I hope I am not overlooking something here, but most scanners can save as pdf, or if you have it in a file you can print to your "pdf printer".
Of course one should always check that the pdf matches the original. I know in the military, I had to certify many copies of things as a "Certified True Copy". I don't know if the control of the pdf or certification of the pdf is an issue for you, but that can be handled up to and including a certification stamp or an electronic signature on the pdf.