SSI OE1022D Independent Synchronous Dual-Channel Lock-In Amplifier

Input Signal Channel

         The low-noise analog front-end amplifier in the OE1022D lock-in amplifier handles differential or single-ended signals with an equivalent input noise of only 5 nV/√Hz. The channel's input impedance is 10 MΩ, and at full-scale output it can detect input signal levels from 1 nV to 1 V. In addition, the OE1022D supports input current measurement with a front-end variable current gain of 106 or 108 V/A. The OE1022D has two independent signal input channels to meet the need for simultaneous multi-signal detection.

Reference Signal Channel

         The OE1022D digital lock-in amplifier has two reference signal channels, each of which can use either internal or external reference mode. In internal reference mode, the instrument's high-precision oscillator and direct digital synthesis algorithm generate the sine wave used to multiply the input signal, and the internal reference is virtually immune to phase noise. Digital phase-shifting technology gives the internal reference signal a phase resolution of 0.001°. Internal reference mode operates over a frequency range of 1 mHz to 102 kHz. In external reference mode, either a sine wave or TTL logic levels can serve as the external reference. The rising or falling edge of the external reference triggers the internal phase-locked loop (PLL) to lock.

Display Features

         The OE1022D uses a 5.6-inch 640×480 TFT color display as its main screen. The data measured by this lock-in amplifier—such as the signal's X, Y, R, and θ values—can be displayed simultaneously as numeric values, bar graphs, XY plots, and polar plots. Data from both channels can be shown at the same time.

Simultaneous Multi-Harmonic Measurement

         A conventional lock-in amplifier can measure only the fundamental signal or a single harmonic component at any one time. For applications that require the amplitude and phase of multiple frequency components simultaneously, traditional lock-in amplifiers therefore fall short. The digital section of the OE1022D combines FPGA and ARM technology to deliver higher processing bandwidth and a more flexible digital architecture, with digital processing accuracy of up to 48 bits. It can measure three harmonics at the same time, making one OE1022D equivalent to six conventional lock-in amplifiers. The highest harmonic signal that can be detected is the 32767th order of the fundamental, though the maximum harmonic frequency must not exceed the instrument's 102 kHz operating frequency. 

PC Software Control

         The standard USB 2.0, RS232-DB9, and GPIB (optional) interfaces ensure that users can fully exploit all OE1022D measurement functions from a control computer, including setting appropriate instrument control parameters and reading measured data. The instrument comes with a free LabVIEW program, making it easy to integrate the OE1022D into complex scientific experiments. In the LabVIEW interface, users can view all control commands and the instrument's responses.

Dual-channel signal channel
    Voltage input mode            Single-ended or differential input
    Full-scale sensitivity            1 nV to 1 V, in 1-2-5 sequence steps
    Current input gain            106or 108 V/A
    Input impedance
        Voltage                10 MΩ//25 pF, AC or DC coupling
        Current                1 kΩ to virtual ground
    Common-mode rejection ratio              >100 dB up to 10 kHz, decreasing at 6 dB/oct
    Dynamic reserve                >120 dB
    Gain accuracy                0.2% typical, 1% maximum
    Voltage noise
        at 997 Hz            5 nV/√Hz
    Current noise
        At 97 Hz             15 fA/√Hz
        at 997 Hz            13 fA/√Hz
    Line frequency filter              50 Hz and 100 Hz
    Input shield grounding            BNC (A/I, B) shield can be directly grounded or connected to floating ground via a 10 kΩ resistor

Dual-channel reference channel
    Input
        Frequency range            1 mHz to 102 kHz
        Reference input            Square wave or sine wave
        Input impedance            1 MΩ
        Square-wave reference level       

Scanning microscope            AFM, STM, SPM

Materials science                Carrier mobility, carrier density, Hall effect, ultrasonic materials

Transport measurement                Conductance measurement, impedance measurement

Noise characterization                Noise density, cross-correlation measurement

Optical experiments                Spectral analysis, spectral measurement, THz measurement, TDLAS

Sensor measurement            Gyroscopes, photoelectric sensors, resonators, accelerometers

Magnetic Sensing                SQUIDs, NV centers, atomic magnetometers, VSM

Biomedical                Microfluidics