Jy. Son et al., Possibility of measuring displacement with sub-nanometre accuracy by ring laser operating in lock-in regime, ELECTR LETT, 35(15), 1999, pp. 1258-1260
The intensity difference between counterpropagating waves in ring lasers wi
th back-reflection waves from external mirrors is analysed to enable a high
ly accurate measurement of displacement to be obtained. The difference is e
xpressed as a periodic function of the distances between the ring laser mir
rors and their corresponding mirrors. The measurement accuracy attainable w
ith the difference can be in the sub-nanometre range.