Aligning of multiple micro-optical components is required for many systems composed of arrays of multiple lens elements, apertures, and filters. Methods of aligning two such wafers using mechanical features are discussed here. Alignment features include binary holes and posts, or grooves and ridges. With the circular holes or rectangular grooves etched into the two wafers, the mating pins or ridges are formed on both sides of a separate element to set both the lateral and vertical positioning. Grayscale technology allows for the printing of V-grooves and V-cones onto any substrate material over a wide range of aspect ratios. When integrated with cylindrical (fiber) or spherical (ball lens) mechanical features, this allows for accurate positioning. Some techniques allow for repositioning as well as disassembly and reassembly. The designs are kinematic or nearly kinematic. The paper discusses tolerances on mating components, and the associated precision of the overall alignment.

This paper presents the design, analysis, and testing of a diffractive optical element (DOE) to be part of the Lunar Orbiter Laser Altimeter (LOLA) instrument. LOLA will be one of six instruments to orbit the Moon for a year or more as part of the Lunar Reconnaissance Orbiter (LRO). The various scientific instruments aboard the LRO will map the lunar environment in greater detail than ever before. LOLA will produce a topographic map of the Moon from a nominal 50km orbit during the one-year mission. LOLA works by bouncing laser pulses off the lunar surface as it orbits the Moon. By measuring the time it takes for light to travel to the surface and back, LOLA can calculate the roundtrip distance. Each pulse consists of five laser spots in a cross-like pattern spanning about 50 meters of the lunar surface. The spots are generated by a DOE from the single, collimated LOLA laser input beam. It is projected that LOLA will gather more than a billion measurements of the Moon's surface elevation creating a high resolution three-dimensional map of the surface.

This paper demonstrates a new tolerancing technique that allows the prediction of microlens optical performance based on metrology measurements taken during the fabrication process. A method for tolerancing microlenses to ensure operating performance using the optical design code ZEMAX® is presented. Parameters able to be measured by available metrology tools are assigned tolerances. The goal of the tolerance analysis is to assess the sensitivity of a microlens design to changes in the shape of the lens surface with regard to specific optical performance criteria related to the intended application. Two designs are presented with the tolerance analysis results. In the first design, the radius of curvature and conic constant are varied for an aspheric lens, and the change in the spot size is determined. For the second design, fiber-coupling efficiency is tabulated for a biconic lens. In each case, a metric can be produced showing the ability of the design to meet performance goals within the specified tolerances. A fabrication technician can then use this tolerancing metric with appropriate metrology data to determine if the device will yield acceptable performance. The metric can also determine if a design is overly sensitive to expected tolerances, thereby allowing the optical designer to evaluate the design from a manufacturing perspective.