Newport LBP2 Series - Page 87

LBP2 User Guide Document No: 50306-001 Rev G 3/12/2020 Page 87
1
3.3
circular beam.
beam diameter (second
moment)
)(22)( zzd 


where :








drdrzrE
drdrzrEr
),,(
),,(
2
2
where
r is the distance from
the centroid
),( yx

is the azimuth angle
and where the first moments
give the coordinates of the
centroid
dxdyzyxE
dxdyzyxxE
x
),,(
),,(



dxdyzyxE
dxdyzyxyE
y
),,(
),,(



3
w
()
beam radius
x
3.4.1
3.4.2
Half a beam diameter. See
above.
4
d
σx
d
σy
d
x,k
d
y,k
d
x,u
d
y,u
beam widths…
second moment
knife edge
smallest
aperture
x
1
x
3.5.2
3.5.1
3.2
3.2.4
Second moment, knife
edge, or smallest slit
methods
beam widths (second moment)
)(4)( zzd
xx



)(4)( zzd
yy



knife edge, 90/10% method
smallest slit method
5
M²
beam
propagation
ratio
x
1
3.7
3.4
Measure of how close the
beam is to the diffraction
limit of a perfect Gaussian
beam.



4
0
2


d
M
6
d
0,u
d
σ0
beam waist
diameter
x
3.11.1
Beam diameter
measurements performed at
the waist.