Fig. 1. Diagram of quality factor distribution

Fig. 2. Schematic of LDV based on liquid lens

Fig. 3. Simplified structure diagram of LDV based on liquid lens

Fig. 4. Schematic of liquid lens’ structure. (a) Schematic of liquid lens; (b) structure diagram of compensation lens

Fig. 5. Flow chart of controlling driving current

Fig. 6. Relationship between driving current and focal length of ETL and position along with size of Gaussian beam waist spot under different lens spacing. (a) Relationship between position of waist spot and driving current; (b) relationship between size of waist spot and driving current; (c) relationship between position of waist spot and focal length of ETL; (d) relationship between size of waist spot and focal length of ETL

Fig. 7. Relationship between position along with size of Gaussian beam waist spot and driving current and focal length of ETL under different offset lens focal length. (a) Relationship between position of waist spot and driving current; (b) relationship between size of waist spot and driving current; (c) relationship between position of waist spot and focal length of ETL; (d) relationship between size of waist spot and focal length of ETL

Fig. 8. Schematic of experimental principle

Fig. 9. Variation of quality factor with driving current for a single point. (a) Result of simulation; (b) experimental result

Fig. 10. Measuring range of LDV under different driving current

Table 1. Main parameters of liquid lenses (without offset lens)

Table 2. Measurement parameters of different compensation lenses