SRS Labs Lock-In Amplifier, SR530 manual Expand Channel, Rcosø Output, Channel 2 Display

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to ON) sets the offset to the previously entered value.

If an attempt is made to advance the offset value beyond full scale, the ON LED will blink. An offset up to 1.024 times the full scale sensitivity may be entered. When the EXPAND is on, this is 10X the full scale output.

Note that the offsets (either manual offset or those generated by the REL function) represent a fraction of the full scale reading, and so their absolute value will change when the sensitivity scale is changed. A signal which has been nulled by an offset will not be nulled when the sensitivity scale is changed. The analog meter and the output BNC indicate the same value given by the equation:

Vout = 10Ae(AvVicosØ+V os) {if the output is X}

where...

Ae

= 1 or 10 per the Expand

Av

=

1/Sensitivity

Vi

=

magnitude of the signal

Ø= phase between signal & reference Vos = offset (fraction of FS < 1.024)

When the DISPLAY is X, X OFST, or X NOISE, the OFFSET keys adjust the X OFFSET (which affects the X (RCOSØ) output). When the DISPLAY is R or R OFST, the OFFSET keys adjust the R OFFSET. When the DISPLAY is X5, the OFFSET up and down keys set the output voltage of D/A output X5 (also on the rear panel) up to ±10.24 V. Adjusting X5 will cancel the RATIO output.

Expand Channel 1

The output EXPAND is toggled by pressing the key in the Channel 1 EXPAND section. The expand status is indicated by the X10, expand on, and the X1, expand off, LED's. Only the Channel 1 OUTPUT is affected, the X (RCOSØ) output is not expanded.

The X5 D/A output may not be expanded.

X (RCOSØ) Output

The analog output, X+Xofst, is available at the X (RCOSØ) BNC connector. An input signal equal

in magnitude to the selected sensitivity which is in phase with the reference oscillator will generate a 10V output. The output impedance is <1Ω and the output current is limited to 20 mA.

The X (RCOSØ) output is affected by the X offset but may not be expanded. The X (RCOSØ) is not affected by the DISPLAY setting except for two cases. When the DISPLAY is set to X OFST, the X (RCOSØ) output is the X offset. When the DISPLAY is set to X NOISE, the X (RCOSØ) output has a bandwidth equal to the ENBW (1 or 10 Hz) instead of the time constant.

Channel 2 Display

The channel 2 outputs are summarized below. Y is equal to RsinØ where Ø is the phase shift of the signal relative to the reference oscillator of the lock-in.

display

CH2

 

 

Y

setting

output expand?

offset?

(RSINØ)

Y

Y+Yofst

yes

yes

Y+Yofst

YOFST

Yofst

yes

yes

Yofst

Ø

Phase

no

no

Y+Y ofst

Ø

Phase

no

no

Y+Y ofst

YNOISE

Y noise

yes

yes

Y+Yofst(enbw)

X6

X6

no

adjust

Y+Yofst

The EXPAND and OFFSET conditions for each display are retained when the DISPLAY is changed. Thus, when the DISPLAY is changed from Y to Ø, the EXPAND and OFFSET turn off. If the DISPLAY is changed back to Y the EXPAND and OFFSET return to conditions set for Y.

Ø Output

The phase, Ø, is given by the equation:

Ø = - tan -1{(Y+Yofst)/(X+Xofst)}

Note that the X and Y offsets affect the value of Ø while the X and Y expands do not.

The Phase Output voltage is 50 mV per degree with a resolution of 2.5 mV or 1/20 of a degree. The output range is from -180 to +180 degrees. The phase output is updated every 3.5 mS. To achieve maximum accuracy, the magnitude, R, should be as large a fraction of full scale as

