New HiSA high-speed autofocus axis for the SensePrecisioner® product family offers higher power density and dynamics in a smaller space.
In industries such as semiconductors and life sciences, there is now a wide range of different imaging techniques that can detect and visualize structures with sub-micrometer dimensions. Modern techniques in microscopy – from optical confocal to magnetic micro- and nanoscopy – enable the identification or diagnosis of the smallest defects or biological bodies. The common denominator in these techniques is that optical assemblies or sensors compensate the z-profile of the object being examined in a highly dynamic and highly precise manner in the vertical direction during the scanning movement in order to ensure a sharp image. This makes z-tracking even more efficient during scanning processes in metrology.
In order to meet the constantly increasing requirements such as faster, more accurate, more precise and more efficient, ITK has developed a new High Speed Autofocus (HiSA) axis unit consisting of an ironless linear direct drive on a voice coil basis, an integrated magnetoresistive position measuring system, precision guides and weight compensation to compensate for the mass of the moving load. Different lightweight construction principles were used to achieve a significant weight reduction (minus 45 percent) compared to the previous model. The combination of direct drive and position measuring system enables a repeat accuracy of 100 nm and a positioning accuracy of < 500 nm. The passive weight compensation simplifies position control and leads to a noticeable reduction in power loss when the load needs to be held in a specific vertical position. A typical application for the new HiSA axis unit concerns the fast vertical axis of the PT-15 3D gantry positioning system from ITK, which is used in the semiconductor industry, among others. Sensors or lenses can be positioned quickly and precisely over the surface of silicon wafers. The HiSA axis unit contributes to a significant increase in precision and productivity. It is particularly advantageous that the linear direct drive is wear-free and has zero backlash. Pitch errors or friction – which occur with spindle-driven axes – are virtually eliminated. The low power loss leads to minimal thermal drift and therefore also to excellent focus stability.
