# A What is the relationship between spectral coherence with respect to a radiation source's mean wavelength and bandwidth?

#### pbeierle

Summary
What is the relationship between spectral coherence with respect to a radiation source's mean wavelength and bandwidth? I have no idea how to estimate, given a particular radiation spectrum from a source, what it's spectral coherence is going to be.
What is the relationship between spectral coherence with respect to a radiation source's mean wavelength and bandwidth? I have no idea how to estimate, given a particular radiation spectrum from a source, what it's spectral coherence is going to be.

Related Atomic and Condensed Matter News on Phys.org

#### Charles Link

Homework Helper
Gold Member
2018 Award
A couple simple calculations should get you there: $L_c=c \Delta t$, and $\Delta t=\frac{1}{\Delta f}$ (approximately). Since $f=\frac{c}{\lambda}$, $|\Delta f|=\frac{c}{\lambda^2}\Delta \lambda$. The result is $L_c=\frac{\lambda^2}{\Delta \lambda}$, so that $\Delta \lambda=\frac{\lambda^2}{L_c}$ if I got all of the algebra right. $\\$ See also http://electron6.phys.utk.edu/optics421/modules/m5/Coherence.htm Factors of 2 and $\pi$ are somewhat arbitrary here.

### Want to reply to this thread?

"What is the relationship between spectral coherence with respect to a radiation source's mean wavelength and bandwidth?"

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving