Adjustable field mask for region selection
For many years we have offered a movable variable rectangular field stop. This was initially designed to mask a region of interest within the field of view of a microscope in order to make localised intensity measurements with a photomultiplier. Subsequent evolutions of the device have formed an integral part of our OptoSplit image splitters to mask a region to be projected to both halves of a camera chip.
In these applications the aperture is intended to be in the centre or close to the centre of the microscope image plane. In order to enable the rapid "crop" and "kinetic" modes of Andor cameras it is necessary to accurately mask at the edge of the image plane. We therefore designed the OptoMask to enable an arbitrary rectangular region to be masked anywhere within the image plane.
Our traditional rectangular diaphragm is still used with our image splitters and photometry systems.