A new series of bearingless angle encoders, the ERP 4080 and the ERP 8080 modular angle encoders, are now being introduced to the marketplace from HEIDENHAIN Corporation. These encoders offer an unequalled combination of small signal periods and large mounting tolerances, making them ideal for many highly resolved and accurate machine applications. Typical applications of these type of angle encoders are clean environments, such as in the electronics industry (wafer positioning), or in the production and testing of storage media (servotrack writing or head testers). Of course, angle encoders can also be used in any other high-precision application with appropriate environmental conditions where highly resolved speed control may be needed as well as positioning requirements. HEIDENHAIN is able to offer these ERPs with small signal periods combined with large mounting tolerances because of the incorporation of a new scanning method. This method utilizes a very small scanning area that is illuminated by a spot laser (VCSEL). The fine grating period of the circular scale (approximately 2 µm) diffracts the light which is then collimated in the scanning reticle and brought into interference. As a result, circular scales with a grating period of 2 µm supply output signals with a signal period of approximately 1 µm. The ERP 4080 has an outside diameter of 44 mm, an insider diameter of 8 mm and 131,072 signal periods. The ERP 8080 has an outside diameter of 108 mm, an inside diameter of 50 mm and 360,000 signal periods. These modular encoders are characterized by high signal quality. The electronics integrated in the scanning head is an especially low-noise unit and permits maximum position stability and reproducibility. Measurements in the single digit nanoradian realm are possible with this encoder.
