Thanks to thermistor data sheet from yuefan and the data tomura-san and I took(see e-log 627). I finished the SHG characterization work.
Since the data sheet doesn't give us a formula but only a few points, I use them to make a cubic interpolate. Then I use the interpolation data to make the plot so that you can see the relationship between crystal temperature and Laser power.
The NTC used seems to be SEMITEC 103JT-050.
According to the datasheet, the R25 = 10kΩ ± 1% and B = 3435K ± 1% (note that this value is correct only between 25deg to 85deg Celsius).