The extended surface forces apparatus. Part I. Fast spectral correlation interferometry

This article describes details of the operation and performance of fast spe ctral correlation interferometry, which allows for considerably improved op eration of the surface forces apparatus. Up to 150 interference fringes can be simultaneously tracked over a wide spectral range, leading to considera bly more precise and simultaneous extraction of multiple optical quantities , over a greatly extended distance range. When used for surface-separation measurement, a precision of 25 pm is readily achievable over a distance ran ging from 0 to > 10 mum. Data acquisition rates are also considerably impro ved, allowing for dynamic measurements. Automated actuation of optical defl ectors introduces a multidimensional scanning capability to the optical pro be with a lateral resolution of 1 mum. The entire process is computer contr olled and features unattended batch processing of complex measurements. Thi s publication illustrates experimental setup, methodology, measurements, an d detailed error calculation for a selection of practically relevant situat ions in the extended surface forces apparatus. (C) 2001 American Institute of Physics.