Nope, couldn't find it in that post, maybe your next one.
Still no justification for why you add, meaning the light beam travels along one segment with the rotation, and then magically teleports back to travel along the other segment again with the rotation.EXPERIMENTAL PROOF (right from
scratch, as required by the RE):
Self-pumped phase-conjugate fiber-optic gyro, I. McMichael, P. Yeh, Optics Letters 11(10):686-8 · November 1986
http://www.dtic.mil/dtic/tr/fulltext/u2/a170203.pdf (appendix 5.1)
Dr. P. Yeh
PhD, Caltech, Nonlinear Optics
Principal Scientist of the Optics Department at Rockwell International Science Center
Professor, UCSB
"Engineer of the Year," at Rockwell Science Center
Leonardo da Vinci Award in 1985
Fellow of the Optical Society of America, the Institute of Electrical and Electronics EngineersThe first phase-conjugate Sagnac experiment on a segment light path with an external pump configuration.

The most ingenious experiment performed by Professor Yeh: light from a laser is split into two separate fibers, F1 and F2 which are coiled such that light travels clockwise in F1 and counterclockwise in F2.
The Sagnac phase shift for the first fiber F1:
+2πR
1L
1Ω/λc
The Sagnac phase shift for the second fiber F2:
-2πR
2L
2Ω/λc
These are two separate Sagnac effects, each valid for the two fibers, F1 and F2.
The use of the phase conjugate mirror permits the revealing of the final formula, the total phase difference:
φ = -2(φ
2 - φ
1) = 4π(R
1L
1 + R
2L
2)Ω/λc
Since Δφ = 2πc/λ x Δt, Δt = 2(R1L1 + R2L2)Ω/c2 = 2(V1L1 + V2L2)c2
The very same formula derived by me:
Δt = (l1 + l2)/(c - v1 - v2) - (l1 + l2)/(c + v1 + v2) = 2[(l1v1 + l2v2)]/c2To obtain the correct Sagnac effect for two separate segments (which feature different lengths and different speeds) of an interferometer which is located away from the center of rotation, one has to
add (not substract) the two distinct components.
FULL JUSTIFICATION FOR THE ADDITION OF THE PHASE SHIFTS HAS JUST BEEN GIVEN.
MATHEMATICAL/THEORETICAL PROOF
The Sagnac phase shift for the first fiber F1:
+2πR1L1Ω/λc
The Sagnac phase shift for the second fiber F2:
-2πR2L2Ω/λc
These are two separate Sagnac effects, each valid for the two fibers, F1 and F2.
The use of the phase conjugate mirror permits the revealing of the final formula, the total phase difference:
φ = -2(φ2 - φ1) = 4π(R1L1 + R2L2)Ω/λc = 4π(V1L1 + V2L2)/λc
dt = l
1/(c - v
1) - l
1/(c + v
1) - (l
2/(c - v
2) - l
2/(c + v
2))
Of course, by proceeding as in the usual manner for a Sagnac phase shift formula for an interferometer whose center of rotation coincides with its geometrical center, we obtain:
2v
1l
1/(c
2 - v
21) - 2v
2l
2/(c
2 - v
22)
l = l
1 = l
22l[(v
1 - v
2)]/c
22lΩ[(R
1 - R
2)]/c
2R
1 - R
2 = h
2lhΩ/c
2By having substracted two different Sagnac phase shifts, valid for the two different segments, we obtain the CORIOLIS EFFECT formula.
The Coriolis effect means that the phase shift will be caused by the physical modification of the light paths (inflection and deflection due to the Coriolis force effect on the light beams).
l
1/(c - v
1) - l
2/(c - v
2) (we combine the terms which feature c - v
1,2)
(l
1c - l
1v
2 - l
2c + l
2v
1)/(c
2 - cv
2 - cv
1 +v
1v
2)
Factoring out c and observing that the terms l
1v
2/c, l
2v
1/c and v
1v
2/c can be neglected, we obtain:
(l
1 - l
2)/(c - v
2 - v
1)
Since l
1 ~= l
2, we can see that the velocity addition equations for the true Sagnac effect, c + v and c - v (in this case c + v
1 + v
2 and c - v
1 - v
2) are not applicable to the Coriolis effect situation.
The Coriolis effect is caused by the physical deflection/inflection of the light beams, not by the modification of the velocities.
Let us proceed now exactly as Professor Yeh did in the phase conjugate mirror experiment described above:
dt = l
1/(c - v
1) - l
1/(c + v
1)
+ (l
2/(c - v
2) - l
2/(c + v
2))
2[(l
1v
1 + l
2v
2)]/c
2Now, we have the correct, true Sagnac effect formula valid for an interferometer which is located away from the center of rotation.
