KEYWORDS: Design and modelling, Lens design, Optical design, Metalenses, Commercial off the shelf technology, Wavefronts, Optics manufacturing, Near field optics, Manufacturing, Flat optics
We present a nano-to-macroscale design methodology for hybrid metalens refractive optical systems, and evaluate our approach by fabricating and characterizing an F/1.4, 22.5mm diameter aperture visible band air-spaced doublet.
Gradient-index (GRIN) optics are commonly optimized with pre-determined materials, but the material choices limit the solution space of optimized index profiles. If the dispersive properties of the materials generating GRIN can be optimized, the performance of the optics can be further improved. This paper proposes a material concentration-based GRIN representation to replace the widely-used index-based representation, allowing simultaneous optimization of materials and the GRIN profile. The paper also proposed an efficient iterative algorithm capable of calculating the refractive indices, Abbe numbers and partial dispersions of material pairs from the optimized GRIN profiles. The new representation and the algorithm are used to optimize an F/2.5 GRIN singlet to diffraction-limited performance over the visible spectrum.
A raytrace method is developed for evaluation of progressive addition lens (PAL) designs with freeform surfaces and gradient index (GRIN) profiles. The raytrace analysis is adapted from a Hartmann test method. More common surface-geometric evaluations for freeform surface PAL designs are presented for comparison. Sur- face geometric and real raytrace methods are compared for evaluation of homogeneous freeform surface PALs. Raytrace evaluation is compared with evaluation results from commercial lens design software for single vision lenses. A GRIN PAL base design is evaluated using the real raytrace method, and characteristic PAL behavior is demonstrated. This raytrace evaluation method enables new directions in using GRIN for ophthalmic lenses.
Annular folded lenses (AFLs) offer high resolution monochromatic imaging in a low telephoto ratio package. Monolithic designs offer advantages but are inflicted with chromatic aberrations. Applying freeform gradient- index media enables more advanced, diffraction-limited monochromatic AFL designs. By optimizing the GRIN profile along with its dispersion, chromatic aberrations can also be corrected, granting high performing poly- chromatic designs.
Scanning confocal Raman microscopy is proposed to measure a gradient index (GRIN) profile at an optical surface. The Raman microscope is calibrated to index of refraction for a binary copolymer GRIN material, and then the index of refraction is mapped on the plano surface of a GRIN polymer lens. The measurement deduces axial shift of 680 μm and identifies lateral tilt or decenter with respect to the nominal position of the GRIN profile. Results suggest that the mapping method is a nondestructive way to measure the GRIN profile of a GRIN lens and its positioning within the lens geometry, to within the sampling precision of the Raman microscope.
The design study herein analyzes the design complexity of high zoom ratio lens systems in the visible, SWIR, and LWIR spectrums with four zoom groups (two internally moving). The aforementioned 12.5x zoom lens systems have been designed for use in the Coast Guard for maritime safety, security, and stewardship. To begin our comparative design study, the most advantageous solutions for distinct power groupings were found using a first order solution finder tool. The results showed that solutions with a PNNP, PNPP, and NPNP power grouping with the aperture stop in the third or fourth group had the most potential. At the end of the design process, a comparison was done for the three different wavebands to analyze the relative design complexity. Design complexity metrics were as follows: element count, number of aspheric surfaces, system total track length, element diameter, and tolerance sensitivity.
The UNESCO International Day of Light, 16 May, serves to highlight the critical and diverse roles that light plays in our daily lives. Light has specific meaning to each local community, and finding that which has the greatest impact can be challenging. In the proper context, local festivals serve as a fertile ground for light appreciation, bringing together diverse local groups. We provide the devices for exploration of colorimetry, imaging, and color matching demonstrations at an otherwise social local festival. Methods of assembly and planning for the multi-day display are outlined.
A typical light field virtual reality head-mounted display (VR HMD) is comprised of a lenslet array and a display for each eye. An array of tiled subobjects shown on the display reconstructs the light field through the lenslet array, and the light field is synthesized into one image on the retina. In this paper, we present a novel compact design of binocular spatially multiplexed light field display system for VR HMD. Contrary to the flat lenslet array and flat display used in current light field displays, the proposed design explores the viability of combining a concentric curved lenslet array and curved display with optimized lenslet shape, size and spacing. The design of placing lenslet array on a spherical surface is investigated and the specification tradeoffs are shown. The system displays highest resolution at the direction wherever the eye gazes. The design form is thin and lightweight compared to most other VR optical technologies. Furthermore, the use of a curved display reduces the complexity of optical design and wastes fewer pixels between subobjects. The design simultaneously achieves a wide field of view, high spatial resolution, large eyebox and relatively compact form factor.
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