Measuring source width and transverse coherence length using Fresnel diffraction from a phase step
| Autor: | Ahad Saber, Rasoul Aalipour, Mohammad Taghi Tavassoly |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Physics
Diffraction business.industry Physics::Optics Interference (wave propagation) 01 natural sciences Atomic and Molecular Physics and Optics Ptychography Coherence length Starlight 010309 optics Transverse plane Optics 0103 physical sciences Reflection (physics) Electrical and Electronic Engineering business Engineering (miscellaneous) Fresnel diffraction |
| Zdroj: | Applied Optics. 59:7712 |
| ISSN: | 2155-3165 1559-128X |
| DOI: | 10.1364/ao.397748 |
| Popis: | Measurement of the source size and specifying its effect on the spatial coherence of propagating light are important for characterizing distant sources such as stars, and imaging with partially coherent light. The common method for measuring spatial coherence is Young’s two-pinhole experiment. For characterizing spatial coherence along a line, one needs to change the location of the pinholes over a large number of pairs of points. But it requires many measurements, which takes significant time. In this paper, we use Fresnel diffraction from a step in reflection to measure the source width and transverse coherence length. It is shown theoretically and experimentally that these quantities are determined by specifying the location of minimum visibility on the diffraction pattern. We utilize a sodium vapor lamp with a variable slit in front of it as an extended one-dimensional incoherent light source. The measurements are made through recording only one diffraction pattern formed by the step. The study is applicable in 2D, and one can characterize weak starlight using highly sensitive equipment. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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