Image-guided robot-assisted microscope objective lens positioning: Application in patch clamping

There are applications where different objective lenses have to be used for microscope imaging. Rotary nose-pieces cannot be used when larger objectives are required and when there is a physical space limitation. It is also very difficult and time consuming to change the objective lens manually and locate and focus on the same spot again; This may prevent any attempt for automating an image-guided robot-assisted procedure using the microscope images with different objective lenses. A linear lens changing mechanism has been developed which makes it possible to slide the objectives under a microscope. Image processing algorithms have been used to determine the optimal position of the lenses with respect to the source of light, compensate for changes in the focal length in case of non-parfocal objectives and to locate and focus on the exact same spot, regardless of the objective change. A 3-DOF micromanipulator has been used to move the microscope with respect to the substrate. As one of the most challenging applications, this can facilitate objective lens change in computer-assisted patch clamping with multiple electrodes.