We report our progress in the development of Differential Aberration Imaging (DAI), a technique that enhances twophoton
fluorescence (TPEF) microscopy by improving rejection of out-of-focus background by means of a deformable
mirror (DM). The DM is used to intentionally add aberrations to the imaging system, which causes dramatic losses to
in-focus signal while preserving the bulk of the out-of-focus background. By taking the difference between TPEF
images with and without added aberrations, the out-of-focus portion of the signal is further rejected. We now introduce
an implementation of DAI using a new type of DM that can be produced at much lower cost.
In adaptive microscope systems, it is often desirable to dispense with the wavefront sensor and perform aberration
correction through optimisation an appropriate quality metric, such as image brightness or sharpness. A sequence
of trial aberrations is applied to the adaptive element and the metric values are calculated. The optimum
aberration correction is derived from these measurements. An important choice in the design of these correction
schemes is the modal aberration expansion. This choice may depend upon several factors, such as the deformable
mirror, the optimisation metric, the aberration statistics or the image properties. We discuss these factors with
particular reference to microscope imaging.
Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when
combined, can provide high-resolution (3.5 μm isotropic), 3-D images of the retina. The AO-OCT system at
UC Davis has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging.
The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction and
a 140-actuator Boston Micromachines DM for high-order correction. Developments to improve performance or
functionality of the instrument are on-going. Based on previous work in system characterization we have focused
on improved AO control. We present preliminary results and remaining challenges for a newly implemented
Fourier transform reconstructor (FTR). The previously reported error budget analysis is also reviewed and
updated, with consideration of how to improve both the amount of residual error and the robustness of the
system. Careful characterization of the AO system will lead to improved performance and inform the design of
Adaptive optics (AO) improves the quality of astronomical imaging systems by using real time measurement of the
turbulent medium in the optical path using a guide star (natural or artificial) as a point source reference beacon. AO has
also been applied to vision science to improve the current view of the human eye. This paper will address our current
research focused on the improvement of fluorescent microscopy for biological imaging utilizing current AO technology.
A Shack-Hartmann wavefront sensor (SHWS) was used to measure the aberration introduced by a Drosophila Melanogaster embryo with an implanted 1 micron fluorescent bead that serves as a point source reference beacon. The measurements show an average peak-to-valley and root-mean-square (RMS) wavefront error of 0.77 micrometers and
0.15 micrometers, respectively. The Zernike coefficients have been measured for these aberrations which indicate that
the correction of the first 14 Zernike coefficients should be sufficient to correct the aberrations we have obtained. These
results support the utilization of SHWS for biological imaging applications and that a MEMS deformable mirror with 1 micron of stroke and 100 actuators will be sufficient to correct these aberrations. The design, assembly and initial results for the use of a MEMS deformable mirror, SHWS and implanted fluorescent reference beacon for wavefront correction will also be discussed.
Implementing the capability to perform fast ignition experiments, as well as, radiography experiments on the National
Ignition Facility (NIF) places stringent requirements on the control of each of the beam's pointing and overall wavefront
quality. One quad of the NIF beams, 4 beam pairs, will be utilized for these experiments and hydrodynamic and
particle-in-cell simulations indicate that for the fast ignition experiments, these beams will be required to deliver
50%(4.0 kJ) of their total energy(7.96 kJ) within a 40 μm diameter spot at the end of a fast ignition cone target. This
requirement implies a stringent pointing and overall phase conjugation error budget on the adaptive optics system used
to correct these beam lines. The overall encircled energy requirement is more readily met by phasing of the beams in
pairs but still requires high Strehl ratios, Sr, and RMS tip/tilt errors of approximately one μrad. To accomplish this task
we have designed an interferometric adaptive optics system capable of beam pointing, high Strehl ratio and beam
phasing with a single pixilated MEMS deformable mirror and interferometric wave-front sensor. We present the design
of a testbed used to evaluate the performance of this wave-front sensor below along with simulations of its expected
Phase modulation of ultrashort UV pulses is developed for application in Quantum Control Spectroscopy (QCS) using a
MEMS based two dimensional phase only modulator. The phase modulator consists of an array of 240 by 200
individually addressable, electrostatic displaceable micromirrors, placed in the Fourier plane of a purely reflective 4f-geometry.
