The state-of-the-art Virtual and Augmented Reality (VR/AR) hardware fails to deliver satisfying visual experience due to missing or conflicting focus cues. The absence of natural focal depth in digital 3D imagery causes the so-called vergence-accommodation conflict, focal rivalry, and possibly damage the eye-sight, especially during prolonged viewing of virtual objects within the arm’s reach. It remains one of the most challenging and market- blocking problems in the VR/AR arena today. This talk will introduce CREAL’s unique near-to-eye light-field projection system that provides high-resolution 3D imagery with fully natural focus cues. The system operates without eye-tracking or severe penalty on image quality, rendering load, power consumption, data bandwidth, form-factor, production cost, or complexity.
MEMS-scanning laser projector have seen tremendous performance improvements in the past year, demonstrating devices with very good performances in terms of size, energy efficiency and image quality that were expected from the theory point of view. The last challenge that was not solved yet is the speckle reduction, which is the main bottleneck for this technology adoption. The paper presents an innovative design to reduce speckle contrast without degrading any other features and benefits of the projection system. The proposed despeckling solution is a single, non-movable part with less than 0.1cc in volume and of 4mm in thickness.
We show a laser beam shaping device made of a deformable continuous reflective membrane fabricated over a scanning
stage. The combination of two actuator schemes enables shaping and smoothing of a laser beam with a unique compact
device. It is designed to shape an input laser beam into a flat top or Gaussian intensity profile, to support high optical load
and to potentially reduce speckle contrast. One single electrode is needed to deform the whole membrane into multiple
sub-reflecting concave elements. The scanning stage is used simultaneously to smooth out the remaining interference
patterns. The fabrication process is based on SOI wafer and parylene refilling to enable the fabrication of a 100 % fill
factor 5 by 5 mm2 deformable membrane. Applications for such device are laser machining and laser display.
Shaping light with microtechnology components has been possible for many years. The Texas Instruments digital
micromirror device (DMD) and all types of adaptive optics systems are very sophisticated tools, well established and
widely used. Here we present, however, two very dedicated systems, where one is an extremely simple MEMS-based
tunable diffuser, while the second device is complex micromirror array with new capabilities for femtosecond laser pulse
shaping. Showing the two systems right next to each other demonstrates the vast options and versatility of MOEMS for
shaping light in the space and time domain.
We present a dynamic laser beam shaper based on MEMS technology. We show a prototype of a dynamic diffuser made
of single crystal silicon. A linearly deformable silicon micromembrane is used to diffuse a laser beam in one dimension.
Resonance frequencies of the membrane can range from 1 kHz to 20 kHz. Mode shapes of the deformable mirror are
excited using magnetic actuation. Diffusing angle can be tuned by adjusting the driving current in the membrane. We
measured a diffusing angle of 1° for an applied current of 40 mA. The aluminum coated mirror can handle 140 W/cm2 of
visible to infrared optical power. Application to smooth out interference pattern generated by a static diffuser is shown.
Laser manufacturing of microstructures using a single focus is a well known technology. Multi-spot optics are applied
for process parallelizing if the demand on throughput in mass production rises or large areas of material have to be
processed. Diffractive optical elements (DOEs) are used for parallel laser processing of a repetitive structure. These
elements split the beam into a periodic spot pattern, where each spot shows the same shape and energy. This allows
simultaneous manufacturing of several equal shaped structures at the same time. For patterning a surface this is state of
the art and the appropriate technique to reduce processing time while maintaining a high lateral resolution as well as a
good relative positioning of the structure due to the DOE.
We investigate the usage of microlens arrays as multifunctional elements for forming an arbitrary shaped laser beam into
a spot-, a ring-spot- or a line-array pattern. It can be shown that the intensity distribution of each spot is equal to the
intensity distribution of all other spots in the whole pattern. The shape of the spots is defined by the angular distribution
of the incident beam. We demonstrate that besides other optical properties the output beam profile strongly depends on
the Fresnel-Number and is influenced by diffraction and interference effects. We present important design rules which
consider geometrical and physical optics. The properties of the spot arrays, like spot diameter, Rayleigh length and beam
divergence in dependency of beam and system properties are investigated. Finally we will show some laser micro
structuring and micro drilling results in different materials.
We present a dynamic laser beam shaper based on MEMS technology. We show a prototype of a dynamic diffuser made
of single crystal silicon. A linearly deformable silicon micromembrane is used to diffuse a laser beam in one dimension.
Resonance frequencies of the membrane can range from 1 kHz to 100 kHz. Diffusing angle can be tuned by adjusting the
driving voltage. We measured a diffusing angle of 0.16° for an actuation voltage of 20 V.
In this paper we present an innovative tunable Fabry-Perot cavity micromachined in silicon. A short summary of the
theoretical background of these filters is presented, followed by technical requirements for the design of the dielectric
mirror composing the Fabry-Perot cavity and the cavity itself. Simulations and experimental data are demonstrated to be
in good agreement. An in plane design is used to allow easy fiber alignment. The Fabry-Perot is tuned by an electrostatic
comb drive actuator supported by a set of four springs to achieve a uniform modulation of the air gap of the filter. Only
15.4 V are required to tune the Fabry-Perot over 73nm bandwidth (covering more than the whole C-band) with a FWHM
varying from 6 to 10nm. Transmission losses are -11dB.
In this paper, we propose a solution for simple, fast and easily controllable way of tuning silicon gratings using Micro
Electro Mechanical Systems (MEMS) to deform the grating itself. Basically the idea is to deform mechanically a silicon
grating using electrostatic actuators, enabling pitch tuning over a large proportion (more than 50% is easily achievable
with our approach). Moreover we can change the spacing of individual layers within the grating. A theoretical analysis
and numerical simulations are presented and a first prototype is fabricated. Bragg gratings, springs and actuators are
realized by silicon micro/nano machining on a silicon platform enabling full integration and passive alignment of all
optical components. Applications range from ultra-sensitive displacement sensors, to telecommunications and biology.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.