Fig. 1. Schematic diagram of low-coherence heterodyne interference clearance measurement based on differential detection

Fig. 2. The relationship between output voltage and VDL optical path and clearance

Fig. 3. Schematic diagram of experimental system

Fig. 4. Time domain and frequency domain signals of 4 mm clearance

Fig. 5. Power spectral intensity curves for single-ended versus differential input

Fig. 6. Comparison of experimental results between single-ended input and differential input

Fig. 7. Relationship of theoretical measurement uncertainty of system and measuring clearance