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We propose new instrumentation to measure the refractive index (RI) of transparent liquids as a function of temperature. The physical phenomenon used to carry out the measurement is the light refraction that occurs in transparent liquids. A width change in a reference object is produced by light refraction, which is related to the RI. Image processing was used to measure the object width using an image from a digital microscope. The instrument measures the RI from a range of 15°C to 100°C with an accuracy of 10 − 4 % . The measurement procedure was calibrated with distilled water and acetonitrile samples, and the Sellmeier and Cauchy equation was used to compare our results. Finally, as an appropriate application, the RI of lophine in a solution was measured.

We present a method for modeling gravitational lensing as gradient-index lenses in the ray-tracing software CODE V. When applied to gravitational lensing by the Sun, these models yield results in agreement with theoretical and experimental results. The extension of this type of model to “lumpy” astronomical objects whose lensing behavior is difficult to predict with traditional methods is discussed.

We analyze the Crown of Light (COL) cut using an angular spectrum evaluation tool. Several light performing features of the COL are discussed. In particular, it is found that the angular spectrum of the COL tends to be concentrated and that this maximizes the brilliance and sparkle probability when the COL is aimed at localized light sources. It is contended that the COL represents a novel paradigm in diamond cuts. A distinctive feature of the COL cut is its dome shaped crown.

For two decades, extraordinary optical transmission (EOT) has amplified exploration into subwavelength systems. Researchers have previously suggested exploiting the spectrally selective electromagnetic field confinement of subwavelength slits for multispectral detectors. Utilizing the finite-difference frequency domain (FDFD) method, we examine electromagnetic field confinement in both 2-dimensional and 3-dimensional scenarios from 2.5 to 6 microns, i.e. midwave infrared (MWIR). We explore the trade space of deep subwavelength slits and its impact on resonant enhancement of the electromagnetic field. This builds fundamental understanding of the coupling mechanisms allowing for prediction of resonant spectral behavior based on slit geometry and material properties.

The performance of free-space optical applications can be improved using beams of different wavelengths for the auxiliary actions of pointing/tracking or turbulence correction. Chromatic dispersion owing to the atmosphere is an issue for multiwavelength systems, and the dispersion of electromagnetic signals is typically predicted based on refractive conditions from standard atmospheric models. However, for long near-horizontal paths near the Earth’s surface, substantial refractive index gradients that are associated with features such as inverse temperature layers and ducts can be encountered. These features can significantly alter the ray trajectory, the chromatic divergence, and the angle of arrival of directional beams relative to standard atmosphere predictions. A ray tracing approach was implemented to examine the chromatic divergence and angle of arrival of the rays through various practical and extreme atmospheric conditions involving a temperature inversion layer. Over a distance of 150 km along the ground, a brief encounter with the layer can cause pairs of rays with wavelengths 532 and 1550 nm to diverge up to 4.5 times greater than their standard atmosphere predictions. For a single wavelength, a linear increase of angle of arrival with initial launch angle was found for the standard atmosphere, but this trend was significantly altered in the presence of an inversion layer. Extreme refractive conditions with a large inversion layer were simulated to produce optical ducting over long distances. Chromatic separation of rays as large as 280 m was observed when only one of the two wavelengths remained in the duct.

We propose two energy-mapping methods to produce a uniformly illuminated area for a nontilted (straight) and a tilted light source toward a target plane. These energy-mapping methods define the positions of the desired points (the destination points of the refracted rays of a light source) on an illuminated area. The surface of the lenses can then be formed through the position of the desired points. Based on these design methods, two freeform lenses, (i) a symmetric lens and (ii) an asymmetric lens, were designed to provide uniformity within a rectangular illumination footprint for a nontilted and a tilted light source, respectively. This method can produce uniformity for a tilted light source within 0 deg to 45 deg toward the normal vector on the target plane. Two freeform lenses for 0 deg and 20 deg tilted toward a target plane were designed. The illumination footprint of the symmetric and asymmetric freeform lenses was evaluated through ray-tracing simulations and experiments. Both models produce over 90% uniformity within an illuminated area.

