The space between the front lens of an objective and the surface of the specimen when the object is in sharp focus is a crucial parameter in microscopy. This distance dictates the ease with which samples can be manipulated or accessed during observation. For example, imaging thick or irregularly shaped samples often requires ample clearance between the lens and the object.
A greater clearance offers several advantages, including reduced risk of collision with the sample, more space for accessories like micromanipulators or microinjection needles, and the ability to image through thicker cover glasses or containers. Historically, instruments prioritized high magnification and resolution, often at the expense of this clearance. Modern designs, however, increasingly recognize the value of optimized space for broader applications.
