1 # calibcant - tools for thermally calibrating AFM cantilevers
3 # Copyright (C) 2008-2012 W. Trevor King <wking@drexel.edu>
5 # This file is part of calibcant.
7 # calibcant is free software: you can redistribute it and/or modify it under
8 # the terms of the GNU General Public License as published by the Free Software
9 # Foundation, either version 3 of the License, or (at your option) any later
12 # calibcant is distributed in the hope that it will be useful, but WITHOUT ANY
13 # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
14 # A PARTICULAR PURPOSE. See the GNU General Public License for more details.
16 # You should have received a copy of the GNU General Public License along with
17 # calibcant. If not, see <http://www.gnu.org/licenses/>.
19 """Calculate `k` from arrays of bumps, temperatures, and vibrations.
21 Separate the more general `calib_analyze()` from the other `calib_*()`
22 functions in calibcant.
24 The relevent physical quantities are :
25 Vzp_out Output z-piezo voltage (what we generate)
26 Vzp Applied z-piezo voltage (after external ZPGAIN)
27 Zp The z-piezo position
28 Zcant The cantilever vertical deflection
29 Vphoto The photodiode vertical deflection voltage (what we measure)
30 Fcant The force on the cantilever
31 T The temperature of the cantilever and surrounding solution
32 (another thing we measure)
33 k_b Boltzmann's constant
35 Which are related by the parameters:
37 zp_sensitivity Zp / Vzp
38 photo_sensitivity Vphoto / Zcant
45 >>> from h5config.storage.hdf5 import HDF5_Storage, pprint_HDF5
46 >>> from .config import CalibrationConfig
48 >>> fd,filename = tempfile.mkstemp(suffix='.h5', prefix='calibcant-')
51 >>> calibration_config = CalibrationConfig(storage=HDF5_Storage(
52 ... filename=filename, group='/calib/config/'))
53 >>> bumps = numpy.array((15.9e6, 16.9e6, 16.3e6))
54 >>> temperatures = numpy.array((295, 295.2, 294.8))
55 >>> vibrations = numpy.array((2.20e-5, 2.22e-5, 2.21e-5))
57 >>> k,k_s = calib_analyze(bumps=bumps, temperatures=temperatures,
58 ... vibrations=vibrations)
59 >>> (k, k_s) # doctest: +ELLIPSIS
60 (0.0493..., 0.00248...)
62 Most of the error in this example comes from uncertainty in the
63 photodiode sensitivity (bumps).
65 >>> k_s/k # doctest: +ELLIPSIS
67 >>> bumps.std()/bumps.mean() # doctest: +ELLIPSIS
69 >>> temperatures.std()/temperatures.mean() # doctest: +ELLIPSIS
71 >>> vibrations.std()/vibrations.mean() # doctest: +ELLIPSIS
74 >>> calib_save(filename=filename, group='/calib/',
75 ... bumps=bumps, temperatures=temperatures, vibrations=vibrations,
76 ... calibration_config=calibration_config, k=k, k_s=k_s)
77 >>> pprint_HDF5(filename) # doctest: +ELLIPSIS, +REPORT_UDIFF
81 <HDF5 dataset "bump": shape (), type "|S1">
83 <HDF5 dataset "num-bumps": shape (), type "<i4">
85 <HDF5 dataset "num-temperatures": shape (), type "<i4">
87 <HDF5 dataset "num-vibrations": shape (), type "<i4">
89 <HDF5 dataset "temperature": shape (), type "|S1">
91 <HDF5 dataset "temperature-sleep": shape (), type "<i4">
93 <HDF5 dataset "vibration": shape (), type "|S1">
95 <HDF5 dataset "vibration-spacing": shape (), type "<f8">
98 /calib/processed/spring-constant
99 <HDF5 dataset "data": shape (), type "<f8">
101 <HDF5 dataset "standard-deviation": shape (), type "<f8">
103 <HDF5 dataset "units": shape (), type "|S3">
106 /calib/raw/photodiode-sensitivity
107 <HDF5 dataset "data": shape (3,), type "<f8">
108 [ 15900000. 16900000. 16300000.]
