|
The Michelson interferometer is a powerful tool for measuring surface flatness. In the design, shown below left, the fibre end is viewed via a beamsplitter cube and the design had to take account of aberrations caused by the presence of the cube. Using ray-tracing software it was possible to design a diffraction-limited optical system that had a 0.32 numerical aperture and gave x20 magnification. This design has now been commercialised by Arden Photonics Ltd in the 'VF-20 Fibre Measurement System', shown below right. |
|
Requirement: Measurement of fibre surface geometry |
|
Reference flat |
|
Fibre end |
|
A particular feature of this design is that by inserting a blocking disc in front of the reference flat, the instrument becomes a standard bright-field microscope. Simply flicking a switch on the front panel of the instrument enables the operator to toggle between the 'inspect' mode and the 'fringe' mode. The images shown right are of a 125um diameter fibre end. For some more fringe patterns, click here. |
|
Inspect mode |
|
Fringe mode |
