The IPIE Adaptive Optical System Application For LEO Observations

Transcription

1 The IPIE Adaptive Optical System Application For LEO Observations Eu. Grishin(1), V. Shargorodsky(1), P. Inshin(2), V. Vygon(1) and M. Sadovnikov(1) 1)Open Joint Stock Company Research-and-Production Corporation Precision Systems and Instruments, Moscow, Russia (2)Applied Science Center Femto, Zelenograd, Russia

2 Алтайский оптико-лазерный центр (АОЛЦ) The dedicated optical facilities for surveillance of near Earth space are of great interest for potentially they can give very important information on the images of space objects necessary for their classification, determination of their attitudes, and analysis of supernumerary situations. Besides, the topicality of optical observations is connected with assimilation of near Earth space and the intensive growth of population of space debris. 2

3 One of the ways for attaining the diffraction limit of angular resolution is compensation of the phase distortion in the light wave with the help of the adaptive optical systems (AOS). Historically, the adaptive optics was developed for solving astronomy tasks. The specific character of using AOS for getting the LEO space object images as compared with the astronomy measurements is stipulated by the next essential factors. Firstly, superfast-acting AOS are needed. Secondly, unlike the astronomy tasks, when observing the LEO space objects there is no reference point source like a star. So, the estimate of the wavefront distortion should be obtained along the extensive object the form of which is unknown a priori. Thirdly, fast angular motion of a space object forces one to use a high-speed rotary support for which the visible angular position of the space object in FoV of the telescope used not time-stable owing to the residual errors of the mechanical targeting system which results in smearing the image if no special measures are assumed. 3

4 A concept of application of AOS for observing LEO space objects with the help of 1-meter telescopes was developed by Institute for Precision Instrument Engineering. The results of Applied Science Center Femto have formed the basis of this concept. In AOS a sensing element of signals for controlling the deformable mirror is used on the base of revealing the components of the sharpness function gradient with the help of a parallel optoelectronic- processor. The specific character of the AOS architecture has resulted in solving all the tree problems above. 4

5 Structural scheme of AOS 1 input lens, 2 multichannel deformable mirror with three drives of angular position, 3 unit of forming the initial signals for the deformable mirror guidance, 4 beam splitter, 5 CCD-camera of the corrected image, 6 unit of electronic control, 7 optical unit, 8 workstation for AOS control, 9 workstation for controlling CCD-camera of the corrected image and recording its data, 10 operator s workplace. 5

6 The technical characteristics of AOS designed for joint operation with meter telescopes having the centrally shaded pupil: number of channels for controlling the deformable mirror.. 30; geometry of zones of the deformable mirror control within the two rings; number of zones within the inner ring. 12; number of zones within the outer ring. 18; type of piezo-drives.... PZT; range of control voltage.... ±200 V; range of the deformable mirror incline angles reduced to an input pupil of 0.6-meter telescope /. 15 angular seconds; time constant of the deformable mirror control in the closed loop of feedback adjustable ms; time constant of controlling the drives of the deformable mirror incline in the closed loop of feedback adjustable ms; interface with PC controlling AOS RS485; interface with PC controlling CCD-camera of corrected image GigE; overall dimensions of the unit being mounted on the telescope taking into account CCDcamera of corrected image and posts of fastening to the flange of telescope: x250x148 mm; overall mass of the unit being mounted on the telescope.8 kg; power supply.. 24 V, 0.8 A. 6

7 Placing AOS on the telescope covered with a thermo-casing Mounting of AOS (optical unit, electronic unit, and CCD-camera of corrected image) at the focus of the 600mm telescope Geometry of zones of 30-channel deformable mirror 7

8 Алтайский оптико-лазерный центр (АОЛЦ) Seasat 1 image Terra image 8

9 Okean-O image 9

10 Aqua, UARS image 10

11 ISS image 11

12 CONCLUSION The described results witness of high effectiveness of application of adaptive optics on the 1-meter class of telescopes solving the tasks of imaging LEO space objects. Due to atmospheric distortions compensation the resulting angular resolution is close to the diffraction limit. This makes the images rich in content in terms of a space object shape analysis and determination of its attitude. In most cases, the possibility of obtaining the such information allows to spend no additional time for performance of the photometric sessions. 12

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14 Алтайский оптико-лазерный центр (АОЛЦ) 14