Scanimage 2018b introduces a new oscilloscope mode to visualize raw data acquired with a high speed digitizer (NI57xx). This data scope can be used to identify noise, digitizer saturation and signal bandwidth issues.
See Data Scope for an overview of the GUI.
Data Scope showing typical PMT power supply ripple noise at 320kHz in power spectrum.
Noise Sources
Different noise sources can be identified in different steps in the acquisition pipeline. To identifiy noise sources, start the datascope and set Pmt Power, Laser, and the Imaging status as described in the table below.
| Noise Source | PMT Power | Laser | Scanning | Noise Frequency | Symptom | Resolution |
|---|---|---|---|---|---|---|
| Power line noise / Ground loop | Off | Shuttered | Off | 50/60Hz | Drifting horizontal bars in image | Connect all equipment to same power outlet (Observe maximum allowed current on outlet). |
Ambient Light (e.g. Computer Monitor, Room Light) | On | Shuttered | Off | 100/120Hz | Drifting horizontal bars in image | Shield microscope from ambient light. |
| PMT Power Ripple Noise | On | Shuttered | Off | 100-500kHz PMT gain dependent | Cross-hatch pattern in image | Ensure noise level is in low bits of signal. |
| Electrical Noise introduced by fast clock signals | Off | Shuttered | On | > 1kHz | ||
| Digitizer Saturation | On | On | On | N/A | ScanImage shows overvoltage warning | Decrease PMT gain and/or laser power. |
Typical noise pattern in image (frame rate: 30Hz). Horizontal bars: 60Hz power line noise. Cross-hatch pattern: PMT power supply ripple noise
