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Gimbal-less Single-Axis and Dual-Axis (Tip-Tilt) MEMS Mirrors
Scanning two axis (tip-tilt) MEMS mirror (or "micromirror")
is an optical beam-steering (or 2D optical scanning) technology that
is used in many industries. There are several major benefits of the
Mirrorcle Technologies Inc. tip-tilt MEMS mirror over competing products. Gimbal-less Two-Axis Scanning Micromirror Devices based on
ARI-MEMS fabrication technology initially developed through research
projects at the Adriatic Research Institute (“ARI”) in Berkeley,
CA, provide ultra low-power and very fast
optical beam scanning in two-axes. The devices deflect laser beams
to optical scanning angles of up to 30° at high speeds in both
axes. Compared to the large-scale galvanometer optical scanners,
our devices require several orders of magnitude less driving power.
Continuous full-speed operation of our electro-static actuators
dissipates less than a few milliwatts of
power.
MirrorcleTech devices are made entirely of
single-crystal silicon, resulting in excellent repeatability and
reliability. Optically flat and smooth mirrors are coated with a thin film with
desired reflectivity. Larger mirrors can be bonded onto actuators
for custom aperture sizes. Mirror sizes from 0.8mm to 7.5mm in diameter
are currently available in stock. Sizes up to 9.0mm were successfully
demonstrated in special applications.
MirrorcleTech's MEMS micromirror technology is highly versatile and
adaptable to various applications. Some devices are fabricated with
somewhat generic quasi-static (point-to-point) performance specifications. Other devices are highly
customizable to achieve specific set of specifications, such as e.g. projection-displays. While the descriptions below mainly pertain to dual-axis devices, there are also multiple single-axis designs available, both point-to-point (quasi-static) and resonant type.
Key Benefits
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The tilt angle is
analog as opposed to on-off. See video of tip-tilt-piston movement under microscope.
This is the key differentiation with digital micromirror
elements which can not be used for
arbitrary-direction optical beam steering. In other words, if a
tilt angle of 6.15° is required, it is simply a matter of applying
the correct voltage and that angle (or any other angle) can be
obtained and maintained for any length of time with nearly zero power consumption.
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Point-To-Point Scanning
The devices are designed and optimized for point-to-point optical
beam scanning mode of operation. A steady-state analog
actuation voltage results in a steady-stage analog angle of
rotation of the micromirror. There
is a one-to-one correspondence of voltages and angles that is
highly repeatable. A number of resonant-type scanning MEMS mirror designs is also offered for video projection and high rate imaging at e.g. 48000 lines/s.
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Modular Design
In order to produce devices with a different mirror size, most
technologies require not only a new fabrication cycle, but in some
cases complete actuator redesign. Mirrorcle Technologies
is the world's only provider of a MEMS based, customizable aperture
size beam steering technology. Namely, sets of electrostatic
actuators optimized for speed, angle, area footprint or resonant
driving are designed and realized in a self-aligned silicon fabrication
process. Metallized, ultra low-inertia
single crystal mirrors made stiff and flat by a special design of
silicon beams are created in a separate fabrication
process. The diameter, as well as geometry of the mirror is
selected specific to a given application, in order to optimize the trade-offs between
speed, beam size, and scan angle. The mirrors are subsequently bonded to the
actuators.
A variety of gibmal-less two-axis
actuator designs are available. The actuators lend themselves
inherently to a modular design approach. Each actuator can
utilize rotators of arbitrary length, arbitrarily stiff linkages,
and arbitrarily positioned mechanical rotation transformers. In
stock categories include 4.25mm x 4.25mm die size, 5.2mm x 5.2mm die
size, and 7.25mm x 7.25mm die size. In most
cases, larger die size allows better performance due to increased
electrostatic force. Beyond die size other parameters are varied such
as e.g. stiffness. One device series for example is designed to operate at large angles (-7.5° to +7.5° of mechanical tilt,) while another series is designed to operate
at small tip-tilt angles but dramatically higher speeds (-1.0° to +1.0° of mechanical tilt).
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High Speed
Point-To-Point Optical Beam Scanning
The major advantage of our proprietary gimbal-less design
is the capability to scan optical beams at equally high speeds in
both axes. A typical device with a 0.8 mm diameter-sized micromirror achieves angular beam scanning of
up to 500 rad/s and has first resonant frequency in both axes at
approximately 4 kHz. Large angle step response settling times
of <100 µs have been demonstrated on devices with micromirrors up to 0.8 mm in diameter. Devices
with 2.0mm diameter mirrors can achieve large angle step settling
times of <1ms, with first resonance of approximately 1.3 kHz.
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Dynamic Mode Scanning
Devices can also operate in the dynamic,
resonant mode. In this mode, low actuation voltages at
frequencies near resonance result in large bi-directional optical
beam angles (e.g. -16° to 16°). Resonant frequencies are in
the range from several kHz up to 24 kHz and higher for MEMS
display applications. Resonance depends on the actuator type (series,)
and the micromirror type and diameter.
Summary of Specifications
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Integrated
Mirror Devices:
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Mirror Sizes: 0.8 mm, 1.2mm, 1.6mm, 2.0mm, and 2.4mm diameter in stock.
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Maximum tilt angle under point-to-point driving: -6° to +6° mechanical each axis, varies with design type.
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Maximum tilt angle under resonant driving: -7° to +7° mechanical
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Single-Axis Option: Most designs can be provided arranged for pure single-axis motion.
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See support page for more info |
Bonded Mirror
Devices:
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Bonded Mirror Sizes: 2.0, 2.4, 3.0, 3.6, 4.2, 4.6mm, and 5.0mm, 6.4mm, and 7.5mm
diameter in stock.
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Maximum tilt angle under point-to-point driving: -6° to +6° mechanical on each axis, varies with design type, and in some cases is limited by mirror size.
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Maximum tilt angle under resonant driving: -7° to +7° mechanical, in some cases limited by mirror size.
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Single-Axis Option: In-stock single-axis actuators can be combined with many of the available mirror sizes.
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See support page for more info
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Typical
Specifications for All Devices:
- Surface Roughness: <10 nm rms
- Driving Methodology: Electrostatic drive, using Mirrorcle's Bias-differential Quad-Channel MEMS drivers
- Mirror Radius of
Curvature:
>5 m
- Mirror Coating: Aluminum or Gold
- Positional
repeatability: better
than 0.001° (1 millidegrees) at room temperature
- Operating Temperature: -40°C to 125°C
- Optical Window: Anti-reflection coated fused silica windows. Removable. See support page for coating choices.
- Optical power handling:
up to 2W any mirror, any wavelength. Above 2W depends on mirror size, coating,
and wavelength. E.g. 3W CW blue or green on a 2mm or larger mirror .
- First resonant rotation
frequency:
>3 kHz for both axes for small mirror sizes, >1.2kHz for 2.0mm size, etc.
MirrorcleTech devices are highly
customizable with several controllable trade-offs (mirror size vs.
speed, angle vs. speed, die size vs. speed, die size vs. cost, etc.)
Custom designs and fabrication is performed for larger orders or under
NRE contracts.
Detailed Descriptions and More Information
Pricing
View price list (in PDF) for prototyping and low-volume quantities.
(Mirrorcle Technologies' Terms and Conditions of Sale apply.)
Please contact us for additional product details, custom
device specifications, and large-quanity
quotations.
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