Micromech Products - Renishaw - Encoders RG2

The RG2 is an open, non contact optical system, eliminating friction and wear whilst permitting reliable high speed, high resolution operation. Its unique filtering optics ensure excellent signal stability even when used in workshop environments.

All readhead types come with industry standard analogue or square wave outouts, with 20 µm analogue signal period and digital resolutions from 5 µm to 10 nm. All systemsincorporate a unique, integral set-up LED, which lights green when optimum reference mark provides a repeatable home or zero position, whilst the limit is used as an end of travel indicator. The RGH22 readheads also have a dual limit switch option, giving a unique output for each end of travel.

An infra-red LED emits light onto the angled scale facets where it is directed back into readhead through a transparent phase grating. This produces sinusoidal interference fringes at the detection plane within the readhead.

The optical scheme averages the contributions from over 80 scales facets and effectively filters out signals not matching the scale period. This ensures signal stability even when the scale is contaminated or slightly damaged.

Thermal charcteristixs often play a significant role in determing overall measurement accuracy. The RGS20 scale is rigidly restrained at its ends and is therefore forced to match the thermal behaviour of the substrate, removing the need to compensate for yet another coefficient of expansion.

Low short-term errors are assured by the unique optical design, typically giving less than + 0.15 µm cyclic error (or sub-divisional errro). This is included within the linearity specification of + 0.75 µm in 60mm or + 3 µm in any metre length.

The RGS20 gold plated scale is lacquer coated for handling protection and easy maintenance. A self-adhesive backing enables quick and easy installation with minimum axis preperation. Continuous lengths are supplied on reels and can be cut to length at the point of installation.

Scale installation is quick and easy using dedicated application tooling which utilises the motion of the machine axis to ensure correct alignment.

To complete the installation, reference mark, limit switch actuators and end clamps are simply gued into place.