Low-cost Mirror Research Articles

Low Computational Cost Mirror Kirchhoff Approximation for Predicting Shadowing Effect

This paper proposes a 2-dimensional low computational cost mirror Kirchhoff approximation (MKA) and the design of simulation parameters to accurately predict the shadowing gain for an arbitrarily shaped conductor cylinder. The disadvantages of the conventional MKA, such as lacking designs for the simulation parameters and a limited applicable range, have motivated the establishment of an extended MKA. The authors propose the design of the simulation parameters for MKA. The applicable range of MKA is extended to an arbitrarily shaped cylinder by multiple planes. This work finds that only the space domain of the zeroth plane and the angular spectrum domain of the last plane need separate windowing functions for accuracy and the calculation time. The details of those windowing functions are introduced, and their necessities are explained. The authors validate the proposed method for an elliptical conductor cylinder with the size of the human body at millimeter waves (17 GHz – 66.5 GHz). Simulations are conducted by changing the object’s location, direction, and frequencies. The results show that the proposed method presents a good accuracy, which has a low root-mean-square error of less than 0.5 dB by comparing it with a full-wave approach based on the method of moment. Furthermore, the calculation time is improved by 1.4 – 67.2 times by comparing it with the uniform theory of diffraction using special functions.

Mirror Surface Machining of Steel by Elliptical Vibration Cutting with Diamond-Coated Tools Sharpened by Pulse Laser Grinding

Low-cost mirror surface machining of die steel is proposed in this research by applying elliptical vibration cutting with diamond-coated tools sharpened by pulse laser grinding (PLG). It is well known that conventional diamond cutting cannot be applied to die steel owing to rapid tool wear. Several attempts have been reported to prevent rapid tool wear, such as using ultrasonic elliptical vibration cutting. The ultrasonic elliptical vibration cutting developed by the authors to achieve mirror surface finish on die steel and prevent rapid wear is widely used in the industry. However, high-cost single-crystalline diamond tools that are finished using a time-consuming lapping process are required to obtain mirror surfaces. The authors, meanwhile, have recently developed the PLG process to efficiently sharpen the cutting edges of hard tool materials such as cubic boron nitride. Therefore, a practical mirror surface machining method for die steel is proposed in this research, namely elliptical vibration cutting with low-cost diamond-coated tools sharpened by the efficient PLG process. The results of the machining experiments confirmed that practical mirror surface machining of die steel can be achieved by the proposed method.

Design and Modeling of Polysilicon Electrothermal Actuators for a MEMS Mirror with Low Power Consumption.

Endoscopic optical-coherence tomography (OCT) systems require low cost mirrors with small footprint size, out-of-plane deflections and low bias voltage. These requirements can be achieved with electrothermal actuators based on microelectromechanical systems (MEMS). We present the design and modeling of polysilicon electrothermal actuators for a MEMS mirror (100 μm × 100 μm × 2.25 μm). These actuators are composed by two beam types (2.25 μm thickness) with different cross-section area, which are separated by 2 μm gap. The mirror and actuators are designed through the Sandia Ultra-planar Multi-level MEMS Technology V (SUMMiT V®) process, obtaining a small footprint size (1028 μm × 1028 µm) for actuators of 550 µm length. The actuators have out-of-plane displacements caused by low dc voltages and without use material layers with distinct thermal expansion coefficients. The temperature behavior along the actuators is calculated through analytical models that include terms of heat energy generation, heat conduction and heat energy loss. The force method is used to predict the maximum out-of-plane displacements in the actuator tip as function of supplied voltage. Both analytical models, under steady-state conditions, employ the polysilicon resistivity as function of the temperature. The electrothermal-and structural behavior of the actuators is studied considering different beams dimensions (length and width) and dc bias voltages from 0.5 to 2.5 V. For 2.5 V, the actuator of 550 µm length reaches a maximum temperature, displacement and electrical power of 115 °C, 10.3 µm and 6.3 mW, respectively. The designed actuation mechanism can be useful for MEMS mirrors of different sizes with potential application in endoscopic OCT systems that require low power consumption.

Dish systems for CSP

Abstract Parabolic dish technology, for concentrating solar power (CSP) applications, has been continuously modified and improved since the pioneering work in the 1970s. Best practice dishes now have features such as lightweight structure, balanced design, high-quality, low-cost mirror panels, and can be deployed rapidly with little in-field labour. This review focuses on the evolution of dish design, by examining features such as mode of tracking, structure and mirror design, for a wide selection of CSP dish examples. The review includes a brief summary of power generation options – both on-dish and central plant – as well as a discussion about options for storage and hybridisation.

