In Memoriam: dr. Jeff Meisner

Jeff Meisner, postdoc in the Optics Group of the Department of Imaging Science, has passed away on January 1st.  Jeff became severely ill one year ago.  The medical doctors considered his condition at the time life-threatening and decided to amputate one of his feet. Around Christmas last year, the disease returned and he was taken to the hospital in Leiden where he died on his 70th birthday.

Jeff was born in Chicago. He came to Leiden 22 years ago after being hired by prof. Walter Jaffe of the Sterrewacht (astronomy). In 2009 there was a joint project of the group of prof. Jaffe and the Optics Group of TU Delft in which Jeff was postdoc. Since then he came frequently to Delft, although most of his projects where still in Leiden.  

One of the projects in Delft where he achieved outstanding results was a collaboration with major European metrology institutes.  During the two years before he became ill, he was hired by TU Delft to develop new optical experiments for the Applied Physics Master. The experiments are very original and plans are made to finish Jeff’s work and to start using these experiments in our education.

At his funeral, a speaker from the University of Leiden called Jeff a brilliant scientist, which indeed he was. Jeff had a very broad knowledge. He called himself experimentalist but he also knew a lot about theory.

Since 2009 Jeff almost always attended the bi-weekly group meetings of the Optics Group to listen to talks by group members and external guests.  The suggestions and remarks he made and the issues he brought up had much added value and were in particular very helpful for the students. When attending talks, he always listened very attentively, asking questions persistently until some controversial issue was resolved. Scientific discussions with him could be intense, but he never personally attacked people; his aim was to find out what was right and what was not.  He had no respect for reputations and would never accept a claim by a speaker merely because of his or her reputation. Jeff’s  own presentations were no-nonsense and to the point. Nevertheless, listeners quickly grasped the high quality of his work.

Jeff had not only passion for science but he also had compassion for people. He was a pacifist and firmly believed in the equality of people. He had no interest in material goods and disliked authorities. He joined demonstrations regularly, for example a demonstration against government plans to reduce support for handicapped children,  although Jeff had no children of his own.

Jeff held strong principles, both morally and regarding scientific work. He also was a very good educator, who could explain difficult issues well. His strong principles came however with a lack of flexibility and an unwillingness to make compromises. He did not want to work on projects where for some reason a suboptimal solution was preferred over the scientifically optimum solution. He therefore did not fit well in the current university organization and he never held a permanent position. 

The last year was very difficult for Jeff. But he did not give up and did not become bitter after his foot had been amputated. After he had obtained a prothesis he started to come to Delft again.  On 16 December 2022, Jeff attended the Christmas dinner in the Optics Group, as he always did.  Although none of us noticed it, he was already not well at the time. 

I speak on behalf of all group members, staff, technicians and students, when I say  that we all liked Jeff and respected him,  that it was a pleasure to have him in the group and that we all have profited from his knowledge and help. We will miss him.

His website:

Happy New Year 2023

We are glad to welcome a new year full of science and wonders. The TUDelft university has been keen to make a promotial video thanking everyone beyond the scene for 2022. We are glad to spot in this clip two of our own people, Thomas Scholte and Roland Horsten!

Two NWO Perspectief Proposal granted for our group

3 people performing research

NWO has granted two Perspectif program proposals where our group is part of:

Leading by light guidance, where the university of Twente is leading and Imaging at the smallest scales where our Department at TUDelft is leading.

Two videos have been produced to present the two projects:

You can find more information here.

OSA ‘Photo of the Year’, second place for Sven Weerdenburg

Our Phd student, Sven Weerdenburg made a photo of our high harmonic generation EUV light source which has made it to the 2nd place of Optica (OSA) ‘Photo of the Year’ contest.

EUV laser light that produce EUV and soft X-ray
A high-power femtosecond infrared laser focused into a pressurized Argon gas jet, leading to a plasma in which high-harmonic generation (HHG) occurs to produce coherent EUV and soft X-rays. —Sven Weerdenburg, Delft University of Technology, Delft, Netherlands.

The other photo contest winners you can find here

Face2Phase 3rd edition November 7-9, 2022 in Delft

The conference addressed phase information in imaging with topics such as lensless imaging, phase retrieval, adaptive and active optics, ptychography, holography, tomography. We also had the honour to have 14 invited speakers from all over the world and many oral and poster presentations. The conference attracted about 100 participants from the Netherlands and from abroad. We thank the support of NWO, ASML, Carl Zeiss, Single Quantum and DOC who helped making this exciting meeting possible.

Subsequently, the SPIE Student Chapter of TUD organised from 9-11 November a series of lectures given by prof. Carl Bender, Washington University, St. Louis, U.S.A,  prof. Ari Friberg, University of Eastern Finland,  Dr. Stefan Witte, Free University Amsterdam and Dr. Yifeng Shao of University of Technology Delft.  The event was attended by approximately 40 students and was considered a big success.

