MEMS scanner mirror based system for retina scanning and in eye projection

Woittennek, Franziska; Knobbe, Jens; Pügner, Tino; Dallmann, Hans-Georg; Schelinski, U.; Grüger, Heinrich

doi:10.1117/12.2079468

Cited by 3 publications

(2 citation statements)

References 15 publications

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“…Optical MEMS or MOEMS (micro opto electro mechanical systems), for example scanner mirrors [5] almost always operate in combination with further components like light sources (LEDs, lasers), optics, electronics or optionally detectors. Some prominent example are laser projection [6], retina scanning [7], LiDAR or other measurement systems. More sophisticated MOEMS have been realized by the integration of a diffraction grating on the tiltable plate of a scanner device replacing the simple mirror [8].…”

Section: Previous Workmentioning

confidence: 99%

Concept for a new approach to realize complex optical systems in high volume

et al. 2017

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A groundbreaking new approach [1] for the fabrication of complex photonic systems, especially such with off-axis optics, has been invented based on planar mounting in combination with a novel folding approach. Up to now volume production of photonic systems has been optimized for on-axis lens based optical systems. Chromatic aberration limits the usage or spectral range of these systems. Applying mirrors instead of lenses may help to suppress chromatic aberrations and wavelength depending absorption. The assembly of reflective optics, often in an off-axis configuration, is a complex process. So far most tools for volume production apply stacking of components in planar technology. Off-axis systems are typically assembled by more or less manually alignment of the components, which is not in favor for mass and low cost production of these systems. The novel approach utilizers a planar substrate featuring preprocessed bending lines. A high accuracy tool for planar assembly places the components onto the substrate. Then the sides of the substrate are bent leading to a predefined three dimensional body. The off-axis optical path inside is generated automatically. This concept is not limited to rectangular shapes but can also be applied to more complex systems, for example the so called "W-configuration" for a Czerny-Turner spectrometer. First tests of the "bend and place assembly" have been performed successfully on a camera setup to prove the working principle.

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Section: Previous Workmentioning

confidence: 99%

Concept for a new approach to realize complex optical systems in high volume

et al. 2017

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“…Improved eye alignment techniques would make these devices more accessible in other environments. Recent work has focused on making capture devices smaller and more compact [Woittennek et al 2015] but have largely ignored the alignment problem.…”

Section: Retinal Biometricsmentioning

confidence: 99%

eyeSelfie

et al. 2015

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Eye alignment to the optical system is very critical in many modern devices, such as for biometrics, gaze tracking, head mounted displays, and health. We show alignment in the context of the most difficult challenge: retinal imaging. Alignment in retinal imaging, even conducted by a physician, is very challenging due to precise alignment requirements and lack of direct user eye gaze control. Self-imaging of the retina is nearly impossible.We frame this problem as a user-interface (UI) challenge. We can create a better UI by controlling the eye box of a projected cue. Our key concept is to exploit the reciprocity, "If you see me, I see you", to develop near eye alignment displays. Two technical aspects are critical: a) tightness of the eye box and (b) the eye box discovery comfort. We demonstrate that previous pupil forming display architectures are not adequate to address alignment in depth. We then analyze two ray-based designs to determine efficacious fixation patterns. These ray based displays and a sequence of user steps allow lateral (x, y) and depth (z) wise alignment to deal with image centering and focus. We show a highly portable prototype and demonstrate the effectiveness through a user study.

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Dynamic wavefront distortion in resonant scanners

2021

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Dynamic mirror deformation can substantially degrade the performance of optical instruments using resonant scanners. Here, we evaluate two scanners with resonant frequencies > 12 k H z with low dynamic distortion. First, we tested an existing galvanometric motor with a novel, to the best of our knowledge, mirror substrate material, silicon carbide, which resonates at 13.8 kHz. This material is stiffer than conventional optical glasses and has lower manufacturing toxicity than beryllium, the stiffest material currently used for this application. Then, we tested a biaxial microelectromechanical (MEMS) scanner with the resonant axis operating at 29.4 kHz. Dynamic deformation measurements show that wavefront aberrations in the galvanometric scanner are dominated by linear oblique astigmatism (90%), while wavefront aberrations in the MEMS scanner are dominated by horizontal coma (30%) and oblique trefoil (27%). In both scanners, distortion amplitude increases linearly with deflection angle, yielding diffraction-limited performance over half of the maximum possible deflection for wavelengths longer than 450 nm and over the full deflection range for wavelengths above 850 nm. Diffraction-limited performance for shorter wavelengths or over larger fractions of the deflection range can be achieved by reducing the beam diameter at the mirror surface. The small dynamic distortion of the MEMS scanner offers a promising alternative to galvanometric resonant scanners with desirable but currently unattainably high resonant frequencies.

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MEMS scanner mirror based system for retina scanning and in eye projection

Cited by 3 publications

References 15 publications

Concept for a new approach to realize complex optical systems in high volume

Concept for a new approach to realize complex optical systems in high volume

eyeSelfie

Dynamic wavefront distortion in resonant scanners

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