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Contents Model SR530 Page Table of Contents Appendix C Gpib Operating NON-OPERATINGPage SR530 Specification Summary Demodulator GpibFront Panel Summary Enbw Abridged Command List Configuration Switches Status Byte DefinitionSignal Inputs Signal FiltersSR510 Guide to Operation Front Panel SensitivityDynamic Reserve StatusDisplay Select Channel 1 DisplayOutput Output ChannelRel Channel Offset ChannelRcosø Output Expand ChannelChannel 2 Display Auto Phase Reference Input Rsinø OutputTrigger Level Reference Mode Phase ControlsReference Display Time ConstantDefaults PowerLocal and Remote SR530 Guide to Operation Rear Panel Page Command Syntax SR530 Guide to ProgrammingCommunicating with the SR530 Front Panel Status LEDsRS232 Echo and No Echo Operation Try-Out with an Ascii TerminalSR530 Command List LOW Norm HighN1,n2,n3,n4 Page Status Byte ErrorsBit Reset Trouble-Shooting Interface ProblemsCommon Hardware Problems include Common Software Problems includeSR530 with the RS232 Interface SR530 with the Gpib InterfaceGpib with RS232 Echo Mode Serial Polls and Service RequestsSR530 with Both Interfaces Lock-in Technique Measurement ExampleUnderstanding the Specifications Shielding and Ground LoopsPage Page SR530 Block Diagram Signal Channel Phase Sensitive DetectorsReference Channel DC Amplifiers and System GainCircuit Description Reference Oscillator Demodulator and Low Pass AmplifierAnalog Output and Control ExpandFront Panel Microprocessor ControlRS232 Interface Power SuppliesGpib Interface Amplifier and Filter Adjustments Multiplier AdjustmentsCalibration and Repair Notch Filters Replacing the Front-End TransistorsAppendix a Noise Sources and Cures Non-Essential Noise SourcesPage Page Case 1 The Simplest Configuration Appendix B Introduction to the RS232Baud Rate Case 2 RS232 with Control LinesStop Bits ParityVoltage Levels Final TipAppendix C Introduction to the Gpib Bus DescriptionAppendix D Program Examples Program Example IBM PC, Basic, via RS232Program Example IBM PC, Microsoft Fortran v3.3, via RS232 Page Program Example IBM PC, Microsoft C v3.0, via RS232 #include stdio.hPage Program Example 4 IBM PC,Microsoft Basic, via Gpib ′INCREMENT X6 Output by 2.5 MV Program Example HP85 via Gpib Documentation Oscillator Board Parts List PC1SW1 DpdtMain Board Parts List BR1BR2 BT1SR530 Component Parts List SR530 Component Parts List 22U MIN PIN DGpib Shielded CX1FU1 CY1MPSA18 SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List 4PDT SPSTX8SR513 Assy SR530 Component Parts List Z80A-CPU Static RAM, I.CTIE Anchor TranscoverMica #4 FlatFront Panel Board Parts List RED LD2 LD1LD3 Quad Board Parts List SR530 Component Parts List PC1 SR530 Component Parts List Miscellaneous Parts List SR530 Component Parts List

SR530, Lock-In Amplifier specifications

The SRS Labs Lock-In Amplifier, model SR530, is a powerful tool designed for high-precision measurements in the realm of scientific research and industrial applications. This state-of-the-art instrument excels in extracting small signals from noisy environments, making it an invaluable asset for experiments in fields such as physics, engineering, and materials science.

One of the main features of the SR530 is its ability to perform synchronous detection, which is key to improving signal-to-noise ratios. By utilizing a reference signal, the device correlates the incoming signal with the reference to effectively filter out noise, allowing for the accurate measurement of weak signals that might otherwise be obscured. This process of phase-sensitive detection is fundamental to the operation of the Lock-In Amplifier.

The SR530 offers a wide frequency range, covering from 0.1 Hz to 100 kHz. This broad frequency response allows it to handle a diverse array of signals, making it suitable for various applications including optical detection, capacitance measurements, and in many cases, voltammetry. The device is also equipped with multiple inputs and outputs, facilitating the integration with other laboratory equipment and enabling complex experimental setups.

Precision is further enhanced with its adjustable time constant, which allows users to optimize the response time based on experimental needs. The user can choose time constants from 10 microseconds to 10 seconds, accommodating fast dynamic measurements as well as those requiring stability over longer durations.

Another remarkable characteristic of the SR530 is its digital processing capabilities. The device features a highly accurate digital voltage measurement system, minimizing drift and ensuring long-term stability. Additionally, the use of microprocessors enhances data handling and allows for features such as programmable settings, facilitating automated measurements.

Moreover, the SR530 includes a range of output options, including analog outputs, which can be used for direct signal processing, as well as digital interfaces for integration with computers. This ensures that users can not only capture high-fidelity data but also analyze and display it efficiently.

In conclusion, the SRS Labs SR530 Lock-In Amplifier stands out due to its sophisticated technology, versatile features, and robust performance. Its precision, flexibility, and ease of use make it an ideal choice for researchers and engineers looking to unlock the potential of weak signal measurement in complex environments.
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