109 <HDF5 dataset "units": shape (), type "|S3">
111 /calib/raw/temperature
112 <HDF5 dataset "data": shape (3,), type "<f8">
114 <HDF5 dataset "units": shape (), type "|S1">
116 /calib/raw/thermal-vibration-variance
117 <HDF5 dataset "data": shape (3,), type "<f8">
118 [ 2.20...e-05 2.220...e-05 2.210...e-05]
119 <HDF5 dataset "units": shape (), type "|S3">
122 >>> bumps,temperatures,vibrations,calibration_config,k,k_s = calib_load(
123 ... filename=filename, group='/calib/')
124 >>> (k, k_s) # doctest: +ELLIPSIS
125 (0.0493..., 0.00248...)
127 >>> os.remove(filename)
131 import numpy as _numpy
133 from scipy.constants import Boltzmann as _kB # in J/K
135 from scipy.constants import Bolzmann as _kB # in J/K
136 # Bolzmann -> Boltzmann patch submitted:
137 # http://projects.scipy.org/scipy/ticket/1417
138 # Fixed in scipy commit 4716d91, Apr 2, 2011, during work after v0.9.0rc5.
141 import matplotlib as _matplotlib
142 import matplotlib.pyplot as _matplotlib_pyplot
143 import time as _time # for timestamping lines on plots
144 except (ImportError, RuntimeError), e:
146 _matplotlib_import_error = e
148 from h5config.storage.hdf5 import HDF5_Storage as _HDF5_Storage
149 from h5config.storage.hdf5 import h5_create_group as _h5_create_group
151 from . import LOG as _LOG
152 from . import package_config as _package_config
153 from .bump_analyze import bump_analyze as _bump_analyze
154 from .bump_analyze import bump_load as _bump_load
155 from .bump_analyze import bump_save as _bump_save
156 from .config import CalibrationConfig as _CalibrationConfig
157 from .T_analyze import T_analyze as _temperature_analyze
158 from .T_analyze import T_load as _temperature_load
159 from .T_analyze import T_save as _temperature_save
160 from .vib_analyze import vib_analyze as _vibration_analyze
161 from .vib_analyze import vib_load as _vibration_load
162 from .vib_analyze import vib_save as _vibration_save
165 def calib_analyze(bumps, temperatures, vibrations):
166 """Analyze data from `get_calibration_data()`
168 Inputs (all are arrays of recorded data):
169 bumps measured (V_photodiode / nm_tip) proportionality constant
170 temperatures measured temperature (K)
171 vibrations measured V_photodiode variance in free solution (V**2)
173 k cantilever spring constant (in N/m, or equivalently nN/nm)
174 k_s standard deviation in our estimate of k
178 We're assuming vib is mostly from thermal cantilever vibrations
179 (and then only from vibrations in the single vertical degree of
180 freedom), and not from other noise sources.
182 If the error is large, check the relative errors
183 (`x.std()/x.mean()`)of your input arrays. If one of them is
184 small, don't bother repeating that measurment too often. If one
185 is large, try repeating that measurement more. Remember that you
186 need enough samples to have a valid error estimate in the first
187 place, and that none of this addresses any systematic errors.
