Augmented reality (AR) and heads up display (HUD) applications overlap images directly on the user’s field of view. To achieve that, optical components with high optical performance and versatility are required. Also, the optical elements must allow an unrestricted view of the world. Traditional optical elements as limited by laws of refraction and reflection, are not versatile, and reduce the transmittance of the devices worn by the AR user. In this paper, we discuss the transparent holographic components’ operation parameters and general optical geometries relevant for HUDs, the holographic substrata available for these applications, their performance characteristics and manufacturability.
Diffractive optics such as holographic optical elements (HOEs) can provide transparent and narrow band components with arbitrary incident and diffracted angles for near-to-eye commercial electronic products for augmented reality (AR), virtual reality (VR), and smart glass applications. In this paper, we will summarize the operational parameters and general optical geometries relevant for near-to-eye displays, the holographic substrates available for these applications, and their performance characteristics and ease of manufacture. We will compare the holographic substrates available in terms of fabrication, manufacturability, and end-user performance characteristics. Luminit is currently emplacing the manufacturing capacity to serve this market, and this paper will discuss the capabilities and limitations of this unique facility.
An innovative integrated spatial filter array (iSFA) was developed for the nulling interferometer for the detection of earth-like planets and life beyond our solar system. The coherent iSFA comprised a 2D planar lightwave circuit (PLC) array coupled with a pair of 2D lenslet arrays in a hexagonal grid to achieve the optimum fill factor and throughput. The silica-on-silicon waveguide mode field diameter and numerical aperture (NA) were designed to match with the Airy disc and NA of the microlens for optimum coupling. The lenslet array was coated with a chromium pinhole array at the focal plane to pass the single-mode waveguide but attenuate the higher modes. We assembled a 32 by 30 array by stacking 32 chips that were produced by photolithography from a 6-in. silicon wafer. Each chip has 30 planar waveguides. The PLC array is inherently polarization-maintaining (PM) and requires much less alignment in contrast to a fiber array, where each PM fiber must be placed individually and oriented correctly. The PLC array offers better scalability than the fiber bundle array for large arrays of over 1,000 waveguides.
This paper surveys the need for oxygen A-band spectroscopy to improve our understanding of clouds and their key role in the climate system. We then report on a novel holographic A-band substrate-guided spectrometer device recently developed at Luminit. This A-band spectrometer prototype is based on an innovative structure of two thick reflection substrate-guided wave-based holograms (SGWHs) that act as dispersive and/or imaging elements to enable a sufficient spectral resolution. The technology is made very attractive by its significantly lower cost compared to currently available systems/devices with similar A-band capability, while providing higher light throughput, a better out-of-band rejection ratio, higher resolution at a smaller size, and better stability and reliability.