Accurate simulation and forecasting of over-the-horizon propagation events are essential for various civilian and defense applications. We demonstrate the prowess of a newly proposed coupled mesoscale modeling and ray tracing framework in reproducing such an event. Wherever possible, routinely measured meteorological data from various platforms (e.g., radar and satellite) are utilized to corroborate the simulated results.

In order to obtain the precise three-dimensional (3-D) points of underwater objects, we propose a corresponding pixel matching algorithm based on coplanar constraint for underwater laser scanning systems. It uses three coplanar constraints of left camera, right camera, and laser plane to achieve high-precision and high-speed pixel matching according to the characteristics of underwater laser scanning system. Results show that the measurement error is

We devote this article to the spectral analysis of volume holograms recorded in materials with diffusion-based formation mechanisms. Two media of different natures were examined: polymer material with dye molecules photoattachable to macromolecules (PQ-PMMA) and photochromic additively colored fluorite crystal (CaF2). Differential spectra of holograms refractive index and absorbance were determined by two approaches: numerical approximation of both spectral and angular hologram response (selectivity hypercontour) by coupled-wave theory and processing hologram spectra by Kramers–Kronig dispersion relations. The principles of the two approaches, results of their application, and advantages and disadvantages are discussed. Kramers–Kronig relations can be usefully applied in cases where the nature of holograms formation is well studied, whereas the hypercontour approach is indispensable for obtaining the values of absorbance and refractive index modulation; therefore, a combination of both the techniques is a powerful tool for fundamental investigation of the hologram formation mechanisms.

X-ray phase-contrast imaging has experienced rapid development over the last few decades, and, in this technology, the phase modulation strategy of phase stepping (PS) is used most widely to measure the sample’s phase signal. However, because of its discontinuous nature, PS has the defects of worse mechanical stability and high exposure dose, which greatly hinder its wide use in dynamic phase measurement and potential clinical applications. We demonstrate preliminary research on the use of integrating-bucket (IB) phase modulation method to retrieve the phase information in grating-based x-ray phase-contrast imaging. Experimental results show that our proposed method can be well employed to extract the differential phase-contrast image, compared with the commonly used PS strategy, the advantage of the IB phase modulation technique is that fast measurement and low dose are promising.

CdS quantum dots (QDs) embedded in a phosphate glass matrix were investigated. The time-resolved Z-scan technique was used to determine the nonlinear refraction and absorption for different concentrations of CdS QDs. The results indicate that the nonlinear absorption presents a reverse saturable character, which is a desirable feature in the design of optical limiting devices. In addition, strong experimental evidence that the main contribution onto the refractive index variation is not of thermal origin was found. The observed variation presents a character similar to an electronic-like effect. These evidences are supported by numerical simulations.

The availability of more affordable, high resolution, infrared (IR) detector arrays has opened up the need for a larger set of IR materials. This has created a renewed interest in chalcogenide glasses as their transmission spans from 1 to 14 μm. The Naval Research Laboratory has shown that the chalcogenide glasses can be diffused to make gradient index (GRIN) lenses. GRIN materials are interesting because they can have unique dispersion properties that do not exist in the currently discovered homogeneous materials, a key parameter for optical designers. When fabricating a GRIN material, the ability to test and characterize its properties is essential. This has prompted the need and development of an IR Mach–Zehnder interferometer for relative index of refraction measurements of GRIN materials. These same, more affordable IR detector arrays have also allowed for what was commonly done in the visible to be developed in the IR. Now, two-dimensional change in refractive index can be measured without scanning, and the fringe density becomes less of an issue in the IR, allowing for larger changes in refractive index over a small area to be measured. An axial chalcogenide GRIN with Δn of 0.13 was measured at a wavelength of 3.39 μm.

