Miniature Acousto-Optic 3D Scanning Microscope

Inventors: Dejan Vucinic, Terrence Sejnowski
Potential Uses: Cancer Imaging, Brain Research, Microsurgery, Surgical Aid, Clinical Research
Miniature, lightweight wearable multiphoton microscope with microsecond 3D random access capable of deep tissue imaging

Multiphoton imaging is one of the most powerful and most actively developed techniques for imaging of brain activity and morphology, and is rapidly finding new uses in imaging of living vasculature, lymph nodes, as well as detection of cancerous cells in blood vessels through intact skin. Existing commercial imaging systems are, however, very large and expensive (over $400,000), restricting experiments in vivo to preparations that can be tailored to the microscope. Even existing handheld confocal microscopes cost in excess of $40,000 and weigh two pounds or more.

Researchers at the Salk Institute have recently invented a means of shrinking a complete acousto-optic scanning microscope into a package under 3" in size and weighing as little as 20 grams (less than _ of an ounce), suitable for head-attached or handheld use. Being compatible with multiphoton excitation, it also permits imaging deep within scattering tissue.

Incorporating a new system of beam steering using acousto-optic deflectors, this microscope offers many advantages over the more common galvanometer-based and piezoelectric systems, including:

• Three-dimensional scanning with no moving parts;
• Inertia-less 3D random access in tens of microseconds, two orders of magnitude faster than most mechanical scanning systems;
• Practically perfect repositioning accuracy when driven by digital signals; and
• Beam intensity modulation built into the physical mechanism of deflection.

In addition, the Salk method makes it possible to build a small and fast microscope that can be attached to a moving experimental subject, enabling a far richer set of experiments to be carried out than possible with traditional stationary microscopes.

Having no moving parts, the Salk design can be made more rugged and less sensitive to movement and vibration than mirror-based scanning microscopes, making it extremely well suited for diagnostic and treatment uses in a clinical setting, e.g. as a surgical aid in non-invasive microsurgery of skin conditions or vasculature. The device could also be used as a replacement for handheld confocal microscopes for imaging cancer, capable of obtaining higher resolution images deeper into the skin, or for live imaging of melanin in skin tissue, or blood flow in small vessels in and around tumors.