Beam expander for coherent illumination and speckle reduction

Borodin Y.P., Dubynin S.E., Kopenkin S.S., Morozov A.V., Putilin A.N.

Publication in Journal of Optical Technology

For Russian citation (Opticheskii Zhurnal):

Морозов А.В., Дубынин С.Е., Путилин А.Н., Копёнкин С.С., Бородин Ю.П. Расширитель пучка для системы когерентной подсветки с низким контрастом спеклов // Оптический журнал. 2023. Т. 90. № 5. С. 76–85. http:doi.org/10.17586/1023-5086-2023-90-05-76-85

Morozov A.V., Dubynin S.E., Putilin A.N., Kopenkin S.S., Borodin Y.P. Beam expander for coherent illumination and speckle reduction [in Russian] // Opticheskii Zhurnal. 2023. V. 90. № 5. P. 76–85. http:doi.org/10.17586/1023-5086-2023-90-05-76-85

For citation (Journal of Optical Technology):

A. V. Morozov, S. E. Dubynin, A. N. Putilin, S. S. Kopenkin, and Y. P. Borodin, "Beam expanders for coherent illumination and speckle reduction," Journal of Optical Technology. 90(5), 271-277 (2023)

Abstract:

Subject of study. The combined optical elements based on holographic optical elements and a lightguide. Aim of study. Development of compact optical systems for converting a collimated beam with a Gaussian energy distribution from a coherent radiation source into a uniform and homogeneous beam with enlarged dimensions and a required cross-sectional shape. Method. Coherent radiation is coupled into the lightguide and out-coupled from it using holographic optical elements. The lightguide and the matched diffuser form a set of secondary point sources, the total field from which, as a result of interference, has the required energy distribution and aperture. Main results. The authors have proposed several modifications of the combined optical elements based on holographic optical elements and a light guide. The total efficiency of such elements was achieved by 40–45% (the diffraction efficiency of individual elements is about 80–85%) with a beam uniformity of about 80% and a decrease in speckle contrast to the level of 20–30%. Practical significance. The technical solutions proposed in the work regarding the development of combined optical elements based on light guides and holographic optical elements can significantly reduce energy consumption, dimensions and weight of visualization systems, especially wearable virtual and augmented reality devices.

Keywords:

holographic optical element, lightguide, beam expander, beam shaper, speckle reducing

OCIS codes: 030.6140, 050.1950, 050.1970, 050.7330, 090.1970, 090.2820, 090.2870, 090.2890, 090.7330

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