189 ps_m = bumps.mean() # ps for photo-sensitivity
191 T_m = temperatures.mean()
192 T_s = temperatures.std()
193 v2_m = vibrations.mean() # average voltage variance
194 v2_s = vibrations.std()
196 # Vphoto / photo_sensitivity = x
197 # k = kB T / <x**2> = kB T photo_sensitivity**2 / Vphoto_var
199 # units, photo_sensitivity = Vphoto/(Zcant in m),
200 # so Vphoto/photo_sensitivity = Zcant in m
201 # so k = J/K * K / m^2 = J / m^2 = N/m
202 k = _kB * T_m * ps_m**2 / v2_m
204 # propogation of errors
208 dk_ps = 2*k/ps_m * ps_s
210 dk_v = -k/v2_m * v2_s
212 k_s = _numpy.sqrt(dk_T**2 + dk_ps**2 + dk_v**2)
214 _LOG.info('variable (units) : '
215 'mean +/- std. dev. (relative error)')
216 _LOG.info('cantilever k (N/m) : %g +/- %g (%g)' % (k, k_s, k_s/k))
217 _LOG.info('photo sensitivity (V/m) : %g +/- %g (%g)'
218 % (ps_m, ps_s, ps_s/ps_m))
219 _LOG.info('T (K) : %g +/- %g (%g)'
220 % (T_m, T_s, T_s/T_m))
221 _LOG.info('vibration variance (V^2) : %g +/- %g (%g)'
222 % (v2_m, v2_s, v2_s/v2_m))
224 if _package_config['matplotlib']:
225 calib_plot(bumps, temperatures, vibrations)
229 def calib_save(filename, group='/', bumps=None, temperatures=None,
230 vibrations=None, calibration_config=None, k=None, k_s=None):
231 with _h5py.File(filename, 'a') as f:
232 cwg = _h5_create_group(f, group)
233 if calibration_config is not None:
234 config_cwg = _h5_create_group(cwg, 'config')
235 storage = _HDF5_Storage()
236 storage.save(config=calibration_config, group=config_cwg)
237 if bumps is not None:
239 del cwg['raw/photodiode-sensitivity/data']
243 del cwg['raw/photodiode-sensitivity/units']
246 cwg['raw/photodiode-sensitivity/data'] = bumps
247 cwg['raw/photodiode-sensitivity/units'] = 'V/m'
248 if temperatures is not None:
250 del cwg['raw/temperature/data']
254 del cwg['raw/temperature/units']
257 cwg['raw/temperature/data'] = temperatures
258 cwg['raw/temperature/units'] = 'K'
259 if vibrations is not None:
261 del cwg['raw/thermal-vibration-variance/data']
265 del cwg['raw/thermal-vibration-variance/units']
268 cwg['raw/thermal-vibration-variance/data'] = vibrations
269 cwg['raw/thermal-vibration-variance/units'] = 'V^2'
272 del cwg['processed/spring-constant/data']
276 del cwg['processed/spring-constant/units']
279 cwg['processed/spring-constant/data'] = k
280 cwg['processed/spring-constant/units'] = 'N/m'
283 del cwg['processed/spring-constant/standard-deviation']
286 cwg['processed/spring-constant/standard-deviation'] = k_s
288 def calib_load(filename, group='/'):
289 assert group.endswith('/')
290 bumps = temperatures = vibrations = k = k_s = None
292 with _h5py.File(filename, 'a') as f:
294 bumps = f[group+'raw/photodiode-sensitivity/data'][...]
298 temperatures = f[group+'raw/temperature/data'][...]
302 vibrations = f[group+'raw/thermal-vibration-variance/data'][...]
306 k = float(f[group+'processed/spring-constant/data'][...])
311 f[group+'processed/spring-constant/standard-deviation'][...])
314 calibration_config = _CalibrationConfig(storage=_HDF5_Storage(
315 filename=filename, group=group+'config/'))
316 calibration_config.load()
317 return (bumps, temperatures, vibrations, calibration_config, k, k_s)
319 def calib_plot(bumps, temperatures, vibrations):
321 raise _matplotlib_import_error
322 figure = _matplotlib_pyplot.figure()
324 bump_axes = figure.add_subplot(3, 1, 1)
325 T_axes = figure.add_subplot(3, 1, 2)
326 vib_axes = figure.add_subplot(3, 1, 3)
328 timestamp = _time.strftime('%H%M%S')
329 bump_axes.set_title('cantilever calibration %s' % timestamp)
331 bump_axes.plot(bumps, 'g.-')
332 bump_axes.set_ylabel('photodiode sensitivity (V/m)')
333 T_axes.plot(temperatures, 'r.-')
334 T_axes.set_ylabel('temperature (K)')
335 vib_axes.plot(vibrations, 'b.-')
336 vib_axes.set_ylabel('thermal deflection variance (V^2)')
338 if hasattr(figure, 'show'):
342 def calib_load_all(filename, group='/'):
343 "Load all data from a `calib()` run."
