Signal Diversity for Laser-Doppler Vibrometers with Raw-Signal Combination

The intensity of the reflected measuring beam is greatly reduced for laser-Doppler vibrometer (LDV) measurements on rough surfaces since a considerable part of the light is scattered and cannot reach the photodetector (laser speckle effect). The low intensity of the reflected laser beam leads to a so-called signal dropout, which manifests as noise peaks in the demodulated velocity signal. In such cases, no light reaches the detector at a specific time and, therefore, no signal can be detected. Consequently, the overall quality of the signal decreases significantly. In the literature, first attempts and a practical implementation to reduce this effect by signal diversity can be found. In this article, a practical implementation with four measuring heads of a Multipoint Vibrometer (MPV) and an evaluation and optimization of an algorithm from the literature is presented. The limitations of the algorithm, which combines velocity signals, are shown by evaluating our measurements. We present a modified algorithm, which generates a combined detector signal from the raw signals of the individual channels, reducing the mean noise level in our measurement by more than 10 dB. By comparing the results of our new algorithm with the algorithms of the state-of-the-art, we can show an improvement of the noise reduction with our approach.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:21

Enthalten in:

Sensors (Basel, Switzerland) - 21(2021), 3 vom: 02. Feb.

Sprache:

Englisch

Beteiligte Personen:

Schewe, Marvin [VerfasserIn]
Rembe, Christian [VerfasserIn]

Links:

Volltext

Themen:

Diversity reception
Journal Article
LDV
Laser speckle
Laser-doppler vibrometry
Signal diversity
Speckle

Anmerkungen:

Date Revised 07.02.2021

published: Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.3390/s21030998

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM321013328