Hello all,
Can anybody give me an idea of how much laser fluence is enough to excite measurable acoustic signals in photoacoustic imaging?
I'm specifically interested in excitation wavelength of 1.7um and for the case of intravascular imaging. The main goal is to image the plaques.
Thanks,
Parinaz
There is no straight answer to this question, the minim excitation fluence depends upon several factors such as the photoacoustics characteristics of the target sample/tissue ( example: wavelength dependent absorption) & the detection efficiency of your detector electronics etc. The ANSI fluence limit for the skin @ 570 nm is 20 mJ/cm2, and you can optimize your minim excitation fluence based on ANSI limit for various clinical applications.
This question is a little bit tricky. From an experimental point of view, Q-switch lasers usually have pulses with a duration in the order of nanoseconds (This is a good thing!) and provide means of optimize fluence; Lets say... basically you may have "enough excitation" to generate PA waves of an absorptive ink target inside water background with Nd-Yag surface illumination of a few miliJoules @ 800 nm. Though, you might need to take care with the detection of PA signals, because ultrasound system and transducer will reduce your sensitivity, which in turn could possibly interfere on your results. Maybe you can take a look at this article.
Article Photoacoustic-based SO 2 estimation through excised bovine p...
As mentioned by Hrebesh Molly Subhash , this is a tricky question as PA signal strength is not only dependent on optical output power. May be following review is a good read for you.
Article Intravascular Photoacoustic Imaging: A New Tool for Vulnerab...
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