Fig. 1. Optical fiber terahertz time-domain spectroscopy system

Fig. 2. Structure of fast rotating optical delay line. (a) Principle diagram; (b) 3D model

Fig. 3. Influence of different parameters on delay distance. (a) θ；(b) R; (c) α

Fig. 4. Schematic of optical simulation structure

Fig. 5. Experimental setup. (a) Schematic; (b) experimental picture

Fig. 6. Light spots at different positions. (a) β＝－1°；(b) β＝－0.5°；(c) β＝0°；(d) β＝0.5°；(e) β＝1°

Fig. 7. Exit light spots at different positions. (a) β＝－1°；(b) β＝－0.5°；(c) β＝0°；(d) β＝0.5°；(e) β＝1°

Fig. 8. Schematics of different eccentricity errors. (a) Horizontal eccentricity; (b) vertical eccentricity

Fig. 9. Schematic of Δy

Fig. 10. Finite element analysis of mechanical structure. (a) 1st order mode; (b) 2nd order mode; (c) 3rd order mode

Fig. 11. Damped oscillation frequency histogram for different modes