Silvia M. Booij

Nanometer deep shaping with fluid jet polishing

We describe the theoretical dependence of various important parameters of the fluid jet polishing process on the material removal rate: the processing time, abrasive concentration, abrasive diameter, particle velocity, and the effect of scanning. Some recent experiments are described that prove that it is possible to remove very small amounts of material, less than 1 nm/min, using either short processing times or an appropriate slurry. The removal spot in the stationary case is compared to that in the translational case both theoretically and experimentally. From both a theoretical and an experimental point of view it is shown that the removal is in the ductile regime.

iTIRM as a tool for qualifying polishing processes

We report on what we believe to be a novel classification method for polishing processes that we apply in our laboratory on a regular basis. Two parameters are deduced from the in situ iTIRM (intensity-detecting total-internal-reflection microscopy) measurement method. Contrary to Prestons law, which gives the removal rate, the parameters of the iTIRM process are a measure of the change in surface quality (roughness, subsurface damage, and scratch and dig) and the duration of the polishing process.

Shaping with fluid jet polishing by footprint optimization

We report on a way to shape surfaces with fluid jet polishing by adjusting the influence function (the shape of the footprint of the nozzle) instead of changing the dwell time of the nozzle on the surface. In that way, the surface is processed homogeneously, and no dip is generated in the center of the workpiece. As a proof of this approach, a lambda/10 flat surface has been generated in our laboratory.

Nanometer accurate shaping with fluid jet polishing

This article describes the Fluid Jet Polishing process. An overview of the theoretical dependence of various important parameters is given. We discuss some results obtained with FJP, including typical material removal rates and roughness values. Some recent experiments are described that show that it is also possible to obtain removal rates as small as one nanometer per minute for glass surfaces. Specific surface profiles are created, both with and without the use of surface protecting masks.

Optimisation of polishing processes by using iTIRM for in-situ monitoring of surface quality

The possibilities of iTIRM, an in-process surface measurement tool, are explored in this research. Experiments are done to test the applicability for qualifying and optimizing finishing processes for optical surfaces. Several optical glasses, different polishing agents and ductile grinding are included in these experiments. It is concluded that iTIRM can be used for both mentioned applications but that it is, at least for now, an R&D tool only and not applicable in production.

Jules Verne - a new polishing technique related to FJP

A variation on the fluid jet polishing (FJP) technique, arbitrarily named Jules Verne (JV), will be described in this article. Jules Verne is a glass processing technique that removes material due to the fact that the tool and the surface are in close contact, and a slurry moves in between the tool and the surface. This approach has both advantages and disadvantages with respect to the original FJP modus: it enables a feed-controlled machining process, but deeper lying areas are harder to reach. A simulation model will be presented that predicts the flow of the slurry in the Jules Verne setup, which is followed by the computation of the trajectories of the particles in the flow. Furthermore, experimental data will be reported demonstrating the feasibility of the JV idea. A model will also be presented simulating the interaction between the surface and the impinging abrasives at a microscopic level, enabling the prediction of the final surface roughness.

In-process measurements of material removal in fluid jet polishing

A prototype of a system for in-process monitoring of material removal in fluid jet polishing (FJP) is presented. The measurements make use of temporal phase unwrapping (TPU) allowing for a large working range. The measurement system will be discussed, with all problems that had to be overcome like water on the surface and vibrations, as well as the FJP system. The basics behind TPU will be presented and the first results will be shown. Finally, the capabilities of the system will be discussed. The presented system enables the in-process monitoring of the footprint as obtained by the FJP technique and measurement of the material removal rate.

Study of blast wave interactions with structures using a phase-stepped double reference beam holographic interferometer

An optical study of blast wave propagation and interaction with multiple structures is presented, as well as a method for obtaining quantitative information on the pressure distribution from a number of phase-stepped images. The blast load distribution on buildings is studied by scaling down the buildings and exposing to a plane shockwave in a shocktube. In the shocktube, the shockwave will propagate and interact with objects. The density distribution around the objects can be visualized using a phase-stepped double reference beam holographic interferometer. The principles and operation of the holographic interferometer are further discussed.