Thorlabs' PNA1 Intensity Noise Analyzer (INA) is a high-precision (18-Bit Analog-to-Digital Conversion) instrument used to measure intensity noise in optical systems. Featuring a DC to 3 MHz input frequency bandwidth, this device overlaps data from several sample rates to optimize resolution bandwidth and provide high frequency-axis resolution over its full bandwidth (see table to the right); the 9 Hz minimum resolution bandwidth is ideal for resolving low-frequency noise sources.
With a nominal noise floor less than -140 dBV2/Hz, this low-noise instrument is designed to identify environmental noise sources, such as ambient lighting or electrical line noise, in an optical experiment. Ideal applications also include light source and instrumentation development, where characterizing noise levels or detection limits is critical.
The PNA1 Noise Analyzer is commonly used to analyze signals from the following devices:
- Biased Detectors
- Amplified Detectors
- Photomultiplier Tubes (PMTs)
- Monitor Ports for Electronic Equipment
- Strain Gauges
- Accelerometers
- Microphones
Features
- High-Precision, Low-Noise Intensity Noise Analyzer for Frequencies Up to 3 MHz
- Multiple Sample Rates for Optimized Resolution Bandwidth
- Input Voltage Range: ±3.85 V
- BNC Signal Input, Internally Terminated with a 10 kΩ Impedance
- Operated with Intensity Noise Analyzer Software
- Displays Data in Frequency or Time Domain
- Frequency-Domain Readout with Power Spectral Density or Relative Intensity Noise (RIN) Units
- Calculates the Total Integrated Relative Intensity Noise (IRIN)
- Requires a User-Supplied Computer
Applications
- Laser Relative Intensity Noise Characterization
- Detection of Noise in Optical Setups (Acoustic Noise, Electrical Noise, Vibration Noise)
- Determining Best Frequencies for Lock-In Detection
- CARS, SRS, or Transient Absorption System Diagnostics
- Error Signal Frequency-Domain Optimization (PID Parameters)
- Spectral Analysis of Laboratory Voltage or Current Signals
When connected to a voltage source through the co-axial input on the front panel of its housing (see the Front & Back Panels tab), the INA samples the input signal with 18-bit resolution. The device can be used with a voltage input up to ±3.85 V and a maximum of 100 mA of current. Common voltage sources include transducers, such as a photodiode used to measure the output of an optical setup, and monitor outputs of electronic equipment. This input is internally terminated with a 10 kΩ impedance; lower input impedances can be achieved by adding on a feed-through terminator, such as the T4119 50 Ω BNC feed-through terminator. For applications requiring a battery-biased photodiode, we recommend using the VT2 variable resistance BNC feed-through terminator.
To provide high frequency-axis resolution at low frequencies, data acquisition occurs at three separate sample rates: 12.5 MHz, 781.25 kHz, and 48.83 kHz. Both the signal conditioning hardware and digital logic design of the INA are optimized for low noise, high-resolution data acquisition. This data is transmitted to a user-supplied PC over a hi-speed USB 2.0 connection.
The PNA1 noise analyzer is powered using the mini-B USB port on the back panel of the housing, which is connected to a Hi-Speed PC USB type-A port. This also provides the USB 2.0 protocol needed to control the device. A USB-ABL-60 USB 2.0 type-A to mini-B cable with a locking screw is included with each device.
Power and Data LED indicators are included on the front panel to easily identify the operation status of the PNA1 noise analyzer. When the device is powered on but not in use, the Power LED is lit and the Data LED is off; the Data LED will be solidly illuminated green when the device is transmitting data.
Software
The PNA1 noise analyzer is operated using the Thorlabs' Intensity Noise Analyzer software. The user-friendly interface included controls for starting and stopping a measurement, and it can display this data in either the frequency or the time domain. Users may choose between visualizing frequency domain data as either Power Spectral Density (PSD) or Relative Intensity Noise (RIN). For more information on the required software, please see the Software tab.
Grounding
Please note that care must be taken to avoid grounding loops, which can cause irregular behavior at the measurement output for low frequencies; details for several ground loop scenarios can be found in the manual. Avoid contacting the nickel-plated end plates of the housing, which are conductive to the device's internal signal ground, with an earth-grounded table.
| Key Specificationsa | ||
|---|---|---|
| Quiescent Noise Floorb | <-140 dBV2/Hz | |
| Broadband Noise Densityc | <60 nV/√Hz | |
| Bandwidth | DC to 3 MHz | |
| Nominal Input Sampling Resolution | 18 Bit | |
| Sample Rates | 12.5 MHz, 781.25 kHz, 48.83 kHz | |
| Resolution Bandwidthd | 390 kHz - 3 MHz | 2.3 kHz |
| 24.5 kHz - 390 kHz | 140 Hz | |
| DC - 24.5 kHz | 9 Hz | |
Figure 1: Simulation of a time-domain meausurement with noise.
Figure 2: Power Spectral Density trace for the curve shown in Figure 1. Note the significant peak at the 10 kHz signal frequency.
Figure 3: RIN trace (blue) obtained by normalizing the PSD trace in Figure 2 by the RMS power in the signal with the frequency-wise integrated RIN trace superimposed (red). Note the significant inflection point in the integrated RIN curve at the signal frequency, which represents a 0.10% increment in integrated noise. The noise from the Gaussian white noise adds in quadrature with the 10 kHz signal to a final percentage of roughly 0.11% integrated RIN.