超低温工作台移动检测-capa

纳米级别的原子显微镜可以用来检测各种表面。被测物体必须以纳米级别幅度移动以得到表面图像。由一家德国公司开发的超低温检测系统使用了一种特殊的驱动电机，实现了这样的位移。

平台的移动依靠电容传感器进行测量。整个显微镜头由液氦冷却到4K，整个移动部件需要在超低温，真空以及强磁场作用下工作。米铱公司为该应用提供了两支电容传感器，成功满足了极端

环境工作要求。

Surfaces  are  inspected  with  nanometre  resolution for Atomic Force Microscopy (AFM). The test item must be able to be moved in the nanometre range for a surface
topography. attocube systems AG in Munich has developed actuator motors for such precise positioning. Using a positioning unit with piezo ceramics, movement in the x,
y and z-axes is possible. The positioning range, which is measured by the sensors, is 1.2mm x 1.2mm. The complete microscope head is cooled with liquid helium to 4K
above the absolute zero point of -273°C (corresponds to 0K). The traversing units operate at 4K ambient temperature in an ultra-high vacuum and under the highest

magnetic fields.
In order to measure the x and y movement, attocube systems AG uses two capacitive sensors from Micro-Epsilon on the nano positioning unit. With a measuring range of
1mm, the sensors have a precision of less than 5nm and operate completely without contact. The extreme ambient conditions are a particular challenge. The sensors must provide  identical  results  at  4K  as  at  room  temperature. This is possible due to the use of special materials for the sensor  and  cable,  which  provide stable  measurements due to low thermal expansion. The sensors are not influenced  by  extreme  ambient  conditions.  This  application can only be solved using capacitive measurement technology.  No  precise  statements  about  the  measurement results were possible using eddy current sensors, as the temperature gradient of the target at 4K is very low and the specific current flow characteristics change.