Hyperspectral imaging sensor systems using tunable lenses. - In: Photonik international ..., ISSN 1865-6633, Bd. 8 (2013), S. 2-5
Hyperspectral imaging systems record information with high resolution in both the spatial and spectral regimes simultaneously. One central challenge remains distribution of the three- or multi-dimensional data, consisting of the spatial soordinates (x,y,z) and the wavelength ([lamda]) in a suitable way on commonly used two dimensional receiver chips. Tunable optics, used in combination with suitable methods and system concepts, offer solutions that optimize capacity as well as recording dynamics.
Spectrally multiplexed chromatic confocal multipoint sensing. - In: Optics letters, ISSN 1539-4794, Bd. 38 (2013), 22, S. 4694-4697
We present a cncept for chromatic confocal distance sensing that employs two levels of spectral multiplexing for the parallelized evaluation of multiple lateral measurement points; at the first level, the chromatic confocal principle is used to encode distance information within the spectral distribution of the sensor signal. For lateral multi-plexing, the total spectral bandwidth of the sensor is split into bands. Each band is assigned to a different laterial measurement point by a segmented diffractive element. Based on this concept, we experimentally demonstrate a chromatic confocal three-point sensor that is suitable for harsh production environments, since it works with a single-point spectrometer and does not require scanning functionality. The experimental system has a working distance of more than 50 mm, a measurement range of 9 mm, and an axial resolution of 50 [my]m.
http://dx.doi.org/10.1364/OL.38.004694
MOEMS tunable microlens made of aluminum nitride membranes. - In: Journal of micro/nanolithography, MEMS and MOEMS, ISSN 1932-5134, Bd. 12 (2013), 2, S. 023012, insges. 8 S.
We present tunable lenses based on aluminum nitride membranes. The achievable tuning range in the refractive power is 0 to 25 dpt with an external pressure load of ≤20 kPa. The lenses are manufactured using MOEMS technology. For 500-nm-thick membranes with a diameter of 3 mm, a spherical deflection profile is found. The system provides good long-term stability showing no creep or hysteresis. A model for the refractive power versus applied pressure is derived and validated experimentally. Based on this model, design guidelines are discussed. One essential parameter is the residual stress of the aluminum nitride layer that can be controlled during deposition.
http://dx.doi.org/10.1117/1.JMM.12.2.023012
Integriertes Design und Fertigung optischer Bauelemente : Herstellung eines hybriden diffraktiv-reflektiven optischen Strahlformers. - In: Optik & Photonik, ISSN 2191-1975, Bd. 8 (2013), 2, S. 48-51
Komplexe, diffraktiv funktionalisierte freiformoptische Bauelemente bieten neue Möglichkeiten für die Realisierung leistungsfähiger, kompakter und robuster optischer Systeme. In diesem Beitrag werden geeignete integrierte Design- und Fertigungsstrategien vorgestellt. Am Beispiel eines hybriden reflektiven Strahlformers, der ablenkende, strahlformende und strahlteilende Funktionalitäten in sich vereint, wird die Leistungsfähigkeit des Ansatzes theoretisch und experimentell untersucht.
https://doi.org/10.1002/opph.201300016
Parallelized chromatic confocal systems enable efficient spectral information coding. - In: SPIE newsroom, (2013), insges. 3 S.
Parallelized imaging systems based on the chromatic confocal approach can be used for hyperspectral imaging and optical profilometry.
http://dx.doi.org/10.1117/2.1201301.004642
Bildgebende hyperspektrale Sensorik unter Einsatz verstimmbarer Optiken. - In: Photonik, ISSN 1432-9778, Bd. 45 (2013), 1, S. 38-41
Hyperspektrale Abbildungssysteme zeichnen räumlich und spektral hochaufgelöste Information eines Objektes gleichzeitig auf. Eine zentrale Herausforderung besteht darin, die Objektinformation aus dem drei- oder mehrdimensionalen Datenvolumen, besthend aus den räumlichen Koordinaten (x,y,z) und der Wellenlänge ([lambda]), geeignet auf dem üblicherweise eingesetzten zweidimensionalen Empfängerchip zu verteilen. Verstimmbare Optiken kombiniert mit geeigneten Systemkonzepten sind ein Lösungsansatz zur Optimierung der Aufnahmekapazität und -dynamik.
Automatic differentiation in the optimization of imaging optical systems. - In: Schedae informaticae, ISSN 2083-8476, Bd. 21 (2012), S. 169-175
Automatic differentiation is an often superior alternative to numerical differentiation that is yet unregarded for calculating derivatives in the optimization of imaging optical systems. We show that it is between 8% and 34% faster than numerical differentiation with central difference when optimizing various optical systems.
http://dx.doi.org/10.4467/20838476SI.12.011.0821
Improving the polishing accuracy by determining the variance of the friction coefficient. - In: Journal of the European Optical Society, ISSN 1990-2573, Bd. 7 (2012), 12049, S. 1-4
The variation of the friction coefficient in the polishing process is investigated comparing the results of a numerical simulation with polishing experiments. To improve the accuracy of the predicted wear in the simulation a method is presented to measure the friction coefficient in relation to the relatie velocity using an offset tool.
https://doi.org/10.2971/jeos.2012.12049
Static and dynamic characterization of AlN and nanocrystalline diamond membranes. - In: Physica status solidi, ISSN 1862-6319, Bd. 209 (2012), 10, S. 1835-1842
http://dx.doi.org/10.1002/pssa.201228180
Replication diffractive optical elements in synthetic quartz glass using the sol-gel-process. - In: Photonik international ..., ISSN 1865-6633, Bd. 7 (2012), S. 45-47
When manufacturing macroscopic monolithic quartz glass products using an established sol-gel-process, the question arises about the minimum size surface structures that can be precisely replicated, and whether such three-dimensional structures would be suitable for beam shaping. The results of the project SINOMS show that the sol-gel-proces offers an alternatice to the fabrication of micro-structures for diffractive optical elements (DOEs) of synthetic quartz glass.