OPN coversJason Heikenfeld holds an electrowetting retroreflector prototype.

Recent Progress in Electrowetting Optics

In your recent feature on electrowetting optics (January 2009), the authors noted that the concept was introduced by Beni and Hackwood in 1981. In fact, the notion of electrowetting optics, and in particular liquid lenses, was patented in 1936 (U.S. Patent 2,062,468) by Charles H. Matz of Winnetka, Ill., U.S.A.

The optics research community can be excused for having overlooked this invention, as it was given the generic title “Optical Device” and apparently never commercialized. It came to my attention courtesy of Dennis Crouch of the Patently-O patent law blog, who was alerted to its existence by an anonymous patent examiner (“Examiner H”) during the prosecution of a U.S. patent application.

Matz claimed “a device to modify the characteristics of a transmitted beam of light in response to the intensity of an impressed electrical potential … adapted for varying the vergency, i.e. the divergence or convergence, of the transmitted beam.” And further, “… adapted to vary the intensity of a transmitted beam of light.”

The construction of the liquid lens was clear: “a plurality of spaced electrodes, and a liquid forming there between a lens of focal length or power controlled by the intensity of the electric field between the electrodes, whereby the intensity or vergency of a beam transmitted through said liquid may be controlled.” The preferred fluid was ethyl acetate, with other suitable fluids including “methyl alcohol, ethyl alcohol, ether, carbon tetrachloride, methyl acetate, distilled water, glycerine, nitrobenzene, and some oils.”

Not surprisingly, Matz saw his invention as being an electro-optic light valve for “sound-recording on motion picture film,” which is likely why Edwin Land (Polaroid Corporation) purchased a 40 percent interest in the patent.

There are perhaps two lessons here. First, we should not rely solely on the academic literature when researching the history of science. The patent literature is equally rich, if poorly documented. Second, we should recognize the exemplary work often performed by patent examiners. While we may laugh at the occasional bad patent, there are many ideas embodied in millions of patents that await rediscovery. We can thank the anonymous Examiner H for having uncovered one of them.

Ian Ashdown
West Vancouver, B.C., Canada

THE AUTHOR RESPONDS: Ian Ashdown is absolutely correct that the patent literature is an excellent resource for tracing the earliest contributions to emerging technologies. I applaud his, Mr. Crouch’s, and Examiner H’s initiative in bringing this 1936 work in electrowetting optics to light (so to speak).

In fact, electrowetting is particularly rich in examples of patents that predate scientific publications. Many of the early scientific reports that we credit in our article appeared first in patents. In our article, we placed emphasized those contributions that were reduced to practice, those that were published, and those that have clearly stimulated the very recent explosion in electrowetting research. We came to the conclusion that the “electro-wetting” was first introduced by Beni and Hackwood by consulting several of the existing leaders in the field.

It would not be entirely surprising if their credit for the term is eventually brought into question. With the assistance of the broader community, including patent examiners, we might discover more decades-old efforts by those who were just as excited about electrowetting optics in the past as we are today!

Jason Heikenfeld
Cincinnati, Ohio, U.S.A.


OPN coversJames P.C. Southall

James P.C. Southall

I have been enjoying your historical pieces in OPN. I thought you might be interested in receiving the following information about James P.C. Southall. At Columbia, after high school, I first attended Columbia College (1946-48) and, after two years, I transferred to their School of Optometry—which Southall had founded—from 1948 to 1950.

At that time, Cliff Treleaven headed the school, and Ed Bechtold taught optics. Our optics text was the 1934 edition of Southall’s Mirrors, Prisms and Lenses. It was published by Macmillan. To save money, books were bought for the students as a whole by the school. When we received these texts, half of the class was given the regular version (including me), and half received, in the same book binding, the text of a book of poetry! As you might imagine, this resulted in great mirth. Of course, all was straightened out within a few days, but no doubt those books have now become collector’s items.

Also for the record, I completed my graduate studies at Ohio State University with Glenn A. Fry. This was from 1953 to 1956. My degree was in physiological optics and our text was Southall’s translation (for OSA) of von Helmholtz’s 3rd Editon of the Handbook of Physiological Optics, which was originally written at the beginning of the 20th century.

Jay Enoch
Berkeley, Calif., U.S.A.

JOHN HOWARD REPLIES: Thank you for your note about Southall. I still have a copy of Mirrors, Prisms and Lenses up on a top shelf. I recall from reading some papers by Hilda Kingslake that Southall, while still teaching at Alabama, had already published a short book called Principles and Methods of Geometrical Optics (1910), in which he had regretted that most English optics texts neglected the great German theoreticians (by which he presumably meant Helmholtz).

And again, around 1918, Southall had hoped to start an optics program at Columbia. (At that time, I believe he was mostly teaching optometry.) And then he dropped a note to George Eastman, suggesting that Rochester, with both Kodak and Bausch & Lomb, would be a good place to start an optics institute. So Southall was one of the triggers for the Institute of Optics.

I am reminded that Rayleigh was very fond of Helmholtz. When John William Strutt (later Lord Rayleigh) was still a fellow at Trinity, he was reading about Helmholtz’s work on sound. Around that time, his friend and fellow student Arthur Balfour invited Strutt to visit the Balfours, and Strutt became attracted to Arthur’s sister Evelyn. When Strutt found out that Evelyn was fond of music, he presented her with his copy of Helmholtz’s Tonempfindungen. About three years later, Evelyn became Lady Rayleigh.

John N. Howard
OPN Contributing Editor, The History of OSA

In the recent OPN feature article on “Optical Filters in Nature” (February 2009), we failed to provide proper credit to the two figures at the top of p. 25. The drawings of the iridescent reflection from cuticles and lamellae should be attributed to Dr. Pete Vukosic at the University of Exeter in the United Kingdom. We regret the oversight.


Please direct all correspondence to the Editor, Optics & Photonics News, The Optical Society, 2010 Massachusetts Ave., N.W., Washington, D.C. 20036. E-mail: opn@osa.org.

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