Changes

Because the wave reflecting off the back of the diamond travels through the diamond twice, the term <math> d _2 - d _1 </math> is twice the thickness of the diamond, in radians. Because this measurement is in unhelpful units, we can multiply it by the wavelength <math> \lambda </math> and divide by <math> 2 \pi </math> for the thickness <math> \tau </math> in meters.

Because the wave reflecting off the back of the diamond travels through the diamond twice, the term <math> d _2 - d _1 </math> is twice the thickness of the diamond, in radians. Because this measurement is in unhelpful units, we can multiply it by the wavelength <math> \lambda </math> and divide by <math> 2 \pi </math> for the thickness <math> \tau </math> in meters.

<math>\frac{( d _2 - d _1 ) \lambda}{2 \pi} = \tau </math>

<math>\frac{( d _2 - d _1 ) \lambda}{4 \pi} = \tau </math>

Therefore, we can rewrite the earlier equation in terms of <math> \tau </math>:

Therefore, we can rewrite the earlier equation in terms of <math> \tau </math>: