Simplistically, what does resolution in microscopy refer to?

Resolution in microscopy fundamentally refers to the ability to distinguish between two close points as separate entities. This capability is crucial in microscopy because it determines how much detail can be perceived in an image. A higher resolution means that even minor distinctions can be observed, allowing for clearer imaging of fine structures.

For example, if two points are very close together, a microscope with high resolution will still show them distinctly separate, while a lower-resolution instrument might make them appear as a single point. This characteristic of resolution is essential in fields like biology and materials science, where understanding the fine details can lead to significant insights.

The other options do not accurately define resolution. Total magnification pertains to how large an image appears, not how distinctly individual points are perceived. Brightness pertains to the light intensity and clarity of the image rather than the detailed structure, while the amount of light passing through the specimen relates to illumination rather than clarity of resolution. Each of these aspects plays a role in microscopy, but resolution specifically focuses on the clarity with which two separate points can be identified.