Q8Engineering Physics
Question
2 marks
Define spatial and temporal coherence.
Answer
Spatial coherence refers to the phase correlation between different points in space, while temporal coherence refers to the phase correlation at a single point over a period of time.
1. Spatial Coherence
Spatial coherence is a measure of the phase relationship between two points on a wavefront. If the phase difference between two points remains constant over time, the field is spatially coherent. This is essential for diffraction and interference experiments.
2. Temporal Coherence
Temporal coherence is the correlation of the phase of a wave with itself at a different time. It is related to the monochromaticity of the source. The time interval over which the phase remains predictable is called the Coherence Time ().
Where is the coherence length.