A low-cost mirror mount control system for optics setups

We describe a flexible, simple to build, low-cost, and computer-controlled optical mirror actuator system, developed for undergraduate research laboratories. Geared motors for hobby robotics are controlled by an Arduino microcontroller in combination with an H bridge to finely position mirror mount actuators. We present a graphical user interface based on the Python script language. The price of the fully controlled actuator system is only a small fraction of the price of a commercial system. It can be quickly implemented due to the use of open-hardware electronics. We discuss the performance of the system and give an outlook for future expansions and use in advanced optical setups.

Concept, modeling, and performance prediction of a low-cost, large deformable mirror

While it is attractive to integrate a deformable mirror (DM) for adaptive optics (AO) into the telescope itself rather than using relay optics within an instrument, the resulting large DM can be expensive, particularly for extremely large telescopes. A low-cost approach for building a large DM is to use voice-coil actuators connected to the back of the DM through suction cups. Use of such inexpensive voice-coil actuators leads to a poorly damped system with many structural modes within the desired bandwidth. Control of the mirror dynamics using electro-mechanical sensors is thus required for integration within an AO system. We introduce a distributed control approach, and we show that the "inner" back sensor control loop does not need to function at low frequencies, leading to significant cost reduction for the sensors. Incorporating realistic models of low-cost actuators and sensors together with an atmospheric seeing model, we demonstrate that the low-cost mirror strategy is feasible within a closed-loop AO system.

Low-cost dichroic mirrors for future Deep Space ground stations

Future Deep Space (DS) ground stations envisioned by running projects funded by major space agencies are based on arrays of reflector antennas operating in different frequency bands. Therefore, a multi-band feeding system is required for each antenna, and a possible solution foresees the use of dichroic mirrors to separate/combine different beams. This paper presents a low-cost and fast manufacturing process for the fabrication of dichroic mirrors, usually referred to as punching technique or metal stamping. In particular, the specific advantages and limits of this fabrication technique are outlined and discussed, showing both electrical performance and manufacturing accuracy measurements from a test prototype. In addition, a typical scenario for future DS ground stations is described, showing the impact of these low-cost dichroic mirrors on the final ground station performance and cost, compared to the standard approach for dichroic mirror manufacturing based on more expensive and time-consuming technologies (e.g. milling machining).

Observations of artificial and natural optical emissions at the HAARP facility

Abstract. Extensive optical observations have been carried out at the High Frequency Active Auroral Research Program (HAARP) ionospheric heating facility since it began operations in 1999. A number of modern optical diagnostic instruments are hosted at remote sites as well as the main transmitter facility, which has recently been expanded from the initial 960 kW prototype configuration to its full 3.6 MW design capability. Upgrades to optical diagnostics have allowed a number of interesting new observations to be made at the 960 kW power level since 2004. Systematic beam-swinging experiments generating quantifiable levels of optical emission at various regions in the sky for the first time clearly show that emission intensity is very sensitive to distance from the magnetic zenith, and drops off rapidly at about 15° zenith angle in directions other than magnetic south. High temporal resolution measurements of emissions in the 557.7 nm green line at start-up and in short transmitter pulses demonstrate that localized irregularities are preferentially excited in the initial seconds of heating, with evolution into a more homogenous spot occurring over a period of about 1 min. High-quality emission altitude profiles at both 630.0 and 557.7 nm have recently been isolated from side-looking data, spanning an altitude extent of over 200 km, which has allowed determination of the effective lifetime of O (1D) over an unprecedented altitude range. An innovative automated remote imager network utilizing low-cost mirror optics has been designed and deployed to make such measurements routinely. Observations of natural optical emissions at the site have revealed the common presence of highly structured but faint co-rotating subauroral precipitation that acts to suppress excitation of artificial F region optical emissions in areas of active precipitation. The observed spatial modulation of artificial optical emissions by structured precipitation is consistent with localized absorption of HF waves in the ionospheric D layer enhanced by the energetic particle precipitation.

Adaptive optics with a programmable phase modulator: applications in the human eye

Adaptive optics for the human eye has two main applications: to obtain high-resolution images of the retina and to produce aberration-free retinal images to improve vision. Additionally, it can be used to modify the aberrations of the eye to perform experiments to study the visual function. We have developed an adaptive optics prototype by using a liquid crystal spatial light modulator (Hamamatsu Programmable Phase Modulator X8267). The performance of this device both as aberration generator and corrector has been evaluated. The system operated either with red (633nm) or infrared (780nm) illumination and used a real-time Hartmann-Shack wave-front sensor (25 Hz). The aberration generation capabilities of the modulator were checked by inducing different amounts of single Zernike terms. For a wide range of values, the aberration production process was found to be linear, with negligible cross-coupling between Zernike terms. Subsequently, the modulator was demonstrated to be able to correct the aberrations of an artificial eye in a single step. And finally, it was successfully operated in close-loop mode for aberration correction in living human eyes. Despite its slow temporal response, when compared to currently available deformable mirrors, this device presents advantages in terms of effective stroke and mode independence. Accordingly, the programmable phase modulator allows production and compensation of a wide range of aberrations, surpassing in this respect the performance of low-cost mirrors and standing comparison against more expensive devices.