Averaging (v
1 + v
2)/2 = v, and (l
1 + l
2)/2 = l, v
1 ~= v
2 = v, l
1 ~= l
2 = l, we obtain:
4lv/c2Moreover, we can see that now the velocity addition equations are valid:
(l
1 + l
2)/(c - v
2 - v
1)
To obtain the Coriolis effect phase shift, we substract the phase differences for each separate segment.
This formula is proportional to the area and the angular velocity.
To get the Sagnac effect phase shift, we have to add the phase differences for each separate segment
This formula is proportional to the linear velocity (and the radius of rotation), and will feature the addition of the two separate speeds and segment lengths. We can average the lengths and the velocities, to get a final formula which features one length and one velocity.
This is the great omission in the calculation done by A. Michelson.
Here are the initial phase shifts:
dt = l
1/(c - v
1) - l
1/(c + v
1)
- (l
2/(c - v
2) - l
2/(c + v
2))
For each separate segment/arm of the interferometer, each with a slightly different length and a slightly distinct velocity, the calculations proceed as follows:
l
1/(c - v
1) - l
1/(c + v
1) = 2l
1v
1/c
2l
2/(c - v
2) - l
2/(c + v
2) = 2l
2v
2/c
2The phase differences have already been obtained.
By substracting these phase differences, one is actually going to derive the Coriolis effect formula:
https://www.ias.ac.in/article/fulltext/pram/087/05/0071Spinning Earth and its Coriolis effect on the circuital light beams
Since the phase differences have already been calculated, one has to ADD them in order to get the final, total Sagnac effect:
2[(l
1v
1 + l
2v
2)]/c
2This fact has never been observed to the present day.
For a Sagnac interferometer, located away from the center of rotation, one has to ADD the separate phase differences in order to obtain the full Sagnac effect:
dt = l
1/(c - v
1) - l
1/(c + v
1)
+ (l
2/(c - v
2) - l
2/(c + v
2))
FULL CORIOLIS EFFECT FOR THE MGX:
4AΩsinΦ/c
2FULL SAGNAC EFFECT FOR THE MGX:
4Lv(cos
2Φ
1 + cos
2Φ
2)/c
2Sagnac effect/Coriolis effect ratio:
R((cos
2Φ
1 + cos
2Φ
2)/hsinΦ
R = 4,250 km
h = 0.33924 km
The rotational Sagnac effect is much greater than the Coriolis effect for the MGX.
Sagnac formula for an interferometer whose center of rotation coincides with its geometrical center:
Δt = l/(c - v) - l/(c + v)Sagnac formula for an interferometer located away from the center of rotation (different radii, different velocities):
Δt = (l1 + l2)/(c - v1 - v2) - (l1 + l2)/(c + v1 + v2)A beautiful generalization of the Sagnac formula for interferometers which are located away from the center of rotation.
Proven by Dr. Yeh's experiment.
Proof:
Δt = l
1/(c - v
1) - l
1/(c + v
1)
+ (l
2/(c - v
2) - l
2/(c + v
2))
Self-pumped phase-conjugate fiber-optic gyro, I. McMichael, P. Yeh, Optics Letters 11(10):686-8 · November 1986
http://www.dtic.mil/dtic/tr/fulltext/u2/a170203.pdf (appendix 5.1)
φ = -2(φ
2 - φ
1) = 4π(R
1L
1 + R
2L
2)Ω/λc
Since Δφ = 2πc/λ x Δt, Δt = 2(R
1L
1 + R
2L
2)Ω/c
2.
l
1/(c - v
1) + l
2/(c - v
2) = (l
1c - l
1v
2 + l
2c - l
2v
1)/(c
2 - cv
1 - cv
2 + v
1v
2)
l
1/(c + v
1) + l
2/(c + v
2) = (l
1c + l
1v
2 + l
2c + l
2v
1)/(c
2 + cv
1 + cv
2 + v
1v
2)
Since we have already added the correct Sagnac differences, corresponding to the (l
1 + l
2)/(c - v
1 - v
2) and (l
1 + l
2)/(c + v
1 + v
2) terms, now the final phase difference can be correctly derived:
(l
1c - l
1v
2 + l
2c - l
2v
1)/(c
2 - cv
1 - cv
2 + v
1v
2) - (l
1c + l
1v
2 + l
2c + l
2v
1)/(c
2 + cv
1 + cv
2 + v
1v
2) = 2[(l
1v
1 + l
2v
2)]/c
2The Coriolis effect formula by contrast is just the physical effect of the Coriolis force upon the light beams, a modification of the paths of the light beams leading to a final formula where the effect is directly proportional to the area and to the angular velocity.
The Sagnac effect is an electromagnetic effect, the modification of the velocities of the light beams, c + v
1 + v
2 and c - v
1 - v
2, leading to the final formula where the Sagnac effect is directly proportional to the linear velocity (radius of rotation x angular velocity) and the length of the segments of the interferometer.