Home Lock-In Amplifiers SRS SR860 DSP Lock-in Amplifier, 500 kHz

SRS SR860 DSP Lock-in Amplifier, 500 kHz

Availability: In stock


Product Code:
54279
Manufacturer: Stanford Research Systems
Special Price £6,472.81 £7,767.37 Regular Price £8,007.60
  • 1 mHz to 500 kHz
  • Low noise voltage and current inputs
  • 1 µs to 30 ks time constants
  • High bandwidth outputs
  • Touchscreen data display - large numeric results, chart recordings & FFT displays
  • 10 MHz timebase input and output
  • GPIB, RS-232, Ethernet and USB
  • HDMI video output

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Superb performance. Outstanding value. They are what you have come to expect from a Stanford Research Systems lock-in amplifier. They are delivered by the new SR860 500 kHz Lock-in Amplifier, the latest in a line of innovative lock-ins from SRS. With unparalleled analog performance, sophisticated new digital signal processing features, a thoroughly modern, intuitive user interface, and a wide range of computer connectivity options, the Stanford Research Systems SR860 is the ideal choice for any synchronous detection application.

With over 30 years of lock-in design experience SRS has made every effort to optimise each detail of the SR860. From a hefty toroidal transformer that eliminates switch-mode noise to iOS connectivity that brings the lock-in to your cell phone to advanced DSP filters that eliminate more noise while speeding up your experiment, the SR860 is truly the ultimate lock-in amplifier. 

Signal Inputs
Lock-in performance starts at the front end. The SR860 front end offers both state-of-the art voltage and current input amplifiers. The voltage input is a switchable single-ended/differential JFET-pair amplifier with 2.5 nV/√Hz of noise at 1 kHz and under 10 nV/√Hz of noise at 10 Hz. The voltage input has a 10 MΩ input impedance and can be AC or DC coupled. Input connector shields can be connected to the instrument ground through a user selectable 10 Ω (Ground) or 10 kΩ (Float) resistor.

The SR860’s built-in current amplifier represents a significant improvement over previous designs. The current input range is selectable from 1 μA or 10 nA. The 1 μA range has 400 kHz of bandwidth and 130 fA/√Hz of noise, while the 10 nA range offers 2 kHz of bandwidth and 13 fA/√Hz of noise.

While the built in voltage and current amplifiers are suitable for most applications, the SR860 is also compatible with the complete range of specialized pre-amplifiers offered by SRS. The SR550 (FET input), SR552 (BJT input), SR554 (transformer input), SR555 (120 kHz current amp) and SR556 (low noise current amp) can all be powered directly from the SR860’s rear-panel preamp power port.

Sensitivity and Input Range
As with previous instruments, the Sensitivity setting of the SR860 is the voltage (or current) which produces a full scale output. But unlike previous designs, the input range of the SR860 can be explicitly set from the front panel without having to consult a confusing “dynamic reserve” equation. Simply choose the sensitivity required by your experiment and then select the smallest input range that doesn’t overload. That’s it.

The SR860’s effective dynamic reserve is simply the ratio of these two settings. For instance with a 10 nV sensitivity setting and a 300 mV input range the effective dynamic reserve of the SR860 is 3 × 107, or nearly 150 dB.

Output Time Constants and Filtering
The SR860 offers traditional RC-response output time constants from 1 µs to 30 ks with rolloffs of 6, 12, 18, and 24 dB/oct. But in addition, the SR860 also offers advanced digital filters which can significantly reduce measurement time while increasing signal to noise. Below 3 s, the advanced filters are Gaussian FIR filters which at the same noise bandwidth as an RC filter have significantly better rise-time and stopband attenuation. These filters also have symmetric rise and fall profiles which preserves feature shapes while scanning in frequency. At time constants longer than 3 s, the advanced filters are linear phase IIR filters which settle nearly twice as fast as their RC counterparts for equivalent stopband attenuation.

Synchronous filtering may also be selected at reference frequencies below 4 kHz. The synchronous filter notches out multiples of the reference frequency and is extremely useful in making low frequency measurement where multiples of the reference frequency would otherwise show up in the lock-in output. Unlike previous designs the synchronous filter in the SR860 can be selected with no loss of output resolution.

Reference Channel
The SR860 has a specified reference frequency range of 1 mHz to 500 kHz. Detection can be done at the fundamental of the reference frequency, or at up to the 99th harmonic. Several reference modes are available: Internal mode uses the SR860’s precision internal oscillator as the reference. External mode locks to an external sine or TTL signal. In Dual Mode, the lock-in detects at the difference frequency between the internally set reference frequency and an externally applied sync signal allowing direct recovery of a double-modulated signal. Finally, in Chop mode, the SR860 provides a digital PID (Proportional-Integral-Derivative) controller signal to synchronize an SR540 Optical Chopper to the internal oscillator of the lock-in. By having the lock-in directly control the chopper, frequency drift can be virtually eliminated.

