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History of the optics group in Delft
The optics group has been directed by several persons since its formal start in 1947.
- Prof. A.C.S. van Heel directed the group from 1947-1966
- Dr. ir. van Vonno and dr. ir. Simons temporarily led the group during the transition period from 1966-1967
- Prof. de Lang was the optics professor from 1967 to 1969
- Prof. dr. ir. H.J. Frankena guided the optics group from 1970-1998
- Prof. dr. ir. J.J.M. Braat was the head of the optics group from 1998-2008
- the current full-time professor in the optics group is Prof. dr. ir. Paul Urbach
A brief history of the group and its professors can be found below:
| Prof. A.C.S. van Heel (1899 – 1966) Abraham van Heel studied at Leiden University and obtained his Ph.D. in 1925. He started his scientific career at Delft University in the recently founded department of Applied Physics. In 1938 he was appointed a lecturer in optics and became a full professor of optics in 1947 until his fully unexpected death in 1966.
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The research interests of van Heel were centred on three main themes:
- optical design
The interest of van Heel in optical design dated from the year 1925 when he spent a year at the Institute of Optics in Paris, working with Fabry and following lectures by Chrétien. He actively participated in the fundamental change brought about in this domain by the advent of the electronic computer. Several prototype computers dating from the 1950’s can still be admired in the Techniek Museum of Delft University. The very first computer was called Testudo, latin for turtle; it was even slower than a human being in tracing rays through a surface. Van Heel always said that it was a useful machine all the same because it continued working while he himself was asleep. An impressive series of Ph.D.-students have worked on optical design under his guidance. As a spin-off from his university activities, one can mention the optics industy ‘Oude Delft’ which was founded in 1939 in the same city.
- optical fabrication
Van Heel founded an internal workshop for optics where, in an early stage, coating research was added to the more standard glass-working. Special work pieces needed in the experiments of students were produced and measurement methods for surface shape and finish were studied.
- optical alignment
The subject with the most widespread application is the alignment method using circular amplitude or phase zone plates. Even in the pre-laser period, it was a simple but powerful method to align objects over large distances. In the devastated country after World War II, many bridges, large buildings and towers were ‘aligned’ using van Heel’s method. Even the periodic movements of the leaning tower of Delft’s Old Church were checked by van Heel at the moment of the ringing of the heaviest bell.
It should be mentioned also that Abraham van Heel was a pioineer in the field of fiber optics. In the beginning of the fifties, he tried to solve the problem of light loss in fibers by using a cladding material. His work resulted in a Nature publication (Vol. 173, page 39, 1954) and is generally considered as the paving of the road towards later telecommunication applications with optical fibers.
During his entire scientific career, A.C.S. van Heel was very devoted to international collaboration, first in Europe, but also with the worldwide optics community. His largest achievement in this field was the founding, together with a dozen of leading optical scientists from all over the world, of the International Commission for Optics (ICO) in 1948, a body he presided from 1950 to 1956. By subltle manoeuvring, he also succeeded in creating a European optical journal, Optica Acta. In all these situations, he could profit from the fact that he came from a smaller country and that he was a fluent speaker of many languages.
During his forty years of teaching, van Heel has inspired many generations of students by his very enthusiastic and outstanding teaching. His course room experiments were famous because of their convincing and entertaining nature. Each year, a fresh bovin eye was brought in from the slaughter house to study in vitro its geometrical optical properties. Van Heel also wrote a dutch textbook on optics which can still be found in the private library of many of his former students. His sudden death in May 1966 was a severe blow to the dutch community.
The old physics building as photographed by a panoramic camera designed by professor van Heel
Professor Hendrik de Lang was born in 1920 and received his physics degree from Groningen University were he continued working after his graduation in Zernike's group. In 1955 he joined the Philips Research Laboratories in Eindhoven, The Netherlands. His research interests were in optical design and in coherent optics. In 1962 he became the group leader of the optics group at Philips and he conducted early research on the polarization properties of HeNe lasers. In 1966 he obtained his PhD degree (cum laude) at Utrecht University. Hendrik de Lang took over the vacant optics chair at Delft University in 1967. In 1969 he returned to Philips and became the group leader of the electron optics group. He retired from Philips in 1980. |
| Professor Hans J. Frankena was born in Haarlem, the Netherlands and received his MS and Ph.D. degrees in Electrical Engineering from the Delft University of Technology. In 1965, he became a lecturer in electromagnetic theory at that department. After his appointment in 1970 as a full professor in Optics at the Department of Applied Physics of the same university, he conducted research in holography, lasers and thin film optics. More recently his attention has also been devoted to integrated optics. |
Professor Frankena's subjects of research included:
- Integrated optical switches and polarization controllers
- Fiber-chip couplers
- Grating structures in integrated optics
- Optical production methods: thin films as well as very accurate aspherical surfaces in glass or quartz
- Optical measurement of surface shape and roughness
- Speckle and shearing interferometry
- Optical aperture synthesis
