Emilio Segrè Visual Archives

More than 30,000 photos of scientists and their work

Attention ESVA Patrons:

The Emilio Segrè Visual Archives’ site is moving soon and adopting an open access approach to digital image sharing. Once we have transitioned to the new site in 2021, we will no longer charge for our high-resolution digital images or usage fees (note that we do not hold copyright to all the images in our collections and you will still need to obtain permission for those which we do not own).

If you are working on a long-term project, we advise you to wait until the migration is complete so that you may obtain our copies for free. If you cannot wait, email us at nbl [at] aip.org and we will do what we can to assist you. We will not be offering refunds for past purchases.

For more information, please visit our FAQ page on the Ex Libris Universum blog. 

Bell Labs F6

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Bell Labs F6

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We charge a usage fee per photo if the photo is published, reproduced in a product or publicly exhibited. This is not a license in the legal sense. As a non-profit institution, we do not make any money providing these photographs. It is only by assessing usage fees that we are able to cover the cost of providing publication quality copies of our photos, preserving the photograph collection according to archival standards, and providing access to the collection by maintaining an online image database. The copyright holder may charge a fee in addition to our service fee.

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Image title: 
Bell Telephone Laboratories laser beam
Credit line: 
Bell Laboratories / Alcatel-Lucent USA Inc., courtesy AIP Emilio Segrè Visual Archives, Physics Today Collection

The two bright areas on the card illustrate the high efficiency of a spectroscopic diffraction grating etched in a new holographic material -- dichromated gelatin. T. A. Shankoff of Bell Telephone Laboratories is directing a laser beam through the grating, which has been formed on the glass slide. Because the beam has a larger diameter than the grating, only the central portion of the beam is diffracted to form the bright spot on the right side of the card. The undiffracted portion of the beam continues straight through the slide to form the doughnut-shaped ring of light to the left. Over 90% of the laser beam has been diffracted from the center of the left-hand beam to form the bright spot on the right. A diffraction grating made from any of the less efficient, conventional holographic materials would have diffracted less than 6% of the beam to produce a much less intense spot.

Original format: 
1 photographic print (black and white; 8 x 10 inches)
Bell Labs Innovations