CS256213B1 - Optical system of a complete symmetric objective for laser anemometry - Google Patents

Abstract

The solution concerns an optical system of a completely symmetrical objective for laser anemometry, which consists of six optical elements, separated by air gaps in an arrangement symmetrical according to the mean air gap arbitrarily variable as needed, wherein both outer elements are identical connecting menisci, both inner elements are identical couplings, while optical elements formed by identical scatterers are arranged between the outer and inner elements. The essence of the solution lies in the fact that the optical system has the following parameters = (2.4 to 2.9) P 1.49* n , 7 i 57 el 58 < V , <65 el f'2 = -(0.75 to 0.9) f' l,60< n < 1.69 e2 30 * Ve2 < 38 = (0.48 to 0.6) f' 1.50 < n , < 1.58 . e3 59 < V , 4 65 „ e3 where: f' is the focal length of the first three optical elements is the focal length of the first optical element is the focal length of the second optical element is the focal length of the third optical element All optical elements (1 to 6) of the system may have an axial aperture with a diameter of a maximum of 33% of the outer diameter of the objective.

Description

The invention relates to an optical system of a completely symmetrical lens for laser anemometry using an Argon or He-Ne laser, which is formed by six lenses separated by air gaps in an arrangement symmetrical according to the middle air gap at an aperture number of half the lens c = 2.5 to 3.5 and a field of view up to - 2°.

Previously known objectives of a similar construction type intended for laser anemometry using an Ar-ion laser are not sufficiently chromatically and aplanatically corrected and are not corrected for the use of a He-Ne laser, which adversely affects the quality of the optical signal and reduces the scope of applicability.

These disadvantages are eliminated by the optical system of a completely symmetrical objective for laser anemometry, which consists of six optical elements separated by air gaps in an L-shaped arrangement symmetrical according to the mean air gap arbitrarily variable as needed, with both outer elements being identical connecting menisci, both inner elements being identical couplings, while between the outer and inner elements are arranged optical elements formed by identical diffusers according to the invention, the essence of which is that it has the following parameters:

f ₃ = (2.4 to (2.9) f' ₂ =-(0.75 to 0.9) f' ₃ = (0.48 to 0.6) f' 1.49 < η , v 1.57 el f' 1.60 < η ₂ <1.69 f' 1.50 < n _e3 <1.58 << 65 < ^ ₂ < 38 ^ť v _e3 <65;

where: f is the focal length of the first three optical elements, fj is the focal length of the first optical element, f ₂ is the focal length of the second optical element and f ₃ is the focal length of the third optical element.

The optical system can have the following values:

R, = - 87.25 ^R 2 = - 55.16 ⁿ l = 1,520 In 1 61 r ₃ = 717.81 ⁿ² 1,630 ^In 2 = 38 ^R 4 = 48.50 ^R 5 = 48.90 n. 1,520 at ₃ — 61 ^R 6 = - 66.40 J r ₇ = 66.40 ⁿ⁴ - 1,520 In 4 with 61 ^R 8 = - 48.90 ^R 9 = - 48.50 ⁿ⁵ — 1,630 4 = 38 ^R10 = -717.81 □ □ ^R 11 = 55.16 ⁿ fi ₌ 1,520 in c S= 61 ^R 12 = 87.25 About 0

d _x = 2.85 e ₁ = 0.29 d ₂ = 2.22 e ₂ = 0.72 d ₃ = 6.28 e ₃ = 2.24 d ₄ = 6.28 e ₄ = 0.72 d ₅ = 2.22 e^ = 0.29 dg = 2.85 is its possibility of use for imaging with transverse

The advantage of the optical system according to the invention is the magnification of -1. For the most pronounced emission frequencies of the Argon. ion. laser, it guarantees in the region near the optical axis a line resolution at least at the level of the Rayleigh diffraction criterion or even better, while at the same time excellent resolution in the region near the optical axis for the wavelength of the He-Ne laser, which achieves both high quality of the optical signal and wider applicability. The complete symmetry of the system then significantly reduces production costs.

An example of an embodiment according to the invention is schematically illustrated in the attached drawing.

