After winning the Dutch Clean Tech Challenge, Willem Kesterloo, Koon Hooning (MSc students of LSC team) and Gijs van Vrede, all students from Delft University of Technology, have won the international CleanTech Challenge 2013 for their ‘Power Window’ concept. They scooped a £10,000 prize to develop their idea for coated windows that produce clean electricity. Judges were impressed by Power Window’s unique method of combining three technologies based on luminescence, fibre optics and photovoltaics. The CleanTech Challenge is a business plan competition co-run by London Business School and University College London. 151 student teams from around the world formed teams and developed their clean technology business ideas through a 3-stage competition with participants receiving guidance, feedback and mentorship from industry professionals. Apparently the power window concept plus our newly discovered luminescent materials are an unbeatable combination? And of course, Koen, Willem and Gijs acted most professionally. Well done!

For more on this visit www.cleantechnologychallenge.com

The Dutch CleanTech Challenge is a competition for entrepreneurial students throughout the country. The CleanTech Challenge (CTC) was firstly organized by the London Business School in 2009. The Dutch CTC is hosted by Yes!Delft Students, the Delft Energy Club and the Financial Study Association Rotterdam and encourages student teams with interdisciplinary backgrounds to develop and pitch their concepts for a sustainable start-up. Koen Hooning, Willem Kesteloo (MSc students of LSC team) en Gijs van Vrede won 3000 euro’s and travel to London to participate in the Global Cleantech Finals organized by the London Business School.

F.l.t.r.: Hans Hellendoorn (TU Delft), Hans van Happen (Cofely), Venugopal Prasanth, Lourens Meijer, Jan-Willem Wiegman, Klaas van der Werff (UfD), Han Blokland (Cofely).

Our former master student Jan-Willem Wiegman was elected today with the third price of the Cofely -TUDelft Energy Efficiency Award. In this award TUDelft master students compete for the brightest idea that can result in energy saving, CO2 reduction or increase the use of sustainable energy sources. He received the 2500 euro award for his master thesis work on Luminescent Solar Concentrators. Congratulations Jan-Willem!

Koen Hooning, one of our master students working on new materials for Luminescent Solar Concentrators (LSC) had been awarded the Delft Energy Initiative Research Grant 2013. The 12.000 euro award will be used to execute his research plan to turn our newly discovered luminescent powder materials into a waveguide that forms the basis of a high efficiency LSC demonstrator. The black phosphors emitting in the infra-red absorb more than 60% of the power of the solar spectrum which is twice as much compared to the current state-of-the-art red dye based organic materials. The latter materials, that are around for some time, have the disadvantage that they suffer from self-absorption, causing an energy loss of about 75% for a LSC with a surface area of one square meter. Our new rare earth based materials have no self-absorption and they are colorless which makes them suitable as semi-transparent thin-film LSC’s that can be used as building integrated power generating windows.

Subsurface light scattering in tissue can be fruitfully used when our trillion-frames-per-second camera is operated in reflection-mode. Only a small fraction of laser light directly reflects from the surface of a person’s skin. The majority of light will enter the tissue and undergo multiple scattering events before part of the light exits the skin again at another location. Reflected femtosecond laser pulses will therefore stretch out to several nanoseconds indicating that, depending on the type of tissue, re-emerging light reaches as deep as several millimeters to even centimetres. It appears possible to use light scattering of femtosecond pulses to obtain subsurface tissue images that cannot be obtained with continuous laser light.

A strong indication that subsurface information can be obtained using our trillion-frames-per-second camera, comes from the movie below, showing the inside of the applicant right arm as a function of time from 0 to 70 picoseconds after pulsed 100 femtosecond laser excitation with 750 nm light. While in the first 10 picosecond no veins can be seen, they show up clearly after about 20 ps. At later times more veins located deeper appear and broaden due to increased blurring as light scattering becomes more and more dominant.

Below are selected movie still frames at specific times 7 picoseconds apart. Click here for more.

This morning Jan Willem Wiegman and Erik van der Kolk were interviewed for Business News Radio featuring there published research on sustainable building integrated luminescent solar concentrators. You can find the full interview (in Dutch) hereunder.

On 5 July Jan Willem Wiegman is graduating from TU Delft with his research into power-generating windows. The Applied Physics Master’s student calculated how much electricity can be generated using so-called luminescent solar concentrators. These are windows which have been fitted with a thin film of material that absorbs sunlight and directs it to narrow solar cells at the perimeter of the window. Wiegman shows the relationship between the colour of the material used and the maximum amount of power that can be generated. Such power-generating windows offer potential as a cheap source of solar energy. Wiegman’s research article, which he wrote together with his supervisor at TU Delft, Erik van der Kolk, has been published in the journal Solar Energy Materials and Solar Cells.

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Medical Imaging with the speed of light

Nothing is faster than light, yet we managed to see light travel millimeter by millimeter with a one-trillion-frames-per-second ultra high speed video camera build from a femto second laser and a streak camera. The imaging technique, devised by MIT researcher Raskar, may be useful in medical imaging with light.

Cheap, fast and easy visualization of breast or brain tissue with light within the near infrared (NIR) transparency window (600-1000 nm), is a holy grail in medical imaging because it does not depend on harmful radiation, radioactive substances, or bulky instrumentation. The clinical value of NIR imaging has so far been limited due to the strong inelastic scattering of light in tissue that causes serious image blurring. A challenging solution to the scattering problem is the use of pulsed light sources and time resolved detection of transmitted light because in that case only unscattered photons that go straight can be selected. The bottleneck of this time-of-flight or time-gated approach has been a limited temporal resolution (>100 pico seconds) and a too poor sensitivity.

We have constructed a one-trillion-frames-per-second video camera based on a streak camera and a femto second laser, that combines a 100 times higher time resolution (~1 ps) and photon counting sensitivity. In the movie below it is explained that the time-of-flight camera can fruitfully be used to image objects in strongly scattering media, much better than can be done with continuous laser light. We are developing this time-of-flight camera further by optimizing it for NIR optical imaging in order to (i) better understand light transport in strongly scattering media and (ii) to perform 2D and 3D image reconstruction of realistic tissue equivalent phantoms.

Imaging the speed of light

Nothing is faster than light, yet we managed to see light travel millimeter by millimeter with a one-trillion-frames-per-second ultra high speed video camera build from a femto second laser and a streak camera. The imaging technique, devised by MIT researcher Raskar, can have impact in applications such as diffuse optical imaging or 3D surface imaging.

Below the camera films with a picosecond time resolution how a femto second laser pulse passes through a strongly scattering polyoxymethylene sample as function of time. It shows the principle of the time-of-flight imaging approach: light that arrives first has travelled straight through the phantom, while light that arrives later has scattered and therefore exits delayed and at different positions. The movie clearly shows that the position and size of the SS cylinders are seen much more clear in the first 10 or 100 ps compared to longer time slots or continuous wave illumination.

Picosecond time-of-flight camera: 3D surface imaging

Nothing is faster than light, yet we managed to see light travel millimeter by millimeter with a one-trillion-frames-per-second ultra high speed video camera build from a femto second laser and a streak camera. The imaging technique, devised by MIT researcher Raskar, can be applied as a time-of-flight camera to do 3D surface imaging. Below the camera films with a picosecond time resolution how a femto second laser pulse (in the form of a expanding spherical shell) passes over a my face. A z-coordinate can be added to the xy-data by making use of the time resolved data.

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www.erikvanderkolk.nl