Numerical Aperture
Definition
n sin α for the relevant specimen-side medium and acceptance-cone half-angle. Numerical aperture depends on refractive index and the acceptance-cone half-angle. It contributes to collection and resolution properties under the actual imaging conditions.
- Context
- Microscope optics
For example, increasing image magnification does not replace the role of the optical system’s numerical aperture in the detail it can resolve.
Magnification alone does not describe resolved detail. Illumination, wavelength, specimen preparation and the rest of the optical system also matter.
Related terms
- Calibration
- A steganalysis technique that estimates the cover image statistics by cropping or decompressing and re-compressing the test image to produce a reference....
- Parfocality
- Parfocality is approximate retention of focus when switching among intended microscope objectives or optical configurations. It improves practical examination, but the degree...
- Resolution
- Resolution describes the ability of a measurement or imaging system to distinguish specified features under stated conditions. Its meaning depends on the...