An effective correction model is proposed to eliminate the refraction error effect caused by an optical window of a furnace in digital image correlation (DIC) deformation measurement under high-temperature environment. First, a theoretical correction model with the corresponding error correction factor is established to eliminate the refraction error induced by double-deck optical glass in DIC deformation measurement. Second, a high-temperature DIC experiment using a chromium–nickel austenite stainless steel specimen is performed to verify the effectiveness of the correction model by the correlation calculation results under two different conditions (with and without the optical glass). Finally, both the full-field and the divisional displacement results with refraction influence are corrected by the theoretical model and then compared to the displacement results extracted from the images without refraction influence. The experimental results demonstrate that the proposed theoretical correction model can effectively improve the measurement accuracy of DIC method by decreasing the refraction errors from measured full-field displacements under high-temperature environment.

We present a simple and cost-effective method for the fabrication of optical elements in the terahertz regime. Caramelized sucrose is used as the refractive medium in the frequency range from 0.1 to 0.4 THz. The absorption coefficient of 7 cm−1 and the high index of refraction of 2.45 at 0.3 THz enables the fabrication of thin optical elements in the near-millimeter wavelength range. The THz beam profiles of the fabricated parabolic lens in focus, evaluated with terahertz pulsed imaging, show the near diffraction limit performance.

Using additive manufacturing techniques in optical engineering to construct a gradient index (GRIN) optic may overcome a number of limitations of GRIN technology. Such techniques are maturing quickly, yielding additional design degrees of freedom for the engineer. How best to employ these degrees of freedom is not completely clear at this time. This paper describes a preliminary design philosophy, including assumptions, pertaining to a particular printing technique for GRIN optics. It includes an analysis based on simulation and initial component measurement.

An optically magnifying device for viewing a distant object is proposed. Since this device can be made in the form of a thin plate and can also have a large viewing area, a flat-plate magnifier is realized. The flat-plate magnifier mounted onto an eyeglass frame as a substitute for each lens provides a light-weight, hands-free magnifier. The flat-plate magnifier is made as a 3 to 4-mm-thick plastic plate and can be made up to 30 to 40 mm in diameter. The flat-plate magnifier is a two-dimensional array of magnifying modules and each magnifying module consists of a micromagnifier and a ray angle adjuster. The micromagnifier comprises a concave mirror and a convex mirror and magnifies the view. The ray angle adjuster is a transparent wedge and expands the viewing area. The flat-plate magnifier is designed so that the achromatic condition is satisfied by cancelling the angular dispersion produced by the micromagnifier with that of the ray angle adjuster. A prototype of the flat-plate magnifier with a diameter of 9 mm and a magnification power of 3 was demonstrated.

We consider optomechanical effects that are related to the appearance of an additional optical phase due to the motion of an ultradispersive medium and the rotational Doppler effect for light. We have theoretically shown that the enhanced Fizeau effect on atoms in a cavity can be observed and the change of phase is sensitive to the mechanical motion. These two effects can be applied to the measurement of rotations as small as 10−17 s−1 Hz1/2. It is worth noting here that the measurement of rotation is not related to Sagnac interferometry.

A three-dimensional (3-D) display system for medical objects by holographic technique has been developed. A shiftable cylindrical lens is introduced to refract the 3-D images projected from the spatial light modulator. The viewing region of the refracted image changes with the position of the cylindrical lens. Through an imaging lens, the refracted images with different viewing regions are imaged into the same target object and a 3-D medical display with an enlarged viewing angle is implemented based on time-multiplexing method. The displayed object can be viewed within 17 deg at the front of the display.