As possible applications, the adaptive recompression of ultrashort UV-pulses and arbitrary phase modulation
for nonlinear spectroscopy and control experiments are discussed. Furthermore, the 2D layout of the device offers the
potential to control multi beam experiments in a much easier way than with conventional experimental methods.
By switching between two tilt angles MEMS mirrors can be used to produce spatial light patterns. This enables the
Digital Micromirror Display (DMD, Texas Instruments) chip to produce the images found in some data projectors. In
this paper we will show how these images can be converted into electrical patterns. We use the electrical gradients in
these patterns to control the movement of particles through dielectrophoresis. We show how this can be used to move
cells within PBS solution and characterize our device. We also discuss possible ways to improve our optical setup
through Adaptive Optics (AO).
There are many potential applications for MEMS micromirror devices for femtosecond pulse shaping applications. Their
broadband reflectivity gives them an advantage in comparison to devices such as liquid crystal- and acousto-optical modulators
because of the possibility to directly shape UV pulses in the range 250 - 400 nm, and thus address UV-absorbing
molecules. The identification and discrimination of biomolecules which exhibit almost the same spectra has sparked
some interest in the last years as it allows real-time, environmental and optical monitoring. Here, we present the last
developments using the Fraunhofer IPMS MEMS phase former capable of accomplishing such goals.
This paper reports on a novel construction of a deformable mirror for laser beam shaping. The deformable mirror is
actuated by screen-printed thick film piezoceramic unimorphs based on lead zirconate titanate (PZT). Different actuator
layouts are realized and will be presented. We use Low Temperature Cofired Ceramics (LTCC) as a substrate material
with a metallization as reflective surface. LTCC offers easy integration of holding structures. The reflective mirror
surface is electroplated copper. After deposition, the copper layer is diamond machined to achieve excellent optical
surface quality <10 nm (rms). We build deformable mirrors with 1, 13 and 19 actuators and a total stroke of more than
20 μm and characterize them with a wave front sensor.
An optical communication system suitable for voice, data retrieval from remote sensors and identification is described.
The system design allows operation at ranges of several hundred meters. The heart of the system is a modulated MEMS
mirror that is electrostatically actuated and changes between a flat reflective state and a corrugated diffractive state. A
process for mass producing these mirrors at low cost was developed and is described. The mirror was incorporated as a
facet in a hollow retro-reflector, allowing temporal modulation of an interrogating beam and the return of the modulated
beam to the interrogator. This system thus consists of a low power, small and light communication node with large
(about 60°) angular extent. The system's range and pointing are determined by the interrogator /detector/demodulator
(Transceiver) unit. The transceiver is comprised of an optical channel to establish line of sight communication, an
interrogating laser at 1550nm, an avalanche photo diode to detect the return signal and electronics to drive the laser and
demodulate the detected signal and convert it to an audio signal. A functional prototype system was built using a
modified compact optical sight as the transceiver. Voice communication in free space was demonstrated. The design and
test of major components and the complete system are discussed.
MEMS deformable mirrors are showing great promise for use in astronomical adaptive optics systems. Recent
experiments at a Lick Observatory 1-meter telescope have demonstrated a 144 actuator device in a visible
wavelength AO imager. MEMS devices with thousands of actuators could be used for high-Strehl and visible
wavelength AO systems on today's large-aperture telescopes (8-10 meters) and future giant (30 meter) telescopes. In
this paper we present several design concepts for multiple-mirror AO systems and discuss our efforts at the
Laboratory for Adaptive Optics to develop components and test system concepts for these systems.
