Optical qualification of the first COMPASS RICH mirrors

1
Optical qualification of the first COMPASS RICH
mirrors

• Experimental set up
• Measured substrates
• Measurement results
• Radius of curvature
• Average deviation from spherical shape
• Results discussion

2
Measured substrates

• 10 Simax substrates (from IMMA Ltd, Turnov)
• Parameters
• Diameter 520 mm
• Thickness 7 mm
• Radius of curvature 6600 mm
• Required max. average deviation from spherical
  shape
• 95 of reflected light inside diameter 3.5 mm
  0.27 mrad

520
3
Experimental set up
4
Results
Quality D parameter diameter with 95 of
reflected light inside.
5
Results
No.9
No.2
6
Mirror No. 2
7
Mirror No. 9
8
Mirror No. 4
Test result negative
Test result positive
After correction corresponding to the COMPASS
requirement
Before correction
Which result is correct?
Question of requirement definition
9
Influence of holder
F
F
g
10
(No Transcript)
11
Spots for varied positions
Pos. A
Pos. B
Pos. C
Pos.D
Pos. E
Pos. F
12
Results influence of holder
13
Prototype mirror (NO. 0)
Thickness only 6 mm
14
Conclusions

• Industry can provide glass mirrors
• diameter 500 mm
• thickness 7 mm
• radius of curvature better than 1 for
  range 5?10 m
• average geom. quality better than 0.2 mrad
• Definition of the quality requirement ?
• Measurement of mirrors fixed on final holder