Long Wave Infrared (LWIR) lenses require performance over a wide wavelength range of 7-14 μacceptance and efficient transmission. The subwavelength structures in the lens designs should conform with the capabilities of the current state of the art Deep Reactive Ion Etching (DRIE). The result of etching high aspect ratio 78:1 features in silicon is presented. The subwavelength structures are model using Finite-Difference Time-Domain (FDTD) simulation and a region of strong positive dispersion has been identified. By using the strong positive dispersion with periodic index steps, an achromatic focusing surface can be fabricated in a single etch step. Using custom modeling software, the propagation of light in the range 7-13 μm is performed on the achromatic surfaces. The surfaces have a very efficiency based on the results from the (FDTD) simulation. The design and performance of chromatic lenses are presented. The lenses enable interesting imaging designs for LWIR imaging applications. Results of testing the achromatic properties of silicon structures is presented.
The design, fabrication and performance of a novel silicon lens for Long Wave Infrared (LWIR) imaging are presented.
The silicon lenses are planar in nature, and are created using standard wafer scale silicon micro-fabrication processes.
The silicon batch processes are used to generate subwavelength structures that introduce spatially varying phase shifts in
the incident light. We will show that the silicon lens designs can be extended to produce lenses of varying focal lengths
and diameters, thus enabling IR imaging at significantly lower cost and reduced weight and form factor. An optical
design program and a Finite-Difference Time-Domain (FDTD) simulation software tool are used to model the lens
performance. The effects of polarization anisotropy are computed for the resultant subwavelength structures. Test
samples with lenses with focal lengths in the range of 10 to 50 mm were fabricated. The test sample also included a
prism structure, which is characterized by measuring the deflection of a CO2 laser beam and compared to theoretical
beam deflection. The silicon lenses are used to produce an image on a VGA micro-bolometer array.
Spherical panoramic virtual displays are a new environment for presenting high resolution visual information to an observer or observers within the display system. The spherical panoramic virtual display consists of a simple optical system and a unique LED scanning projector system. The image is collimated and is very high resolution over a very wide field of view. The image is generated by the projector forms a seamless image. The image has very high contrast ratio unlike many other projection based technologies. The technology of spherical panoramic virtual displays will be discussed with an emphasis for applications in flight simulation. Resolution, screen refresh rate, and modulation rate are calculated for compact fully immersive system. The design of the system with respect to contrast ratio, resolution, and aberrations will be analyzed with optical ray tracing calculations. Brightness and color gamut calculations will be presented for the system based on the commercially available LED components in the projector system.
Spherical panoramic virtual displays are a new environment for presenting high resolution visual information to an observer. The virtual image is seen with both eyes. The new environment provides the wide field of view image, typically 180 degrees in horizontal and vertical directions, forming a collimated image over a half dome. The users stand in front of a dome window and see a collimated image filling most of their visual field. The spherical panoramic virtual display consists of an optical systems and a unique projector system. The system relies on the Schmidt principle for a spherical mirror in reverse to form the image. The optical system has a very high degree of symmetry. At the center of the system, the image is free of all aberrations. Away from the center, the aberrations are function of the users position, the size of the display system and the apparent focal distance. An example calculations of the aberrations will be presented. The projection system has three properties, projects light in one direction, is substantially transparent, and is spherical in nature. An example of a scanning projector is discussed. Examples of potential applications are presented.
Current results for diode pumped solid state lasers are driven by advances in diode laser technology. Diode arrays in the 10 - 20 watt range are now available in useful formats which allow coupling into side- and end-pumped laser configurations. Side-pumped designs have traditionally produced higher output power at the expense of mode quality. End-pumped devices, on the other hand, have shown high mode quality but have been limited in their output power or pulse energy. Results are given which demonstrate new end-pumped laser coupling and cavity configurations which allow both high mode quality and increased power output.