High-speed high-resolution laser diode-based photoacoustic microscopy for in vivo microvasculature imaging

Abstract

Laser diodes (LDs) have been considered as cost-effective and compact excitation sources to overcome the requirement of costly and bulky pulsed laser sources that are commonly used in photoacoustic microscopy (PAM). However, the spatial resolution and/or imaging speed of previously reported LD-based PAM systems have not been optimized simultaneously. In this paper, we developed a high-speed and high-resolution LD-based PAM system using a continuous wave LD, operating at a pulsed mode, with a repetition rate of 30 kHz, as an excitation source. A hybrid scanning mechanism that synchronizes a one-dimensional galvanometer mirror and a two-dimensional motorized stage is applied to achieve a fast imaging capability without signal averaging due to the high signal-to-noise ratio. By optimizing the optical system, a high lateral resolution of 4.8 μm has been achieved. In vivo microvasculature imaging of a mouse ear has been demonstrated to show the high performance of our LD-based PAM system.

Photoacoustic Imaging in Medicine – A Review

“…In recent years, several applications in medicine have been reported using advanced PAM imaging systems (Such as Laser Diode (LD) based PAM systems) towards a low-cost and aiming for a portable PAM system for point-of-care and wearable applications [70,71]. LD-based PAM imaging has been investigated to reduce the size of bulky lasers usually used in PAM and also for economic issues [71].…”

“…In recent years, several applications in medicine have been reported using advanced PAM imaging systems (Such as Laser Diode (LD) based PAM systems) towards a low-cost and aiming for a portable PAM system for point-of-care and wearable applications [70,71]. LD-based PAM imaging has been investigated to reduce the size of bulky lasers usually used in PAM and also for economic issues [71]. A sample image generated from an original 4060 by 2700 pixels data (taken with permission from [71]) for in vivo LD-based PAM microvasculature imaging of an 8.12 mm by 5.4 mm area from a mouse ear is illustrated in Fig.…”

“…In this review paper the utilized strategy for achieving it was performing a literature search through the Internet, selecting 189 references to build our review, and contacting with two authors of two different references [71,111] for giving us permission to process and publish their figures' data. In the following section II: we will talk about the most famous PA techniques including A. PAT, A.1.…”

Exploiting the potential of commercial objectives to extend the field of view of two-photon microscopy by adaptive optics

“…AR-PAM also waives the necessity for single-mode fiber (SMF) or costly single-mode lasers to produce high-quality focused laser beam. Thus, lower cost multimode pulse laser like laser diode or light-emitting diode (LED) can be used as the light source [16][17][18]. On the other hand, SMF is replaced with fiber bundle or multimode fiber (MMF) for optical delivery in AR-PAM.…”

Super-low-dose functional and molecular photoacoustic microscopy

“…High detection sensitivity is not only important for high-quality imaging, but also enables the detection of more low-absorbing chromophores at a lower concentration, reduces photobleaching, toxicity, or perturbation, and allows for more choices of low-cost low-power lasers at a broader spectrum. For instance, in ophthalmologic examination 16 , low laser energy is preferred for more safety and comfort; in high-speed OR-PAM, increased pulse repetition rates (PRR) limits the laser pulse energy [17][18][19][20] ; wearable or portable OR-PAM prefers lightweight low-power lasers 21 ; long-term monitoring of pharmacokinetics or hemodynamics requires low-dose imaging to reduce photobleaching or phototoxicity.…”