D-015, D-050, D-100 Sub-nm Resolution Capacitive Position Sensors
The Latest Information on Capacitive Nanometrology Position Sensors is Available Here
ORDERING INFORMATION
- Measuring Range to 300 µm
- Resolution < 0.01 nm
- Linearity: < 0.05%
- Bandwidth to 10 kHz
- Integrated Linearization System (ILS)
- Custom Designs
D-015.00 Capacitive Position Sensor, 15 µm, Aluminum
D-050.00 Capacitive Position Sensor, 50 µm, Aluminum
D-100.00 Capacitive Position Sensor, 100 µm, Aluminum
Measurement Method
Capacitive position sensors are analog, non-contact devices. A two electrode capacitive position sensor consists of two RF driven plates that are part of a capacitive bridge. One plate (target) is fixed, the other plate (probe) is connected to the object to be positioned. Since the plate size is not changed and dielectric medium (air) remains unchanged, capacitance is directly related to the distance between the plates. Ultra-precise electronics convert the capacitance information into a signal analogous to the distance.Resolution
Resolution on the order of picometers is achievable with short range, two electrode capacitive position sensors (single electrode capacitive position sensors provide significantly less resolution, linearity and accuracy than two electrode sensors).
Resolution of PI 15 µm D-015 Capacitive Position Sensor compared to
Laser Interferometer (Bandwidth set to 3 kHz).
Theoretical measurement resolution is only limited by quantum noise. In practical applications, stray radiation, electronics-induced noise and geometric effects are the limiting factors. For example, with the 100 µm range D-100.00 Sensor and E-509.C1 Electronics, the effective noise factor is 0.02 nm/ÖHz. At 100 Hz bandwidth, for example the resolution is 0.2 nm. The maximum bandwidth is 10 kHz (jumper selectable). Fig. 5.3/2 compares the signal of a D-015 15 µm capacitive position sensor (measuring the motion of a piezo positioner) to an interferometer and clearly shows the superior resolution of the capacitive position sensor technique.
