Affiliation:
1. Chinese Academy of Sciences
Abstract
Pinholes in Al/MgF2 were first inferred by the
transmittance enhancement in Larruquert group’s research. However, no
direct proof was reported to verify the existence of the pinholes in Al/MgF2. In the past 80 years,
pinholes were first observed by dark-field microscopy and bright-field
microscopy in the transmission mode. They were small and on the order
of several hundred nanometers to several micrometers. Essentially, the
pinhole was not a real hole, partially because of the lack of the Al
element. Increasing the thickness of Al cannot reduce the size of the
pinholes. The occurrence of the pinholes was dependent on the
deposition rate of the Al film and the substrate heating temperature,
and it was independent of the substrate materials. This research
eliminates an otherwise easily ignored scattering source, and it will
benefit the development of ultra-precise optics, including mirrors for
gyro-lasers, the detection of gravitational waves, and coronagraph
detection.
Funder
Joint Fund of Astronomy
National Natural Science Foundation of
China
Subject
Atomic and Molecular Physics, and Optics,Engineering (miscellaneous),Electrical and Electronic Engineering