Measuring the absorption coefficient of biological materials using integrating cavity ring-down spectroscopy

Cone, Michael T.; Mason, John D.; Figueroa, Eleonora; Hokr, Brett H.; Bixler, Joel N.; Castellanos, Cherry C.; Noojin, Gary D.; Wigle, Jeffrey C.; Rockwell, Benjamin A.; Yakovlev, Vladislav V.; Fry, Edward S.

doi:10.1364/optica.2.000162

Cited by 34 publications

(27 citation statements)

References 21 publications

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“…Figure 7.21 shows an example in which ICRDS was used to measure the base absorption (i.e., with the pigment removed) of 60 million RPE cells in a 3 mL solution [44]. Also shown is the attenuation (scattering plus absorption) spectrum obtained with the same sample in a spectrophotometer.…”

Section: Cavity Ring-down Spectroscopymentioning

confidence: 99%

“…7.21 Absorption coefficient of 6 Â 10 7 human retinal pigmented epithelium (RPE) cells in a 3 mL solution; also shown is the attenuation (scattering + absorption) spectrum. Adapted from [44] attenuation at 500 nm (4.6 cm À1 ) and the absorption (~0.02 cm À1 ). This is a factor of 230; the absorption is less than one-half of 1 % of the attenuation.…”

Section: Cavity Ring-down Spectroscopymentioning

confidence: 99%

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The Dawn of Quantum Biophotonics

et al. 2016

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Section: Cavity Ring-down Spectroscopymentioning

confidence: 99%

Section: Cavity Ring-down Spectroscopymentioning

confidence: 99%

The Dawn of Quantum Biophotonics

et al. 2016

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“…Physically, the phase shift between these two signals is related to the value of the Si PD internal junction capacitance C j that, in turn, depends on the laser power illuminating its sensitive area. The value of C j is, in fact, given by the following relationship: (1) where S is the Si PD sensitive area, q the electron charge, ε 0 and ε r the vacuum and Si permittivity's, N a and N d the acceptor and donor concentrations, V R the applied reverse bias voltage and ψ 0 the built-in potential [10]. Considering the photovoltaic operating condition of the Si PD, in eq.…”

Section: Techniques and Experimental Set-up For Thementioning

confidence: 99%

“…OWADAYS optical methods are widely used in chemistry and, more generally, in biosciences for the identification and characterisation of chemical and biological substances as well as nanostructured composite materials [1][2][3][4][5][6][7]. Among the optical methods, measurements of absorption, emission and scattering of the light can be usefully applied either for laboratory on site investigations or for remote sensing applications [8][9].…”

Section: Introductionmentioning

confidence: 99%

High-Sensitivity High-Resolution Optical Phase Shift Detection Technique Using a Si Photodiode Operating in Photovoltaic Mode

2015

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In this paper we report the optimisation of the operating conditions and the maximisation of the performances of the phase shift detection technique allowing to approach the best sensitivity and resolution in terms of light power variations. The system is based on the synchronous demodulation technique and uses a Si photodiode operating in photovoltaic mode biased through a small amplitude sinusoidal modulating signal. Employing a commercial lock-in amplifier for phase measurements and varying the signal modulating frequency, we prove that it is possible to obtain the maximum theoretical phase shift variation range equal to 90° with a resulting sensitivity and resolution equal to 3100°/µ µ µ µW and 3pW, respectively. We demonstrate that these results are more than two orders of magnitude greater than those ones achievable by employing a Si photodiode in photoconductive mode. As a case-example for chemical applications, we apply the proposed technique to detect the variations of the molar concentration of a methylene blue solution by measuring the variations of the transmittance of a laser beam passing through the substance. The experimental findings are compared with those ones achieved by using a commercial spectrophotometer and the conventional amplitude detection technique employing the lock-in amplifier. Despite the achieved results are limited by the fixed phase resolution of the employed lock-in amplifier, the here proposed approach allows to measure molar concentration variations with a resolution of 79pM resulting 1354 times higher than that one obtained using the spectrophotometer and 33 times better than the value achieved with the amplitude detection technique.

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“…The measurement of changes in intensity or in phase of an electromagnetic field, after interacting with matter, is the most simple and effective way to extract relevant information on the properties of a system under investigation, whether a biological sample [1,2] or a digital memory disc [3]. Intensity measurements enable absorption/transmission estimation, the base of imaging and spectroscopy, pervasive and fundamental techniques in all science fields, from chemistry [4] to material science [5] and physics [6].…”

Section: Introductionmentioning

confidence: 99%

Unbiased estimation of an optical loss at the ultimate quantum limit with twin-beams

Losero

Berchera

Meda

et al. 2018

Sci Rep

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Loss measurements are at the base of spectroscopy and imaging, thus permeating all the branches of science, from chemistry and biology to physics and material science. However, quantum mechanics laws set the ultimate limit to the sensitivity, constrained by the probe mean energy. This can be the main source of uncertainty, for example when dealing with delicate systems such as biological samples or photosensitive chemicals. It turns out that ordinary (classical) probe beams, namely with Poissonian photon number distribution, are fundamentally inadequate to measure small losses with the highest sensitivity. It is known that quantum-correlated pair of beams, named “twin-beam state”, allows surpassing this classical limit. Here we demonstrate they can reach the ultimate sensitivity for all energy regimes (even less than one photon per mode) with the simplest measurement strategy. One beam of the pair addresses the sample, while the second one is used as a reference to compensate both for classical drifts and for fluctuation at the most fundamental quantum level. This capability of selfcompensating for unavoidable instability of the sources and detectors allows also to strongly reduce the bias in practical measurement. Moreover, we report the best sensitivity per photon ever achieved in loss estimation experiments.

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Measuring the absorption coefficient of biological materials using integrating cavity ring-down spectroscopy

Cited by 34 publications

References 21 publications

The Dawn of Quantum Biophotonics

The Dawn of Quantum Biophotonics

High-Sensitivity High-Resolution Optical Phase Shift Detection Technique Using a Si Photodiode Operating in Photovoltaic Mode

Unbiased estimation of an optical loss at the ultimate quantum limit with twin-beams

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