The Naval Prototype Optical Interferometer (NPOI) is the longest baseline at visible
wavelengths interferometer in the world. The astronomical capabilities of such an
instrument are being exploited and recent results will be presented. NPOI is also the
largest optical telescope belonging to the US Department of Defense with a maximum
baseline of 435 meter has a resolution that is approximately 181 times the resolution
attainable by the Hubble Space Telescope (HST) and 118 times the resolution attainable
by the Advanced Electro-Optical System (AEOS). It is also the only optical
interferometer capable of recombining up to six apertures simultaneously. The NPOI is a
sparse aperture and its sensitivity is limited by the size of the unit aperture, currently that
size is 0.5 meters. In order to increase the overall sensitivity of the instrument a program
was started to manufacture larger, 1.4 meter, ultra-light telescopes. The lightness of the
telescopes requirement is due to the fact that telescopes have to be easily transportable in
order to reconfigure the array. For this reason a program was started three years ago to
investigate the feasibility of manufacturing Carbon Fiber Reinforced Polymer (CFRP)
telescopes, including the optics. Furthermore, since the unit apertures are now much
larger than r0 there is a need to compensate the aperture with adaptive optics (AO). Since
the need for mobility of the telescopes, compact AO systems, based on Micro-Electro-
Mechanical-Systems (MEMS), have been developed. This paper will present the status of
our adaptive optics system and some of the results attained so far with it.
The past decade has seen a significant growth in research targeted at space based observatories for imaging exosolar planets. The challenge is in designing an imaging system for high-contrast. Even with a perfect coronagraph that modifies the point spread function to achieve high-contrast, wavefront sensing and control is needed to correct the errors in the optics and generate a "dark hole". The high-contrast imaging laboratory at Princeton University is equipped with two Boston Micromachines Kilo-DMs. We review here an algorithm
designed to achieve high-contrast on both sides of the image plane while minimizing the stroke necessary from each deformable mirror (DM). This algorithm uses the first DM to correct for amplitude aberrations and the second DM to create a flat wavefront in the pupil plane. We then show the first results obtained at Princeton
with this correction algorithm, and we demonstrate a symmetric dark hole in monochromatic light.
We present preliminary findings on the characteristic behavior and initial performance of Boston Micromachine
Corporations' (BMC) 4096-actuator micro-electrical mechanical systems (MEMS) deformable mirror (DM). This
device is examined for its application in the Gemini Planet Imager high-contrast adaptive optics (AO) system. It is
also being considered for use in next generation AO systems on the extremely large telescopes. Testing of this device
has been in progress at the Laboratory for Adaptive Optics (LAO) on the Extreme Adaptive Optics (ExAO) testbed
in experiments designed to qualify performance for imaging extrasolar planets. In this paper we present first test
results including actuator stroke (3.0 microns at 200 V), individual actuator RMS surface (10.3 nm surface), actuator
yield for two DM arrays (94.4% and 98.8%), actuator crosstalk (no more than 32%), stroke at the highest spatial
frequency (1.2 nm surface), and sub-nanometer closed loop flattening capabilities over a 30-actuator diameter.
R&D on Adaptive Optics in the Institute of Optics & Electronics (IOE), Chinese Academy of Sciences (CAS) began in
1979. In this paper, several recent achievements will be reported: 1. AO for astronomical telescopes. AO system for 1.2
m telescope at Yunnan Astronomical Observatory was built in 1998. It was updated in 2004, and high resolution images
approaching diffraction limit were obtained. A new AO telescope with 1.8m aperture is being built, and a 4m AO
telescope is being planned. 2. AO for ICF facility. A 19-element AO system with hill-climbing control algorithm for
"Shenguang I" ICF facility was built in 1985, which was the first AO system used in ICF facility in the world. A set of 8
AO systems was installed in a bundle of ICF prototype for "Shenguang III" ICF facility. A new system is being built for
further development of ICF facility. 3. AO for retinal imaging. In 1999, the first AO system with 19-element DM was
built for retinal imaging. Several AO systems with 37-element deformable mirror (DM) were built and used for vision
research and clinical inspection. It is being integrated with an OCT system for high resolution retinal imaging. All of the
main subsystems, such as DMs, wavefront sensors, and high speed processors, were built in the Laboratory on Adaptive
Optics of IOE, CAS.
For many astronomical systems, Adaptive Optics (AO) plays an important role. Here, we report some preliminary studies
on MEMS (Micro-Electro-Mechanical-System) Project for micro actuators in AO applications at the Institute of Optics
and Electronics, Chinese Academy of Science. This paper presents a few MEMS actuators based on repulsive
electrostatic driven mechanism, which can achieve large out-of-plane strokes through eliminating the electrostatic pull-in
effect. Design principles, including the layout and the physical dimension of electrodes, and FEA models are illustrated;
it provides helpful guidance for designing electrostatic repulsive actuators for being implemented in Deformable Mirrors
(DMs). Some repulsive electrostatic driven micro actuators are given, the analysis focus on the displacement versus
applied voltage and resonant frequency. Repulsive electrostatic driven actuators can achieve large strokes and high
resonant frequencies, they meet the important requirements for DMs.
