Fig. 1. Schematic of FMCW fiber-optic displacement sensor

Fig. 2. Optical measurement structure of FMCW optical-fiber displacement sensor

Fig. 3. Schematic of DMA transfer process. (a) Sawtooth wave modulation signal output; (b) beat frequency signal acquisition

Fig. 4. DMA interrupt calculation process

Fig. 5. Schematic of calculating steps of beat signal. (a) Interception of valid signal; (b) calculation of theoretical wave peaks; (c) calculation of theoretical troughs; (d) calculation of amplitude and zero bias; (e) trends in extrapolating beat signals; (f) standard beat signal at fixed point

Fig. 6. Phase solution results of inverse cosine look-up method. (a) Calculation of relative amplitude; (b) curve of arccosine tables

Fig. 7. Result of integral period phase accumulation. (a) Δφ>π; (b) Δφ<π

Fig. 8. Experimental devices

Fig. 9. Standard deviation and time consuming of displacement drift at different fixed points

Fig. 10. Standard deviation of measurement error under different displacements. (a) 200 mm; (b) 400 mm; (c) 600 mm

Fig. 11. Linearity and repeatability test results