Document ID: chunk:federal_register_of_legislation:F2024L01024:front:0:p196
Version: federal_register_of_legislation:F2024L01024
Segment Type: other
Provision Reference: 
Character Range: 567274–570238

2 kg;
                Note: 6A004.a.2. and 6A004.a.3. do not apply to mirrors specially designed to direct solar radiation for terrestrial heliostat installations.
6. A. 004. a. 4. Mirrors specially designed for beam steering mirror stages specified by 6A004.d.2.a. with a flatness of λ/10 or better (λ is equal to 633 nm) and having any of the following:
                  a. Diameter or major axis length greater than or equal to 100 mm; or
                  b. Having all of the following:
                     1. Diameter or major axis length greater than 50 mm but less than 100 mm; and
                     2. A Laser Induced Damage Threshold (LIDT) being any of the following:
                         a. Greater than 10 kW/cm2 using a "CW laser"; or
                         b. Greater than 20 J/cm2 using 20 ns "laser" pulses at 20 Hz repetition rate;
6. A. 004. b. Optical components made from zinc selenide (ZnSe) or zinc sulphide (ZnS) with transmission in the wavelength range exceeding 3,000 nm but not exceeding 25,000 nm and having any of the following:
1. Exceeding 100 cm3 in volume; or
2. Exceeding 80 mm in diameter or length of major axis and 20 mm in thickness (depth);
6. A. 004. c. "Space‑qualified" components for optical systems, as follows:
1. Components lightweighted to less than 20% "equivalent density" compared with a solid blank of the same aperture and thickness;
2. Raw substrates, processed substrates having surface coatings (single‑layer or multi‑layer, metallic or dielectric, conducting, semiconducting or insulating) or having protective films;
3. Segments or assemblies of mirrors designed to be assembled in space into an optical system with a collecting aperture equivalent to or larger than a single optic 1 m in diameter;
4. Components manufactured from "composite" materials having a coefficient of linear thermal expansion, in any coordinate direction, equal to or less than 5 x 10‑6/K;

6. A. 004. d. Optical control equipment as follows:
1. Equipment specially designed to maintain the surface figure or orientation of the "space‑qualified" components specified by 6A004.c.1. or 6A004.c.3.;
2. Steering, tracking, stabilisation and resonator alignment equipment as follows:
                  a. Beam steering mirror stages designed to carry mirrors having diameter or major axis length greater than 50 mm and having all of the following, and specially designed electronic control equipment therefor:
                     1. A maximum angular travel of ±26 mrad or more;
                     2. A mechanical resonant frequency of 500 Hz or more; and
                     3. An angular "accuracy" of 10 μrad (microradians) or less (better);
                  b. Resonator alignment equipment having bandwidths equal to or more than 100 Hz and an "accuracy" of 10 μrad or less (better);
6. A. 004. d. 3. Gimbals having all of the following:
a. A maximum slew exceeding 5°;
b. A bandwidth of 100 Hz or more;
c. Angular