THE CRAO'S CONTRIBUTION FOR THE WSO / UV PROJECT N.V.STESHENKO

1. The flight set of the T-170M telescope optics - the mainmirror of 1715 mm in diameter and the secondary mirror of 400 mmin diameter - manufactured by the Lytkarino optical glass firm(LZOS), will be coated by two-component (Al+MgF2) reflecting layerin the vacuum chamber VUAZ-2.6 in the Crimean astrophysical observatory.

This chamber is now in operation but in order to coat the T-170M optics it is under modernization: a) the mechanism for rotation of a mirror during the sputtering will be inserted - the construction was developed and has been manufacturing now; b) the chamber is supplied with tantalum cells for thermal evaporation of MgF2; the construction was developed and tested in the 1 m vacuum chamber; c) the vacuum chamber VUAZ-2.6 is supplied by nitrogen coolings to obtain better vacuum, the coolings are available. All these actions will improve the quality of the reflecting layer. The modernization of the vacuum chamber will be finished to the end of 2007.

2. To measure a reflection coefficient in UV region, we have a device that was used in 1983 to study a reflectivity of the optics of the space mission ASTRON. The ASTRON optics was coated with Al + Mg F2 in a 1 m vacuum chamber of the CrAO. During 3 year work in space the reflection coefficient has degraded only by 1-2%. Some preventive measures and modernization of this measering set will be made in 2007.

3. After the flight set of T-170M optics is transported to the CrAO, we shall study it in cooperation with the LZOS workers in a vacuum chamber of 3.2 m in diameter in the autocollimation system with a flat mirror of 1.8 m in diameter. The chamber was manufactured, now it is under assembling and its inner equipment is under development: the mechanical system of technological support of the main mirror (we shall have 81 support points to compensate the Earth gravity instead of 54), the technological frame of the secondary mirror, the system of a light source and image detector.

The 1.8 m spherical mirror is manufactured to check the flat mirror by the Common method. This work will be finished to the end of 2007.

The interferogram of control spherical mirror, diameter 1.8 mm, R = 14 m.

4. If it is found that the T-170M optics is not quite good for operate in UV, it will be improved in CrAO in cooperation with LZOS persons by the ion beam figuring method in the special vacuum chamber using the Crimean technology. The 1m ion chamber to improve the secondary mirror is manufactured and tested and has shown a high quality in figuring a complex optical surface up to λ/50 for 632 nm. We have the vacuum chamber for the primary mirror, and its inner equipment is under manufacturing.

5. If necessary, CrAO can participate in testing and certification of the LSS. We had carried out a similar work in 70-s in preparation the UV spectrograph for the orbital solar telescope OST-1, that operated successfully at the space station Salyut-4 in 1975. We have the device that was used for this testing.

6. We are studing a possibility of our participation it the Ground Segment.