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