The objective used in the FDTD solution is as follows:
NA = 1.2 (filled lens); Background refractive index n = 1.33; Wavelength 1064 nm.
According to the equation posted here, we can estimate the beam waist as w0 = 380 nm.
NA = 1.2 (filled lens); Background refractive index n = 1.33; Wavelength 1064 nm.
According to the equation posted here, we can estimate the beam waist as w0 = 380 nm.
By fitting the FDTD data with a Gaussian function, we can get the beam waist w0 = 371 nm, this value is quite close to the above value 380 nm.
Notice the focal field of a highly focused beam is no longer an exacct Gaussian beam.
Notice the focal field of a highly focused beam is no longer an exacct Gaussian beam.