Fig. 1. Interference system model of multimode fiber extended light source

Fig. 2. Mode interference in MMF. (a) Ray propagation in MMF; (b) mode interference pattern at fiber end

Fig. 3. Interferogram contrast varying with spot size under different cavity lengths

Fig. 4. Effect of rotating ground glass speed on speckle contrast under different pupil apertures

Fig. 5. Effect of core diameter of multimode fiber on speckle contrast under different CCD exposure time

Fig. 6. Effect of core diameter of multimode fiber on speckle contrast under different NAs

Fig. 7. Speckle patterns of output light from multimode fibers with different core diameters collected in experiment (without ground glass). (a) 62.50 μm; (b) 0.25 mm; (c) 0.50 mm; (d) 0.75 mm; (e) 1.00 mm; (f) 1.50 mm; (g) 2.00 mm; (h) 3.00 mm

Fig. 8. Experimental interferograms of multimode fibers with different core diameters. (a) 62.50 μm; (b) 0.25 mm; (c) 0.50 mm; (d) 0.75 mm; (e) 1.00 mm; (f) 1.50 mm; (g) 2.00 mm; (h) 3.00 mm

Fig. 9. Experimental results. (a) Phase result measured by single-mode fiber light source with large numerical aperture; (b) phase result measured by multimode fiber extended source; (c) relative residual

Fig. 10. Relationship between actual speckle contrast and core diameter of multimode fiber

Fig. 11. Actual minimum boundary curve of core diameter of multimode fiber

Fig. 12. Relationship between actual fringe contrast and core diameter of fiber

Fig. 13. Background image speckle contrast curve of plastic multimode fiber extended light source interferometer with different core diameters collected by experiment

Fig. 14. Interferogram SNRs of light sources with different core diameters

Fig. 15. Normalized uniform distribution of interferometer background