Compact disc , invention

The first BioCD took its inspiration from the compact disc. The compact disc was invented in 1970 by Claus Campaan of Phillips Laboratory. The concept is purely digital and uses null interferometers that are far from quadrature, as appropriate for the readout of two binary intensity states. The interferometers were common-path and stable, as required for the mechanical environment of portable compact disc readers. The original BioCD used the same physics as the compact disc, but modified the on-disc microstructures to change from the digital readout to an analog readout that operated in quadrature for sensitive detection of surface-bound proteins7,8. Because the quadrature condition is established by diffraction off of microstructures on the disc, this is called the microdiffraction-class (MD-Class) of BioCD. 

The following selection is about the invention of the compact disc, and explains how it works. 

The compact disc (CD) was invented in 1965 by James Russell, who was actually granted 22 different patents for the various parts of the CD playing and recording system. But it was not until the early 1980s, when... 

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