The last five years have witnessed unprecedented interest in MEMS (Microelectromechanical Systems), MST (Microsystem Technologies) and Micromachines (M³). Of great interest has been the creation of many new companies whose desire it is to commercialize the technology. During 1999 and 2000, an unprecedented number of startups, especially in the optical MEMS sector, have been created. It is estimated that there are over 750 companies, research institutes, and universities currently involved with M³ worldwide. Over 150 of these are U.S. based companies who wish to commercialize this technology. This paper addresses a number of the significant issues associated with the barriers that have existed to the successful commercialization of M³ by new as well as established companies. These issues include R & D, marketing, infrastructure support and venture capital funding. An M³ 'Report Card' is provided assessing current status of the industry with respect to these issues and comparing the grades with those reported in June 1998 and June 1999. Recommended strategies are provided that are expected to help overcome these barriers to commercialization. Current (2000) market and projections for the year 2004 are provided.

A silicon micromachined deformable mirror ((mu) DM) has been developed by Boston University and Boston Micromachines Corporation (BMC). The (mu) DM employs a flexible silicon mirror supported by mechanical attachments to an array of electrostatic parallel plate actuators. The integrated system of mirror and actuators was fabricated by surface micromachining using polycrystalline silicon thin films. The mirror itself measures 3 mm X 3 mm X 3 micrometer, supported by a square array of 140 electrostatic parallel- electrode actuators through 140 attachment posts. Recently, this (mu) DM was characterized for its electro-mechanical and optical behavior and then integrated into two laboratory-scale adaptive optics systems as a wavefront correction device. Figures of merit for the system include stroke of 2 micrometer, resolution of 10 nm, and frequency bandwidth of 6.7 kHz. The device is compact, exhibits no hysteresis, and has good optical quality.

Inexpensive wavefront sensors and deformable mirrors are essential for addressing potential commercial applications for adaptive optics like laser beam control and ophthalmology. Silicon micromachined deformable mirrors offer the potential for low cost and high actuator density, but there are some problems with the architectures currently available like low mirror quality and high actuator crosstalk. Shack-Hartmann wavefront sensors are still based on traditional charge coupled device (CCD) arrays making them very expensive at high frame rates. To address the need for low cost deformable mirrors, we have implemented a new architecture of silicon deformable mirror designed to be low cost, have low actuator crosstalk, and still maintain good mirror quality. Furthermore, we built and tested a CMOS Shack-Hartmann wavefront sensor to address the needs of the adaptive optics community for high speed wavefront sensing.

The NSF Center for Adaptive Optics (CfAO) is coordinating a five to ten year program for the development of MEMS-based spatial light modulators suitable for adaptive optics applications. Participants in this multi-disciplinary program include several partner institutions and research collaborators. The goal of this program is to produce MEMS spatial light modulators with several thousand actuators that can be used for high-resolution wavefront control applications and would benefit from low device cost, small system size, and low power requirements. We present an overview of the CfAO MEMS development plan along with details of the current program status. Piston mirror array devices that satisfy minimum application requirements have been developed, and work is continuing to enhance the piston devices, add tip-tilt functionality, extend actuator stroke, create a large array addressing platform, and develop new coating processes.

The performance of different MEMS mirrors from Boston University, MEMS Optical LLC, University of Colorado and OKO Technologies was studied in respect to an application in a model-free adaptive optics system. The frequency response characteristic was determined in a simple laser beam focusing set-up. Closed-loop adaptation experiments were performed using a VLSI controller system implementing a stochastic parallel gradient descent optimization algorithm. The system behavior using different MEMS mirror types, esp. adaptation speed, was compared.

We have developed a high resolution programmable adaptive optic device based on an optically-addressed liquid crystal electro-optical valve (OALEV) controlled by an achromatic three-wave lateral hearing interferometer (ATWLSI). This loop, which can work at 4 Hz, corrects the wavefront of our 100-TW Nd:Glass. Beyond this application, we were able to generate high resolution programmable phase plates to shape the far- field pattern of low-energy cw-lasers as well as high power lasers.

One technique for correcting scintillation is to use adaptive optics, which have good resolution (several thousand actuators) and high temporal bandwidths (several hundred Hertz). This type of correction is economically possible using liquid crystal technology. For liquid-crystal-based wavefront control to be effective in high-performance imaging systems, the device must be phase flat, highly efficient with respect to an unpolarized input, and capable of broadband modulation. This paper discusses the feasibility of using certain liquid- crystal modulators and addressing structures to achieve this type of performance.

A comparative analysis of different electrical control methods of liquid crystal (LC) modulators is presented, and the dual- frequency control method is considered in detail. Theoretical evaluations of the speed and LC heating using dual-frequency control are reported. Methods to optimize the control voltage parameters are described. Next, it is shown how, using specific physical LC properties, it is possible to create a LC wavefront corrector that can be controlled modally. Modal wavefront correctors for the control of both low and high order aberrations are described. We describe some novel operating configurations of modal LC lenses. Finally, we make some brief comparisons of nematic with ferroelectric LCs for adaptive optics.

