OBJECTIVE LENS FOR VISIBLE AND NEAR INFRARED SPECTRUM Russian patent published in 2011 - IPC G02B13/14 G02B9/60 

FIELD: physics.

SUBSTANCE: first component has on the beam path a biconvex lens 1 whose more convex surface faces the object space, a positive meniscus 2 whose convex surface faces the object space, and a biconcave lens 3 whose more gentle surface faces the object space. The second component is in form of biconvex lens 4 whose more gentle surface faces the image space. The third component is in form of a plane-concave lens 5 whose flat surface faces the image space. The refraction index of lenses 1, 2 and 4 is greater than 1.65, and that of lens 3 is not less than 1.8 and that of lens 5 is equal to approximately 1.5. The aperture diaphragm lies on the concave surface of the third lens of the second component. The second component can be displaced along an optical axis.

EFFECT: simple design, high field-of-view angle, high image quality owing to higher light transmission, reduced vignetting and high transfer constant of modulation, wider working spectral range of the objective lens.

2 cl, 7 dwg, 2 tbl