High-resolution phase-shifting Ronchi test.

A method adding phase-shifting capacity in two mutually perpendicular axes to the Ronchi test is presented in this work. The phase of the object with the position of the reflected ray on the grating was identified and used to solve the equation of reflection in two orthogonal directions. In this manner, the test-surface figure was obtained.

Common-pull, multiple-push, vacuum-activated telescope mirror cell.

A new concept for push-pull active optics is presented, where the push-force is provided by means of individual airbag type actuators and a common force in the form of a vacuum is applied to the entire back of the mirror. The vacuum provides the pull-component of the system, in addition to gravity. Vacuum is controlled as a function of the zenithal angle, providing correction for the axial component of the mirror's weight.

HyDRa: polishing process convergence rate optimization.

In an effort to optimize the hydrodynamic radial (HyDRa) polishing process for applications where the amount of material that has to be removed implies long polishing times, we have developed a method to determine the optimum correction fraction that has to be made for a given error map, in terms of the level of determinism of the process, the number of iterations, and their associated polishing runs as well as run times.

HyDRa: polishing with a vortex.

We present a hydrodynamic, deterministic polishing tool (HyDRa) based on the fluid-jet polishing (FJP) principle. In contrast to other FJP methods, the polishing flux is accelerated with pressurized air and then expelled at high velocity, forming a radial, grazing abrasive pattern that exerts no net force of the tool on the surface to be polished, since the vacuum and thrust forces that are created at the tool's output balance each other out. The grazing effect minimizes microroughness, making it appropriate for finishing high-quality surfaces.

Low-cost, phase-shifting mechanisms for Newton-type interferometers.

Using standard optical shop equipment, it is possible to implement simple, low-cost, phase-shifting Newton interferometers sufficiently accurate for surface evaluation. The simplification of the phase-shifting mechanism is compensated with image-processing algorithms that can deal with vibrations and uneven, nonsequential steps. The results are cross-compared with a Fizeau phase-shifting interferometer to verify the effectiveness of the method.

Deterministic convergence in iterative phase shifting.

Previous implementations of the iterative phase shifting method, in which the phase of a test object is computed from measurements using a phase shifting interferometer with unknown positions of the reference, do not provide an accurate way of knowing when convergence has been attained. We present a new approach to this method that allows us to deterministically identify convergence. The method is tested with a home-built Fizeau interferometer that measures optical surfaces polished to lambda/100 using the Hydra tool.

Static and dynamic removal rates of a new hydrodynamic polishing tool.

A new tool for hydrodynamic radial polishing, HyDra, allows for the local polishing of optical surfaces with a controllable wear rate. The results of the removal rate for different polisher types and sizes, applied air pressures for slurry expulsion, and tool height with respect to the working surface, are reported. We present a numerical analysis of the volumetric removal rate for the dynamic experiments as well as a comparison with a similar technique.