SRS Labs Lock-In Amplifier, SR530 manual Rsinø Output, Reference Input, Trigger Level

Page 18

down, the offset advances in larger and larger increments, the largest increment being 10% of full scale. When the offset is turned OFF the applied offset returns to zero but the offset value is not lost. The next press of the upper offset key (return 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(AvVisinØ+V os) {if the output is Y}

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 Y, Y OFST, or Y NOISE, the OFFSET keys adjust the Y OFFSET (which affects the Y (RSINØ) output). When the DISPLAY is Ø, the OFFSET keys do nothing. When the DISPLAY is X6, the OFFSET up and down keys set the output voltage of D/A output X6 (also on the rear panel) up to ±10.24V.

Expand Channel 2

The output EXPAND is toggled by pressing the key in the Channel 2 EXPAND section. The expand status is indicated by the X10, expand on, and the X1, expand off, LED's. Only the Channel 2 OUTPUT is affected, the Y (RSINØ) output is not expanded. Ø and X6 may not be expanded.

Y (RSINØ) Output

The analog output, Y+Yofst, is available at the Y (RSINØ) BNC connector. An input signal equal in magnitude to the selected sensitivity which is 90° out of 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 Y (RSINØ) output is affected by the Y offset but may not be expanded. The Y (RSINØ) is not affected by the DISPLAY setting except for two cases. When the DISPLAY is set to Y OFST, the Y (RSINØ) output is the Y offset. When the DISPLAY is set to Y NOISE, the Y (RSINØ) output has a bandwidth equal to the ENBW (1 or 10 Hz) instead of the time constant.

Reference Input

The REFERENCE INPUT BNC is located in REFERENCE INPUT section. The input is ac coupled and the impedance is 1 MΩ . The dc voltage at this input should not exceed 100 V and the largest ac signal should be less than 10 V peak.

Trigger Level

The TRIGGER MODE indicator toggles from POSITIVE to SYMMETRIC to NEGATIVE when the TRIGGER MODE key is pressed.

If the center TRIGGER MODE LED is on, the mode is SYMMETRIC and the reference oscillator will lock to the positive zero crossings of the ac reference input. The ac signal must be symmetric (e.g. sine wave, square wave, etc.) and have a peak to peak amplitude greater than 100 mV. A signal with 1 Vrms amplitude is recommended. The phase accuracy of the reference channel is specified for a 1Vrms sinewave in the symmetric trigger mode.

If the upper TRIGGER MODE LED is on, the mode is POSITIVE. The trigger threshold is +1V and the reference oscillator will lock to the positive going transitions of the reference input. This mode triggers on the rising edges of a TTL type pulse train. The pulse width must be greater than 1 µ S.

If the lower TRIGGER MODE LED is on, the mode is NEGATIVE. The trigger threshold is -1V and the reference oscillator will lock to the negative

14

Page 17 Page 19
Image 18
Page 17 Page 19
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 DefinitionSR510 Guide to Operation Front Panel Signal InputsSignal Filters SensitivityDisplay Select Dynamic ReserveStatus Channel 1 DisplayRel Channel OutputOutput Channel Offset ChannelExpand Channel Rcosø OutputChannel 2 Display Auto Phase Rsinø Output Reference InputTrigger Level Reference Display Reference ModePhase Controls Time ConstantPower DefaultsLocal and Remote SR530 Guide to Operation Rear Panel Page Communicating with the SR530 Command SyntaxSR530 Guide to Programming Front Panel Status LEDsRS232 Echo and No Echo Operation Try-Out with an Ascii TerminalSR530 Command List LOW Norm HighN1,n2,n3,n4 Page Errors Status ByteBit Common Hardware Problems include ResetTrouble-Shooting Interface Problems Common Software Problems includeSR530 with the RS232 Interface SR530 with the Gpib InterfaceSerial Polls and Service Requests Gpib with RS232 Echo ModeSR530 with Both Interfaces Lock-in Technique Measurement ExampleUnderstanding the Specifications Shielding and Ground LoopsPage Page SR530 Block Diagram Reference Channel Signal ChannelPhase Sensitive Detectors DC Amplifiers and System GainCircuit Description Reference Oscillator Demodulator and Low Pass AmplifierFront Panel Analog Output and ControlExpand Microprocessor ControlPower Supplies RS232 InterfaceGpib Interface Multiplier Adjustments Amplifier and Filter AdjustmentsCalibration and Repair Notch Filters Replacing the Front-End TransistorsAppendix a Noise Sources and Cures Non-Essential Noise SourcesPage Page Baud Rate Case 1 The Simplest ConfigurationAppendix B Introduction to the RS232 Case 2 RS232 with Control LinesVoltage Levels Stop BitsParity 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 SW1 Oscillator Board Parts ListPC1 DpdtBR2 Main Board Parts ListBR1 BT1SR530 Component Parts List SR530 Component Parts List Gpib Shielded 22U MINPIN D CX1CY1 FU1MPSA18 SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List SR530 Component Parts List SPSTX8 4PDTSR513 Assy SR530 Component Parts List Z80A-CPU Static RAM, I.CMica TIE AnchorTranscover #4 FlatFront Panel Board Parts List RED LD1 LD2LD3 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.
Top Page Image Contents