APOCHROMATIC OBJECTIVE FOR WIDE SPECTRUM AREA Russian patent published in 2021 - IPC G02B9/16 G02B9/04 

FIELD: optics.

SUBSTANCE: objective can be used in telescopic systems, including astronomical telescopes for visual observation. An apochromatic objective includes two optically coupled components. The first component is a biconvex lens made of grade Y glass and the second is a double-lens positive meniscus made of grade Z glass, containing a biconcave lens made of grade X glass, the air gap between the components is d₁ and the air gap between the lenses of the second component is d₂. Refraction indices and Abbe numbers of the glasses X, Y and Z comply with the following conditions: 1.7≤n_X≤1.8 and 34≤ν_X≤36; 1.6≤n_Y≤1.7 and 51≤ν_Y≤54, 1.6≤n_Z≤1.7 and 30≤ν_Z≤33, and the air gaps comply with the conditions d₁≤0.0018f, d₂≤d₁, wherein n_X is the refraction index of the grade X glass; n_Yis the refractive index of the grade Y glass; n_Z is the refractive index of the grade Z glass; ν_X is the Abbe number of the grade X glass; ν_Y is the Abbe number of the grade Y glass; ν_Z is the Abbe number of the grade Y glass; f is the focal length of the objective.

EFFECT: provided is simple and compact design with an extended operating spectral range (400 to 900 nm) and improved chromatic aberration correction.

1 cl, 3 dwg, 1 tbl