The Use of High-Frequency Pulsed Laser Diodes in Fringe Type Laser Doppler Anemometry

Dopheide, D.; Pfeifer, H. J.; Faber, M.; Taux, G.

doi:10.2351/1.4745243

Cited by 12 publications

(3 citation statements)

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“…As laser diodes are often used [6][7][8] as a light source in LDF instruments, for this pulsed-LDF method also a laser diode has been used, which fulfills the mentioned criteria for the pulsed light source. The LDF time signals are collected by sampling with an analog-to-digital AD card.…”

Section: Methodsmentioning

confidence: 99%

Pulsed-laser Doppler flowmetry provides basis for deep perfusion probing

Kolkman

Hondebrink

Bolt

et al. 2001

Review of Scientific Instruments

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A setup for pulsed-laser Doppler flowmetry ͑LDF͒ measurements has been built and tested. Measurements were carried out comparing continuous-wave and pulsed LDF. With pulsed LDF a higher peak power can be injected into the tissue without exceeding the safety limits. This enables a much larger spacing between the locations of illumination and detection. Thus, the penetration depth, and thus the measurement volume, can be enlarged using the pulsed-LDF method. This method will allow, e.g., monitoring of the cerebral perfusion.

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Section: Methodsmentioning

confidence: 99%

Pulsed-laser Doppler flowmetry provides basis for deep perfusion probing

Kolkman

Hondebrink

Bolt

et al. 2001

Review of Scientific Instruments

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“…Sb and Sc show that the optical frequency of the HF-pulsed laser diode changes during one single laser pulse period, even after the injection current becomes constant.1214 Such changes increase if the 'pulse increases. It has been shown that the frequency settling time may be as short as about 1 and the frequency response of laser diodes can be extended using modified injection current waveforms.18"9 I Time The amplitude change of the APD output signals shown in Figs. 6a and 6b presents again the local shift of the fringe system in the measuring volume, caused by the mode hopping or frequency jitter of the HF-pulsed laser diode.…”

Section: Influence Of the Laser Diode's Frequency Change On The Lda Fmentioning

confidence: 99%

Investigation of the dynamic emission spectra of high-frequency pulsed laser diodes for LDA applications

et al. 1996

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In this paper the dynamic emission spectra of high-frequency pulsed (HF-pulsed) laser diodes have been studied in order to investigate the spectral stability of each laser pulse and to examine the influence of the HF-pulsed laser diode's mode hopping and frequency jitter on the interferential fringe system in LDA applications.It has been shown that, by choosing appropriate operating points, a HF-pulsed laser diode can be operated to have optical characteristics such as mono-mode emission, a stable wavelength from pulse to pulse and high optical output peak power. The selection of optimal operating points for LDA applications may be not required if semiconductor lasers with periodically structured laser resonators of for example the distributed-feedback (DFB) type or the distributed-Braggreflector (DBR) are used.Keywords: laser diode, laser Doppler anemometry, high-frequency pulsed laser diode, mode hopping and frequency jitter, laser chirp, interferential fringe pattern, fibre optics, DBR laser diode.

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“…suited for use in flowrate measurements [7,91. A wavelength-stabilized diode laser LDA with a highly sensitive avalanche photodiode has been developed [8].…”

Section: Miniaturized Diode Laser Ldamentioning

confidence: 99%

Three-component Laser Doppler Anemometer for Gas Flowrate Measurements up to 5 500 m³/h

1994

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In the Physikalisch-Technische Bundesanstalt (PTB) the primary standard for on-line flowrate measurements using the laser Doppler anemometer (LDA) technique has been extended to a three-component LDA to improve velocity profile measurements in the boundary layers of a nozzle flow. The LDA flowrate measuring facility now consists of a two-colour argon ion LDA and a wavelength-stabilized GaAlAs diode laser LDA. The gas flowrate is obtained by numerical integration of the measured velocity profiles across the exit plane of the nozzle. High local resolution of the velocity profile measurements is achieved by perpendicular orientation of the measurement volumes of the two-component gas laser LDA and the semiconductor diode laser LDA (LD-LDA). This allows the resolution in the boundary layer to be improved significantly to velocity gradients. The present work presents the LD-LDA system for precise velocity profile measurements at flow velocities of up to 120 m/s; selected profile measurements are described in detail to demonstrate the high resolution and the symmetry of the flow profile. For the first time a wavelength-stabilized miniaturized diode laser LDA has been successfully applied in precise velocity measurements, and comparisons with well-established gas laser LDAs have been made. The uncertainty of the flowrate measurement up to 5 500 m3/h is 0,l YO for air at atmospheric pressure. A turbine gas meter, type Elster G2500, was calibrated with the LDA and used as a transfer standard for an intercomparison with the Nederlands Meetinstituut (NMI) in the flowrate range up to 5 500 m3/h with and without the installation of perforated plates to condition the flow in the inlet section of the gas meter. The results of the comparison experiment clearly show the reliability and accuracy of the online flowrate measurement of gases and underline the necessity for a detailed research programme to investigate the relationship between installation effects, upstream flow conditions and the measurement uncertainty of gas meters. The design of a test rig now under construction at the PTB is shown. This will allow the diode laser LDA technique to be applied to the measurement of installation effects according to OIML Recommendation R-32.

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The Use of High-Frequency Pulsed Laser Diodes in Fringe Type Laser Doppler Anemometry

Cited by 12 publications

References 0 publications

Pulsed-laser Doppler flowmetry provides basis for deep perfusion probing

Pulsed-laser Doppler flowmetry provides basis for deep perfusion probing

Investigation of the dynamic emission spectra of high-frequency pulsed laser diodes for LDA applications

Three-component Laser Doppler Anemometer for Gas Flowrate Measurements up to 5 500 m³/h

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The Use of High-Frequency Pulsed Laser Diodes in Fringe Type Laser Doppler Anemometry

Cited by 12 publications

References 0 publications

Pulsed-laser Doppler flowmetry provides basis for deep perfusion probing

Pulsed-laser Doppler flowmetry provides basis for deep perfusion probing

Investigation of the dynamic emission spectra of high-frequency pulsed laser diodes for LDA applications

Three-component Laser Doppler Anemometer for Gas Flowrate Measurements up to 5 500 m3/h

Contact Info

Product

Resources

About

Three-component Laser Doppler Anemometer for Gas Flowrate Measurements up to 5 500 m³/h