# Investigation of longitudinal spatial coherence for electromagnetic optical fields

## TL;DR

This paper develops a theoretical model to understand how the angular spectra of electromagnetic light fields influence their longitudinal spatial coherence, validated through experiments measuring coherence and polarization.

## Contribution

It introduces a new theoretical formulation linking angular spectra to longitudinal coherence, supported by experimental validation.

## Key findings

- Angular spectra significantly affect longitudinal spatial coherence.
- Experimental results confirm the theoretical predictions.
- Degree of cross-polarization correlates with angular spectra.

## Abstract

For light fields, the coherence in longitudinal direction is governed by both the frequency spectra and angular spectra they possess. In this work, we develop and report a theoretical formulation to demonstrate the effect of the angular spectra of electromagnetic light fields in quantifying their longitudinal spatial coherence. The experimental results obtained by measuring the electromagnetic longitudinal spatial coherence and degree of cross-polarization of uniformly polarized light fields for different angular spectra validate the theoretical findings.