Single-Point Diamond Turning of Features with Large Azimuthal Slope

PubDate: October 8, 2021

Teams: Facebook Reality Labs

Writers: Alex Sohn, Neil Naples

PDF: Single-Point Diamond Turning of Features with Large Azimuthal Slope

Abstract

Molded plastic optics, specifically anamorphic and freeform components, have become almost exclusively reliant on single-point diamond turning of molds and masters. Since diamond turning is a deterministic process, it can integrate mechanical and optomechanical features into the same machining operation and guarantee alignment with optical surfaces. With the advent of slow tool servo (STS) and fast tool servo (FTS) machining processes, it became possible to diamond turn non-rotationally symmetric optical surfaces and other features. However, STS and FTS are both limited by tool clearance when surfaces become steep in the azimuthal (rotational) direction. Large primary clearance tools are one way to address this, but those tools are costly, can be time consuming to manufacture, and have fragile edges susceptible to wear and damage. Diamond milling is another possibility for dealing with large azimuthal slopes, but this usually comes at the price of diminished surface roughness and surface figure error related to long cycle times. We present here a process for diamond turning steep azimuthal slopes using conventional diamond turning tools by taking advantage of multi-axis motions available on diamond turning machines with a vertical Y-axis.