A novel liquid crystalline material for optical phase modulation is proposed. The material consists of banana shaped dimer molecules, which form a lamellar phase, e.g. a smectic phase. A helical superstructure is induced by means of chiral fragments included in the molecular structure. Due to polyphilic segregation of hydrogenated and fluorinated molecule segments a cancellation of transversal dipole moments can be avoided and a net polarization of single layers will be obtained. The polarized layers may form ferroelectric or antiferroelectric structures. Application of an electric field in light propagation direction will deform the helix until total unwinding without reorienting the optical axes of the material, but changing the refractive index for one polarization direction. An estimation of the refractive indices of the material, its index modulation capability and the behavior under electric field is presented in this paper. The possible application of the material in phase modulators is discussed.

We present here results of laboratory and field experiments using two novel active optic elements, an electro-static membrane mirror, and a dual frequency nematic liquid crystal. These devices have the advantage of low cost, low power consumption, and compact size. Possible applications of the devices are astronomical adaptive optics, laser beam control, laser cavity mode control, and real time holography.

Phase screens are often used to simulate atmospheric turbulence in systems designed to test adaptive optics techniques. This paper presents the design and implementation of a dynamic phase screen using a simple and inexpensive twisted nematic liquid crystal display taken from a video projector and placed in a pupil plane. The details of the optical system layout, the system alignment procedure, and the operating parameters of the liquid crystal display are discussed. Examples of turbulence (having strength and statistics similar to measured values of atmospheric turbulence in a variety of scenarios) are written to the phase screen, and the effects of the turbulence on image quality are measured and presented.

High-resolution phase-contrast wavefront sensors based on optically addressed phase spatial light modulators and micro- mirror/LC arrays are introduced. Wavefront sensor efficiency is analyzed for atmospheric turbulence-induced phase distortions described by the Kolmogorov and Andrews models. A nonlinear Zernike filter wavefront sensor based on an optically addressed liquid crystal phase spatial light modulator is experimentally demonstrated. The results demonstrate high-resolution visualization of dynamically changing phase distortions within the sensor time response of about 10 msec.

Curvature sensing is a non-interferometric wave front sensing method. Its resolution is only limited by the sensor resolution, and it only requires one pixel for each point. In order to understand its applicability it was tested in a controlled laboratory environment. We tried various optical configurations and different data processing methods, such as Projection on convex sets and finite elements. In edition it is presented that a simple silicon wafer, on the back of which porous silicon is etched, can serve as deformable mirror. This is the first report, to our knowledge, of the piezoelectric and piezo-optic response of porous silicon.

Known the wave-fronts of the ICF amplifiers is very important for improving the design and adjustment of the amplifiers and designing the adaptive optical system that can be used to shape the beam or clean it up. Because the pulse of ICF laser is ns scale, the wave-front can not be measured with common methods. In this paper, a method with a Hartmann-Shack wave- front sensor based on the progressive scan CCD camera is introduced. The test results show that this method is effective.

Wavefront reconstruction techniques using the least-squares estimators are computationally quite expensive. We compare wavelet and Fourier transforms techniques in addressing the computation issues of wavefront reconstruction in adaptive optics. It is shown that because the Fourier approach is not simply a numerical approximation technique unlike the wavelet method, the Fourier approach might have advantages in terms of numerical accuracy. To optimize the wavelet method, a statistical study might be necessary to use the best basis functions or 'approximation tree.'

Spatial and temporal properties of spontaneously pattern generations in an optoelectronic system composed of an electronically addressable spatial light modulator, detector array, and two-dimensional optical feedback are experimentally demonstrated. The square root dependence of the main spatial frequency of the generated pattern on the positive and negative diffraction lengths of the optical feedback under the inversion property of the spatial light modulator is presented. The optoelectronic system has a serial process, but the property of the pattern generation are almost equivalent to them in an all-optical system based on an optically addressed spatial light modulator. The optoelectronic feedback system can function as the simulator of a two-dimensional optical system and the controller for an all-optical system, because it has the wide range of control parameters and high conductivity to an electronic system. We demonstrate the simulation of the optical system including many spatial light modulators and the dynamic control of the optical feedback system.

An opto-electronic technique for high-resolution wave-front phase imaging is presented and demonstrated experimentally. The technique is analogous to the conventional Zernike phase- contrast approach, but uses modern spatial light modulator technology to increase robustness and improve performance. Because they provide direct measurements of wave-front phase (rather than wave-front slope measurements, as in Shack- Hartmann sensors), robust phase-contrast sensors have potential applications in high-speed, high-resolution adaptive optic systems. Advantages of the opto-electronic approach over alternative advanced phase-contrast techniques (such as a related phase-contrast sensor which uses a liquid-crystal light valve exhibiting a Kerr-type optical response to perform Fourier filtering) are discussed. The SLM used for the experimental results is a 128 X 128-element pixilated phase-only liquid crystal spatial light modulator from Boulder Nonlinear Systems, Inc.

