Renishaw Designs Encoders for Ultra-Low Thermal Expansion

The new RELM high accuracyt linear encoder from Renishaw joins the company’s SiGNUM range of intelligent,high performance encoders combining accuracy to +/-1 micron/meter and resolution to 20 n-m with speeds higher than 10 m/s amd temperatures to 85 degrees C.

Initially available in Invar, which provides a thermal expansion of 1.3 microns/m/K, the RELM scale offers a choice of IN-TRAC reference mark positions and dual optical limits. The 20 micron spars allow the RELM to offer a performance level similar to that of more delicate fine-pitch encoder systems. Non-contact performance provides high reliability to satisfy demanding precision motion requirements and high throughput manufacturing operations.

The SiGNUM RELM linear encoder system comprises the SR readhead, Si interface, 20 micron RELM spar in defined lengths as well as features including IN-TRAC and intelligent signal processing. The IN-TRAC auto phase optical reference mark is repeatable in both directions across the entire speed and temperature range.

According to the company’s press release, the ST readhead is sealed to IP64 and include filtering optics to provide immunity to dirt, dust and scratches. The scale can be mounted directly to the substrate using mechanical clips or a specially formulated adhesive backing tape. The Si interface can be mounted remotely and a small connector on the readhead can easily be fed through machines where access is restricted.

As part of the SiGNUM range, the RELM encoder system benefits from SiGNUM intelligent signal processing which ensure excellent reliability and ultra-low cyclic error (typically greater than or equal to 40 nm). In addition, comprehensive SiGNUM software enables optimum set-up and real-time system diagnostics via a PC’s USB port.