Update to Absolute QE

1
Update to Absolute QE Photon Flux

• Need to know illumination power at CCD
• Measure illumination power in integrating sphere
  during QE measurements
• Use K ( power at CCD/Power at sphere) to
  determine light level at CCD
• What if K is not constant but K(l)?
• Measure K for newly design integrating sphere
• Better uniformity at CCD?
• No need to 2-sphere illumination

2
K Factor from Monochromator

• K appears to depend on l
• Is this dependence in illumination system or
  photodiode calibration?
• Could have a 10 effect on QE measurement in
  near IR

3
K from Monochromator and Filter Wheel
4
Conclusion

• Is K a function of l or this in the photodiode
  calibration?
• Is there some l dependent absorber in system?
• Either way, this will change the shape of the
  absolute QE curve