For research proposes can you indicate what is camera intrinsic matrix of sr300 and r200?
Librealsense or RealSense SDK should give you that.
There's no unique intrinsic matrix since different cameras will have slightly different values because of manufacturing differences. Even if you change the frame resolution you would get a different intrinsic matrix since the principal point and the focal lengths have to be scaled.
Having said that, it seems that RealSense provides a generic one-size-fits-all intrinsic parameters.
Have a look here and you can get all the parameters you need for the intrinsic matrix:
The intrinsic matrix for 640x480 images would be:
[463.889 0 320] [0 463.889 240] [0 0 1 ]