Lens-Free Fluorescent Microscope for Imaging Deep Inside Body
Microscopes are a ubiquitous tool in the life sciences and their applications extend into clinical practice. Doctors use them to peer into the eye, examine tissues for signs of cancer, and to help perform surgeries. But, microscopes are bulky, so it’s impossible to use them to image many of the areas deep inside the body. Moreover, optical lenses tend to create a trade-off between a large field of view and a high resolution.
Overcoming such obstacles has forced a team at Rice University to develop a microscope that doesn’t use any lenses at all, and which is so small that it may end up on the tips of endoscopes, be used as an implant for long term monitoring of brain activity, and other applications that been longed for but not attempted due to the size of existing microscopes.
The Rice team’s wide-field fluorescent microscope can focus on a volume of a few cubic millimeters while imaging details at the micrometer scale. Moreover, the size of the field of view can be increased by simply increasing the size of the sensor. And because the sensor is a conventional complementary metal–oxide–semiconductor (CMOS) detector, this is not a problem.
In order to actually create a crisp, high quality image, the device relies on an “amplitude mask,” which seems to be a precisely engineered diffraction grating. The sensor captures the light that comes through the mask, which still looks nothing like the object being imaged. In order to create the final image, an algorithm that takes into account the amplitude mask converts the imaging data into a high resolution picture.
Because the device produces a focused image at a range of distances from the microscope, it is able to create 3D movies of objects within a volume of a few cubic millimeters.