appropriately. We present three approaches to condition the signal appropriately: high-pass filtering the reference signal, precise offset tuning the reference level by low-pass filtering, and by using a voltage divider network. We assess the performance of the lock-in instrument by comparing it to a benchmark device and by determining protein concentration with single-color absorption measurements. We validate the concentration values obtained with the proposed instrument using chemical concentration measurements. Finally, we demonstrate that accurate retrieval of phase information can be achieved by using the same instrument.

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Low-cost, digital lock-in module with external reference for coating glass transmission/reflection spectrophotometer

Cited by 25 publications

References 15 publications

A Digital Lock-In Amplifier for Use at Temperatures of up to 200 °C

A Digital Lock-In Amplifier for Use at Temperatures of up to 200 °C

Aparato experimental para medidas de atividade óptica da sacarose usando um amplificador Lock-in

Portable digital lock-in instrument to determine chemical constituents with single-color absorption measurements for Global Health Initiatives

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