def get_T(E='auto'):
"""
get transmission from current CHX attenuator settings
call: get_T(E='auto')
E='auto': read beamline energy from PV (currently DCM) | e.g. E=7645: manual input of energy
reports Si wafer and metal foil configuration as well as transmission
return transmission
dependencies: calls att_conf()
imports xfuncs, numpy
by LW 12/10/2015
"""
# attenuator setup
att_conf=att_setup()
Si_th=np.array(att_conf[2])
Cu_th=np.array(att_conf[1])
abs_mat=att_conf[0]
if E is 'auto':
#E=8000 # temporary: don't have channel access -> set E to 8000eV
E=caget('XF:11IDA-OP{Mono:DCM-Ax:Energy}Mtr.RBV') ### get energy automatically with channel access
print ('getting energy from global PV: E=',E,'eV (currently not implemented in test version (no channel access) -> 8000eV default)') # future: add PV name for house keeping
if E> 30000 or E< 2000:
raise attfuncs_Exception("error: Input argument E has to be 2000<E<30000 [eV]")
else:
if E<= 30000 and E>=2000:
E=np.array(E)
print ('manual input: E= ',E,'eV')
else:
raise attfuncs_Exception("error: could not convert energy argument. Input argument E has to be 2000<E<30000 [eV] or 'auto'")
abs_th=np.append(Cu_th,Si_th)
read_conf=np.zeros(len(abs_th))
for m in range(0,len(abs_th)): ### uncomment when chennel access and PVs available
read_conf[m] = caget ('XF:11IDB-BI{Attn:%02d}Pos-Sts'%(m+1))
#read_conf[m]=caget("'XF:11IDB-ATT{slot:",str(int(m+1)),"}RBV-VALUE'")
# read_conf=np.array([0,1,0,1,0,1,0,0,1]) ### just for testing!! comment/delete!
sT=np.zeros(len(abs_th))
for m in range(0, len(abs_th)):
sT[m]=xf.get_T(abs_mat[m],E/1000.,abs_th[m])
x=sT*read_conf;x[x==0]=1
T_tot=np.product(x)
Si_ind=read_conf[len(Cu_th):len(read_conf)]
Cu_ind=read_conf[0:len(Cu_th)]
print ('Found:')
print ('Si wafer configuration: ',Si_th*Si_ind,' Cu foil configuration: ',Cu_th*Cu_ind)
print ('current Transmission at ',E, 'eV: T= ','{:.2e}'.format(T_tot))
return T_tot
def calc_T(T,E='auto', foil_mode='Si'):
"""
calc_T(T,E='auto',foil_mode='Si'): funtion to calculate CHX attenuator settings for a commanded transmission
required arument:
T: commanded tranmission (e.g. 1e-3)
optional arguments:
E='auto': get beamline energy from PV (currently: DCM) | E=7894: manual overwrite of energy parameter
foil_mode='Si'|'mix': 'Si': calculating optimal configuration using only Si wafers (for coherence applications) | 'mix': using Si wafers and metal foils
function returns dictionary of the form: {'tot_index':a,'Si_index':Si_ind,'Cu_index':Cu_ind}
'tot_index': 'binary' np.array, where '1' means attenuator 'in', '0' means attenuator 'out'
'Si_index': same as above, just for the Si wafer slots
'Cu_index': same as above, just for the metal foil slots
dependencies: imports numpy and xfuncs
calls att_setup() to get physical configuration of attenuator system
by LW 12/09/2015
"""
T=np.array(T)
if E is 'auto':
#E=8000 # temporary: don't have channel access -> set E to 8000eV
E=caget('XF:11IDA-OP{Mono:DCM-Ax:Energy}Mtr.RBV') ### get energy automatically with channel access
print ('getting energy from global PV: E=',E,'eV (currently not implemented in test version (no channel access) -> 8000eV default)') # future: add PV name for house keeping
if E> 30000 or E< 2000:
raise attfuncs_Exception("error: Input argument E has to be 2000<E<30000 [eV]")
else:
if E<= 30000 and E>=2000:
E=np.array(E)
print ('manual input: E= ',E,'eV')
else:
raise attfuncs_Exception("error: could not convert energy argument. Input argument E has to be 2000<E<30000 [eV] or 'auto'")
if foil_mode is 'Si':
print ('selected foil mode is "Si" -> only Si wafers will be used for attenuation')
elif foil_mode is 'mix':
print ('selected foil mode is "mix" -> both Si wafers and metal foils will be used for attenuation')
else:
raise attfuncs_Exception("error: foil_mode has to be either 'Si' or 'mix'")
# attenuator setup
att_conf=att_setup()
Si_th=np.array(att_conf[2])
Cu_th=np.array(att_conf[1])
abs_mat=att_conf[0]
if foil_mode is 'Si':
Cu_th=Cu_th*0
# calculate all available absorption possibilities
abs_th=np.append(Cu_th,Si_th)
f=str('{:0'+str(len(abs_th))+'b}')
a=np.zeros(len(abs_th))
T_tot=np.zeros(2**len(abs_th))
sT=np.zeros(len(abs_th))
for m in range(0, len(abs_th)):
sT[m]=xf.get_T(abs_mat[m],E/1000,abs_th[m])
for l in range(0, 2**len(abs_th)):
k=f.format(l)
a=np.zeros(len(abs_th))
for h in range(0, len(abs_th)):
a[h]=int(k[h])
x=sT*a;x[x==0]=1
T_tot[l]=np.product(x)
# determine best attenuator configuration
diff=np.abs(T_tot-T);
best_T=T_tot[np.argmin(diff)]
k=f.format(np.argmin(diff))
for m in range(0, len(abs_th)):
a[m]=int(k[m])
Si_ind=a[len(Cu_th):len(a)]
Cu_ind=a[0:len(Cu_th)]
print ('*'*40)
print (T, best_T)
print ('*'*40)
caput ('XF:11IDB-BI{Attn}Val:Trans-SP', T) #set point
caput ('XF:11IDB-BI{Attn}Val:Trans-I', best_T) #the best available
# some output and return value
print ('requested transmission: ','{:.2e}'.format(float(T)),' closest match: ','{:.2e}'.format(best_T),' difference: ','{:.2e}'.format(best_T-T))
print ('Si wafer configuration: ',Si_th*Si_ind,' Cu foil configuration: ',Cu_th*Cu_ind)
return {'tot_index':a,'Si_index':Si_ind,'Cu_index':Cu_ind}
