Full Title Nonlinear Optical Analogous Correction for Distortions in Wide Spectral Band Imaging Telescopes Tech Area / Field

• PHY-OPL: Physics / Optics and Lasers
• SAT-AST: Space, Aircraft and Surface Transportation / Astronomy

Brief Description of Technology
The Institute for Laser Physics has accumulated significant experience in the design and realization of remote object imaging, and possesses unique technologies for remote object imaging in wide spectral band incoherent radiation by cheap and lightweight telescopes, and for the implementation of nonlinear optical techniques for the correction of distortions caused by poor-quality and dynamically loaded optical elements, in the first place by a drastically lit primary mirror. These technologies comprise: (1) principles and methods for the correction of distortions in special telescopes (the so-called non-reciprocal or bypass optical scheme), as well as in internal optical relays; (2) the technologies of analogous, i.e., lacking interim computer data, processing and hence fast and cheap nonlinear-optical methods for the correction of distortions, induced by an aberrant beamlet into the wide spectral band and a weak optical signal from the remote object. These methods are based on the use of (a) dynamic holography, and in particular, dynamic holography in plain media; (b) the negative optical feedback correction technique; (c) the combination of (a) and (b); (3) a technology for special optical elements, involved in scheme realization, in particular that of optically addressed liquid crystal spatial light modulators (OA LC SLM), which can be used both for dynamic holography and negative feedback schemes. The correction units, based on the discussed approaches, provide corrections down to a diffraction-limited value of dynamic (today - several 100 Hz, in perspective - several kHz) distortions within the magnitude of dozens (in perspective - hundreds) of radiation wavelengths, imposed on incoherent weak radiation signals with spectral bands of several dozen nanometers (in perspective - in the overall visible spectral range).

The feasibility of this method has been demonstrated in theory, numerical simulations, and several experiments. In particular, we have developed (1) an imaging system (green spectral band) with a diffraction-limited performance at the aperture of the primary mirror, using a primary mirror with a diameter of 300 mm which is comprised of 6 poor-quality and mutually non-adjusted segments; (2) a telescope with dynamic correction for distortions in the spectral band with a width of several dozen nanometers. Various schemes of correction units and corrected imaging telescopes have been elaborated, in particular those which provide a nearly diffraction-limited performance in the overall visible spectrum of incoherent radiation.

Methods for the numerical design of special lasers and optical imaging systems, including that of OA LC SLM, laser and laser element technology, special optical components and dynamic holography elements, as well as facilities for telescope testing are at our disposal.

Legal Aspects
Some of the technical solutions and optical schemes are protected by Authorship Certificates of Soviet Union. No patents.

Special Facilities in Use and Their Specifications
Facilities for the fabrication of the special elements, in particular, that of OA LC SLM, specialized software complexes for the numerical design of special optical and laser systems, facilities for laser system and telescope testing.

Scientific Papers
1. A.A. Leshchev, G.A. Pasmanik, V.G. Sidorovich, M.V. Vasil’ev, V.Yu. Venediktov. Izvestiya Academii Nauk SSSR. V.55, 2, p.260-266, 1991. (In Russian).

2. A.A. Leshchev, M.V. Vasil'ev, V.Yu. Venediktov. The dynamic correction of large-scale optical aberrations. Proceedings SPIE, V.2096, pp.50-54, (1993).

3. A.A. Leshchev, V.G. Sidorovich, M.V. Vasil'ev, V.Yu. Venediktov. Non-reciprocal optical systems with phase-conjugating mirrors - a new class of optical imaging system. International Journal of Nonlinear Optical Physics, V.3, N.1, pp.89-100, (1994).

4. A.A. Leshchev, P.M. Semenov, M.V. Vasil'ev, V.Yu. Venediktov. A laser telescope with overall compensation via phase conjugation of the output beamlet. Technical Digest of EuroCLEO'94, CWF58, Amsterdam, 1994.

5. A.A. Leshchev, V.G. Sidorovich, G.A. Pasmanik, M.V. Vasil'ev, V.Yu. Venediktov. Non-reciprocal optical systems with phase-conjugating mirrors - a new class of optical imaging systems. Proceedings SPIE, V.2201, pp.998-1003, (1994).

6. A.A. Leshchev, V.G. Sidorovich, O.V. Solodyankin, P.M. Semenov, M.V. Vasil'ev, V.Yu. Venediktov. A wide aperture laser telescope with phase-conjugation compensation of the segmented main mirror. Proceedings SPIE, V.2201, pp.1004-1007, (1994).

7. R.B. Andreev, V.M. Irtuganov, A.A. Leshchev, P.M. Semenov, M.V. Vasil'ev, V.Yu. Venediktov. Experimental realization of a laser telescope with overall compensation for distortion via phase conjugation. Proceedings SPIE, V.2478, paper 36 (1995).

8. V.A. Berenberg, M.V. Vasil’ev, V.Yu. Venediktov, A.A. Leshchev, L.N. Soms. Polychromatic correction for lense distortions, using an optically addressed liquid crystal spatial light modulator. Journal of Optical Technology, 1997, #9 (to be published).

9. A.A. Ageichik, S.A. Dimakov, O.G. Kotyayev, A.A. Leshchev, Yu.A. Resunkov, A.L. Safronov, V.E. Sherstobitov, V.V. Stepanov. Use of the dynamic holography technique for the correction of aberrations in telescopes. Proceedings SPIE, V.2771, (1995), pp.156-163.

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