Logo of the face2phase conference

CARLA Camp 31 May & 1 June 2022

Together with the industrial and academic photonics communities, we are creating inclusive pan-European photonics career camps aimed at university students and early-stage researchers (graduates, undergraduates, Master’s students, PhD students and early stage post-docs) from all STEM (Science, Technology, Engineering and Mathematics) and Photonics focused areas. It will give you a peek into the vast opportunities that the photonics careers landscape offers and provide you with a roadmap for better employability.

Date: 31 May & 1 June 2022
Time: 10:00-18:30/21:00
Location: TUDelft (Delft, NL) on the 31, HTC (Eindhoven, NL) on the 1st

Listen to inspiring presentations about Photonics careers and testimonials and network with experts from academia and industry in a casual atmosphere with food and drinks included.

There will be included a visit of TNO (Delft) and of ASML (Eindhoven)

We have a great list of invited guests, expert on photonics from all the Netherlands:

Silvania PereiraTUDelft
Andrea fioreTU Eindhoven
Arie den BoefARCNL
Joseph PellerWageningen University
Gijs van SoestErasmus Medical center
Itir Dogru YükselUtrecht University
Ad LagendijkTwente University
Esther Alarcon LladoAMOLF
Michel OrritLeiden university
Luca MaresiEuropean Space Agency

For the program of each day, see the flyer below. You can register to this link before the 20 of May 2022. Be the first one!

Follow CARLA on LinkedIn and Instagram to receive updates on the event and for weekly posts about careers in photonics!

Omar El Gawhary appointed as member of the Council of Experts on National Measurement Standards

Since February 2022, Omar El Gawhary, from the Optics group of ImPhys, has been appointed as member of the Council of Experts on National Measurement Standards (Raad van deskundigen van de nationale meetstandaarden).

The Council, appointed by the Dutch Ministry of Economic Affairs and Climate (EZK) advises the Dutch Government on strategic choices concerning the National Measurement Standards and monitors the activities of the National Metrology Institute of the Netherlands (VSL). The council consists of nine members and Omar will be responsible for the domains Optics and Length metrology.

New superconducting material raises the operating temperature of space detectors

Superconducting niobium nitride (NbN) hot electron bolometers (HEBs) are so far the most sensitive heterodyne detectors for high-resolution spectroscopy at supra-terahertz frequencies (1 – 6 THz). They take advantage of a local oscillator to convert a THz line into a GHz line. Within this frequency range, many atomic, ionic, and molecular spectral lines provide information about star formation in galaxies.

The heterodyne mixers have been successfully applied in the SOFIA airborne telescope, the STO2 balloon telescope and the Herschel Space Observatory. They will also fly on NASA’s GUSTO balloon telescope, to be launched in the end of 2022, and have been selected as detectors for the proposed OASIS space mission. The supra-terahertz frequency range is not accessible for any ground-based telescope because the radiation is blocked by the earth’s atmosphere.

One drawback of HEBs is their limited intermediate frequency (IF) bandwidth, which covers a limited amount of spectral lines in one measurement. Another restriction comes from the low operating temperature (around 4 Kelvin) due to their low superconducting critical temperature of 8-10 Kelvin. Cooling down to 4 Kelvin, either by using a vessel with liquid helium or a mechanical pulse tube, is suboptimal for a space observatory considering the constraints on mass, volume, electrical power and cost.

A team of scientists at TU Delft, SRON,  Chalmers University and RUG, led by Jian-Rong Gao (OP@TUD and SRON ), has recently demonstrated a HEB based on a new superconducting material of magnesium diboride (MgB2). Behnam Mirzaei, who produced the detector at TU Delft, and Yuner Gan, who performed measurements and data analysis at SRON, have shown for the first time a low-noise performance of such a detector at 5.3 THz and at an operating temperature of 20 Kelvin or above.

Also, the team measured a large IF bandwidth, which is about three times larger than the bandwidth of a NbN HEB. The larger bandwidth can cover more spectral lines within one single measurement, which makes the observations more efficient and more accurate. The MgB2 thin film was developed at Chalmers University (S. Cherednichenko) and has a superconducting critical temperature of 38.5 Kelvin.

The higher operating temperature of 20 Kelvin is particularly attractive for space applications because of the availability of the compact, low-mass, low-dissipation, and space qualified Stirling coolers. The latter can significantly reduce the cost and complexity of space instruments. Therefore, the new detectors can increase the opportunities for new space instruments and telescopes, such as an M-class far-infrared space mission recommended in ESA Voyage 2050 and a next generation of THz observatories with a number of telescopes operated as an interferometer in space.

Y. Gan, B. Mirzaei, J.R.G. Silva, J. Chang, S. Cherednichenko, F. van der Tak, and J.R. Gao, Low noise MgB2 hot electron bolometer mixer operated at 5.3 THz and at 20K, Appl. Phys. Lett. 119, 202601 (2021)