A team of UCLA engineers has developed a portable, affordable, and easy to use microscope which they hope will revolutionize healthcare in developing nations. In order to reduce both the cost and weight of their device, the researchers eliminated the heaviest and most expensive component of most microscopes – the lenses. The researchers instead use holograms, which are formed when light that passes through or bounces off of a sample interacts with light which has not contacted the sample.
The new microscope uses a simple sensor chip to capture the holograms, and data can then be sent to a laptop or remote cloud server for processing. The microscope features two modes: a “transmission mode” which lets it analyze blood or water, and a “reflection mode” which can be used to obtain images of opaque samples.
More from the researchers’ paper in Biomedical Optics Express:
This field-portable dual-mode holographic microscope has a weight of ~200 g with dimensions of 15 x 5.5 x 5cm, where a laser source is powered by two batteries. Based on digital in-line holography, our transmission microscope achieves a sub-pixel lateral resolution of ?2 µm over a wide field-of-view (FOV) of ~24 mm2 due to its unit fringe magnification geometry.
Despite its simplicity and ease of operation, in-line transmission geometry is not suitable to image dense or connected objects such as tissue slides since the reference beam gets distorted causing severe aberrations in reconstruction of such objects. To mitigate this challenge, on the same cost-effective and field-portable assembly we built a lensless reflection mode microscope based on digital off-axis holography where a beam-splitter is used to interfere a tilted reference wave with the reflected light from the object surface, creating an off-axis hologram of the specimens on a CMOS sensor-chip.
Full-text of the paper at Biomedical Optics Express: Field-portable reflection and transmission microscopy based on lensless holography