1. Optical image tube with Medipix readout
John Vallerga, Jason McPhate, Anton Tremsin and Oswald Siegmund
Space Sciences Laboratory
University of California, Berkeley

2. Motivation
Original:
Optical imaging detector for adaptive optics wavefront sensor
Noiseless readout
kHz frame rate
GHz count rate
High QE
Long life (low MCP gain)
Additionally:
UV, neutron sensitive image tubes
High spatial resolution (Timepix)

3. Imaging, Photon Counting Detectors
Photocathode converts photon to electron
MCP(s) amplify electron by 104 to 108
Rear field accelerates electrons to anode
Patterned anode measures charge centroid

4. Vacuum Tube Design

5. Vacuum Tube Design

6. Vacuum Tube Design

7. Vacuum Tube Design

8. Thick Film Ceramic Header
Internal mounting/GND surface for Medipix
Route ~60 Medipix signals out of vacuum
Multi-layered to better match Medipix pitch
Maintain hermetic seal of tube to ≤10-9 Torr
Provide land pads for external I/F connectors

9. Medipix on a Header

10. Vacuum Tube Design

11. MCP/Medipix Serial I/F Board

12. Original Medipix mode readout (UV)
This is the very bad case of large events in Medipix mode. For normal medipix operation, we would try to make the spot size small. But in this case,we tried to make the spots large, leading to the poor resolution. But it is illustrative of what no centroiding can get you
Zoom
256 x 256 (14 mm)

13. Timepix readout Remember the AFTP code
4-4 corresponds to 2^(4+(4-1)/6) or 2^4.5
Next slide is the center of the right image

14. TOT centroids result in factor of 8 improved resolution!
Remember the AFTP code
4-4 corresponds to 2^(4+(4-1)/6) or 2^4.5
Next slide is the center of the right image
256 x 256 converted to 4096x4096 pixels (3.4µm pixels)

15. Second tube process
Success!
Qualification: poor optical QE

16. Quantum efficiency (factor of 4 too low)

17. First tests in darkroom
Use existing vacuum box for HV connections, stable mount

18. Optical bench

19. First Light!

20. Linearity and Resolution
Projected pinhole pattern
(1 x 2 mm)

21. Flat field (red diode)

22. Old watch

23. Old watch
(radium dial)

24. Old watch

25. Gain and Event Threshold

26. Gain and Event Threshold

27. Summary and future work
Demonstration of successful use of Medipix2 in sealed MCP tube
More laboratory and telescope tests to be done
Looking for industrial partner to incorporate our various readout technologies into their tubes
Delayline, cross strip, Medipix, Timepix, etc.
Standard industrial design
Better and more consistent photocathodes
UV, neutron imaging tubes