We show that custom adaptive very large scale integrated (VLSI) circuit controllers can directly control commercially available wavefront phase correctors. These controllers achieve real-time wavefront compensation under conditions of strong intensity scintillations. Their control strategy is based on the optimization of a measurable performance index. Optimization is carried out using parallel perturbative stochastic gradient descent. We describe VLSI image-plane processors designed to compute a variety of application specific performance metrics in real-time.

We have developed a high-resolution wavefront control system based on an optically addressed nematic liquid crystal spatial light modulator with several hundred thousand phase control points, a Shack-Hartmann wavefront sensor with two thousand subapertures, and an efficient reconstruction algorithm using Fourier transform techniques. We present quantitative results of experiments to characterize the performance of this system.

An adaptive laser beam focusing system comprising a 4 X 4 segment (5 X 5 actuator) MEMS deformable mirror developed at Boston University is presented. Mirror actuators were controlled by a circuit using VLSI chips implementing a stochastic parallel gradient descent algorithm. The system allowed for an enhancement of the iteration rate up to 5900 s^-1, limited only by the used computer equipment. Results of experiments for characterization of the MEMS mirror response and the adaptation speed of the system are reported. A further improvement of adaptation speed was achieved by modification of the control algorithm implementing a self- optimization of one parameter.

A conventional Zernike filter measures wavefront phase by superimposing the aberrated input beam with a phase-shifted version of its zero-order spectral component. The Fourier- domain phase-shifting is performed by a fixed phase-shifting dot on a glass slide in the focal plane of a Fourier- transforming lens. Using an optically-controlled phase spatial light modulator (SLM) instead of the fixed phase-shifting dot, we have simulated and experimentally demonstrated a nonlinear Zernike filter robust to wavefront tilt misalignments. In the experiments, a liquid-crystal light valve (LCLV) was used as the phase SLM. The terminology 'nonlinear' Zernike filter refers to the nonlinear filtering that takes place in the Fourier domain due to the phase change for field spectral components being proportional to the spectral component intensities. Because the Zernike filer output intensity is directly related to input wavefront phase, a parallel, distributed feedback system can replace the wavefront reconstruction calculations normally required in adaptive- optic phase correction systems. Applications include high- resolution phase distortion suppression for atmospheric turbulence, optical phase microscopy, and compensation of aberrations in optical system components. A factor of eight improvement in Strehl ratio was obtained experimentally, and simulation results suggest that even better performance could be obtained by replacing the LCLV with a more sophisticated optically-controlled phase SLM.

An amplitude modulated laser radar has been developed by ENEA (Italian Agency for New Technologies, Energy and Environment) for periodic in-vessel inspection in large fusion machines. Its overall optical design has been developed taking into account the extremely high radiation levels and operating temperatures foreseen in large European fusion machines such as JET (Joint European Torus) and ITER (International Thermo- nuclear Experimental Reactor). The viewing system is based on a transceiving optical radar using a RF modulated single mode 840 nm wavelength laser beam. The sounding beam is transmitted through a coherent optical fiber and a focusing optic to the inner part of the nuclear reactor vessel by a stainless steel probe on the tip of which a suitable scanning silica prism steers the laser beam along a linear raster spanning a -90 degree(s) to +60 degree(s) in elevation and 360 degree(s) in azimuth for a complete mapping of the vessel itself. All the electronics, including the laser source, avalanche photodiode and all the active components are located outside the bioshield, while passive components (receiving optics, transmitting collimator, fiber optics), located in the torus hall, are made of fused silica so that the overall laser radar is radiation resistant. The signal is acquired, the raster lines being synchronized with the aid of optical encoders linked to the scanning prism, thus yielding a TV like image. Preliminary results have been obtained scanning large sceneries including several real targets having different backscattering properties, colors and surface reflectivity ranging over several decades to simulate the expected dynamic range of the video signals incoming from the vessel.

Electro-optical (EO) sensors on future aerospace systems will require extensive beam delivery control. While both beam shaping and steering have been demonstrated in the past, simultaneous demonstration of these techniques (for a common aperture) has not. We demonstrate the use of phase-retrieval based algorithms which has been previously used for simultaneous beam shaping and steering in the far field. Experimental results using a segmented, phase-only, liquid crystal wavefront control device are presented.

