Microscopy with an infinite depth of field

In classical microscopy, an image’s depth of field is directly dependent on the numerical aperture (NA) of the microscope objective. The higher it becomes, the smaller is the part of the object structure which can be imaged axially. If a high NA is used to gain a high lateral resolution, only an axial area of a few hundred nanometers can be imaged sharply. For some applications, this phenomenon is an advantage, as it enables, for instance, optical sections through biological specimens. There are, however, numerous fields of application in which a high lateral resolution and a large depth of field would be desirable. Among them are, for example, fields of manufacturing control, the inspection of wafers, or microfluidic flow cytometry. Using coherence imaging microscopy it is possible to achieve high lateral resolutions while at the same time gaining an infinite depth of field. In this talk, we will explain the principle of this interferometric technique and present practically relevant sample images. In addition, we will demonstrate further advantages of this technique, for example, the possibility to obtain spectral information of the object structure.