Optics theory and practice in Iberoamerica: introduction to the feature issue.

This feature issue of Applied Optics (AO) on Optics Theory and Practice in Iberoamerica (OTPI) collects significantly expanded refereed papers presented at the multiconference RIAO-OPTILAS-MOPM, held in Cancún, Mexico, Sept. 23-27, 2019. All authors who participated at the conference were contacted and invited to contribute to this special issue.

Material selection for GRIN-based achromatic doublets.

We use first-order optical principles to examine the ability of gradient index (GRIN) lenses to correct chromatic aberrations. We consider radial GRIN lenses with flat surfaces, with a flat diffractive surface, and with curved surfaces. We model the GRIN material system as a locally varying, subwavelength blend of three materials.

ORIF versus arthroplasty for open proximal humerus fractures: Nationwide Inpatient Sample data between 1998 and 2013.

Background: Limited data exists in analyzing open reduction and internal fixation (ORIF) and arthroplasty in the management of open proximal humerus fractures. We analyzed differences in hospital course between these procedures, patient demographics, complication rate, length of stay, hospital charges, and mortality rate.

Materials And Methods: This is a retrospective review of the Nationwide Inpatient Sample database.

U.S. Army Research Laboratory focus issue: introduction.

The U.S. Army Research Laboratory (ARL) is the premier laboratory for land forces in the United States.

Optics research at the U.S. Army Research Laboratory.

The U.S. Army Research Laboratory (ARL) is the Army's premier laboratory for land forces.

A Biomechanical Comparison of Different Tendon Repair Techniques.

Previous studies have examined multiple suture techniques for the repair of ruptured tendons. In this study, we investigated how the two- and four-stranded Krackow suture weave techniques compared with a novel Krackow/Bunnell suture technique. Our hypothesis was that the Krackow/Bunnell suture would have greater strength compared with the two- and four-stranded Krackow suture in terms of resistance to pullout from the muscle tendon.

Dispersion design in gradient index elements using ternary blends.

We show that a gradient-index element designed from a blend of three materials allows a designer to specify independently the element's refractive index and its change in refractive index with respect to wavelength. We show further the effectiveness of this approach by comparing modeled chromatic performance of deflectors consisting of a single material, a binary blend of materials, and a ternary blend.

Chromatic analysis and design of a first-order radial GRIN lens.

From the expression for optical power of a radial first-order graded-index (GRIN) lens with curved surfaces, we derive an expression for chromatic aberration. Our expressions for optical power and chromatic aberration are valid under the paraxial approximation. By applying a series of further simplifying assumptions, namely a thin lens and thin GRIN, we derive a set of equations with which one can design an achromatic GRIN lens.

Reflections on 35 years with Applied Optics: outgoing editorial.

Applied Optics' Editor-in-Chief, Joseph N. Mait reflects on his experience as a reader, author, reviewer and eventual editor of the journal. Dr.

An editor's role and responsibility.

Following an editorial emphasizing the importance of reviewers, Applied Optics' Editor in Chief Joseph N. Mait explains the critical role of the editor.

In praise of reviewers.

Applied Optics Editor-in-Chief, Joseph N. Mait, comments on the value of peer review in improving the work published by authors.

Applied Optics Golden Anniversary commemorative reviews: introduction.

Applied Optics presents three special issues to end its retrospective of Applied Optics' 50 years. The special issues are interference, interferometry, and phase; imaging, optical processing, and telecommunications; and polarization and scattering. The issues, which contain 19 commemorative reviews from some of the journal's luminaries, are summarized.

Midlife and transitioning through it.

Applied Optics Editor in Chief Joseph N. Mait closes out the 50th Anniversary of Applied Optics with a final commemorative editorial.

Multimodality treatment of a multifocal osteoblastoma-like tumor of the lower extremity.

Osteoblastoma-like tumor is a rare condition with limited information on its orthopedic management in the current medical literature. The tumor histologically resembles an osteoblastoma, although the radiographic features are similar to those observed in primary vascular lesions. The treatment in the previously reported cases involved aggressive procedures including amputation, en bloc resection, and chemotherapy because of the uncertainty regarding the biological behavior of the tumor.

Imaging systems and applications.

Imaging systems are used in consumer, medical, and military applications. Designing, developing, and building imaging systems requires a multidisciplinary approach. This issue features current research in imaging systems that ranges from fundamental theories to novel applications.

Space-bandwidth scaling for wide field-of-view imaging.

We examine the space-bandwidth product of wide field-of-view imaging systems as the systems scale in size. Our analysis is based on one conducted to examine the behavior of a plano-convex lens imaging onto a flat focal geometry. We extend this to consider systems with monocentric lenses and curved focal geometries.

Performance-based tests and self-reported questionnaires provide distinct information for the preoperative evaluation of total hip arthroplasty patients.

Our objectives were to assess relationships between self-reported questionnaires and 2-minute walk test (2MWT) and timed get-up-and-go test (TUG) in preoperative total hip arthroplasty patients. A total of 162 patients completed the Western Ontario and McMaster Universities Osteoarthritis Index and Short Form 36 and performed 2MWT and TUG. Correlations between self-reported questionnaires and 2MWT and TUG were mild to moderate, indicating that the 2MWT and TUG capture additional dimensions of preoperative total hip arthroplasty function not measured by the Western Ontario and McMaster Universities Osteoarthritis Index and Short Form 36.

Millimeter-wave compressive holography.

We describe an active millimeter-wave holographic imaging system that uses compressive measurements for three-dimensional (3D) tomographic object estimation. Our system records a two-dimensional (2D) digitized Gabor hologram by translating a single pixel incoherent receiver. Two approaches for compressive measurement are undertaken: nonlinear inversion of a 2D Gabor hologram for 3D object estimation and nonlinear inversion of a randomly subsampled Gabor hologram for 3D object estimation.

Three-dimensional analysis of subwavelength diffractive optical elements with the finite-difference time-domain method.

We present a three-dimensional (3D) analysis of subwavelength diffractive optical elements (DOE's), using the finite-difference time-domain (FDTD) method. To this end we develop and apply efficient 3D FDTD methods that exploit DOE properties, such as symmetry. An axisymmetric method is validated experimentally and is used to validate the more general 3D method.

Design and analysis of a diffractive optical filter for use in an optoelectronic error-diffusion neural network.

The design, fabrication, experimental characterization, and system-performance analysis of a diffractive optical implementation of an error-diffusion filter for use in digital image halftoning is reported. A diffractive optical filter was fabricated as an eight-level phase element that diffuses the quantization error nonuniformly in both the weighting and the spatial dimensions, according to a prescribed algorithm. Ten identical diffractive elements were fabricated on ten different wafers and subsequently characterized experimentally.

Diffractive optics and micro-optics: introduction to the feature issue.

This issue of Applied Optics features 16 papers related to the fabrication, design, and application of diffractive and micro-optical elements. A companion feature in the Journal of the Optical Society of America A [J. Opt.

Binary subwavelength diffractive-lens design.

We present a procedure for the design of binary diffractive lenses with pulse-width-modulated subwavelength features. The procedure is based on the combination of two approximate theories, effective medium theory and scalar diffraction theory, and accounts for limitations on feature size and etch depth imposed by fabrication. A design example is presented.