Fig. 1. Reflective variable spot focusing system

Fig. 2. Equivalent optical path diagram of variable spot optical system

Fig. 3. Relationship between spot radius and focal length adjustment range of adaptive mirror

Fig. 4. Relationship between spot radius and focal length of the collimating mirror

Fig. 5. Relationship between spot radius and focal length of the focusing mirror

Fig. 6. Distribution of light field in the cross-section of light spot under different focal lengths of deforming mirror. (a) F₀=-2.5 m; (b) F₀=-10 m; (c) F₀=∞; (d) F₀=+10 m; (e) F₀=+2.5 m

Fig. 7. Optical system with variable spot for laser cladding

Fig. 8. Laser spot size on working plane at different air pressures of adaptive mirror. Corresponding cavity pressure , focal length of adaptive mirror and spot diameter are (a) 550 kPa, -2.97 m, 3.1 mm; (b) 410 kPa, -6.79 m, 4.0 mm; (c) 380 kPa, -9.37 m, 5.7 mm; (d) 300 kPa, 588.23 m, 7.1 mm; (e) 250 kPa, 14.40 m, 7.9 mm

Fig. 9. Variable spot focusing system

Fig. 10. Variable-spot cladding workpiece produced by laser cladding