Series of optical incremental linear sensors RG4

Production:

Renishaw plc (Graet Britain)

RG4 encoder is an open contactless optical linear system with zero friction and no mechanical wear, reliably operating at high speed and with high resolution. A scale step of 40 μm provides operation at a higher speed and increased tolerances during installation. In addition, a large number of different types of scales can be used in RG4 systems.

Reading heads of the linear encoders RG4 sense an analog signal with a period of 40 μm or have a digital resolution in the range from 10 μm to 50 nm. All systems have a unique tuning indicator, the green glow of which means the optimal setting of the system. Reading heads of all models can output zero point and / or limit switch signals. The zero mark signal provides repeatability of the initial or zero position, and the signal of the limit switch serves as an indicator for stopping the movement.

The radiation from the infrared LED is reflected from the inclined strokes of the scale tape and, passing through the transparent diffraction grating, returns to the reading head. As a result, in the plane of the detector sinusoidal interference fringes are formed. The optical scheme implemented in the RG4 system is not fundamentally different from the optical scheme of the RG2 system, however the infrared radiation of the LED in this case is reflected from the scale tape not parallel, but perpendicular to the axis of the scale. The optical scheme averages the contribution to the interference pattern from a large number of scale strokes, ignoring signals that do not correspond to the period of the scale. Thus, the output signal is stable even if the scale tape is dirty or slightly damaged.

The principle of operation of the RG4 series encoders makes it possible to use different types of scales.