Fueled by the recent developments in high volume consumer products, as well as by advancements in simulation tools and fabrication techniques, meta-optical elements (MOEs) are becoming increasingly adopted into a variety of photonics applications. While not a substitution for conventional optics, meta-surfaces possess unique characteristics that distinguish them from refractive alternatives, paving the way for new generations of photonics modules and systems. Innate MOE characteristics include superior wavefront control, scalability, polarization management and multi-functionality. MOE advantages become especially apparent in the infrared (IR), with increased diffractive powers, looser fabrication tolerances, and compatibility with semiconductor fabrication techniques using affordable optical materials. In this talk I’ll discuss transitioning from conventional bulky, multi-element IR lenses to wafer-level assemblies with MOEs. New lens design forms incorporating MOEs, with significantly reduced weight and volume will be presented, offering unique opportunities in developing scalable, and cost-effective multi-element IR imaging modules.

MIT Lincoln Laboratory has designed and prototyped a series of all-reflective two mirror imaging telescopes offering long focal lengths within a small package volume. These designs take advantage of multiple reflections between the two surfaces to correct aberrations across the field and provide the path length necessary to place the image plane within a compact distance. These designs trade optical throughput, reduced by the large obscuration ratio, for volumetric and mass gains due to their extremely small size, making the form ideal for imaging bright objects in space constrained environments such as small satellites (SmallSats) and cube satellites. We show two different designs for the visible-NIR with 150mm apertures and >1m focal lengths that offer high image quality performance and flat fields across their fields of view. Prototype units were produced using diamond turning and results will be presented including imaging performance.

In this report we describe the effect of the uncoated and the coated grinded lens edges on the imaging performance of a high performance short wave infrared (SWIR) imager inside a fully achromatized multispectral SWIR/VIS zoom camera. The experimental result of various black coatings for the lens edges to prevent stray light in the VIS-SWIR spectrum is presented. SWIR cameras show significant advantages for the long range observation under different weather conditions (e.g, haze, mist or fog) due to the reduction of wavelength-dependent scattering extinction. The design of such a SWIR imager in a combined visible (450nm to 900nm) and the SWIR spectral (900nm to 1700 nm) camera with a continuous optical zoom factor of 15x for a limited space and relatively high pixel pitch of 15μm force the use of relatively high F-numbers to achieve narrow fields of view less than 1.5° with a reasonable resolution is a great challenge. Particularly unwanted stray light inside the camera significantly degrades the imaging performance of the SWIR sensor. A good anti-reflection coating on the lens elements improves the ghost images. However, especial prevention techniques are required to reduce the flare stray light that typically arises from reflection or scattering from non-optical path surfaces e.g., mount surfaces or edge surfaces of lenses. The mechanical baffles or stops can reduce these stray lights but it requires precise design and cost. The most common approach to prevent the stray light from the edges of the optical elements is to apply a black coating on the grinded lens edges. The available coatings for edge blackening are typically optimized for VIS spectral range and their blackening effect is limited in the SWIR spectrum by Fresnel reflection due to the index of refraction mismatch at the glass boundary. Here we have applied the appropriate black coating on the selective lens edges based on simulation as well as experiments and demonstrated the improved stray light performance in the SWIR channel.

The multispectral camera reported herein consists of a single aperture optic, splitting the incoming light onto three independent sensors. Having a common beam path, it is possible to employ a motion blur compensating de-scanner unit, allowing the generation of high-speed panoramic stitches for quick look arounds. The fast aperture optics has a F-number spanning from F/2.8 in the wide field of view to F/3.8 in the narrow field of view. Additionally, the optic is corrected for chromaticity errors over the whole wavelength range. For each sensor we managed to maintain focus and exactly match horizontal fields of view over the complete zoom range. The individual imaging sensors employed are a SXGA SWIR sensor, a 4K VIS CMOS sensor and a SXGA low light level sensor for night vision capability. Thus, it is possible to see under almost all possible atmospheric and light conditions. As all sensors can be read out simultaneously with subsequent on-board processing, we can combine image analysis with image fusion such as navigation light detection within SWIR images. Additionally, the SWIR sensor is able to detect laser light using ALPD (asynchronous laser pulse detection).

Risley Prisms are traditionally used to point narrow band imaging sources (such as lasers) via the rotation of two or more prisms relative to each other. A less common application is the ability to steer broader spectral band imagery in each of the SWIR, MWIR, and LWIR spectral bands by utilizing achromatized prism pairs enabling high speed step stare and/or two-dimensional scanning at large pointing angles without the use of a gimbal or scanning mirror. In this paper, the recent advancements, capabilities, and limitations will be discussed.

Precision glass molding is a critical manufacturing technique for high precision, non-spherical, low cost lens’. In this work, laser-based polishing and “flame” polishing are utilized as surface tension driven finishing step for precision glass molding preforms across all of RPO’s Classic line of chalcogenide glasses. Surface quality is compared across finishing techniques, composition, as well as compared to pressed lens’.

Imaging multiple wavebands through a common aperture with transmissive optics brings new challenges for the optical system designer. Very few commonly available lens materials operate in both the visible and midwave infrared leading to complex lenses with many elements to correct for chromatic aberrations. NRL is developing new materials to fill that gap. These new materials enable greater flexibility for designers of lenses for advanced defense applications and potentially reduce the size, weight and cost of next-generation optics. This paper will discuss optical and physical properties of the new materials, progress in their development and the advantages of using NRL materials in transmissive optics designs for multiband applications.