Linear motion guides keep optics on track

Edited by the Engineeringtalk editorial team Dec 22, 2006

In the demanding worlds of optical engineering and instrument manufacture, precision linear motion guides not only enhance performance, but also cut costs and reduce maintenance requirements.

In the demanding worlds of optical engineering and instrument manufacture, the latest precision linear motion guides from THK not only enhance performance, but also cut costs and reduce maintenance requirements.

As an example of the cost savings which can be achieved, the use of THK's HCR circular guides in the altitude rotation mechanism of medium aperture astronomical telescopes has helped to cut the cost of the telescope mounting pedestal to just one tenth that of the previous design.

This means that far more of the telescopes, which are extensively used for research in the infrared band, can be built.

The HCR guides used in the telescope drive eliminate the need for complex mechanisms to achieve smooth precise circular motion.

Delivered as complete assemblies, ready for immediate installation, they have equal load ratings in radial, reverse radial and lateral directions, allowing them to provide an effective solution in a wide variety of large diameter rotary applications.

In a very different application, miniature RSR series linear guides from THK are making it easy to change the lamps used as a light source in large planetarium projectors.

The optical assembly of these projectors is compact, so access to the lamps can only be gained by moving multiple lenses and mirrors out of the way.

Doing this manually would be time consuming, but the space to fit an automatic mechanism is very limited.

RSR microguides, which are available with rail widths of just 1mm, provided the solution and, because types with metal endplates were selected, the guides are easily capable of withstanding the high operating temperatures that result from their close proximity to the projector lamp.

At the heart of THK's latest products is the company's market-leading Caged Ball technology of re-circulating steel balls running in precision raceways, in an arrangement which eliminates ballon-ball contact and friction, as well as minimising lubrication requirements.

THK guides find application not only in optical instruments, but also in the manufacture of the lenses used in those instruments.

Type SRG super roller guides are, for example, improving the surface finish of lenses produced in one of the latest CNC lens grinding machines.

This means that the lenses require less polishing, cutting production time and costs.

SRG guides combine THK's caged ball technology with linear rollers, resulting in greatly increased radial and lateral stiffness compared with conventional roller guides, as well as smoother running and reduced variation of running resistance with changes in operating temperature.

All of these benefits were important for the lens grinding application, as was the very low maintenance requirement of the guides.