Lock-In Amplifiers

Devices

  • Stanford Research Lock-In Amplifier (GPIB, RS-232) SR-810; SR-830; SR-850; Tested 02/2021 SR-844; Untested
  • Stanford Research Lock-In Amplifier (GPIB, RS-232, Ethernet) SR-860; SR-865a; Tested 01/2021

Functions

lock_in_name() 

lock_in_name() -> str

The function returns device name.

lock_in_ref_frequency(*frequency) 

lock_in_ref_frequency(frequency: float) -> none
lock_in_ref_frequency() -> float

Example: lock_in_ref_frequency(100000) sets the reference frequency to 100 kHz.

The function for querying or setting the reference frequency in Hz. If called with no argument the current reference frequency in Hz is returned. If called with an argument the reference frequency is set. Frequency range is 4 mHz to 102 kHz (SR-810, 830, 850); 1 mHz - 500 kHz (SR-860); 1 mHz - 4 MHz (SR-865a); 25 kHz - 200 MHz (SR-844, 1F mode); 50 kHz - 200 MHz (SR-844, 2F mode). The details about 2F mode are given in the lock_in_harmonic() function.
For SR-860, 865a the query command, lock_in_ref_frequency(), returns the internal reference frequency whenever the reference mode is either Internal, Dual, or Chop. The query returns the external frequency when operating in External mode.

lock_in_phase(*degree) 

lock_in_phase(degree: float) -> none
lock_in_phase() -> float

Example: lock_in_phase(100) sets the phase to 100 degrees.

The function for querying or setting the phase of the lock-in in degrees. If there is no argument the function will return the current phase. If called with an argument the specified phase will be set. The phase may be programmed from -360.000 to 719.999 (SR-850), from -360.000 to 729.999 (SR-810, 830), from -360000 to 360000 (SR-860, 865a), from -360 to 360 (SR-844) and will be wrapped around at ±180°.

lock_in_auto_phase() 

lock_in_auto_phase() -> none

Example: lock_in_auto_phase() performs the auto phase function.

This function adjusts the reference phase so that the current measurement has a Y value of zero and an X value equal to the signal magnitude, R. The outputs may take many time constants to reach their new values. Do not send the command again without waiting the appropriate amount of time. This function is only available for SR-844, SR-860, SR-865.

lock_in_time_constant(*timeconstant) 

lock_in_time_constant(timeconstant: str) -> none
lock_in_time_constant() -> str

Example: lock_in_time_constant('100 ms') sets the time constant to 100 ms.

The function for querying or setting the time constant of the lock-in in ms. If there is no argument the function will return the current time constant. If there is an argument the specified time constant will be set.
Currently for SR-810, 830, 850 the specified time constant should be from the array:
[10 us, 30 us, 100 us, 300 us, 1 ms, 3 ms, 10 ms, 30 ms, 100 ms, 300 ms, 1 s, 3 s, 10 s, 30 s, 100 s, 300 s, 1 ks, 10 ks, 30 ks].
For SR-860, 865a 1 us and 3 us are also available.
For SR-844 the following values can be used:
[100 us, 300 us, 1 ms, 3 ms, 10 ms, 30 ms, 100 ms, 300 ms, 1 s, 3 s, 10 s, 30 s, 100 s, 300 s, 1 ks, 10 ks, 30 ks].
If there is no time constant setting fitting the argument the nearest available value is used and warning is printed.

lock_in_ref_amplitude(*amplitude) 

lock_in_ref_amplitude(amplitude: float) -> none
lock_in_ref_amplitude() -> float

Example: lock_in_ref_amplitude(0.150) sets the level of the modulation frequency to 150 mV.

This function queries or sets the level of the modulation frequency in V. If there is no argument the function will return the current level. If there is an argument the specified level will be set. For SR-810, 830, 850 the allowed levels are between 4 mV and 5 V. For SR-860, 865a the allowed levels are between 1 nV and 2 V. If the argument is not within this range an error message is printed and the level of 4 mV will be set.
This function is not available for SR-844.

lock_in_get_data(*channel) 

lock_in_get_data(channel1: int) -> float
lock_in_get_data(channel1: int, channel2: int) -> float, float
lock_in_get_data(channel1: int, channel2: int, channel3: int) -> float, float, float
lock_in_get_data() -> float

Example: lock_in_get_data(1, 2, 3) returns 3 float values for X, Y, and R signals in Volts.

This function can be used to query measured values from the lock-in amplifier. If no argument is specified the ‘X’ signal is returned. If a parameter is passed to the function the value at the corresponding channel is returned. Possible channel numbers and their meaning are the following:
SR-810, 830, 850, 860, 865a:
‘1’ - X signal in Volts; ‘2’ - Y signal in Volts; ‘3’ - R signal in Volts; ‘4’ - Phase ‘theta’ of data in degrees; [‘1’, ‘2’] - X and Y signals in Volts; [‘1’, ‘2’, ‘3’] - X, Y, and R signals in Volts.

lock_in_sensitivity(*sensitivity) 

lock_in_sensitivity(sensitivity: str) -> none
lock_in_sensitivity() -> str

Example: lock_in_sensitivity('10 uV') sets the sensitivity to 10 uV.

