Compressive 3D imaging spectrometer

Optical sensing for nuclear detonation detection involves space‐based detection within the visible wavelength. Emerging optical detectors will leverage unique diffractive optics to help enhance and discriminate signals of interest from other background emitters. Because of the precision required to achieve these objectives, innovative designs and manufacturing methods are required to benefit Nuclear Detonation Detection (NDD) and commercial applications with similar signal discrimination requirements. These, space‐based imaging systems are examples of the types of systems that can benefit from the perspective of increased degrees of freedom or increased size of the trade space. Many of these types of systems experience dynamic instabilities that are due to thermal and or mechanical variations of the system. Adequate control of the systems can generally be performed by a variety of optical and mechanical means, although, for many applications, the flexibility of the systems in terms of size, weight, or cost can be severely compromised. Increasing the number of methods that can be used to control the systems increases the degrees of freedom of the system or size of trade space. Increasing the degrees of freedom or size of the trade space can allow the designer added flexibility to minimize the size, weight, and cost of the system. To address the need for compact lightweight robust optics that can integrate both complex optical functions and chromatic compensation, diffractive and 3D freeform gradient‐index (GRIN) optical materials will be developed that combine the benefits of freeform surfaces with freeform optical‐index materials, to implement complex higher‐order polynomial optical functions. Possibilities for using diffractive and GRIN lenses as components of imaging optical systems have been investigated for several decades. The elements have proved competitive in their unique focusing and aberration properties and in terms of their additional degrees of freedom for optical design, and high optical characteristics can be achieved for simple systems consisting of a few elements combined in a variety of ways. In Phase I, we will demonstrate the VIRGO technology capable of manufacturing robust, space‐compatible freeform GRIN and diffractive optical elements. After refining the optical system requirements, we will design and demonstrate: 1) 3D freeform GRIN pupil masks and phase corrector plates; 2) achromatic freeform GRIN lens elements; 3) gradient‐index zone lens (similar to Fresnel lenses, but implemented with gradient contours); 4) freeform‐surfaced (including aspheric and off‐axis) 3D freeform GRIN lenses; and 5) metasurfaced freeform GRIN lenses. These elements will be used to show the ability to simultaneously achieve optical power, geometric aberration correction, and chromatic aberration correction, in a single monolithic element. We will employ the rising notation of pupil engineering, which incorporates techniques for controlling the spread of the axial point spread function, as well as methods for governing the impact of focus errors on the modulation transfer function. We will also perform preliminary environmental testing that will show that the technology can withstand typical launch loads as specified in MIL‐STD‐1540 or the NASA General Environmental Verification Standard (GEVS: GSFC‐STD‐7000) with respect to environmental and outgassing conditions typical of space‐based payloads launched and operating in space.