Patent ID: 7349078

Claim:
A method of characterizing a lens, said method comprising: generating a laser beam; converging the laser beam along an optical axis at a distance f ext and corresponding focal point f 0 ; placing a test lens along said optical axis, wherein said test lens is characterized by an effective focal length f i that is substantially independent of incident irradiance; generating an output beam from said laser beam using said test lens, said output beam comprising an observable output intensity profile at an observation plane located a distance Z 0 from the focal point f 0 ; varying placement of said test lens along said optical axis; monitoring on-axis intensity I of said observable output intensity profile of said output beam along said optical axis at said observation plane as the placement of said test lens along said optical axis is varied; plotting a z-scan signature of said test lens using said monitored intensity I, where said z-scan signature is a plot of intensity as a function of ΔZ, where ΔZ represents a distance between a position of said test lens and said focal point f 0 along said optical axis; and characterizing the focal length f i of said test lens by determining a slope m 0 of said plotted z-scan signature at ΔZ=0.