We present a numerical study of the near-surface underwater solar light statistics using the state-of-the-art Monte Carlo radiative transfer (RT) simulations in the coupled atmosphere-ocean system. Advanced variance-reduction techniques and full program parallelization are utilized so that the model is able to simulate the light field fluctuations with high spatial [O(10 −3 mm) ] and temporal [O(10 −3 mm) ] resolutions. In particular, we utilize the high-order correction technique for the beam-surface intersection points in the model to account for the shadowing effect of steep ocean surfaces, and therefore, the model is able to well predict the refraction and reflection of light for large solar zenith incidences. The Monte Carlo RT model is carefully validated by data-to-model comparisons using the Radiance in a Dynamic Ocean (RaDyO) experimental data. Based on the model, we are particularly interested in the probability density function (PDF) and coefficient of variation (CV) of the highly fluctuating downwelling irradiance. The effects of physical factors, such as the water turbidity of the ocean, solar incidence, and the detector size, are investigated. The results show that increased turbidity and detector size reduce the variability of the downwelling irradiance; the shadowing effect for large solar zenith incidence strongly enhances the variability of the irradiance at shallow depths.

We proposed a new design method for single freeform reflective (or refractive) surface tailored to redistribute the radiant flux onto a prescribed illumination pattern. Unlike the conventional optimization approaches based on the grid mapping, in this study we estimated each segmental freeform surface by locally solving a second-order differ- ential equation, which formulates the energy transportation between each domain cell. With finite element method via Hermite element, we validated a series of smooth reflective/refractive surfaces to reallocate the radiant flux from a point source toward a target plane with specific patterns. The proposed technique offers a large flexibility by varying the vectors of each ray with multiple refraction (or reflection), which imposes no restric- tion on the target distribution, collective solid angle, or even target topog- raphy. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attri- bution of the original publication, including its DOI. (DOI: 10.1117/1.OE.53.3.031307) Subject terms: freeform design; uniform illumination; nonimaging optics.

The design equations of a freeform single lens optical systems for redistributing the input radiation in a prescribed manner over a given target set are presented in explicit form. These equations are derived here and their analysis is carried out in geometrical optics approximation. The qualitative properties of solutions to such problems are discussed in detail and illustrated by examples. Difficulties arising in numerical computations of solutions in the rotationally symmetric case are also noted.

An infrared (IR, 3–5 and 8–12 μm)/microwave (MW, 2.7 GHz) micromirror array type of beam combiner was fabricated for test and analysis. A model based on transmission line theory, Snell’s law, and phase monopulse radar theory was built to analyze the boresight angle errors. Three types of boresight angle errors—inherent error, refraction-induced error and combiner inserting error—were calculated. The results indicated that combiner inserting error was the most important error. Using this theoretical model, a beam combiner was optimized, fabricated, and investigated experimentally. Measured by a phase monopulse radar, the boresight angle error introduced by the beam combiner was

A laser collimator is a narrow-field imaging system that is designed for near-diffraction-limited performance when operating at a single wavelength. Although a traditional design might consist of a homogeneous doublet, the design of an axial gradient-index (GRIN) singlet for such an application is described. The analysis begins with third-order aberration thin lens optical design principles in order to examine the effects of spherochromatism from the GRIN. The final design is optimized in CODE V® using GRIN aluminum oxynitride (ALON®), which allows for diffraction-limited operation from the visible through 5 μm. A tolerance analysis is performed on the slope, nonlinearity, and tilt of the GRIN profile in order to assess sensitivity to fabrication errors.

Over 100 doublets were designed using a polychromatic gradient-index (GRIN) design model to analyze the benefits of radial GRIN profiles in broadband visible to short-wave infrared (vis-SWIR) imaging system applications. The polychromatic GRIN design model can be applied to any GRIN material, but for this work, titania silicate glass was investigated. A multielement design study with Petzval lenses was performed to show improved color correction when using GRIN elements. Results from the doublet and Petzval designs illustrate that in broadband vis-SWIR imaging applications, GRIN can either improve system performance or reduce a cemented homogeneous doublet to a GRIN singlet.

