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Better Resolution

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TAU Research Briefs

Better Resolution Pays

The quality and information content of an optical image is limited by its finest detectable details, its resolution. This is constrained by three, quite practical factors: the finite size of the imaging lens, the finite size of the detector's elements (pixels) and unavoidable "noise" (random signal) generation in the pixels. New optical data processing methods can help yield super- resolution in imaging and the reduced spread of optical beams (which is much the same thing) in scanning. Such techniques allow detecting spatial details finer than those available in the original captured image. TAU Profs. David Mendlovic and Emanuel Marom have been leaders in this exciting, highly applicable field.

The TAU researchers have designed special optical setups and complementary digital (computer) signal processing methods to bring out hidden spatial details not visible in the original recorded image. The hidden information is restored using opto-electronic means in imaging applications and special optical masks in scanning applications. For example, the image of the clown on the left was detected by a low-resolution camera with pixels large compared to the original figure. The resulting poor, low-resolution image (middle image) can be reconstructed (right image) by applying the TAU researchers' novel subpixeling super-resolution computer algorithm.

Scanning systems, such as barcode scanners, capture an image by illuminating it with a scanning light beam. These light beams tend to spread out (diffract) as they propagate through free space. The TAU researchers have synthesized a novel non-diffractive light beam, within a certain range, spreads little if at all (figure below). This requires using special diffractive optical elements designed and produced by the TAU team.

A variant of this approach has been integrated into the scanning head of a barcode scanner in collaboration with Symbol Technologies, who partially supported this research and who have licensed the related patent. The TAU beam also remains highly circular (middle figures on left), which further improves the proper scanning of two-dimensional barcode patterns.