Sine Output
The SR860 offers a precision sine wave output which can be set with 6 digits of frequency resolution and an amplitude range from 1 nV to 2 V. The SR860 output is unique in that it can be configured as a single-ended or as a differential (balanced) signal. A DC offset of up to ±5 V can be applied to the sine output. A rear-panel logic-level sync signal synchronized to the sine output is also provided.

Timebase
Rear-panel 10 MHz inputs and outputs are provided allowing the SR860 to be locked to an external frequency reference (such as the FS725 10 MHz Rubidium Frequency Standard). Alternatively, the 10 MHz output from the SR860 can be used to synchronize several lock-ins or other test equipment with a 10 MHz timebase input.

FFT Displays
Lock-in amplifiers are traditionally time-domain instruments but sometimes it’s easier to understand a signal in the frequency domain. The SR860 is at home in both worlds. An FFT display shows the spectrum of the input signal at the front end, the post-mixer signal, or the spectrum of the signal after the time-constant filters. Using the FFT displays can simplify tracking down sneaky noise sources that would otherwise get lost in the “one-number” output of a conventional lock-in amplifier.

Front-Panel Touchscreen Display
The centre of the SR860’s front panel is a full-colour 640 × 480 touchscreen which can be set to display up to 4 channels of data. (When a dark lab is required, the LCD screen can be blanked from the front panel or from the remote interface.) Each data channel can be configured to display X, Y, R, Θ, Aux In (1-4), Aux Out (1-2), X noise, Y noise, Sine Amplitude, Sine Out DC Level, Reference Phase, or Reference Frequency. The screen can be set up to show the data channels as large numbers, easily visible from across the room, or as a “strip-chart” display showing a complete history of each channel with selectable time scales from 0.5 s/div to 2 days/div. Even when not displaying a measurement, all measurements are always being saved by the SR860 insuring that no data is ever lost. The touchscreen also continually displays key lock-in setup parameters such as phase, reference frequency, and sine amplitude. And a rear-panel HDMI port allows the LCD screen to be viewed on any HDMI monitor or TV.

It should be emphasized that as useful as the touchscreen display is for displaying data, it’s not necessary to use the touchscreen to control common instrument functions on the SR860. All commonly used controls: time constant, reference frequency, sine amplitude and offset, input configuration, and more, are controllable with dedicated front panel knobs or buttons. Infrequently accessed configuration settings, such as the TCP/IP settings and other communication settings, are accessed through menus shown on the touchscreen.

Computer Connectivity
The SR860 comes standard with virtually every remote interface imaginable. GPIB (IEEE488.2) and RS-232 are of course provided, as well as USB (Test and Measurement Class) and Ethernet (VXI-11 and telnet). The SR860 hosts its own webserver allowing the instrument to be monitored and controlled remotely with just a browser. When connected to a Wi-Fi enabled network, the SR860 can be controlled remotely from an iPhone or iPad with free iOS app downloadable from the Apple App Store. The app allows remote configuration of the instrument and monitoring of live data from your handheld device.

A front-panel USB port allows data and screen-shots to a USB flash drive. Data can be saved either as comma delimited files or MATLAB compatible .MAT files. Incorporating screen shots and data into reports or spreadsheets has never been easier.

 

Additional Information

Specification
Max. Frequency 500kHz
Type DSP

SR860 500 kHz Lock-In Amplifier

Signal Channel

Voltage inputs

Single-ended (A) or differential (A-B)

Sensitivity (output scale)

1 nV to 1 V (voltage input)
1 fA to 1 µA (current input)

Voltage Input range

10 mV to 1 V (peak).

Current input range

1 µA or 10 nA (peak)

Max input before overload

1 V (peak) or 1 µA (peak)

Input impedance

 

     Voltage input

10 MΩ + 25 pF, AC (>1 Hz) or DC coupled

     Current input

1 kΩ or 100 Ω to virtual ground

Gain accuracy

±1 % (<200 kHz), ±2 % (to 500 kHz). Signal amplitude must be less than 30% of input range.

Noise

2.5 nV/√Hz at 1 kHz (10 mV input range, typ.)

