Lens-free digital microscope opens up new fields of view

February 12, 2016 // By Julien Happich
At next week's SPIE Photonics West 2016, imec will demonstrate a lens-free microscope for large field-of-view live imaging at micrometer resolution.

The compact microscope is based on holographic imaging where the light diffracted by an illuminated object and captured by an image sensor is software post-processed to compute the focused image. Hence a single 2D image capture is sufficient to volumetrically image a 3D sample.

"The current demonstration features a 4.7x3.5mm CMOS sensor, however, we have built systems with much larger sensor sizes for some of our customers too. The inspected area scales with the sensor size", explained Andy Lambrechts, Program Manager and Team Leader for the Integrated Imaging CMORE program at imec.

"We have coupled the lens free microscope to a GPU accelerated image processing unit. This allows fast and user-friendly operation of the system. For very large area inspection, computational requirements will scale up with the inspected area".

"No lens means that we can focus on a certain depth, without any mechanical movement, by re-computation in software. The inspected area or field of view is a parameter in the system design and linked to the magnification of the system.

The magnification is not depending on the height of the sample. It is pre-calibrated and can be reported to the user. The software can use auto-focus to automatically detect the distance to the sample and this can be reported to the user as well", Lambrechts added.

Of course, compared to conventional optical microscopes, lens-free digital microscopy removes the need for expensive and bulky optical lens components to acquire and visualize microscopy images. The unit features a micrometer-scale accuracy comparable to that of traditional optical microscopes, while being much smaller and less expensive, but also much faster to use (thanks to the larger field-of-view).

For now, imec is focusing on the customisation of the technology towards the requirements of its partners. The ready-to-use demo kit is a starting point for those partners, and can also be delivered as is, including a light source, image sensor, control and read-out electronics and a