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pykat
Commits
91678a90
Commit
91678a90
authored
Jan 15, 2016
by
Daniel Brown
Browse files
adding Paul's fitting function
parent
e43923a0
Changes
1
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Inline
Side-by-side
pykat/optics/gaussian_beams.py
View file @
91678a90
...
...
@@ -7,7 +7,59 @@ import cmath
from
scipy.special
import
hermite
from
pykat.SIfloat
import
SIfloat
def
fit_beam_size
(
z_data
,
w_data
,
w0guess
,
z0guess
,
lam
=
1064e-9
,
show_plot
=
True
,
plotpts
=
100
,
title
=
'Beam scan fit'
,
w2zero
=
True
,
filename
=
None
):
"""
Function to fit a beam size (w0 and z) to a 2D intensity array. Plotting can
be switched on or off.
Returns best fit of (w0, z)
Contributed by Paul Fulda on 15/01/16
"""
import
scipy.optimize
def
zw0z02w
(
z
,
w0
,
z0
,
lam
):
z_R
=
pl
.
pi
*
w0
**
2
/
lam
w
=
w0
*
pl
.
sqrt
(
1
+
((
z
-
z0
)
/
z_R
)
**
2
)
return
w
popt
,
pcov
=
scipy
.
optimize
.
curve_fit
(
lambda
z_data
,
w0
,
z0
:
zw0z02w
(
z_data
,
w0
,
z0
,
lam
),
z_data
,
w_data
,
p0
=
[
w0guess
,
z0guess
])
w0out
=
popt
[
0
]
z0out
=
popt
[
1
]
z_fit
=
pl
.
linspace
(
min
(
z_data
),
max
(
z_data
),
plotpts
)
w_fit
=
zw0z02w
(
z_fit
,
w0out
,
z0out
,
lam
)
if
show_plot
or
filename
is
not
None
:
import
pylab
as
pl
um
=
1e6
pl
.
figure
()
pl
.
plot
(
z_data
,
w_data
*
um
,
'bo'
,
label
=
'Data'
)
pl
.
plot
(
z_fit
,
w_fit
*
um
,
'b'
,
label
=
'Fit'
)
pl
.
tight_layout
pl
.
grid
()
pl
.
xlabel
(
'Position [m]'
)
pl
.
ylabel
(
'Beam size [$\mu$m]'
)
pl
.
xlim
((
min
(
z_data
),
max
(
z_data
)))
if
w2zero
:
pl
.
ylim
((
0
,
max
(
w_data
)
*
um
))
pl
.
legend
(
loc
=
0
)
pl
.
title
(
title
)
if
filename
is
not
None
:
pl
.
savefig
(
filename
)
return
w0out
,
z0out
class
gauss_param
(
object
):
"""
Use beam_param instead, will be the future name of this object.
...
...
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