The Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) team is developing Giant Steerable Science Mirror (GSSM) for Thirty Meter Telescope (TMT). This paper will combine PSSn to analyze the error characteristics of GSSM. To evaluate the performance of the large telescope under different kinds of error source, the normalized point source sensitivity is introduced, which is firstly studied by the group of thirty meter telescope team to balance all the deviation of the telescope and also budget the error. First and foremost, the character of the normalized point source sensitivity is studied in the very first part and the advantage in the evaluation in all the frequency domain. Then the PSSn is compared with the traditional metric, such as RMS and the multiplication property is discussed. The experienced formula is used to show the relationship between the PSSn and the error sources, static and dynamic. Lastly, the method is applied to a large aperture telescope.
Large telescopes are developing, and promoted by new technological developments. In order to study the method of mirror seeing detection for large aperture optical system, the relationship between mirror seeing and slope information is derived first. In order to evaluate the results more comprehensively, the normalized point source sensitivity was introduced to evaluate the results. Finally, according to the previous analysis, the experiment was carried out. The change normalized point source sensitivity under different conditions is calculated. By comparing with RMS of wavefront, the better statistical characteristic of sensitivity of normalized point source was verified.
The Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) team is developing Giant Steerable Science Mirror (GSSM) for Thirty Meter Telescope (TMT) which has got into the preliminary design phase in 2017. To develop the passive support structure system for the largest elliptic-plane flat mirror and a smoothest tracking mechanism for the gravity-variant condition, CIOMP had developed a 1/4 scale, functionally accurate version of the GSSM prototype as the pre-construction of GSSM. The prototype incorporates the same optical-mechanical system and servo control system as GSSM. The size of the prototype mirror is 898.5mm×634mm×12.5 mm with elliptic-plane figure and is supported by 18 points whiffletree on axial and 12 points whiffletree on lateral. The main objective of the preconstruction includes validate the conceptual design of GSSM and increase more confidence when meet the challenge during the development of GSSM. The assembling, integration and verification of the prototype have been completed based on the test results. CIOMP has got the sufficient test results during the pre-construction phase and got into the preliminary design for GSSM.
BaTiO<sub>3</sub> film is deposited on single crystal MgO substrate with pulsed laser deposition, and its crystal structure and surface roughness are characterized by X-ray diffraction instrument and atomic force microscope. BaTiO<sub>3</sub> film crystal quality is analyzed under three different oxygen partial pressure and three different annealing temperatures. The result shows that when the oxygen partial pressure is 15Pa, crystal surface (001) and (002) diffraction peak of BaTiO<sub>3</sub> thin films have higher intensity. It indicated that the film has a good c-axis orientation. When the annealing temperature is 800°C, the intensity of diffraction peak is the maximum, and peak shape is sharper. BaTiO<sub>3</sub> crystal film is obtained with highly preferred orientation, and film density is improved. Thus the film has less surface roughness and good crystalline state.