A differential Michelson interferometer with orthogonal single frequency laser for nanometer displacement measurement

Abstract

A novel differential Michelson laser interferometer is proposed to eliminate the influence of environmental fluctuations for nanometer displacement measurement. This differential interferometer consists of two homodyne interferometers in which two orthogonal single frequency beams share common reference arm and partial measurement arm. By modulating the displacement of the common reference arm with a piezoelectric transducer, the common-mode displacement drift resulting from the environmental disturbances can be well suppressed and the measured displacement as differential-mode displacement signal is achieved. In addition, a phase difference compensation method is proposed for accurately determining the phase difference between interference signals by correcting the time interval according to the average speed in one cycle of interference signal. The nanometer displacement measurement experiments were performed to demonstrate the effectiveness and feasibility of the proposed interferometer and show that precision displacement measurement with standard deviation less than 1 nm has been achieved.

Compensation Method for Polarization Mixing in the Homodyne Interferometer

“…As shown in Equation 15, the cross term of t p1 t s1 r p1 r s1 caused by the polarization mixing of the PBS 1 has been completely eliminated after using the P 2 and the P 3 with a high extinction ratio, the PBS 2 and the PBS 3 have the same parameters as those listed in Section 2, and gain adjustment is applied according to Equation (12). From Equation 15, parameters A and D are equal to zero, whereas parameter C is equal to parameter E. At this point, the signals I x and I y have become quadrature signals in Equation (15).…”

“…The real matrix Equation 17of the P 2 and the P 3 is substituted into Equation (8). Then, the two intensity signals can be obtained by adopting the gain coefficients of the four detectors according to Equation (12) as follows:…”

“…Others have proposed their solutions to improve the optical configurations. Yan proposed an optical structure that consists of two homodyne interferometers in which two orthogonal single-frequency beams share a common reference arm and partial measurement arm [11,12]. A series of experiments demonstrate that the proposed interferometer is able to realize sub-nanometer accuracy without nonlinearity for nanometer displacement and nanometer accuracy for millimeter displacement.…”

Displacement Sensor State Detection Method Based on Laser Interference

“…In order to test and evaluate the thrust performance of the thruster, the measurement accuracy of the micro-thrust measuring device is required to be high. Based on the torsion pendulum structure, the method of laser interference and displacement sensor combined measurement is used to compare the displacement measurements of the two measurement methods at the measuring arm, and the error of the displacement sensor system is corrected and the residual system error of the sensor is moved, the state detection of the high-precision displacement sensor is realized [4,5]. Figure 1 is a schematic diagram of the combined measurement method of the displacement sensor and the laser interference.…”

Optical direct detection of thermal vibrations of ultralow stiffness micro-nano structures.

“…a photodiode or photomultiplier tube)[55][56][57]. If the object and reference beams are at the same wavelength or frequency, the method is referred to as homodyne detection[58][59][60][61]. If the beams are at two different frequencies, the method is referred to as heterodyne detection[57,[62][63][64].…”