This paper presents preliminary development results of a high-stroke (>8 μm), 489 actuator, 163-piston/tip/tilt-segment
deformable mirror (DM) and progress on a proof-of-concept 925-piston/tip/tilt-segment DM. It also presents a compact
512-channel driver box used to drive the 489 actuators of the 163-PTT-segment design.
The performance of microelectromechanical systems deformable mirrors (MEMS DMs) continues to improve in areas of
stroke, open-loop positioning, actuator count, and drive electronics. However, a key area lacking in the development of
these devices is good optical coatings suitable for a broad spectrum of applications and wavelengths. This paper
discusses the progress Iris AO has made towards coating its MEMS DMs with gold, protected aluminum, protected
silver, and dielectric coatings.
We present a novel unimorph deformable mirror with a diameter of only 10 mm that will be used in adaptive resonators
of high power solid state lasers. The relationship between applied voltage and deformation of a unimorph mirror depends
on the piezoelectric material properties, layer thicknesses, boundary conditions, and the electrode pattern. An analytical
equation for the deflection of the piezoelectric unimorph structure is derived, based on the electro-elastic and thin plate
theory. The validity of the proposed analytical model has been proven by numerical finite-element modelling and
experimental results. Our mirror design has been optimized to obtain the highest possible stroke and a high resonance
The fabrication and initial performance results of high-aspect ratio 3-dimensional Micro-Electro-Mechanical System (MEMS) Deformable Mirrors (DM) for Adaptive Optics (AO) will be discussed.
The DM systems were fabricated out of gold, and consist of actuators bonded to a continuous face
sheet, with different boundary conditions. DM mirror displacements vs. voltage have been measured
with a white light interferometer and the corresponding results compared to Finite Element Analysis
(FEA) simulations. Interferometer scans of a DM have shown that ~9.4um of stroke can be achieved
with low voltage, thus showing that this fabrication process holds promise in the manufacturing of
future MEMS DM's for the next generation of extremely large telescopes.
A homogeneous aligned nematic liquid crystal (LC) cell can be used to phase modulate light. It has a series of
attractive characteristics of compactness, high density integration, low cost and possibility of batch production
in adaptive optics. However a problem has long existed for such devices is that they may be used only to control
the phase of light polarized along the LC extraordinary axis since only the extraordinary light index can be
varied by the application of the electric field. For a liquid crystal adaptive optics system using for astronomical
imaging, low level un-polarized light is collected by the telescope. So the high optical efficiency is important
and key factor for an adaptive optics system using for compensate atmosphere turbulence. If a polarizer placed
before LC, 50% of incident un-polarized light is wasted. In this paper, a simple method is detailed described
for phase modulating un-polarized light. Un-polarized light can be thought of as the superposition of any two
orthogonal polarization states that are mutually incoherent.
Iceland-spar OE crystal split incident un-polarized
light into two polarized light, two same LCs modulated these two polarized light separately. After that, both
these two polarized light beam are combined using another
Iceland-spar OE crystal. These double LC adaptive
optics system can phase modulate all incident un-polarized light, no light intensity is wasted.
MEMS deformable mirror (DM) has yet to be incorporated into a facility AO instrument especially for atmospheric
compensation. Apart from these drawbacks such as limited stroke, reliability, its optical efficiency should
also be concerted. The wavefront corrector in AO system should existing high optical efficiency especially atmospheric
compensation under faint stars. However the MEMS DM fabricated by surface process must have etch
holes in the surface of mirror. The diffraction results from etch holes decrease its optical efficiency. An MEMS
deformable mirror is fabricated by commercial PolyMUMPs. There is array of etch holes to ensure that the
sacrifice layer is released fully. The far field intensity distribution was simulated. The result has been analyzed
and used to constructed a simple modal of the studied MEMS DM.