Fig. 1. Thermal bonded crystal elements

Fig. 2. Hot isostatic pressing process

Fig. 3. Experimental results of hot isostatic pressure

Fig. 4. SEM images of bonding surface before and after hot isostatic pressing

Fig. 5. Three-point bending method for measuring the flexural strength

Fig. 6. D Vickers hardness and fracture toughness measurement by indentation method

Fig. 7. Element Vickers hardness test diagram

Fig. 8. Transmittance spectra of elements 1，2，3 and single crystal Yb∶YAG in the range of 250~3 000 nm

Fig. 9. Schematic of optical uniformity test

Fig. 10. R₂ wavefront error measurement results for element 1 and 3

Fig. 11. Optical uniformity distribution of single crystal Yb∶YAG

Fig. 12. Optical uniformity distribution of element 3