The article explores the possibility of athermalizing a gradient-index (GRIN) lens so that the effective focal length (EFL) of the element remains constant over a change in temperature. This is accomplished by designing the lens so that the surface curvatures and index profile compensate for one another over a change in temperature to maintain constant optical power. The means to determine how the lens geometry and index profile change with temperature for both a homogeneous and radial GRIN are explained. An analytic model for the purpose of identifying athermalized GRIN singlets is described and validated against the previous work in this field. The model is used to identify an athermalized polymer radial GRIN element and compare it with four other polymer elements of the same focal length but different index profiles, including a homogeneous one. Comparison of these singlets in CODE V® optical design software shows that the athermalized GRIN element maintains its nominal EFL over a temperature change the best of the five in the group while the homogeneous element (having no GRIN profile to counteract the effect of temperature on the surface curvatures) has the poorest performance. A numerical model to analyze more complicated GRIN systems is discussed.

The need for affordable and sustainable ophthalmic systems for measurement and correction of refraction is well recognized. Power- adjustable spectacles based on the Alvarez principle (transversal lateral movement of two lenses) have emerged as an innovative technology for this purpose. Within this framework, our aim is to design a new power- adjustable sphero-cylindrical refractor. The system is comprised of two lenses and three independent lateral movements. The lenses have a pla- nar and a third-degree polynomial surface. They are arranged with their planar surfaces in contact, so that the incoming light is only refracted by two surfaces. First, we present the theory of such a system. Second, we propose an optical design methodology. Third, we provide a design example capable of measuring sphere powers ranging from −5.00 Dt o þ5.00 D and cross-cylinders from −2.00 D to 2.00 D. Finally, a prototype of the lenses was manufactured using free-form machining. © 2013 Society of

Here, an off-axis optical reflective integrator is designed to transform a parallel Gaussian beam into a uniform intensity beam with a rectangular cross section, which is used in solar simulation systems. The integrator is designed using the faceted structure based on geometrical optics and nonimaging optics, and fabricated by ultra-precision turning to achieve a high efficiency and precision. The advancement in this study is to reduce the stepwise discontinuity among the facets to make it applicable for turning. To improve existing refractive integrators that are large in size and complex in structure, the off-axis optical reflective integrator only needs a mirror that is simple and easy to use. Comparing with an existing reflective integrator whose substrate is a spherical surface, the integrator designed here by the edge ray tracing method is aimed to achieve a smooth connection with flat or conic facets, to reduce the image distortion caused by the large tilt angles, and the discontinuity among the facets. Both the simulations and experiments show that above 90% of illumination uniformity can be achieved using this new design.

Our acquaintance with rays and refraction is based on previous work carried out by scientists, practitioners, artisans, and optics users. Here a selection of illustrations from ancient books and documents is presented, testifying to the substantive development that took place at the turn of 1600. Achievements at the roots of our continuing advances in optical sciences are acknowledged. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE)

This paper describes a process for designing a faceted freeform Fresnel lens. Where a traditional Fresnel lens uses a profile revolved around a central axis, a freeform Fresnel lens uses individual triangular or trapezoidal facets that comprise a freeform surface. This type of lens combines the capability of a freeform surface with the benefits of a Fresnel lens, in particular: thin profile, low cost, small size, and relatively simple geometry calculations. An algorithm is presented to design such a lens that generates an output intensity distribution without depending on symmetry in the light source, the lens aperture, or the output intensity distribution. Two example systems are presented, demonstrating how a freeform Fresnel lens can reshape a beam of light without relying on symmetry.

A first-order formula for calculations of the direction cosines of the rays refracted by Risley prisms was derived. The formula was obtained by representing the deviation of the ray passing through a prism by the product of rotation matrices, and using the series expansion of the product. It can be applied to the system of an arbitrary number of prisms or a combination of Risley prisms. Related errors were discussed and some numerical calculations were made and compared with the exact solutions using the refraction equation. The scan patterns of a single Risley prism or a combination of two Risley prisms calculated using the generalized first-order formula are in good agreement with the exact solutions.

Polyethylene-based materials are used in many infrared products, including motion detectors. However, little data exists for their infrared optical properties, except at wavelengths longer than 22 μm. The refractive indices of two such materials were measured in the 9.25 to 10.6 μm spectral range, using refraction through thin prisms.

