Long range high position sensors in harsh conditions!

The NCG-1-AL-UHV position sensors from Queensgate, based upon highly advanced proprietary capacitive technology, are the longest range devices in the company’s portfolio. Their measurements can span across 11,000µm. Designed for precision positioning in the most uncompromising of environments, they have a sensing mechanism that utilizes gold-plated ceramic capacitive plates and exhibits a combination of rugged construction plus strong operational performance of 0.12µm resolution (thanks to very low noise electronics).

NanoSensor®s maintain their zero position when they are powered down making them a highly optimized alternative or addition to interferometry for short distance measurements. Low thermal changes at the point of measurement mean the sensors are suitable for system drift and stability measurement. The sensors are radiation hard to 107Gy, have an extended working temperature range (covering -200°C to +150°C), are non-magnetic and are suitable for placement in ultra-high vacuum environments (up to 1 × 10-10Torr). Their relatively simple installation, with just one or two electrical feedthroughs, reduces system complexity and cost over optical measurement systems. A standard model capacitive sensor NCG-1-AL is also available for use in air.

Queensgate’s NCG-1-AL-UHV position sensors are designed to be accompanied by the company’s NS-2000/NS-2000SM single axis or NS-2304 multi-axis sensor controllers. Among the key applications for these devices are insertion redevises, X-ray monochromators, precision manufacturing and other large scale science experiments.

High resolution position sensor.

Employing capacitance micrometry, the NX NanoSensor® from Queensgate delivers sensitivity levels that are able to measure changes in position to an atomic scale.

This state-of-the-art non-contact position measuring system relies on 2 sensor plates - a target and a probe, which between them form a parallel plate capacitor. Through the use of an appropriate electronic controller, the spacing of these two plates can be accurately ascertained. Among the key applications for the NX NanoSensor are stage feedback, vibration measurement, metrology, deformation measurements, precision manufacturing, drift measurement, precision beam steering and microscopy.

Via NX NanoSensor position can be determined to a margin of better than 7pm, with a linearity to 0.02% and a bandwidth from 50Hz up to 10KHz. There is provision for the system to be tuned so that either the positional accuracy is improved or conversely the responsiveness to dynamic motion is heightened. Plate shapes that are round, square or rectangular can be selected. Active areas of 22.5mm2, 113mm2 and 282mm2 are offered. Working in tandem with the NX NanoSensor, the NS2000 controller module measures any changes in the parallel plate capacitance and subsequently produces an analogue voltage that is directly proportional to the difference in position of the target and a probe sensor plates.

The non-contact measurement and non-self-heating mechanism means that NX NanoSensor products do not impact the values they are measuring, thereby giving true nanoscale measurements. Furthermore, they use a non-hysteretic technique, which means the position is repeatable. Numerous material options can be used in their construction; Super-Invar, Zerdur, aluminium, stainless steel and ceramic - allowing thermal properties to be matched to the stability required by the specific application, in order to safeguard against position drift. Ultra high vacuum, radiation hardened, non-magnetic and cryogenic variants can be specified.

Closed loop nanopositioning actuators.

Queensgate Instruments’ latest Digital Piezo Translator (DPT) series of actuators incorporate capacitive sensors in order to deliver precise positioning and rapid settling. These highly advanced actuators can be implemented in a wide variety of applications, including interferometry, semiconductor mask-wafer chuck alignment, beam alignment, cavity tuning, adaptive optics, scanning probe microscopy and a multitude of different metrology tasks.

There are two new series of DPT, the DPT-D with the best in class positioning performance and the more compact DPT-E which is a low voltage replacement for the previous generation DPT-C series. Air and Ultra High Vacuum variants are available as standard. Their Super-Invar construction gives superior thermal properties (with a thermal expansion coefficient of 0.25nm/Kelvin) which enhances position stability. Position resolutions down to 0.09nm (RMS) are offered as each unit delivers <2ms response time, 0.5nm (RMS) repeatability. They are able move loads of up to 60kg across their entire closed loop range, with closed loop ranges from 20um to 110μm.

DPT devices benefit from a built-in calibration function, derived from the Queensgate ID chip arrangement. These ID chips store calibration data on the actuator itself and thereby facilitate plug-and-play operation with the digital controller. Controllers and actuators can be interchanged as required, avoiding the need for recalibration, important when the actuator is incorporated into a mechanism or is inaccessible.

Among the array of accessories accompanying these actuators are various end pieces, mirror holders and mounting blocks. An operational temperature range of -30°C to 80°C is supported as standard, but higher temperature variants can be offered.