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The Fly Height Test

Inside Western Digital: How Tomorrow's Storage Gets Made
The Fly Height Test

I know that part of my job is to make this tour fun and interesting for you, but sometimes we ran into barriers of multiple types. Take this photo of WD’s fly height test. As just mentioned, fly height is the distance between the magnetic head and the disk surface during a read/write operation. This is the machine that measures that distance. Given the lighting and angles and reflective enclosure surfaces, this was the best photo we were able to get. Maybe just use your imagination.

Other barriers proved to be more linguistic in nature. My generous engineer guide at this point explained the fly height test to me as follows. We both spoke English as a native language, although his dialect was clearly from Silicon Valley.

“[The] MicroPhysics Fly Height tester measures the spacing between the head and disk by using a rotating transparent replica of the magnetic disk together with an actual magnetic recording head with substantially improved accuracy at very low fly heights compared to the current industry standard methods. This fly height tester does not require a spacing varying calibration and does not make use of polarized light. The technique can be performed at substantially normal incidence to the Head/Disk interface and the precision of the spot location is not compromised as it can be on a non-normal incidence system.”

And moving on...

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