The function queries or sets the sensitivity of the lock-in. If there is no argument the function will return the current sensitivity as a string. If there is an argument the specified sensitivity will be set.
Currently for SR-810, 830, 850 the specified sensitivity should be from the array:
[2 nV, 5 nV, 10 nV, 20 nV, 50 nV, 100 nV, 200 nV, 500 nV, 1 uV, 2 uV, 5 uV, 10 uV, 20 uV, 50 uV, 100 uV, 200 uV, 500 uV, 1 mV, 2 mV, 5 mV, 10 mV, 20 mV, 50 mV, 100 mV, 200 mV, 500 mV, 1 V].
For SR-860, 865a 1 nV is also available.
For SR-844 the following values can be used:
[100 nV, 300 nV, 1 uV, 3 uV, 10 uV, 30 uV, 100 uV, 300 uV, 1 mV, 3 mV, 10 mV, 30 mV, 100 mV, 300 mV, 1 V].
If there is no sensitivity setting fitting the argument the nearest available value is used and warning is printed.

lock_in_auto_sensitivity() 

lock_in_auto_sensitivity() -> none

Example: lock_in_auto_sensitivity() performs the auto sensitivity function.

This function automatically sets the sensitivity of the instrument. The measured values may take many time constants to return to their steady state values. Do not send the command again without waiting the appropriate amount of time. This function is only available for SR-844, SR-860, SR-865.

lock_in_ref_mode(*mode) 

lock_in_ref_mode(mode: str) -> none
lock_in_ref_mode() -> str ['Internal', 'External', 'Dual', 'Chop']

Example: lock_in_ref_mode('External') sets the device to external modulation mode.

This function queries or sets the modulation mode, i.e. if the internal modulation or an external modulation input is used. If there is no argument the function will return the current modulation mode. If there is an argument the specified modulation mode will be set. Possible modulation modes are the following:
SR-810, 830, 850, 844: [‘Internal’, ‘External’].
SR-860, 865a: [‘Internal’, ‘External’, ‘Dual’, ‘Chop’].

lock_in_ref_slope(*mode) 

lock_in_ref_slope(mode: str) -> none
lock_in_ref_slope() -> str ['Sine', 'PosTTL', 'NegTTL']

Example: lock_in_ref_slope('PosTTL') sets the reference trigger to TTL rising edge.

This function queries or sets the reference trigger when using the external reference mode. If there is no argument the function will return the current reference trigger. If there is an argument the specified reference trigger mode will be set. Note that at frequencies below 1 Hz, the a TTL reference must be used.
Possible reference trigger modes are the following: [‘Sine’, ‘PosTTL’, ‘NegTTL’]. They correspond to sine zero crossing, TTL rising edge, TTL falling edge, respectively.
This function is not available for SR-844.

lock_in_sync_filter(*mode) 

lock_in_sync_filter(mode: str) -> none
lock_in_sync_filter() -> str ['Off', 'On']

Example: lock_in_sync_filter('On') turns on synchronous filtering.

This function queries or sets the synchronous filter status. If there is no argument the function will return the current status. If there is an argument the specified status will be set. Note that synchronous filtering is turned on only if the detection frequency is less than 200 Hz.
Possible synchronous filter status are the following: [‘Off’, ‘On’].
This function is not available for SR-844.

lock_in_lp_filter(*mode) 

lock_in_lp_filter(mode: str) -> none
lock_in_lp_filter() -> str ['No', '6 dB', '12 dB', '18 dB', '24 dB']

Example: lock_in_lp_filter('12 dB') sets the low pass filter slope to 12 dB/oct.

This function queries or sets the low pass filter slope. If there is no argument the function will return the current slope. If there is an argument the specified slope will be set.
Possible low pass filter slopes are the following: [‘6 dB’, ‘12 dB’, ‘18 dB’, ‘24 dB’]. They correspond to 6 dB/oct, 12 dB/oct, 18 dB/oct, 24 dB/oct, respectively.
For SR-844 ‘No’ can also be used, which means No Filter mode.

lock_in_harmonic(*harmonic) 

lock_in_harmonic(harmonic: int) -> none
lock_in_harmonic() -> int

Example: lock_in_harmonic('2') sets the detection harmonic of the second harmonic.

This function queries or sets the detection harmonic. The argument is an integer from 1 to 19999 (SR-810, 830, 850) or from 1 to 32767 (SR-850). The function will set the lock-in to detect at the specified harmonic of the reference frequency. The value of the detected frequency is limited by 102 kHz. If the argument used requires a detection frequency greater than 102 kHz, then the harmonic number will be set to the largest value available for which the frequency is less than 102 kHz.
For SR-860, 865a the value of the argument is limited to 1 ≤ i ≤ 99.
For SR-844 the value of the argument is limited to 1 ≤ i ≤ 2. The frequency range for the second harmonics detection is limited to 50 kHz to 200 MHz. More details are given in the lock_in_ref_frequency() function.

lock_in_command(command) 

lock_in_command(command: str) -> none

Example: lock_in_command('OFSL 0'). This example sets the low pass filter slope.
The parameter equals to 0 selects 6 dB/oct.

The function for sending an arbitrary command from a programming guide to the device in a string format. No output is expected.

lock_in_query(command) 

lock_in_query(command: str) -> str

Example: lock_in_command('OFSL?'). This example queries the low pass filter slope.

The function for sending an arbitrary command from a programming guide to the device in a string format. An output in a string format is expected.