Premium
A frequency‐domain non‐contact photoacoustic microscope based on an adaptive interferometer
Author(s) -
George Deepu,
Lloyd Harriet,
Silverman Ronald H.,
Chitnis Parag V.
Publication year - 2018
Publication title -
journal of biophotonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 66
eISSN - 1864-0648
pISSN - 1864-063X
DOI - 10.1002/jbio.201700278
Subject(s) - optics , interferometry , materials science , frequency modulation , signal (programming language) , photoacoustic effect , laser , modulation (music) , phase (matter) , phase modulation , microscope , beam (structure) , physics , radio frequency , acoustics , telecommunications , quantum mechanics , computer science , phase noise , programming language
A frequency‐domain, non‐contact approach to photoacoustic microscopy (PAM) that employs amplitude‐modulated (0.1–1 MHz) laser for excitation (638‐nm pump) in conjunction with a 2‐wave mixing interferometer (532‐nm probe) for non‐contact detection of photoacoustic waves at the specimen surface is presented. A lock‐in amplifier is employed to detect the photoacoustic signal. Illustrative images of tissue‐mimicking phantoms, red‐blood cells and retinal vasculature are presented. Single‐frequency modulation of the pump beam directly provides an image that is equivalent to the 2‐dimensional projection of the image volume. Targets located superficially produce phase modulations in the surface‐reflected probe beam due to surface vibrations as well as direct intensity modulation in the backscattered probe light due to local changes in pressure and/or temperature. In comparison, the observed modulations in the probe beam due to targets located deeper in the specimen, for example, beyond the ballistic photon regime, predominantly consist of phase modulation.