VELO RF foil thinning

An overview of the project in thinning an aluminium foil for the VELO section of the LHCb experiment. The foil was to be thinned from 0.3 mm to 0.1 mm and this report describes the very first tests. Approximate etching was used and a vacuum test and metrology test was performed. The first results look promising as the piece remains vacuum tight after etching and the first metrology data shows a good etch with further development required