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The 225 is a GP-IB programmable lock-in amplifier designed with optical measurements in mind.
It features dual inputs, making spectral scanning systems with more than one detector a reality, and square wave demodulation to give the best possible signal-to-noise ratio with the signals normally encountered in chopped light systems.
The high impedance input is ideal for connection to photoconductors, including lead sulphide and lead selenide, or to the output of our pyroelectric detector head.
Features:
- 2 remotely selectable inputs for automatic detector changeover in spectral scanning systems
- Squarewave response gives best signal-to-noise ratio in optically chopped systems
- Modular input amplifiers to cover all existing optical detectors
- Integrating A to D output allows digital signal averaging in place of conventional RC time constant
- All functions programmable via GP-IB
| Specification | |
| Inputs | 2 remotely/manually selected |
| Frequency range: | 0.5Hz to 100kHz |
| Sensitivity (10V output) | 1µV to 1V in decade steps |
| Input Impedance | 100MW//25Pf, Pseudo differential |
| Dynamic Reserve | 20dB to 80dB, depending on sensitivity setting |
| Gain Accuracy | +1% |
| Gain Stability | 200ppm/C |
| Reference Mode | Fundamental or 2f |
| Phase Control | 0.025° increments plus 90° increments |
| Output Stability | 5ppm/C to 500ppm/C depending on sensitivity |
| Time Constant | 10ms to 10s. Digital signal averaging available via 228A. Integrating period 100ms to infinity |
| Interface | GP-IB control of all functions |
| Phase Display | 3-digit LC display shows current phase setting |