Micromirror array for protein micro array fabrication

We have designed, fabricated and characterized a micromirror array for protein microarray fabrication that has a simple structure, and the straightforward fabrication process for the mirror will allow the use of low-cost mirrors in protein pattern applications. The characteristics of an exposure system utilizing the micromirror array have been demonstrated by means of an experiment employing a photoresist that is in general use in the semiconductor industry. The micromirror dimensions were 54 × 54 μm2, with a 30 μm separation between mirrors, and a 5.5 μm gap from the bottom electrode so that the mirror had an approximately 10° deflection angle. The size and separation of the mirror were designed in consideration of the protein pattern size and pitch, in contrast with the commercial Texas Instruments Digital Light Processor, which is utilized in the components of projection display systems. The exposure system combined with the micromirror has been used in the photochemical synthesis of chemical ligands via protein immobilization on a chip. Several photosynthesis experiments for peptide array synthesis have been carried out using the micromirror array. Parallel experiments on photochemical ligand synthesis on a chip can easily be performed in the laboratory using this exposure system.

Calibration of a low-cost piezoelectrical mirror for DSPI

A cheap piezoelectrically driven mirror can be easily constructed in the laboratory. It can be located in one arm of a DSPI interferometer in order to introduce a controlled phase step. A procedure to calibrate this device is shown, that is based on the evaluation of the fringes obtained with the interferometer, by mean of the cross-correlation between profiles of the fringes. To evaluate the performance of the calibrated device, the phase map of a simulated plane object is calculated, using the four-step algorithm for the images of a speckle interferogram.

Low-cost adjustable mirror mount

Complex optical systems commonly employ adjustable optical mounts for alignment purposes. The design of a low-cost adjustable mirror mount that provides simple tilt and height adjustments is described. This mirror mount employs conventional machining and standard off-the-shelf hardware and is, therefore, very suitable for low-cost rapid prototyping applications. A diamond-machined metal mirror is directly assembled to the mount with three screws and two precision dowel pins. The adjustments are provided by three spring-loaded screws between the mount and a fixed base plate. Two set screws are used for locking purposes after the adjustments have been made.

ICF-related experiments at CEL-V

Implosion experiments performed at Centre d'Etudes de Limeil-Valenton in the indirect drive scheme using the two-beams Nd:glass laser facility Phebus at the energy level = 6 kJ (blue light) are presented. A final density of compressed DT close to 100 ρ0 has been obtained; it has been deduced from radiochemistry of the activated silicon atoms in the pusher. The best irradiance uniformity on the microballoon was evaluated to = 15% rms. Phebus has also been equipped with an optical fiber oscillator to study the effect of a smoothing technique on coupling processes: It appeared that at 0·53 μm absorption efficiency is increased by =15–20%. With the eight-beams Octal laser, hydrodynamic instabilities development in accelerated planar targets has been investigated both for direct and indirect drives; the mixing zone detected at the light-heavy interface does not present visible bubble-and-spike like structures and is less developed in the indirect configuration. Atomic physics in laser plasmas is also deeply studied; a particular effort has been made on absorption spectroscopy, a powerful diagnostic of ionization dynamics in cold and dense plasmas. Experiments have been realized either in multilayered targets or using rear-side X-ray emission of thin Au foils to heat the samples. To reach fuel ignition conditions, more powerful lasers, in the range of megajoule, will be needed. Their design needs further technological developments to reduce the capital cost in $/W. At Limeil, we work mainly on high-damage threshold optical coatings, using the sol-gel process, high-quality, low-cost mirror fabrication, using the replica technics, and incoherent laser pulse generation for beam smoothing.

A Holographic Interferometer for Measuring Radiation Energy Deposition Profiles in Transparent Liquids

An apparatus has been designed for real-time and double-exposure holographic interferometry to determine radiation absorbed dose distributions in transparent liquids. The change in refractive index of the liquid due to a temperature rise after irradiation is measured interferometrically. In a cylindrically symmetrical radiation field, the dose distribution can be computed from data supplied by the reconstruction of the holographic interferogram taken as side-view profile of the change in optical pathlength. Relatively inexpensive components such as a low-powered He-Ne laser together with a conventional photographic shutter and low-cost mirrors and lenses were used. The mathematical procedure for unfolding the three-dimensional dose distribtion is described, and an example is given for use with a high-intensity, pulsed, 2-MV electron source.