LCC25 (thorlabs) model¶

This class (variable_waveplate_gui.py) is the model to drive the LCC25 variable waveplate controller.

It ads the use of units with pint and the wavelength calibration to obtain make the variable waveplate a quarter waveplate for a given wavelength.

copyright:	by Hyperion Authors, see AUTHORS for more details.
license:	BSD, see LICENSE for more details.

class hyperion.instrument.polarization.variable_waveplate.VariableWaveplate(settings)¶

This class is the model for the LCC25 analog voltage generator for the variable waveplate from thorlabs.

do_interp(w, x, y)¶

This function interpolates the voltage value for the wavelength value w, using the calibration data (x,y) where x is wavelength and y is voltage

Parameters:	w (pint quantity) – desired wavelength x (pint quantity) – wavelength vector from calibration y (pint quantity) – calibrated voltage values
Returns:	the voltage for the desired wavelength
Return type:	pint quantity

finalize(state=False)¶: Closes the connection to the device

freq¶

Modulation frequency when the operation mode is ‘modulation’ (mode = 0)

: getter :

Asks for the current frequency

Returns:	The frequency value
Return type:	pint quantity

: setter :

Parameters:	F (pint Quantity) – frequency in Hz. It can be any value between 0.5 and 150Hz.

get_analog_value(channel)¶

Gets the analog voltage of the channel.

Parameters:	channel (int) – Port number. Range depends on device
Returns:	voltage: voltage in use for the channel
Return type:	pint quantity

idn()¶: Ask for the identification

initialize()¶: initializes the connection with the controller

load_calibration(cal_file)¶

This method loads the calibration file cal_file

Parameters:	cal_file (string) – calibration file complete path, including extension (txt expected)

mode¶

Operation mode

The possible modes are:

‘Modulation’: sends a 2kHz sin wave modulated with a square wave where voltage 1 is one limit and voltage 2 is the second. the modulation frequency can be changed with the command ‘freq’ in the 0.5-150 Hz range.

‘Voltage1’ : sends a 2kHz sin wave with RMS value set by voltage 1

‘Voltage2’ : sends a 2kHz sin wave with RMS value set by voltage 2

‘QWP’ : uses the calibration file to set the voltage that acts as a quarter-wave plate for the specified wavelength.

: getter :

Gets the current mode

Returns:	current mode
Return type:	string

: setter :

Sets the mode

Parameters:	mode (string) – type of operation.

output¶

Tells if the output is enabled or not.

Getter:
Returns:	output state
Return type:	logical
Setter:
Parameters:	state (logical) – value for the amplitude to set in Volts

quarter_waveplate_voltage(wavelength, method='lookup')¶

This method gives the voltage needed to set on the LCC25 to get a quarter waveplate (QWP) behaviour for a given wavelength. It is based on a calibration file that relates the QWP voltage to a wavelength and (so far) uses a linear fit to those data points.

Parameters:	wavelength (pint Quantity) – The input wavelength method (string) – method to extrapolate between measured data points
Returns:	the QWP voltage
Return type:	pint quantity

set_analog_value(channel, value)¶

Sets the analog voltage of the channel.

Parameters:	channel (int) – Port number. Range depends on device value (pint quantity) – The input value in Volts between 0 and 25 (Pint type)

set_quarter_waveplate_voltage(wavelength)¶

This method sets the quarter-wave plate (QWP) voltage to the variable-wave plate for a given wavelength. It uses Voltage 1 for output.

Parameters:	wavelength (pint Quantity) – The input wavelength
Returns:	the voltage set to the controller
Return type:	pint quantity