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Characterizing GCLAD as a non-contact detector for biomedical applications

Timmerman, M. (2016) Characterizing GCLAD as a non-contact detector for biomedical applications.

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Abstract:Photoacoustic (PA) imaging is a rapidly growing �field that has the potential to improve non-invasive imaging capabilities. Conventional detectors such as transducers have several disadvantages such as narrow bandwidth, limited sensitivity and the fact that contact with the sample is required. Optical methods provide better bandwidth and resolution but have other limitations. These detection methods often contain complicated optics and depend on the reflectivity of the sample. Since biological tissue is mostly rough and poorly reflective the addition of reflective tape is often required. However, this is not always possible or desired for example when imaging the eye or burned tissue. Therefore GCLAD provides an alternative fully non contact detection method for photoacoustic and ultrasound imaging that does not depend on the reflectivity of the sample. GCLAD is a line detector that measures the deflection of an optical beam propagating parallel to the sample as the refractive index of the air caused by an acoustic wave travelling through the sample is affected. GCLAD was originally developed for materials testing and therefore research needs to be performed to exploit the potential of GCLAD as a detection method for biomedical applications. Underlying principles are outlined and characterizing experiments are performed. Research into the effect of the air gap between the probe beam and the sample surface show that only slight attenuation takes place and that signals can clearly be detected at distances of over 10 cm away from the sample. Furthermore, the results are reproducible and the scans require little time. Possibly the most important advantage of GCLAD as a detector for biomedical applications is being fully non contact. Comparison of GCLAD with line-integrated data of a commercial laser vibrometer point detector shows an 83% agreement. Finally it is demonstrated that GCLAD can be used to image an artery-sized absorber using a detector several centimetres away from the sample.
Item Type:Internship Report (Master)
University of Auckland, New Zealand
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
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