This paper reports the use of Laser Induced Fluorescence (LIF) of plants to discriminate between crops and weeds for potential use in an intelligent crop spraying system. Past and current work in intelligent crop spraying has concentrated on using multi-spectral reflectance data in particular using near infrared (NIR) and color. Texture and shape image processing has also been used with limited success and is usually computationally expensive. Also, most of these approaches are error prone since they rely on ambient solar illumination and so are susceptible to errors caused by cloud variations, shadows and other non-uniformities. There are several commercial spraying systems available that detect presence or absence of plants using the NIR 'red-edge' effect without discrimination between species. 'Weedseeker' and 'Detectspray' are two examples of such systems, the 'Weedseeker' system being one of the few active systems, incorporating its own light source. However, both systems suffer from poor spatial resolution. The use of plant or chlorophyll fluorescence for discrimination between species is a relatively under researched area. This paper shows that LIF of several crops and weeds can be used to discriminate between species. Spectra are presented for two crop and two weed species over a range of discrete laser excitation wavelengths. The technique can be directly implemented with a laser imaging system for real-time detection and discrimination of crops and weeds.

We demonstrate the utility of laser illuminated imaging for clandestine night time surveillance from a simulated airborne platform at standoff ranges in excess 20 km. In order to reduce the necessary laser per pulse energy required for illumination at such long ranges, and to mitigate atmospheric turbulence effects on image resolution, we have investigated a unique multi-frame post-processing technique. It is shown that in the presence of atmospheric turbulence and coherent speckle effects, this approach can produce superior results to conventional scene flood illumination.

Large deployable space-based optical systems will likely require complex structure position controls in conjunction with an adaptive optic to maintain optical tolerances necessary for near diffraction-limited performance. A real- time holographic (RTH) compensation system can greatly reduce the requirements and complexity of the position control system and enable the use of novel or imperfect optical components for large mirror surfaces. A hologram of the distorted primary is recorded with a local beacon at 532 nm (approximately 100 nJ/exposure) on an optically addressed spatial light modulator and transferred as a phase grating to a ferroelectric liquid crystal layer. The hologram is played back with target light containing the same optical distortion. A corrected image is obtained in the conjugate diffracted order where the phase of the optical distortion is subtracted from the distorted image. We report recent test results and analysis of a RTH- compensated deformed mirror of 0.75 m diameter. The short exposure hologram is recorded at video frequencies (30 Hz) at bandwidths up to 5 kHz. Correction for tens of waves of static and dynamic optical distortions including mechanical and thermal warp, mechanical vibration, and air turbulence are shown for monochromatic (532 nm) and broadband (532 +/- 40 nm) illuminated targets. We also report on the generation of blazed gratings in electrically addressed spatial light modulators to achieve greatly enhanced diffraction efficiencies and to perform beam steering.

Paper presents the results of experimental demonstration of dynamic holographic correction in mid-IR, using optically addressed liquid crystal spatial light modulators and method of two-wavelength holography, when the hologram is recorded at one wavelength and reconstructed at some shifted wavelength. On such a basis one can realize the dynamic interferometer, providing the arbitrary scaling of the wave front distortions and thus to record the dynamic hologram on the differential wavelength, which can be used for dynamic holographic correction of distortions in mid-IR. Method feasibility was confirmed in experiment.

The reflective type optically addressed spatial light modulators (OASLMs) with an amorphous hydrogenated carbon (a- C:H) light-blocking layer (LBL) sandwiched between an intrinsic hydrogenated silicon carbide (a-Si:C:H) photoconductor and broad-band and narrow-band dielectric mirrors have been developed. FLC was used as a light modulating medium. The DHF effect in an FLC with tilt angle (Theta) equals 39 degrees and SS (Clark-Lagerwall) effect with angle 22,5 degree(s) were employed. The study showed that a flexible design of the OASLMs are possible. As a result of optimal design of the reflective type OASLMs with the dielectric mirrors of two types, the following performance characteristics have been obtained. Diffraction efficiency (DE) was about 30%, net diffraction efficiency (NE) was about 20% (spatial frequency equal 30 lp/mm and frame refreshment rate equal 200 Hz). This net diffraction efficiency practically does not depend on the direction of the reading- out light polarization for the OASLMs operating on the DHF mode.

The model of laser signal, reflected from the object, observed through the scattering layer medium is constructed on the basis of one-dimensional transfer equation exact solution. Optimum threshold algorithm of detection is developed. Detection characteristics are calculated. Layers parameters combinations, providing maximum camouflage effect, are analyzed.

The Air Force Research Laboratory is using a small-scale heterodyne laser radar (ladar) system for range-resolved imaging, among other applications. This system, called the Heterodyne Imaging Laser Testbed (HILT), is used for obtaining pulsed reflection returns from targets that are located on the ground at a distance of approximately 1 km. Over the past year, the resolution of the HILT's reflection tomographic images has improved from approximately 30 cm to approximately 10 cm. Presented in this paper are a description of HILT and tomographic image reconstructions of ground targets.