All-optical scanhead for ultrasound and photoacoustic dual-modality imaging

Abstract

We propose a new scanhead design for combined ultrasound (US)/photoacoustic (PA) imaging that can be applied to dual-modality microscopy and biomedical imaging. Both imaging modalities employ the optical generation and detection of acoustic waves. The scanhead consists of an optical fiber with an axicon tip for excitation, and a microring for acoustic detection. No conventional piezoelectric device is needed, and the cost of the design makes it suitable for one-time, disposable use. Furthermore, a single laser pulse is employed to generate both US and PA signals. A subband imaging method can be applied to the receiver to enhance the contrast between the US and PA signals. Phantom data demonstrate the feasibility of this approach.

Characterizing cellular morphology by photoacoustic spectrum analysis with an ultra-broadband optical ultrasonic detector

“…By setting the probe laser (TLB 6700, Velocity Tunable Laser) wavelength at the slope of the ring transmission dip, the incident ultrasound waves could be recorded by the varying output intensity detected by a high speed photodetector (125MHz, Model 1801, Newport) from the device. Micro-ring has been utilized in highresolution PA imaging [27,28], as well as real-time THz pulse detection [29]. The device has demonstrated an ultra-broadband intrinsic frequency response from nearly DC to 350 MHz at −3dB [22].…”

A new fiber-optic non-contact compact laser-ultrasound scanner for fast non-destructive testing and evaluation of aircraft composites

“…The fundamental sensitivity limit is determined by the Johnson-Nyquist noise associated with acoustic detection over a finite spatial aperture and signal bandwidth no matter the modality. 2,3,12,18,19 As will be demonstrated below, the Sagnac-based, non-contact detector developed for our LU system approaches the JohnsonNyquist noise limit and is as sensitive as the best acoustic detectors operating over the same detection area and signal bandwidth.…”

“…For example, contact optical resonators show some promise for wideband detection. [18][19][20][21][22] Also, capacitive micromachined ultrasound transducers (CMUTs) have been built with wide bandwidth and high sensitivity. [23][24][25] Although all of these broadband approaches may be effective OA signal detectors, they cannot be used for a large number of non-destructive testing and evaluation (NDT&E) applications where acoustic contact is not desirable, and sometimes not even allowed.…”

A 25-mm diameter probe for photoacoustic and ultrasonic endoscopy

“…Ultrasound image contrast relies on bulk mechanical properties of tissue, providing limited functional information, whereas PAT's spectroscopic imaging capability provides a wealth of physiological or functional information, including hemoglobin concentration, oxygen saturation of hemoglobin [8][9][10][11][12], velocity of blood flow [13,14], temperature [15], pH [16], etc. Due to these benefits, PAE [1,2] and other minimally invasive imaging techniques based on PAT [6,17,18] have been intensely developed for applications in such clinical areas as the cardiovascular [18][19][20][21][22][23][24][25], gastrointestinal [2,26,27], and urogenital [28][29][30][31] systems. These techniques are expected to provide a useful complement to other endoscopic modalities, such as endoscopic ultrasound (EUS) [32,33], endoscopic optical coherence tomography (OCT) [34][35][36][37][38][39][40], confocal endoscopy [41,42], and endoscopic polarized scanning spectroscopy [43,44].…”