Product Code: ICA10_M302

YAGboss - Laser Micro-Sculpting of Metal Surfaces for the Manufacture of High Precision Optical Encoder Scale
Authors:
Stephanie Giet, Heriot Watt University; Edinburgh Scotland
Frank Albri, Heriot Watt University; Edinburgh Scotland
Matthew D. Kidd, Renishaw plc; Edinburgh Scotland
Jonathan D. Shephard, Heriot Watt University; Edinburgh Scotland
Nick J. Weston, Renishaw plc; Edinburgh Scotland
Duncan P. Hand, Heriot Watt University; Edinburgh Scotland
Presented at ICALEO 2010

High-precision positioning is a significant aspect of process control. In this context, high resolution positioning feedback provided by high accuracy optical position encoders (OPE) is an invaluable tool which is implemented on a wide range of automated systems where precise positioning is the key to successful applications or technology development. OPEs consist of two main elements: a scale and a read-head. Although OPE have been part of the industrial landscape for the last 30+ years, their current fabrication scheme is no longer in line with the requirements of increasingly more demanding applications such as electronic assembly or semiconductor manufacturing requiring nanometre resolution. Indeed, mechanical embossing and lithography techniques traditionally used to manufacture the diffractive scales found in OPE are limited in resolution and flexibility without being able to combine mass production capability.
This industrial partnership introduces a novel laser-based high precision micro-sculpting technique for the development of diffractive scales. It focuses on improving the scales resolution whilst retaining commercially-viable process rates to realise the production of 100s of meters of sinusoidal surface features, 200nm±10nm deep and 4µm±0.1µm wide. In this paper, we investigate how the characteristics of the generated surface features (shape, width, depth) depend on the combination of laser parameters, temperature control and processing atmosphere. Samples of 8µm-pitch scales marked on stainless steel are assessed by metrology and in conjunction with a read-head to evaluate their efficiency.