Centre for Sensors, Instruments and Systems Development

Universitat Politècnica de Catalunya

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Development of new metrological applicat...

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Project

Development of new metrological applications on micro and nanometrical scale based on adaptive optics techniques.

Principal investigator

Santiago Royo Royo [+info]

Summary

The use of wavefronts with high degree of complexity (wild aspherics, rotationally symmetrical, with high-order modes induced, etc.) is becoming more and more usual in modern optical metrology techniques. This project aims to take advantage of the recently developed optoelectronic instrumentation (custom phase plates, adjustable afocal variators, micromachined deformable mirrors (MMDM) and  programmable phase modulators (PPM)) in order to take advantage of Adaptive Optics techniques in optical profilometry systems which we expect will be able to solve realworld applications both in the biomedical and industrial fields.

To obtain these complex wavefronts different systems of tailoring the wavefront phase to the desired shape will be used. They all have quite different characteristics. Phase plates and adjustable afocal variators are robust, well characterised systems which need be precisely defined and positioned to properly work. MMDMs are dynamic systems able to introduce quick changes in the wavefront shape, although with a limited displacement range. PPMs are also dynamic, though its speed of phase change is slower than that of MMDMs, although they allow larger phase changes in the wavefront via wrapping the wavefront phase. The wavefronts generated by these elements will be measured and characterized using new deflectometric techniques based in cylindrical microlens arrays, and will be compared with the results obtained using Shack-Hartmann units of equivalent characteristics, and with a normal Ronchi test setup.

Through these four types of phase modification units, properly characterized, the development of new optical instrumentation for surface profilometry will be possible. The first two applications to be solved involve two optical metrology techniques where the research team has a wide experience: digital deflectometry and confocal profilometry. The first application pursues introducing phase changes which reduce the high dynamic ranges appearing in the wavefronts generated by personalized progressive addition lenses, in particular when high additions
are present. In the second application, we intend to expand confocal profilometry techniques to 3D metrology of surfaces placed behind thick plates (for instance, for the measurement of encapsulated photodetectors and microdisplays) or deep inside refractive media (for instance, for the measurement of registers at different levels in the new generations of optical disks for massive data storage). The modification of the wavefronts will avoid the effects of refractive index mismatch and spherical aberration which greatly degrade the lateral resolution and the capability of optical sectioning proper of confocal techniques.

Publications

Ph.D.: Jesus Caum Aregay, "Caracterización de frentes de onda densamente muestreados." (2010)

Ph.D.: Miguel Ares Rodriguez, "Técnicas de reconstrucción y compensación activa de frentes de onda complejos, Ares Rodríguez, Miguel (2009) " (2009)

Comunicació a congrés nacional (en anglès): "Laguarta, F. (2007): "Optical techniques for 3D surface measurements on the micro and nano scales". UIMP. Conferència invitada. Santander, España." (2007)

Comunicació a congrés internacional (en anglès): "Ares, M., Royo, S.(16-19 Abril 2007): "Large dynamic range wavefront sensor based on a cylindrical microlens array." Publicación: Actas del Congreso " (2007)

Comunicació a congrés internacional (en anglès): "Ares, M., Royo, S., Caum, J., Pizarro, C.: "Comparison of B-Spline and Zernike Fitting Techniques in complex Wavefront Surfaces"." (2005)

Comunicació a congrés internacional (en anglès): "Ares, M., Royo,S.: "Adaptive optics system to accurately measure highly aberrated wavefronts." Publicación: Actas del Congreso " (2007)

Comunicació a congrés internacional (en anglès): "Blanco, P., Cifuentes, A., Arasa, J., Pizarro, C., Royo, S. (2007): "Efficient LED spatial measurement to improve optical modelling". SPIE Press. Vol. 6616-48. P.1-9" (2007)

Comunicació a congrés internacional (en anglès): "Cadevall, C., Oriach, C., Artigas, R., Pintó, A., Laguarta, F. (2007): "Improving the measurement of thick and thin films with optical profiling techniques". SPIE, Vol. 6616" (2007)

Book chapter: "Ares, M., Royo, S. (2008): "Adaptive optics system to compensate complex-shaped wavefronts". Adaptive Optics for Industry and Medecine, Imperial College Press, 206-211 "

Paper: "Ares M., Royo S., Sergievskaya I., Riu J. (2010), “Active optics null test system based on a liquid crystal programmable spatial light modulator”, Appl. Opt., v.49 (32), 6201-6206, 2010."

Paper: "Ares, M., Royo, S. (2006): "Comparison of cubic B-Spline and Zernike fitting techniques in complex wavefront reconstruction" Appl.Opt. 45 6954-6964 (2006)"

Paper: "Ares, M., Royo, S., Caum, J. (2007): "Shack-Hartmann sensor based on a cylindrical microlens array." Optics Letters 32 769-771. "

Paper: "Laguarta, F., Pintó, A. (2006):"Development of a line-scan CCD-based fringe tracker for optical interferometry". Applied Optics. Vol.45, nº26.6694-6701."

Paper not indexed: "Oriach Font, C., Laguarta, F., Cadevall, C., Artigas, R., Pintó, A. (2008): "Deep 3D Optical Metrology". USA"

Patent: "Optical device and procedure to reconstruct and compensate a wave front coming from a complex optical element."

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