Infrared objective system lens
AssigneeKern & Co. AG
InventorRoman Boutellier
Life of this patent
Estimating the term…
Abstract
This invention provides an infrared lens system for the wavelength range of 3.5 .mu.m-5 .mu.m of F/1 and having an angle of field of 3.2.degree.. The lens system consists of three lens elements. As viewed from the object side the first element is a positive lens (1) made of silicon (Si), the second element (3) is made of calcium fluoride (CaF.sub.2) and the third is a positive lens (2) made of silicon (Si). This lens system is intended for use in a thermal imaging device, having a scanning mirror (4) and a radiation detector (5) with a sapphire cover (6). Thus a low cost achromatic infrared objective system is provided.
Claims2
An infrared objective system lens with an image field that is convex toward the lens with a radius of curvature of 17.5, wherein the elements of the system have the following numerical values:
- ______________________________________ Lens Element f = 100.0 Axial Thicknesses Number Radius of Curvature and Separations Material ______________________________________ R.sub.1 = 335.5 t = 10.0 Si R.sub.2 = 819.8 s = 59.6 air R.sub.3 = 914.5 t = 5.4 CaF.sub.2 3 R.sub.4 = 260.0 s = 1.6 air R.sub.5 = 49.2 2 t = 9.1 Si R.sub.6 = 51.8 ______________________________________
- where the indicated values of R.sub.1, R.sub.2, R.sub.5 and R.sub.6 may vary by .+-.5%, the indicated values of R.sub.3 and R.sub.4 may vary by .+-.20%, f is the focal length of the system and R is the radius of curvature of the indicated elements.
An infrared objective system lens with an image field that is convex toward the lens with a radius of curvature of 25, wherein the elements of the system have the following numerical values:
- ______________________________________ Lens Element f = 100.0 Axial Thicknesses Number Radius of Curvature and Separations Material ______________________________________ R.sub.1 = 143.5 t = 11.6 Si R.sub.2 = 180.4 s = 30.8 air R.sub.3 = 561.0 t = 4.0 CaF.sub.2 3 R.sub.4 = 685.0 s = 28.7 air R.sub.5 = 65.9 t = 8.5 Si 2 R.sub.6 = 80.3 ______________________________________
- where the indicated values of R.sub.1, R.sub.2, R.sub.5 and R.sub.6 may vary by .+-.5%, the indicated values of R.sub.3 and R.sub.4 may vary by .+-.20%, f is the focal length of the system and R is the radius of curvature of the indicated elements.
Dependencies are inferred from the claim text.