#!/usr/bin/python
+#
+# calibcant - tools for thermally calibrating AFM cantilevers
+#
+# Copyright (C) 2007,2008, William Trevor King
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation; either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+# 02111-1307, USA.
+#
+# The author may be contacted at <wking@drexel.edu> on the Internet, or
+# write to Trevor King, Drexel University, Physics Dept., 3141 Chestnut St.,
+# Philadelphia PA 19104, USA.
"""
Aquire and analyze cantilever calibration data.
# bump family
@splittableKwargsFunction()
-def bump_aquire(zpiezo, push_depth=200, npoints=1024, freq=100e3) :
+def bump_aquire(zpiezo, push_depth=200, npoints=1024, push_speed=1000) :
"""
Ramps closer push_depth and returns to the original position.
Inputs:
zpiezo an opened zpiezo.zpiezo instance
push_depth distance to approach, in nm
npoints number points during the approach and during the retreat
- freq rate at which data is aquired
+ push_speed piezo speed during approach and retreat, in nm/s
Returns the aquired ramp data dictionary, with data in DAC/ADC bits.
"""
# generate the bump output
+ nm_per_step = float(push_depth) / npoints
+ freq = push_speed / nm_per_step # freq is sample frequency in Hz
start_pos = zpiezo.curPos()
pos_dist = zpiezo.pos_nm2out(push_depth) - zpiezo.pos_nm2out(0)
close_pos = start_pos + pos_dist
out = numpy.concatenate((appr, retr))
# run the bump, and measure deflection
if config.TEXT_VERBOSE :
- print "Bump %g nm" % push_depth
+ print "Bump %g nm at %g nm/s" % (push_depth, push_speed)
data = zpiezo.ramp(out, freq)
return data
# with proper spacing relative to the surface.
@splittableKwargsFunction()
-def move_just_onto_surface(stepper, zpiezo, Depth_nm=100, setpoint=2) :
+def move_just_onto_surface(stepper, zpiezo, Depth_nm=-50, setpoint=2) :
"""
- Uses z_piezo_utils.getSurfPos() to pinpoint the position of the surface.
- Adjusts the stepper position as required to get within stepper_tol nm
- of the surface.
- Then set Vzp to place the cantilever Depth_nm onto the surface.
-
+ Uses z_piezo_utils.getSurfPos() to pinpoint the position of the
+ surface. Adjusts the stepper position as required to get within
+ stepper_tol nm of the surface. Then set Vzp to place the
+ cantilever Depth_nm onto the surface. Negative Depth_nm values
+ will place the cantilever that many nm _off_ the surface.
+
If getSurfPos() fails to find the surface, backs off (for safety)
and steps in (without moving the zpiezo) until Vphoto > setpoint.
"""
# and finally, the calib family
@splittableKwargsFunction((move_just_onto_surface, 'stepper', 'zpiezo'),
- (bump, 'zpiezo', 'freq', 'log_dir', 'Vphoto_in2V'),
+ (bump, 'zpiezo', 'log_dir', 'Vphoto_in2V'),
(move_far_from_surface, 'stepper'),
(T, 'log_dir'),
(vib, 'zpiezo', 'log_dir', 'Vphoto_in2V'),
(analyze.calib_save, 'bumps','Ts','vibs','log_dir'))
def calib_aquire(stepper, zpiezo, num_bumps=10, num_Ts=10, num_vibs=20,
- bump_freq=100e3,
log_dir=config.LOG_DIR, Vphoto_in2V=config.Vphoto_in2V,
**kwargs):
"""
Inputs :
stepper a stepper.stepper_obj for coarse Z positioning
zpiezo a z_piezo.z_piezo for fine positioning and deflection readin
- setpoint maximum allowed deflection (in Volts) during approaches
- num_bumps number of 'a's (see Outputs)
- push_depth_nm depth of each push when generating a
- num_temps number of 'T's (see Outputs)
+ num_bumps number of 'bumps' (see Outputs)
+ num_temps number of 'Ts' (see Outputs)
num_vibs number of 'vib's (see Outputs)
log_dir directory to log data to. Default 'None' disables logging.
+ Vphoto_in2V function to convert photodiode input bits to Volts
+
+ + other kwargs. Run calib_aquire._kwargs(calib_aquire) to see
+ all options. Run calib_aquire._childSplittables to see a list
+ of kwarg functions that this function calls.
+
Outputs (all are arrays of recorded data) :
bumps measured (V_photodiode / nm_tip) proportionality constant
Ts measured temperature (K)
move_just_onto_surface(stepper, zpiezo, **move_just_onto_surface_kwargs)
bumps = numpy.zeros((num_bumps,), dtype=numpy.float)
for i in range(num_bumps) :
- bumps[i] = bump(zpiezo=zpiezo, freq=bump_freq, log_dir=log_dir,
+ bumps[i] = bump(zpiezo=zpiezo, log_dir=log_dir,
Vphoto_in2V=Vphoto_in2V, **bump_kwargs)
if config.TEXT_VERBOSE :
print bumps
projects / calibcant.git / blobdiff