344 assert group.endswith('/'), group
345 bumps,temperatures,vibrations,calibration_config,k,k_s = calib_load(
346 filename, group+'calibration/')
348 for i in range(calibration_config['num-bumps']):
349 (raw_bump,bump_config,z_axis_config,deflection_channel_config,
350 processed_bump) = _bump_load(
351 filename=filename, group='%sbump/%d/' % (group, i))
352 bump_details.append({
353 'raw_bump': raw_bump,
354 'bump_config': bump_config,
355 'z_axis_config': z_axis_config,
356 'deflection_channel_config': deflection_channel_config,
357 'processed_bump': processed_bump,
359 temperature_details = []
360 for i in range(calibration_config['num-temperatures']):
361 (raw_temperature,temperature_config,processed_temperature
362 ) = _temperature_load(
363 filename=filename, group='%stemperature/%d/' % (group, i))
364 temperature_details.append({
365 'raw_temperature': raw_temperature,
366 'temperature_config': temperature_config,
367 'processed_temperature': processed_temperature,
369 vibration_details = []
370 for i in range(calibration_config['num-vibrations']):
371 (raw_vibration,vibration_config,deflection_channel_config,
372 processed_vibration) = _vibration_load(
373 filename=filename, group='%svibration/%d/' % (group, i))
374 vibration_details.append({
375 'raw_vibration': raw_vibration,
376 'vibration_config': vibration_config,
377 'deflection_channel_config': deflection_channel_config,
378 'processed_vibration': processed_vibration,
382 'bump_details': bump_details,
383 'temperatures': temperatures,
384 'temperature_details': temperature_details,
385 'vibrations': vibrations,
386 'vibration_details': vibration_details,
387 'calibration_config': calibration_config,
392 def calib_analyze_all(filename, group='/', maximum_relative_error=1e-5,
394 "(Re)analyze all data from a `calib()` run."
395 assert group.endswith('/'), group
396 bumps,temperatures,vibrations,calibration_config,k,k_s = calib_load(
397 filename, group+'calibration/')
398 changed_bump = changed_temperature = changed_vibration = False
399 for i in range(calibration_config['num-bumps']):
400 bump_group = '%sbump/%d/' % (group, i)
401 (raw_bump,bump_config,z_axis_config,
402 deflection_channel_config,processed_bump) = _bump_load(
403 filename=filename, group=bump_group)
404 sensitivity = _bump_analyze(
405 data=raw_bump, bump_config=bump_config,
406 z_axis_config=z_axis_config,
407 deflection_channel_config=deflection_channel_config)
408 bumps[i] = sensitivity
409 rel_error = abs(sensitivity - processed_bump)/processed_bump
410 if rel_error > maximum_relative_error:
411 _LOG.warn(("new analysis doesn't match for bump %d: %g -> %g "
412 "(difference: %g, relative error: %g)")
413 % (i, processed_bump, sensitivity,
414 sensitivity-processed_bump, rel_error))
417 _bump_save(filename, bump_group, processed_bump=sensitivity)
418 for i in range(calibration_config['num-temperatures']):
419 temperature_group = '%stemperature/%d/' % (group, i)
420 (raw_temperature,temperature_config,processed_temperature
421 ) = _temperature_load(
422 filename=filename, group=temperature_group)
423 temperature = _temperature_analyze(
424 raw_temperature, temperature_config)
425 temperatures[i] = temperature
426 rel_error = abs(temperature - processed_temperature
427 )/processed_temperature
428 if rel_error > maximum_relative_error:
429 _LOG.warn(("new analysis doesn't match for temperature %d: "
430 "%g -> %g (difference: %g, relative error: %g)")
431 % (i, processed_temperature, temperature,
