Title :
Optoacoustic sensor based on self-assembled arrays of polystyrene microspheres
Author :
Guo, Xinqing ; Churgin, Matthew ; Buma, Takashi
Author_Institution :
Dept. of Electr. & Comput. Eng., Univ. of Delaware, Newark, DE
Abstract :
Optical techniques are a promising technology for high frequency ultrasound imaging arrays. We are exploring an optoacoustic structure based on self-assembled dielectric microspheres. Polystyrene microspheres are readily available in sub-micron diameters, making monolayer arrays potentially attractive for realizing extremely thin optoacoustic sensors. A monolayer of 0.35 mum diameter polystyrene microspheres are formed by self-assembly on a water surface. This layer is transferred to a glass substrate and coated with a 40 nm thick gold film to enhance the optical reflectivity. This structure is attached to the side of a water tank containing a 85 MHz spherically focused f/2 lithium niobate transducer. The probe laser is a temperature controlled Fabry-Perot AlGaAs diode laser with a wavelength of 785 nm. The recorded optical signal and pulse echo data have peak frequencies of 95 MHz and 85 MHz, respectively. The corresponding -6 dB bandwidths are 90 MHz and 70 MHz, respectively. These encouraging results suggest the potential of optoacoustic detection by self-assembled arrays of polystyrene microspheres.
Keywords :
Fabry-Perot resonators; III-V semiconductors; acousto-optical devices; acousto-optical effects; aluminium compounds; echo; gallium arsenide; gold; lithium compounds; monolayers; optical films; optical glass; optical polymers; optical sensors; reflectivity; self-assembly; semiconductor lasers; temperature control; ultrasonic imaging; ultrasonic transducers; wide band gap semiconductors; AlGaAs; Au; LiNbO3; frequency 70 MHz; frequency 85 MHz; frequency 90 MHz; frequency 95 MHz; glass substrate; gold film coating; lithium niobate transducer; optical reflectivity enhancement; optoacoustic detection potential; optoacoustic sensor; polystyrene microsphere monolayer; pulse echo data; self-assembled dielectric microsphere array; size 0.35 mum; size 40 nm; temperature controlled Fabry-Perot diode laser; ultrasound imaging array; wavelength 785 nm; Dielectric substrates; Frequency; Optical arrays; Optical films; Optical imaging; Optical recording; Optical sensors; Sensor arrays; Ultrasonic imaging; Ultraviolet sources; Optoacoustic; etalon; microspheres; monolayer; nanosphere lithography; plasmon resonance; self assembly;
Conference_Titel :
Ultrasonics Symposium, 2008. IUS 2008. IEEE
Conference_Location :
Beijing
Print_ISBN :
978-1-4244-2428-3
Electronic_ISBN :
978-1-4244-2480-1
DOI :
10.1109/ULTSYM.2008.0214