BPMeasure.spt

Graphs | Interpretation | Data

This script measures the beam-pointing sensor readings as the laser current is incremented up to the nominal laser current setting.

Graphs

The graph BPMeasure.ps shows the BP readings versus laser current.

• Sample 1: Example of a good BPMeasure.spt result.
• Sample 2: Example of a good bpmeasure.spt with a non-zero beamposition setpoint.

Interpretation

Check the graph for two things:

• the sensor output should be reasonably linear
• the sensor should not saturate

The graph contains data for each BP sensor, BP0 and BP1. If the BPD beamposition setting is zero, these lines should overlap. If the bp sensor reading at 15A is less than 60, then there could be problems with the sensor signal being too low. Also, if the maximum reading is above 3500, then there could be problems with the sensor signal being too high. Ensure that the sensor isn't saturating. See Note 6 .

Data

There is one output file, BPMeasure_data.txt. This file contains nine data columns:

1. Laser current in Amps
2. Number of BP0 samples taken at this laser current, typically 128
3. The average BP0 sensor reading, in raw ADC units
4. The maximum BP0 sensor reading, in raw ADC units
5. The minimum BP0 sensor reading, in raw ADC units
6. Number of BP1 samples taken at this laser current, typically 128
7. The average BP1 sensor reading, in raw ADC units
8. The maximum BP1 sensor reading, in raw ADC units
9. The minimum BP1 sensor reading, in raw ADC units