What Is the Coherence Length of a Highly Stabilized He-Ne Laser?

[kingyof2thejring]

Homework Statement

A magnetic-field technique for stabilizing a He-Ne laser to 2 parts in 10^10 has been patented. At 632.8 nm, what would be the coherence length of a laser with such frquency stability.

Homework Equations

Coherence time =1/delta frequency
coherence length = c/delta frquency

The Attempt at a Solution

dont know what 10^10 stands for and how to solve this
help would be much appreciated.

 

[quasar987]

I think it means that the technique assures you that if you choose to give the laser a frequency f, then the actual frequency of the laser will effectively be f with an uncertainty of only ±(2*f*(10^-10)).

See what I "did"? I shopped up f into 10^10 equal parts, then said that the uncertainty of f is 2 of those parts: 2*(f/[10^10])

 

[JeffKoch]

10^10 means 10 raised to the power of 10, which is 10 billion. So the frequency is stable to 2 parts in 10 billion.

What is the frequency of the HeNe laser?