Interferometer with a wavelength-tuned diode laser for surface profilometry

Abou‐Zeid, A.; Wiese, P.

doi:10.1088/0957-0233/9/7/017

Cited by 9 publications

(8 citation statements)

References 5 publications

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“…42 The obvious advantage of this is that the entire unit would not possess any moving parts with no additional optical components thereby resulting in a unit with very high degree of mechanical stability. Interferometry utilizing tunable lasers has been employed for surface profilometry 43 and length metrology. 44 It is interesting to note that Ishii et al 45 suggested that interferometers using phase shifters such as a PZT could be replaced with tunable laser sources.…”

Section: Resultsmentioning

confidence: 99%

Real-time detection of ambient aerosols using photothermal interferometry: Folded Jamin interferometer

Sedlacek

2006

Review of Scientific Instruments

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Work in our laboratory has been directed at the development of a new class of instrumentation that can directly measure ambient aerosol absorption through photothermal interferometry. The hallmark of this approach is its ability to directly measure aerosol absorption without interference from aerosol scattering since the signal originates from the thermal dissipation of the spectrally absorbed energy. While the principle of the photothermal technique for the detection of aerosols was demonstrated in the mid-1980s, this interferometric technique remains a laboratory technique largely due to sensitivity to mechanical vibrations and other environmental factors that result in unwanted signal interference and commensurate reduction in detection sensitivity. In order to realize its application outside the laboratory, a folded Jamin interferometer design has replaced both the traditional Mach-Zehnder and unfolded Jamin configurations. The folded Jamin affords many advantages, which include high degree of common mode noise rejection, insensitivity to rotation and translation of optical components, inherent double pass configuration, and compact size. In this article, we report on the performance of this optical configuration and present representative data for both absorbing and nonabsorbing aerosols.

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Section: Resultsmentioning

confidence: 99%

Real-time detection of ambient aerosols using photothermal interferometry: Folded Jamin interferometer

Sedlacek

2006

Review of Scientific Instruments

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“…Comprehensive treatments of the theory of the PTI technique are presented in a number of studies (e.g., [ 138 , 139 , 141 , 142 ]), while the technique also finds common application in metrology [ 150 – 153 ]. Moosmüller et al [ 144 ] provided a review of PTI for particle absorption measurements following the critical advance of the folded Jamin interferometer by Moosmüller and Arnott [ 146 ].…”

Section: Measurement Techniquesmentioning

confidence: 99%

Characterizing elemental, equivalent black, and refractory black carbon aerosol particles: a review of techniques, their limitations and uncertainties

et al. 2013

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Elemental-, equivalent black- and refractory black-carbon are terms that have been defined in order to dissect the more general term, black carbon, into its component parts related to its specific chemical and optical properties and its impact on climate and health. Recent publications have attempted to clarify the meaning of these terms with respect to their environmental impact, particularly on climate. Here, we focus on the measurement aspects, reviewing the most commonly implemented techniques for the direct and indirect derivation of black carbon properties, their strengths, limitations, and uncertainties, and provide a non-exhaustive bibliography where the reader can find more detailed information. This review paper is designed as a guide for those wishing to learn about the current state of black carbon measurement instrumentation, how calibration is carried out, when one instrument may have the advantage over another, and where new techniques are needed to fill important knowledge gaps.

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“…If the optical pathlength in one arm of the interferometer changes, a commensurate shift in the interference pattern will take place. So sensitive are these interferometric techniques to pathlength changes they are routinely used in the field of metrology where sub-nanometer scales can be realized (Ishii et al 1987;Downs 1990;Stone et al 1999;Abou-Zeid and Wiese 1998). For the specific application of this technique for measuring light absorption, the optical pathlength change is induced when the dissipation of the spectrally absorbed energy creates a temperature gradient.…”

Section: Theorymentioning

confidence: 99%

Photothermal Interferometric Aerosol Absorption Spectrometry

Sedlacek

Lee

2007

Aerosol Science and Technology

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Aerosol light absorption still remains a difficult quantity to measure at the precision, accuracy and temporal resolution necessary to quantitatively bound the contribution of this direct effect on aerosol radiative forcing. These continuing difficulties are due, in part, because aerosol extinction is dominated by light scattering. In response to these and other issues, the aerosol community has been developing a new generation of instrumentation that can measure aerosol absorption without the need to deposit aerosols on a filter. Here we introduce work on the application of photothermal interferometry (PTI) towards this measurement problem. The advantages of this approach are: its complete insensitivity to aerosol scattering (true for any photothermal technique) and high sensitivity resulting from use of an interferometric technique. Using NO 2 as a calibration standard, the accuracy of the PTI technique was measured to be 5% (95% confidence interval). Measurement at a 10-second time constant yields a precision of 0.2 Mm −1 (95% confidence interval) and a lower limit of detection of 0.4 Mm −1 for a sample pathlength of 5 cm. Using laboratory-generated nigrosin aerosols an intercomparison between the PTI and a 3-λ Particle Soot Absorption Photometer (PSAP) gives a slope of 0.96 ± 0.02. Acquisition of absorption coefficients for ambient aerosols reveals very good agreement between the two instruments except for periods of high relative humidity (>70%) whereupon the PSAP reports a larger absorption coefficient.

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Interferometer with a wavelength-tuned diode laser for surface profilometry

Cited by 9 publications

References 5 publications

Real-time detection of ambient aerosols using photothermal interferometry: Folded Jamin interferometer

Real-time detection of ambient aerosols using photothermal interferometry: Folded Jamin interferometer

Characterizing elemental, equivalent black, and refractory black carbon aerosol particles: a review of techniques, their limitations and uncertainties

Photothermal Interferometric Aerosol Absorption Spectrometry

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