Ratis is a family of plane-parallel piezo stages for nanopositioning and scanning developed by Nanoscan Technology. Ratis piezo stages are capable of moving the objects with sub-nanometer precision. Their unique feature is a large aperture (45 mm in diameter) in the center while outer dimensions are only 100õ100 mm. This could be useful in applications require clear optical path in the center of the stage.
Piezo stages are made of solid metal bar processed with EDM wire-cutting and precise CNC machining. Movable central part hangs on flexible springs and is driven with piezo actuators. Ratis design provides excellent linearity and flatness of the movement, in contrast to the classical scanners based on piezoelectric tubes, where the scan surface is a sphere. In addition, plane-parallel scanners have higher mechanical strength, compared with fragile piezoelectric tubes.
Ratis multi-axes scanners are equipped with capacitive displacement sensors for digital closed-loop control. It provides high accuracy and linearity of movement and eliminates the creep effect of piezoceramics. Capacitance measurements are made with TDC (time-to-digital conversion) technology where all measuring electronics is located as close as possible to the sensors. Such a design leads to the low noise and high speed displacement control.
To control Ratis piezo stages universal controllers EG-3000 or EG-1000 are used as well as NSpec software.
Applications of Ratis nanopositioning stages include:
- Scanning probe microscopy (e.g. atomic force microscopy)
- Biology research
- Micromanipulation etc.