Maestro Lens Mounting Lenses 4 and 6 Mounting

Maestro Lens Mounting • Lenses 4 and 6 – Mounting method: Potted on OD with elastomer (athermalized) – Lens diameter = 10. 63 inches – Lens CTE ( l) = 3. 5 x 10 -6/ F – Elastomer • CTE ( e) • = 178. 0 x 10 -6/ F = 0. 4992 – Cell, Aluminum (to match L 5 CTE) • CTE ( c) = 13. 0 x 10 -6/ F 1

Athermalization Calculation • Assume elastomer layer is constrained – Thermal expansion of elastomer (h = thickness of elastomer layer) = e*((1+ )/(1 - ))* T*h = 2. 994 e T*h – Thermal expansion of cell (D = diameter of lens) = c* T*(D/2+h) – Thermal expansion of lens = l*(D/2)* T – The mounting is athermalized if the expansion of the elastomer equals the cell expansion less the lens expansion: – 2. 994 e T*h = c* T*(D/2+h) - l*(D/2)* T • This is true if: – h = ( c- l)*(D/2)/(2. 994 e - c) = 0. 097 inches • After adjusting for shape effects (finite width) – h = 0. 102” for L 4 and 0. 102” for L 6 2

Finite Element Model of Lens L 4 Elastomer Layer 3

Finite Element Model of Lens L 6 4

Lens L 4 Results, No Axial Locators – 1 g Z cases are on elastomer and on elastomer supplemented by axial supports. – 1 g Y and Z hydro cases do not include gravitational acceleration 5

Lens L 6 Results, No Axial Locators • 1 g Z cases are on elastomer and on elastomer supplemented by axial supports. 1 g Y and Z hydro cases do not include gravitational acceleration 6

Lens L 4 Results, Three Axial Locators 1 g Y and Z hydro cases do not include gravitational acceleration 7

Lens L 6 Results, Three Axial Locators 1 g Y and Z hydro cases do not include gravitational acceleration 8

Lens L 4 Results, Six Axial Locators 1 g Y and Z hydro cases do not include gravitational acceleration 9

Lens L 6 Results, Six Axial Locators 1 g Y and Z hydro cases do not include gravitational acceleration 10

Residual Deformation if Bonded on Three Points Assume 500*sin(3* ) -inch deformation when bonded (Actual 1 g trifoil is < 1. 75 -inch) Residual trifoil in lens L 4 is 2. 7 -inch (0. 54%) Residual trifoil in lens L 6 is 3. 05 -inch (0. 61%) Conclusion: The lens can be supported on 3 OD points while bonding. When the weight is removed from the 3 support points 99. 4% of the trifoil present during bonding will disappear. 11

Thermal Stress and Elastomer Thickness Lens 4 12

Thermal Distortion, 100 deg F Change, L 4 Lens and Cell Elastomer (a narrow strip with the same shape factor is required). 13

Thermal Results, 100 deg F Change, L 4 • To investigate large thermal distortions an aluminum cell was added to the model and the methodology revised to allow accurate distortion calculation (I. e. normalize CTE’s to the glass value to remove large dimensional changes related only to thermal expansion). • Results for various configurations of the elastomer layer: – Case – Full lens height – Half height, half circumf. Lens distortion 0. 81 waves P-V 0. 092 waves P-V 0. 058 waves P-V 14