The phase of a field is often more important than the amplitude. This is in particular true for focusing of light.
To improve the quality of imaging it is often desirable to consider the phase in the exit pupil of the imaging system. The determination of both phase and amplitude are essential in coherent lensless imaging.
Phase can be measured directly using interferometry, but that requires a highly stable measurement system. Alternatively one can retrieve the phase from several intensity measurements. This is the topic of phase retrieval.
In the topic of phase retrieval the aim is to design and implement measurement systems and algorithms to compute the phase from intensity measurements. Examples are the retrieval of the phase in the exit pupil of an imaging system from through focus intensity measurements in at least two planes. Another method of phase retrieval is ptychography, where the complex transmission or reflection function of an object is retrieved from far field intensity measurements for a sequence of partial illuminations of the object. It is also possible to use spatial light modulators to introduce a known perturbation of a field. By measuring the intensity the unknown field can be reconstructed.
Phase retrieval methods are very important in coherent imaging a very short wavelengths (e.g. EUV and x-rays) at which no good optical components exist.
They also play an important role in 3D imaging.
Projects.View all on the projectspage.
SENSING USING QUANTUM OCT WITH AI ...
Extreme UV and Soft X-Ray metrology
Continuous progress in the semi-conductor industry are leading to smaller, faster and more energy efficient chips for our modern society. Critical parameters for this industry, such as overlay and critical dimension (CD), ...
projectExtreme UV and Soft X-Ray metrology
Far field nanoparticle detection
We investigate and optimize new techniques to detect nanostructures and nano-particles in semiconductor, and plastic-based fabrication technologies. The technique should be fast, operate in-line and applicable to large areas. Since the structures ...
projectFar field nanoparticle detection
Graded Index optics
Recent progress in the making of media with a variable refractive index has the potential to change lens design significantly. With these new materials, curved light rays are used to make high-quality ...
projectGraded Index optics
Lensless imaging with EUV and Soft X-Rays (LINX)
LINX is a NWO-TTW perspective programme with the aim to apply various lensless imaging techniques, from ptychography to scatterometry, while using wavelengths in the EUV and Soft X-Ray regime. This programme is ...
projectLensless imaging with EUV and Soft X-Rays (LINX)
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The Photonic Career Hub – CARLA
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Beijing Institute of Space Mechanics and Electricity
A delegation of 50 people from BISME (Bejing Institute of Space Mechanics and Electricity) has visited the Optics Group. The delegation was in the Netherlands to attend the 6th International Symposium ...
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Weekend of Science – Oct 5-6, 2019
The Weekend of Science is a national science weekend. Every year, various technical institutions open their doors to provide extra activities. This year the theme of our Weekend of Science is: LIGHT. Date ...
News - September 25, 2019Weekend of Science – Oct 5-6, 2019
Face2Phase – Oct 21-23, 2019
The conference Fase2Phase, 2nd Edition, addresses imaging with phase information and covers topics such as lensless imaging, aberration retrieval, adaptive and active optics, ptychography, holography, tomography, phase retrieval and applications. Date : 21 ...
News - September 10, 2019Face2Phase – Oct 21-23, 2019