This paper describes the use of microwaves to accurately image objects behind dielectric walls. The data are first simulated by using a finite-difference time-domain code. A large model of a room with walls and objects inside is used as a test case. Since the model and associated volume are big compared to wavelengths, the code is run on a parallel supercomputer. A fixed 2-D receiver array captures all the return data simultaneously. A time-domain backprojection algorithm with a correction for the time delay and refraction caused by the front wall then reconstructs high-fidelity 3-D images. A rigorous refraction correction using Snell's law and a simpler but faster linear correction are compared in both 2-D and 3-D. It is shown that imaging in 3-D and viewing an image in the plane parallel to the receiver array is necessary to identify objects by shape. It is also shown that a simple linear correction for the wall is sufficient.

Measurement of seawater salinity, with a high accuracy, has become a key issue in thermodynamic ocean control. One of the most direct ways is to measure the seawater refractive index, which can then be related to the salinity. Refractometry is the most direct and simplest way to measure refractive index. Recent advances in high resolution position sensitive devices (PSDs) compel us to consider the physical limits and resolution of beam deviation measurement methods, such as refractometers, when additional constraints such as compactness are imposed. This work proposes to assess what can be achieved with such technology with respect to the current technical state of the art. In particular, we present the resolution dependence to refractive index variations, and derive the limits of such a solution for designing seawater sensors based both for coastal and deep sea applications

This PDF file contains the editorial “Refraction by Time and Technology” for OE Vol. 48 Issue 09

We present a formula connecting the change in the output of a multiple-channel waveguide to a micron-scale alteration in the physical properties of a segment of the waveguide. The analysis is motivated by the need to "tune" the properties of photonic devices after fabrication, necessitated by the present impossibility of fabrication to within the severe tolerances required to produce desired output characteristics. The results point to a method by which tuning can be carried out in an optimal manner. Example device application is illustrated by use of a simulation program.

The anomalous spectral behaviors of a chirped Gaussian pulsed beam diffracted by an annular aperture in the turbulent atmo- sphere are studied. On the basis of the extended Huygens-Fresnel prin- ciple and by introducing a hard aperture function into a finite sum of complex Gaussian functions, the approximate analytical expression for the spectral intensity of chirped Gaussian pulses diffracted by an annular aperture in the turbulent atmosphere is derived. The corresponding ex- pressions for a circular aperture, a circular black screen, and the unap- ertured case are given as special cases of the general results. The rela- tive spectral shift of diffracted chirped Gaussian pulses in the turbulent atmosphere versus the different values of the radius of the annular ap- erture and the different values of the position parameter are also studied and illustrated with numerical calculations. The results of this work have potential applications in information encoding and transmission in a tur- bulent atmosphere. © 2009 Society of Photo-Optical Instrumentation

A method of surface figure measurement is described based on the transmitted wavefront of an optical element obtained from a Mach-Zehnder interferometer. Given known values for the refractive index and center thickness, along with the sample's transmitted wavefront, the unknown surface profile is reconstructed in a deterministic way. The technique relies on knowledge of one of the surfaces of the element, such as an easy-to-measure plano or spherical surface, and is well suited for testing aspheric surfaces. Reverse raytracing is used to bring the transmitted wavefront from the detector to the unknown surface considering the refraction at the surfaces in the system. Reverse raytracing also removes the effects of transmission through a thick lens and the induced aberration associated with the interferometer. In the interferometer, the wavefront transmitted through the sample is tested against a plano reference. This method also has the ability to make measurements on multiplexed surfaces, such as a lenslet array, which traditionally cannot be measured without moving the sample. The surface profile of a plano-convex lens has been produced and verified against other metrology techniques for calibration purposes. Surface measurements on a cylindrical lens and a lenslet array are also presented.

