Abstract
The problem of image magnification in a bright field multi-focus imaging microscope is discussed. Such microscope allows simultaneous observation of two objects axially separated by a distance that exceeds the depth-of-field of the microscope, so-called multi-planar imaging. It is shown that the tunable lens required for operation of the microscope can be used in constant magnification imaging in the single focus regime, but not in multi-focus. Additionally, it is presented that the microscope allows for multi-planar imaging with satisfactory quality with a selected magnification of the image of one of the two objects. While the microscope uses a thermal lens as the tunable lens, the scheme of the optical setup needed to achieve the desired operation of the microscope is universal and applies to all kinds of tunable lenses used in microscopy.