#####################################################################
# #
# optotunelens.py #
# #
# Copyright 2013, Monash University #
# #
# This file is part of the labscript suite (see #
# http://labscriptsuite.org) and is licensed under the Simplified #
# BSD License. See the license.txt file in the root of the project #
# for the full license. #
# #
#####################################################################
from .UnitConversionBase import *
from scipy.special import lambertw
from numpy import exp, abs
[docs]
class OptotuneLens(UnitConversion):
base_unit = 'V'
derived_units = ['distance','I']
[docs]
def __init__(self, calibration_parameters=None):
# These parameters are loaded from a globals.h5 type file automatically
self.parameters = calibration_parameters
# I[A] = slope * V[V] + shift
# Saturates at saturation Volts
self.parameters.setdefault('current_cal', 0.05) # A/V
self.parameters.setdefault('I_Max', 0.3)
# we fit the function Pos(I) = a*exp(b*I)+c*I+d
self.parameters.setdefault('a', 0)
self.parameters.setdefault('b', 0)
self.parameters.setdefault('c', 0)
UnitConversion.__init__(self,self.parameters)
# We should probably also store some hardware limits here, and use them accordingly
# (or maybe load them from a globals file, or specify them in the connection table?)
[docs]
def distance_to_base(self,percentage):
#here is the calibration code that may use self.parameters
# The inverse function is I = 1/(b*c)(-c*W((a*b/c)*exp((b/c)*P+a))+b/P+ba)
# Where W is the product log (Lambert W) function
amps = 1.0/(self.parameters['b']*self.parameters['c']) \
*(-self.parameters['c']*lambertw((self.parameters['a']*self.parameters['b']/self.parameters['c'])*exp((self.parameters['b']/self.parameters['c'])*(percentage+self.parameters['a']))) \
+self.parameters['b']*percentage \
+self.parameters['b']*self.parameters['a'])
volts = amps/ self.parameters['current_cal']
return (volts > 0) * abs(volts)
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def distance_from_base(self,volts):
amps = max(min(self.parameters['current_cal'] * volts,self.parameters['I_Max']),0)
percentage = self.parameters['a']*exp(self.parameters['b']*amps) + self.parameters['c']*amps - self.parameters['a']
return percentage
[docs]
def I_to_base(self,current):
return current/self.parameters['current_cal']
[docs]
def I_from_base(self,volts):
return volts*self.parameters['current_cal']