Probevolumen

Probevolumen, or probe volume, is a term used in experimental science to describe the three-dimensional region of a sample from which a measurement derives. It is the portion of the sample that contributes to the detected signal and is defined by the interaction of illumination, detection geometry, and instrument optics. The shape and size depend on the technique and setup.

In optical spectroscopy and imaging, the probe volume corresponds to the overlap of the excitation light and the detection path. In confocal and multiphoton microscopy, it is often modeled as a three-dimensional confocal volume, governing spatial resolution and sensitivity. Typical dimensions span sub-micrometer to a few micrometers laterally, with similar or slightly larger axial extents.

In magnetic resonance imaging and spectroscopy, the probe volume is the imaging voxel or the localized region from which signal is collected. The measured signal is an integral over this volume, so tissue heterogeneity within the voxel can affect quantification through partial-volume effects.

In ultrasound and other acoustic measurements, the probe volume is determined by the transducer focus and the acoustic properties of the medium. It defines the region contributing to backscattered or transmitted signals.

Understanding and controlling the probe volume is essential for accurate quantification, spatial resolution, and comparison across experiments. It influences measurements of concentration, diffusion, and activity and is a key consideration in experimental design and data interpretation.