432 temperature-processed_temperature, rel_error))
433 changed_temperature = True
436 filename, temperature_group,
437 processed_T=temperature)
438 for i in range(calibration_config['num-vibrations']):
439 vibration_group = '%svibration/%d/' % (group, i)
440 (raw_vibration,vibration_config,deflection_channel_config,
441 processed_vibration) = _vibration_load(
442 filename=filename, group=vibration_group)
443 variance = _vibration_analyze(
444 deflection=raw_vibration, vibration_config=vibration_config,
445 deflection_channel_config=deflection_channel_config)
446 vibrations[i] = variance
447 rel_error = abs(variance - processed_vibration)/processed_vibration
448 if rel_error > maximum_relative_error:
449 _LOG.warn(("new analysis doesn't match for vibration %d: %g -> %g "
450 "(difference: %g, relative error: %g)")
451 % (i, processed_vibration, variance,
452 variance-processed_vibration, rel_error))
453 changed_vibration = True
456 filename, vibration_group, processed_vibration=variance)
458 calib_group = '%scalibration/' % group
460 if changed_bump and not dry_run:
461 calib_save(filename, calib_group, bumps=bumps)
462 if changed_temperature and not dry_run:
463 calib_save(filename, calib_group, temperatures=temperatures)
464 if changed_vibration and not dry_run:
465 calib_save(filename, calib_group, vibrations=vibrations)
467 new_k,new_k_s = calib_analyze(
468 bumps=bumps, temperatures=temperatures, vibrations=vibrations)
469 rel_error = abs(new_k-k)/k
470 if rel_error > maximum_relative_error:
471 _LOG.warn(("new analysis doesn't match for k: %g -> %g "
472 "(difference: %g, relative error: %g)")
473 % (k, new_k, new_k-k, rel_error))
475 calib_save(filename, calib_group, k=new_k)
476 rel_error = abs(new_k_s-k_s)/k_s
477 if rel_error > maximum_relative_error:
478 _LOG.warn(("new analysis doesn't match for k_s: %g -> %g "
479 "(difference: %g, relative error: %g)")
480 % (k_s, new_k_s, new_k_s-k_s, rel_error))
482 calib_save(filename, calib_group, k_s=new_k_s)
483 return (new_k, new_k_s)
485 def calib_plot_all(bumps, bump_details, temperatures, temperature_details,
486 vibrations, vibration_details, calibration_config, k, k_s,
487 maximum_relative_error=1e-5):
488 calib_plot(bumps, temperatures, vibrations)
489 for i,bump in enumerate(bump_details):
490 sensitivity = _bump_analyze(
491 data=bump['raw_bump'], bump_config=bump['bump_config'],
492 z_axis_config=bump['z_axis_config'],
493 deflection_channel_config=bump['deflection_channel_config'],
495 rel_error = abs(sensitivity - bump['processed_bump']
496 )/bump['processed_bump']
497 if rel_error > maximum_relative_error:
498 _LOG.warn(("new analysis doesn't match for bump %d: %g != %g "
499 "(difference: %g, relative error: %g)")
500 % (i, sensitivity, bump['processed_bump'],
501 sensitivity-bump['processed_bump'], rel_error))
502 # nothing interesting to plot for temperatures...
503 for i,vibration in enumerate(vibration_details):
504 variance = _vibration_analyze(
505 deflection=vibration['raw_vibration'],
506 vibration_config=vibration['vibration_config'],
507 deflection_channel_config=vibration['deflection_channel_config'],
509 rel_error = abs(variance - vibration['processed_vibration']
510 )/vibration['processed_vibration']
511 if rel_error > maximum_relative_error:
512 _LOG.warn(("new analysis doesn't match for vibration %d: %g != %g "
513 "(difference: %g, relative error: %g)")
514 % (i, variance, vibration['processed_vibration'],
515 variance-vibration['processed_vibration'], rel_error))