Fully motorized optical-resolution photoacoustic microscopy

Abstract

We have developed fully motorized optical-resolution photoacoustic microscopy (OR-PAM), which integrates five complementary scanning modes and simultaneously provides a high imaging speed and a wide field of view (FOV) with 2.6 μm lateral resolution. With one-dimensional (1D) motion-mode mechanical scanning, we measured the blood flow through a cross section of a blood vessel in vivo. With two-dimensional (2D) optical scanning at a laser repetition rate of 40 kHz, we achieved a 2 kHz B-scan rate over a range of 50 μm with 20 A-lines and 50 Hz volumetric-scan rate over a FOV of 50 μm × 50 μm with 400 A-lines, which enabled real-time tracking of cellular dynamics in vivo. With synchronized 1D optical and 2D mechanical hybrid scanning, we imaged a 10 mm × 8 mm FOV within three minutes, which is 20 times faster than the conventional mechanical scan in our second-generation OR-PAM. With three-dimensional mechanical contour scanning, we maintained the optimal signal-to-noise ratio and spatial resolution of OR-PAM while imaging objects with uneven surfaces, which is essential for quantitative studies.

Photodynamic Therapy-Induced Microvascular Changes in a Nonmelanoma Skin Cancer Model Assessed by Photoacoustic Microscopy and Diffuse Correlation Spectroscopy

“…In addition, since the focal distance is very critical to obtain the highest resolution imaging, rough tissue surface due to diseased skin in Gli mice might have resulted in the variations in the focal length, which will affect the spot size. As Li et al have shown, a slight difference in height caused by a tumor can make an area appear devoid of vessels and correcting the height of the scanner allows for improved visualization of microvasculature [37]. We will be adapting our system and algorithm to accommodate these types of physiological variations.…”

Multiparametric photoacoustic microscopy of the mouse brain with 300-kHz A-line rate

“…To boost the speed of PAM while maintaining the slow B-scan rate for the CBF measurement, we adopted the synchronized one-dimensional optical and two-dimensional (2-D) mechanical hybrid scan. 11 As shown in Fig. 2(a), the galvanometer scanner steers the laser spot along the Y-axis within the acoustic focus of the transducer at a round-trip rate of 2.1 kHz as the linear stage mechanically translates the optical-acoustic dual foci along the X-axis at a constant speed of 0.88 mm∕s, during which the laser output is switched between 532 and 558 nm at a 3.3-μs interval to produce dual-wavelength A-line pairs.…”

All-optical highly sensitive akinetic sensor for ultrasound detection and photoacoustic imaging

“…For the purpose of measuring the lateral resolution of the system the 10x Olympus objective was used. We verified the resolution by applying the step-edge method [25]. For this method a sharp-edged object is imaged for the experimental quantification of the imaging system resolution.…”