METHOD OF MANUFACTURING MULTISECTOR SPIRAL PHASE PLATE WITH VARIABLE PHASE DELAY (SVR) Russian patent published in 2020 - IPC G02F1/03 B82Y40/00 

FIELD: optics.

SUBSTANCE: invention relates to production of optical elements, which enable conversion of Gaussian beams into circular beams with radial polarization. Method of manufacturing multisector spiral phase plate with variable phase delay (SVR) with number of sectors equal to N_max on a plate from Iceland spar, crystal axis of which is oriented parallel to plate surface, in which the number of sectors N_{max is} divided into 4 groups, in each of which the number of sectors N_max/4 is selected, and successive etching of each sector of the plate with the exception of the first one, the thickness of which is equal to the thickness of the crystal plate, at the specified depth: h=(2(N-1)λ)/(N_max|n_o-n_e|), where λ is wavelength, N is sector number, n_o and n_e are refraction indices for ordinary and extraordinary waves respectively, is carried out by moving a focused beam of near-IR laser radiation of nanosecond pulse duration in the plane of contact of the crystalline plate and the pressed graphite plate, within the sector, wherein direction of first and subsequent movement lines are selected parallel to sector radius, from which movement is started and which is carried out from sector edge SVR to its center, then the process is repeated for each of subsequent sectors until completion of SVR formation, wherein in each of the groups the power density, the pulse repetition rate, the focused beam movement speed and the number of displacements for each of the sectors parallel to the sector sectors lines are entered, the values of which are given in the claim, and after completion of SVR formation annealing is performed in furnace at temperature not lower than 500 °C and not higher than 550 °C with annealing duration of not less than 12 hours.

EFFECT: higher SVR manufacturing quality.

1 cl, 41 dwg