US Patent 7295506 - Elliptical nanotip for scanning probe memory

http://www.freepatentsonline.com/7295506.html

Scanning probe tips can have radius of curvature in the nanometer range which allows them to produce high resolution marks useful in data storage. However tips with faceted or narrow cross-sectional diameter may be difficult to accurately position relative to a pit of a storage medium during a read operation. This patent from Hewlett-Packard discloses an elliptical shape tip to aid in positioning. Claim 1 reads:

1. A device comprising: a substrate comprising at least one pit having a substantially elliptical shape; a probe having a tip, wherein the tip contains a substantially elliptical cross-sectional shape, and wherein the tip is used to create the at least one pit in the substrate; and wherein one or both of the substrate and the probe are configured to move with respect to each other such that the tip is moved into and out of the at least one pit through the relative movement.

However some relevant prior art such as US 5,503,010 (Figs. 3, 4, 10) and US 6,218,086 (Fig. 2) may have been overlooked during the examination.