Page 140 - ELT_15th July 2020_Vol 373_Part 2

E50 EXCISE LAW TIMES [ Vol. 373

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43. 8A604.c.4 8A604.c.4 8A604.c.4
c. “Space-qualified” compo- c. “Space-qualified” compo-
nents for optical systems, nents for optical systems, at
as follows : follows :
1. Components light- 1. Components light-
weighted to less than weighted to less than
20% “equivalent den- 20% “equivalent densi-
sity” compared with ty” compared with a
a solid blank of the solid blank of the same
same aperture and aperture and thickness;
thickness : 2. Raw substrates, pro-
2. Raw substrates, pro- cessed substrates having
cessed substrates surface coatings (single-
having surface coat- layer or multi-layer, me-
ings (single-layer or tallic or dielectric, con-
multi-layer, metallic ducting, semiconduct-
or dielectric, conduct- ing or insulating) or
ing, semiconducting having protective films;
or insulating) or hav- 3. Segments or assemblies
ing protective films; of mirrors designed to
3. Segments or assem- be assembled in space
blies of mirrors de- into an optical system
signed to be assem- with a collecting aper-
bled in space into an ture equivalent to or
optical system with a larger than a single optic
collecting aperture 1 m in diameter;
equivalent to or larg- 4. Components manufac-
er than a single optic tured from “composite”
1 m in diameter; materials having a coef-
4. Components manu- ficient of linear thermal
factured from “com- expansion, in any coor-
posite” materials hav- dinate direction, equal
ing a coefficient of to or less than 5 x 10-
linear thermal expan- 6/K;
sion equal to or less
than 5 x 10-6 in any
coordinate direction;
44. Changes in 8a605.a.6. Output wavelength 8A605.a.6. Output wavelength ex-
entry at exceeding 975 nm but not ex- ceeding 975 nm but not exceeding
8A605.a.6.a ceeding 1,150 nm and any of the 1,150 nm and any of the following :
following : a. ‘Single transverse mode’ out-
a. ‘Single transverse mode’ put and any of the following :
output and any of the fol- 1. Output power exceed-
lowing : ing 1,000 W; or
1. Average output pow- 2. Having all of the follow-
er exceeding 1,000 W; ing :
or a. Output power ex-
2. Having all of the fol- ceeding 500 W;
lowing : and
a. Average output b. Spectral band-
EXCISE LAW TIMES  15th July 2020  140