A biological microscope is generally a type of optical microscope that is primarily designed to observe cells, tissues, and other biological specimens. Multiple objective lenses can be attached, which gives these microscopes a magnification that can range anywhere from 10x - 1,000x or more. Since these systems are used mainly to look at very flat samples (e.g. microscope slides, petri dishes, well-plates, etc.), the objective lenses have short working distances and high numerical apertures. Some specialised versions of these microscopes are capable of performing fluorescence imaging and are known more specifically as fluorescence microscopes.