Mechanical Ruling

Mechanical Ruling

Classically-ruled master gratings are produced by first evaporating a coating of gold or aluminum onto a highly-polished substrate, and then mechanically burnishing triangular grooves using a precision diamond tool.

The incredible specifications required for the ruling of gratings demand such a high degree of technology, that few facilities in the world are able to produce them. The ruling engines at HORIBA Jobin Yvon are among only 10 to 15 successfully operating ruling engines in the world today.

The most important requirement of the ruling engine is that the diamond carriage follows an exact path on each stroke. Any lateral displacement will introduce an error in the groove spacing of the finished grating. The carriage rides on perfectly-smooth tracks, under the very precise control of a heterodyne laser interferometer which controls the carriage displacement in order to maintain absolute parallelism and displacement accuracy.

Finally, the exact profile of the groove must be faithfully maintained across the entire surface of the grating. Any wear of the ruling tool during the course of operation must be compensated; an Atomic Force Microscope (AFM) is devoted to this control.

Given the difficulties (and associated high costs) of ruling a grating, most of the gratings used in instruments are more-affordable replicas of the directly ruled master grating.

HORIBA Jobin Yvon has one of the widest inventories of ruled masters from which we produce high precision replicas.