Fiberized Sagnac Interferometer for Ultrasound Measurement

Fomitchov, Pavel A.; Krishnaswamy, Sridhar; Achenbach, Jan Drewes

doi:10.1007/978-1-4613-0383-1_83

Cited by 3 publications

(3 citation statements)

References 5 publications

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“…Optical fibre interferometers have also been used for ultrasonic detection by placing them in contact with the rear surface of metals [4] and by embedding them in epoxy-based materials [4,5]. Fibre interferometers have also been used in close proximity to a sample for very sensitive detection of surface acoustic waves [6,7]. These interferometers perform best with narrowband acoustic signals.…”

Section: Introductionmentioning

confidence: 99%

An optical fibre interferometer for remote detection of laser generated ultrasonics

Mitra

Shelamoff

Booth

1998

Meas. Sci. Technol.

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A 15 MHz bandwidth active homodyne fibre-optical interferometer for remote detection of laser-induced ultrasonic waves in metallic and non-metallic targets is reported. The fibre interferometer design and associated electronics are described in sufficient detail for it to be easily constructed. The interferometer uses a low-power He-Ne laser and the reflected signal from the natural surface of the target at a distance of 200 mm. Despite its use of an open air path in the sensing arm and an all-fibre design, the interferometer achieved a single-pulse noise equivalent displacement of 0.4 nm and a figure of merit of 0.1 pm Hz −1/2 .

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Section: Introductionmentioning

confidence: 99%

An optical fibre interferometer for remote detection of laser generated ultrasonics

Mitra

Shelamoff

Booth

1998

Meas. Sci. Technol.

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show abstract

“…Reflection of sampling beams from testing surface (6) and for the CW beam by: (7) where v is the frequency oflaser light, ov is the frequeney shift by the AOM, li and 12 are the optical paths of the CW and the CCW beams before and after frequeney shifting respectively. The total statie phase differenee between the sampling beams is therefore: (8) where !il = l 2 ccw -l2Cw• whieh depends only on the position ofthe AOM within the Sagnac loop and on the amount offrequency shift by the AOM, both ofwhich can be adjusted to the desired value. The two sampling beams travel through the AOM once each and have the same optical frequency (v+Öv) at the plane of the photodetector.…”

mentioning

confidence: 99%

“…This frequency separation of all the parasitic interferences from the desired signal beam interference allows for the use of low-noise and high-coherence sources, which also have reduced intensity noise compared to typicallaser diodes. Also, this approach avoids phase noise associated with conventional phase modulation teehniques such as those using an eleetro-optie modulator [8].…”

mentioning

confidence: 99%