Title Compact laser driver for ultrasonic arbitrary position and width pulse sequences generation /
Authors Svilainis, Linas ; Chaziachmetovas, Andrius ; Eidukynas, Valdas ; Aleksandrovas, Arturas ; Varatinskas, Marijus
DOI 10.1109/TIM.2021.3120144
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Is Part of IEEE transactions on instrumentation and measurement.. Piscataway, NJ : IEEE. 2021, vol. 70, art. no. 7006815, p. 1-15.. ISSN 0018-9456. eISSN 1557-9662
Keywords [eng] arbitrary position and width pulse sequences ; acoustic point source ; diode lasers ; laser ultrasound ; laser driver ; thermoelastic regime ; ultrasonic transducers
Abstract [eng] Laser ultrasound offers several benefits in comparison to immersion or air coupled ultrasound: it directly generates stress on the sample surface; it has a wide bandwidth and a small acoustic source can be produced. Conventionally, high power pulsed lasers are required therefore equipment is bulky and expensive. Here we propose to use mid-power laser diodes, which are small and low cost. To solve the low signal amplitude problem with lower power lasers, the use of spread spectrum signal, arbitrary position and width binary pulse sets is proposed. To date, a laser driver for this task has not been available. This paper describes the development of such a compact driver, where the essential electronics occupy an area of 10x20 mm. The whole system with a fixture for kinematic mount is comparable in size to a conventional piezoelectric ultrasonic transducer. The driver can supply pulse sets of up to 40 A. Individual pulse duration can vary between 20 ns to 1000 ns (0.5-25MHz ultrasound range) and the total pulse train duration is limited by the laser type used. Experiments show that up to 10 s long pulse sets can be used at 10A current, without laser degradation. Current waveforms, beam profile and optical response signals were measured for three rectified topologies. It was concluded, that the GaN based constant current switch topology has the best performance, but a power MOSFET in a source current feedback topology can also be used to generate pulses down to 20 ns. Photoacoustic response signals from chirp and phase shift keying modulation have been demonstrated.
Published Piscataway, NJ : IEEE
Type Journal article
Language English
Publication date 2021
CC license CC license description