Harmonic distortion

-80 dB (<100 kHz), -60 dB (>100 kHz)

CMRR

90 dB at 1 kHz (DC coupled)

Dynamic reserve

120 dB (typ)

Reference Channel

Frequency range

0.001 Hz to 500 kHz

Timebase

10 MHz In/Out (phase locks the internal frequency to other SR860s.)

Input impedance

1 MΩ or 50 Ω

Phase setting resolution

(360/232) degrees

Phase noise

 

     Int. reference

<0.0001° rms at 1 kHz (100 ms, 12 dB/oct)

     Ext. reference  (typ)

<0.001° rms at 1 kHz (100 ms, 12 dB/oct)

Phase drift (typ)

 

Sine Out to signal In (200 mVrms)
<0.002°/°C below 20 kHz (DC coupled)
<0.02°/°C below 200 kHz
<0.2°/°C below 2 MHz

Harmonic detection

Detect at N × fref where N<99 and (N × fref ) < 2 MHz

Dual F reference

Detect at fdual =│fint - fext
All frequencies must be less than 2 MHz

Chopper reference

SR860 drives SR540 Chopper (via Aux Out 4) to lock the chopper to fint

Demodulator

DC stability

Digital output values have no offset drift

Time constants

1 µs to 30 ks

Low pass filters

Typical RC-type filters or advanced Gaussian/Phase-Linear filters

Filter slope

6, 12, 18 or 24 dB/oct rolloff

Synchronous filter

Available below 4 kHz

Harmonic rejection

-80 dB

Low latency output

Rear-panel BlazeX output with <2 µs delay (plus LPF rise/fall times).

Internal Oscillator

Frequency

1 mHz to 500 kHz

Frequency accuracy

25 ppm + 30 µHz (with internal timebase)

External timebase

10 MHz timebase input/output on rear panel

Frequency resolution

6 digits or 0.1 mHz (whichever is greater)

Sine Output

Outputs

Differential or single-ended

Output impedance

50 Ω source

Amplitude

1 nVrms to 2 Vrms (specified amplitude is differential into 50 Ω loads)
Output amplitude is halved when used single-ended
Output amplitude is doubled into a high impedance load

Amplitude resolution

3 digits or 1 nV, whichever is greater

DC offset

±5 V, differential or common mode

Offset resolution

3 digits or 0.1 mV, whichever is greater

Output limit

±6 V, sum of DC offset and peak amplitude

Sync

Logic level sync on rear panel (via BlazeX output)

Data

Data channels

4 data channels are displayed and graphed (green, blue, yellow, orange)

Data sources

Each data channel can be assigned any of these data sources:
X, Y, R, Θ, Aux In 1 to 4, Aux Out 1 to 2, X noise, Y noise, Sine Out Amplitude,
Sine Out DC Level, Reference Phase, or Reference Frequency

Data history

All data sources are continually stored at all chart display time scales.
The complete stored history of any data source can be displayed at any time.

Offset

X, Y and R may be offset up to ±999 % of the output scale

Expand

X, Y and R may be expanded by ×10 or ×100

Ratio

X and Y may be ratioed by Aux In 3. R may be ratioed by Aux In 4

Capture buffer

1 Mpoints internal data storage. Store (X), (X and Y), (R and Θ) or (X, Y, R and Θ)
at sample rates up to 1.25 MHz. This is in addition to the data histories for the chart display.

Data streaming

Realtime streaming of data, either (X), (X and Y), (R and Θ), or (X, Y, R and Θ) at sample rate to 1.25 MHz over Ethernet interface

Scanning

One of the following parameters may be scanned:
fint, Sine Out Amplitude, Sine Out DC Level, Aux Out 1 or 2.

FFT

Source

Input ADC, demodulator output, or filter output

Record length

I1024 bins

Averaging

Exponential rms

Inputs and Outputs

CH1 output

Proportional to X or R, ±10 V full scale thru 50 Ω

CH2 output

Proportional to Y or Θ, ±10 V full scale thru 50 Ω

X and Y rear-panel outputs

Proportional to X and Y, ±10 V full scale thru 50 Ω

BlazeX

Low latency output of X, ±2.0 V full scale or logic level reference sync output, either thru 50 Ω

Aux outputs

4 BNC D/A outputs, ±10.5 V thru 50 Ω, 1 mV resolution

Aux inputs

4 BNC A/D inputs, ±10.5 V, 1 mV resolution, 1 MΩ input

Trigger input

TTL input triggers storage into the internal capture buffer

Monitor output

Analog output of the signal amplifier

HDMI

Video output to external monitor or TV, 640 × 480, 60 Hz

Timebase I/O

1 Vrms, 10 MHz clock to synchronize internal reference frequency to other units

General

Interfaces

IEEE488.2, RS-232, USB device and Ethernet.

USB flash

Front-panel slot for USB flash storage of screen shots and data

Preamp power

9-pin D connector to power SRS preamps

Power

60 W, 100/120/220/240 VAC, 50/60 Hz

Dimensions

17" × 5.25" × 17" (WHL)

Weight

22 lbs.

Warranty

One year parts and labor on defects in materials and workmanship

 

 

 


 

 
 
 




 

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