Terminology glossary
Environmental Conditions
attocube ’ s nanopositioners can be used in different environmental conditions such as ultra-high vacuum . One or more suitable suffixes in the article name describe the environment for which a nanopositioner is designed and tested in-house . Moreover , all ANP nanopositioners are suitable for measurements in a magnetic field as they are built of completely non-magnetic materials .
• / RT – Room Temperature
/ RT positioners are manufactured for use at ambient conditions ( room temperature , dry atmosphere , ambient pressure ).
• /( U ) LT – ( Ultra- ) Low Temperature
These positioners are suitable for repeated cooling and operation in cryogenic temperatures .
• / HV – High Vacuum
At attocube the high vacuum range is specified down to 10 -8 mbar .
• / UHV – Ultra-High Vacuum
The ultra-high vacuum range is specified down to 5x10 -11 mbar for most of our positioners . A few rotators and goniometers use UHV compatible grease . Due to the increased outgassing of these types at elevated temperatures we specify them for 10 -9 mbar as a precaution ( noted in specification sheets ). Most of our positioners can be baked out up to 150 ° C .
Position Control
Most of attocube ’ s nanopositioners are available in open and closed loop versions .
• Open Loop Positioning
In this mode , the positioner is simply driven forward or backward , without an encoder to read back the actual position or a feedback loop to control the desired target position .
• Closed Loop Positioning
Positioners with an integrated encoder (/ RES , / RES + or / NUM , / NUM +) can be used for closed loop position control . A feedbackloop integrated into the control electronics minimizes the difference between target position and actual position . Setpoints can either be defined in a software interface or on the front panel of the electronics .
• Resistive Encoder (/ RES )
A Resistive encoder (/ RES ) is used for our ANP nanopositioners . The working principle of this encoder type is based on a potentiometer . It is the method of choice for applications at cryogenic temperatures , ultra high vacuum and highest magnetic fields . The / RES encoder measurement refers to the absolute sample position , for most linear steppers a repeatability of 1 μm is achieved . For ultra low temperatures ( T < 1 K ) a special / RES + sensor is available which is included in all our / ULT models .
• Optoelectronic Encoder (/ NUM )
The usage of a glass grating and the interpretation of the generated Moiré pattern characterizes the working principle of the / NUM and / NUM + encoder . The measurement refers to the relative sample position with a position resolution of 1 nm and a repeatability of typically 50 nm for most linear stepping positioners . An absolute position information is also available via a reference mark . The + -version / NUM + features a reduced thermal dissipation of only 50 mW making it especially suited for / HV and / UHV positioners . The / NUM and / NUM + encoders are available for our ECS series positioners .