A two-rotating-prism system is an inexpensive lightweight two-dimensional beam steering device. It can be designed to be achro- matic over a wide spectral range. However, the current two-prism achro- matic design has a singularity problem at the center of the "field of view": if a beam is to be steered through the center, one of the prisms must make an instantaneous 90° flip. In our work we proposed a solution to this problem by adding a third prism to the system. The main thrust of this study was optimization of the apparatus by minimizing dispersion effects as well as predicting the theoretical speed and manner in which the beam may be steered. © 2007 Society of Photo-Optical Instrumentation

Advances in digital image optics have increased the significance of lateral color aberration because it is easily seen in the projected area. The choice of optical glass plays a role in the elimination of lateral color aberration. Current optical software still has difficulty in finding the optimal combination of optical glasses for twelve or more elements in a projection lens, the choice being among at least 300 optical glasses that have been developed. Even the modern damped least squares, a ray-tracing-based method, is limited, owing to its inability to identify an enhanced optical system configuration. As an alternative, this research proposes a new optimization process by using algorithms involving the theory of geometric optics in a projector lens, real encoding, multiple dynamic crossover, and random gene mutation techniques. Results and conclusions show that attempts to achieve negligible axial and lateral color aberration are successful.

To improve airborne search and rescue operations and the general aerial surveillance efficiency, new concepts of multiple field-of-view and variable-resolution imagers have been developed. These imagers provide surveillance operators with simultaneous wide area coverage and high-resolution imaging. Over the last years, several optical steering systems have been developed and field tested in operational conditions. These developments helped us to develop a novel camera steering system using achromatic Risley prisms. This simple and sturdy steering system allowed us to move rapidly and precisely the field of view of an infrared camera. To improve its performance, a three-dimensional (3D) refraction model was applied to enable fast pointing direction calibration and correction of distorted images. Image deformations were analyzed, and a fast linear image correction based on homographic transformation and the 3D refraction model are presented. Experimental results of mosaicking applications with real imaging systems in the 3- to 5-µm, 8- to 12-µm infrared, and 850- to 860-nm visible bands demonstrate the improvements achieved with the homographic image distortions correction and the fast pointing calibration procedure.

Molecular contamination of optical surfaces from outgassed material has been shown in many cases to proceed from acclimation centers and to produce many roughly hemispherical "islands" of contamination on the surface. The mathematics of the hemispherical scattering is simplified by introducing a Virtual source below the plane of the optic, in this case a mirror, allowing the use of Mie theory to produce a solution for the resulting sphere .in transmission. Experimentally, a fixed wavelength in the vacuum ultraviolet was used as the illumination source and scattered light from the polished and coated glass mirrors was detected at a fixed angle as the contamination islands grew in time.

Coherent laser light was tuned by cumulative refraction of light waves in a semiconductor laser cavity, while the wavelength of electroluminescence was not tuned by any noticeable amount. This effect is explained by the fact that the laser light has perfect spatial coherence, while the electroluminescence has a spatial coherence of 0.7 µm, smaller than the width of the wavefront. The refraction angle of 2.4 deg means that more than 16 triangular electrodes are involved in the refraction. This observation of coherent tuning may lead to a new optoelectronic device, a coherent filter, which filters out only coherent light from a coherent-incoherent mixture.

Laser drilling is very important in many industries such as automotive, aerospace, electronics, and materials processing. It can be used to produce critical components with novel hole geometry for advanced systems. Percussion drilling and trepanning are two laser drilling methods. In the conventional trepanning method, a laser beam is scanned along a circular or spiral orbit to remove material to achieve a desired hole shape. These orbits generally trace a circular path at the inner wall of the holes. This suggests that an annular beam can be used to accomplish trepanning, a technique we refer to as optical trepanning. The ray-tracing technique of geometrical optics is employed in this paper to design the necessary optics to transform a Gaussian laser beam into an annular beam of different intensity profiles. Such profiles include uniform intensity within the annulus, full Gaussian with maximum intensity, and half Gaussian with maximum intensities at the inner and outer surfaces of the annulus.