Predrag Milojkovic

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. We also derive expressions for the dispersive property of a GRIN element. Our analysis enables us to derive the relationship between material pairs that indicate their suitability as a material pair for a GRIN achromat. We use this relationship to search a standard glass catalog for attractive GRIN material pairs for a particular achromat design. We compare the optical performance of our GRIN design to that of a conventional homogeneous doublet and demonstrate that our approach is capable of identifying material pairs that perform well for achromatic GRIN lenses which would not generally be considered for conventional achromatic design. We also demonstrate our approach is capable of designing GRIN achromats with superior performance.

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. As a means to understand system cost, and not just performance, we also assess the volume and mass associated with these systems. Our analysis indicates monocentric lenses imaging onto a curved detector outperform other systems for the same design constraints but do so at a cost in lens weight.

Special Section Guest Editorial: Gradient Index Optics

In the past century, every component of an optical system has become lighter and smaller, except the lenses. Typical lenses have too few degrees of freedom—just the refractive index, and the front and back surface shapes—to meet the demands of the vast array of modern optical systems which collect, project, or otherwise manipulate light. (Even in imaging systems, where computational power has the potential to eliminate the tight coupling between lenses and performance, more capable lenses would increase the trade space that optical designers have available to them).

Active computational imaging for circumventing resolution limits at macroscopic scales

Macroscopic imagers are subject to constraints imposed by the wave nature of light and the geometry of image formation. The former limits the resolving power while the latter results in a loss of absolute size and shape information. The suite of methods outlined in this work enables macroscopic imagers the unique ability to capture unresolved spatial detail while recovering topographic information. The common thread connecting these methods is the notion of imaging under patterned illumination. The notion is advanced further to develop computational imagers with resolving power that is decoupled from the constraints imposed by the collection optics and the image sensor. These imagers additionally feature support for multiscale reconstruction.

Structured Light Optical Super-Resolution: Encoding for Limited Optical Bandwidth

Structured illumination finds widespread use in microscopy and optical profilometry. A marriage of the principle underlying these methods promises novel solutions to the resolution problem that plagues consumer cameras.

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 elements 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.

Multichannel, agile, computationally enhanced camera based on the PANOPTES architecture

A multi-channel, agile, computationally enhanced camera based on the PANOPTES architecture is presented. Details of camera operational concepts are outlined. Preliminary image acquisition results and an example of super-resolution enhancement of captured data are given.

Ternary versus binary material systems for gradient index optics

Previous work developed a first-order theory for picking optimal pairs of materials for gradient index (GRIN) achromatic singlets. This work extends that concept to include the addition of a third material to a GRIN blend, to improve performance further. Several ternary-based GRIN lens designs are compared to binary versions. Implications for material development in gradient index optics are discussed.

Materials figure of merit for achromatic gradient index (GRIN) optics

A new figure of merit is developed for ranking pairs of materials as candidates for gradient index (GRIN) optics capable of good color correction. The approach leverages recent work which derives a connection in GRIN lenses between the optical properties of constituent materials and the wavelength dependence of the lens power. We extend the analysis here, the effectiveness of which is evidenced by a simulated f/3 GRIN lens with diffraction-limited performance over the visible spectrum, using the top material pair selected out of a database of >60,000 possible candidates.

Review of multiscale optical design.

Multiscale optical design is an approach that has been successfully utilized for over 100 years by optical designers and engineers to overcome challenges and achieve desired optical system performance. The benefits of the design paradigm include improving light collection, creating specific symmetries that can be exploited, collecting additional information about the object space, partitioning the optical field to enable piecewise correction of aberrations, and alleviating packing constraints. The purpose of this paper is to review the historical emergence of the use of multiscale optical design and present key examples of developments that have expanded its capabilities over the years.