The optical system consists of six optical elements, centered on the optical axis in the order of connecting meniscus 1, diffuser 2, coupling 3, coupling 4, diffuser 5 and connecting meniscus 6^. Connecting meniscuses 1 and 6, diffusers 2 and 5 and couplings 3 and _4 are always identical. Air gaps el to e5 are created between the individual optical elements. The aperture number c of half the objective is 2.5 - 3.5 and the field of view is up to - 2°.

The following table lists the design parameters of the proposed optical system, recalculated so that the focal length of the first three elements f’ = 100 mm, with a tolerance of 0.03 for the radii of curvature R, air gaps e and mean thickness d and a tolerance of ± 3 for the Abbe numbers y. The radii R are given using the optical sign convention.

^R 1 = - 87.25 ^d l = 2.85 ^R 2 - 55.16 ⁿ l - 1,520 ⁱⁿ = 61 1 ^e l = 0.29 ^R 3 = 717.81 ⁿ² = 1,630 ⁱⁿ 2 = 38 ^d 2 = 2.22 ^R 4 = 48.50 ^e 2 = 0.72 ^R 5 = 48.90 n s= 1,520 v. — 61 ^d 3 = 6.28 ^R 6 = - 66.40 J ^θ 3 = 2.24 r ₇ - 66.40 ⁿ⁴ = 1,520 at ₄ ss 61 ^d 4 = 6.28 ^R 8 - 48.90 ^e 4 0.72 ^R 9 = - 48.50 ⁿ⁵ — 1,630 = 38 ^d 5 = 2.22 ^R10 -717.81 □ □ ^e 5 ⁸³ 0.29 ^R 11 = 55.16 ⁿ⁶ — 1,520 r - 61 ^d 6 = 2.85 ^R 12 = 87.25 About

The optical system according to the invention is particularly suitable for use in laser anemometry using an Argon ion or Helium-Neon laser, where it is required to obtain a high quality optical signal.

Claims (3)

SUBJECT OF THE INVENTION 1. An optical system of a completely symmetrical objective for laser anemometry, which consists of six optical elements separated by air gaps in an arrangement symmetrical according to the mean air gap arbitrarily variable as needed, wherein the two outer elements are identical coupling menisci, the two inner elements are identical couplings, while optical elements formed by identical diffusers are arranged between the outer and inner elements, characterized in that it has the following parameters: = ( 2.4 to 2.9) f'f' ₂ =-(0.75 to 0.9) f· f' = (0.48 to 0.6) f* 1.49- < n _el < 1.57 1.60 χ ηθ ₂ <1.69 1.50 χ n _e3 < 1.58 58 < V < 65 ^e l 30 x < 38 59 \ ^v e ₃ -χ 65 where: f' is the focal length of the first three optical elements, is the focal length of the first optical element, f'2 is the focal length of the second optical element and is the focal length of the third optical element. , 2. Optical system according to point 1, marked by the fact that R. - 87.25 ^d l 2.85 and ^R 2 = - 55.16 ⁿ l - 1,520 ⁱⁿ - 61 X ^e i 0.29 ^R 3 717.81 ⁿ² = 1,630 in 2 = 38 ^d 2 = 2.22 ^R 4 48.50 ^e 2 0.72 ^R 5 48.90 n. 1,520 = 61 ^d 3 = 6.28 ^R 6 = - 66.40 j □ ^e 3 = 2.24 ^R 7 = 66.40 ^nA 1,520 V A 61 ^d 4 = 6.28 ^R 8 = - 48.90 4 ^e 4 0.72 ^R 9 = - 48.50 ⁿ c 1,630 38 ^d 5 = 2.22 ^R10 -717.81 □ 0 ^e 5 = 0.29 ^R 11 55.16 = 1,520 ν' r — 61 ^d 6 = 2.85 ^R 12 87.25 Ό 0 where the radii R are given using optical sign convention. 3. The optical system according to points 1 and 2, characterized in that all optical elements (1 to 6) of the system have an axial opening with a diameter of at most 33% of the outer diameter of the objective.