Patent ID: 8775114

Claim:
A method of determining phase sensitivity of an accelerometer based on an analysis of harmonic components of an interference signal, comprising the steps of: obtaining an interference signal in a time domain generated from a signal reflected by an accelerometer and a fixed mirror using a single photo-detector; transforming the interference signal in the time domain into a signal in a frequency domain including a plurality of harmonic signals by Fourier transform; and determining the phase sensitivity of the accelerometer using initial phase of vibration displacement of the accelerometer, which is included in the interference signal in the frequency domain, wherein the step of determining the phase sensitivity comprises the steps of: obtaining an output phase of the accelerometer from a first harmonic component; determining a linear phase line using a harmonic order and a measured phase from each harmonic component; determining a linear phase from a phase of points in each harmonic order nearest to the linear phase line, and determining the initial phase of the vibration displacement by dividing the linear phase by the harmonic order and averaging the divided phase; and determining phase lag of the accelerometer from difference between the output phase and the initial phase; wherein the step of determining the linear phase line comprises the steps of: plotting points on a coordinate plane, which are apart from the measured phases by integer multiples of π; drawing an optional straight line that passes through an origin of the coordinate plane, and calculating a sum of squared effort (SSE) between the straight line and the nearest points; and repeating a process of calculating the SSE while a slop of the straight line is gradually increased stepwise, and determining the straight line having a minimum SSE as the linear phase line; and wherein the linear phase line can be expressed by a following equation, and the slop of the straight line exists between −π and π, φ L =(φ 1 +mπ)n [Equation] where φ L is the linear phase line, φ 1 is the initial phase, n is harmonic order, and m=0, ±1, ±2, . . . .