Type ELH108 High Precision Sensing Head
                         for High vacuum use

These high precision tilt sensors are based on the ELECTROLEVEL a gravity sensing electronic inclinometer The sensor is housed in a machined Aluminium alloy casing, allowing its use on spacecraft and wind tunnel testing installations where lightweight and ability to operate for long periods under high vacuum conditions are required.

For high vacuum application the sensor has some special features.:-

• All components and materials used in sensor construction are selected for minimum outgassing under vacuum.
• An electronic buffer amplifier is incorporated in each sensing head. This provides a low impedance signal source to reduce the effect of the connecting cables on the calibration of the sensors.
• A temperature sensor built into the sensing head allows the correction of measurement errors caused by temperature drift in the sensors .
• A custom designed multicore cable is used to connect to the sensors. Its PTFE insulation enables operation over a wide temperature range and gives low outgassing under vacuum.

The ELH108 is one of a family of sensors which use the ELECTROLEVEL tilt transducer. A curved glass tube holds a conducting fluid and a bubble of gas.
Just like a conventional spirit level, the bubble always settles at the highest point in the tube. Using electrodes built into the tube, the position of the bubble is measured electronically to a very high accuracy. In use , the smallest movement of the sensor will cause the fluid to flow and the output signal to change. the resolution of the sensor is thus effectively infinite, and unlike mechanical sensors, there is no stiction or friction or hysteresis to cause inaccuracy and nothing to wear out.