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The invention is to provide a method in which waviness generated on a
glass substrate surface during pre-polishing is removed, thereby
finishing the glass substrate so as to have a surface excellent in
flatness. The invention relates to a method for finishing a pre-polished
glass substrate surface using any one of processing methods selected from
the group consisting of ion beam etching, gas cluster ion beam etching
and plasma etching, the glass substrate being made of quartz glass that
contains a dopant and comprises SiO.sub.2 as a main component, and the
method for finishing a pre-polished glass substrate surface including: a
step of measuring flatness of the glass substrate surface using a shape
measurement unit that comprises: a low-coherent light source whose
outgoing light flux has a coherence length shorter than twice an optical
distance between front and back surfaces of the glass substrate; a path
match route part that divides the outgoing light flux from the
low-coherent light source into two light fluxes, causes one of the two
light fluxes to make a detour by a given optical path length relative to
the other light flux, and then recombines the light fluxes into a single
light flux and outputs it; and an interference optical system that
acquires an interference fringe which carries wave surface information of
the glass substrate surface by radiating an outgoing light flux from the
low-coherent light source onto a reference surface and the glass
substrate surface held on a measurement optical axis and making lights
returning from the reference surface and the glass substrate surface
interfere with each other; and a step of measuring a concentration
distribution of the dopant contained in the glass substrate, wherein
processing conditions of the glass substrate surface are set up for each
site of the glass substrate based on the results obtained from the step
of measuring flatness of the glass substrate and the step of measuring a
concentration distribution of the dopant contained in the glass
substrate, and the finishing is carried out while keeping an angle formed
by a normal line of the glass substrate and an incident beam onto the
glass substrate surface at from 30 to 89.degree..
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< Porous light-emitting compositions
> PROBE, PROBE SET, PROBE CARRIER, AND TESTING METHOD
> METHOD FOR CONTROLLING PRESSURE-DIFFERENCE BUBBLE TRANSFER, AND GAS EXCHANGE APPARATUS, ELECTRICAL CONDUCTIVITY MEASURING APPARATUS, TOTAL ORGANIC CARBON MEASURING APPARATUS, REACTOR AND CELL CULTURE APPARATUS USING THE METHOD
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~ 00544
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