| 摘要 |
PROBLEM TO BE SOLVED: To provide a bright wide-angled infrared lens composed of three lenses comprising a positive meniscus lens provided with an aspherical surface and with a convex face directed to the object side, a negative meniscus lens with a convex face directed to the object side, and a positive lens with a convex face directed to the object side, in this order from the object side, and having an excellent image-focusing function suitable for 8-12μm of wavelength band. SOLUTION: This infrared lens is composed of three lenses comprising the first lens L1 comprising a positive meniscus lens with a convex face directed to an object side and having an image side face formed into an aspherical surface shape, the second lens L2 comprising a negative meniscus lens with a convex face directed to the object side, and the third lens L3 with a convex face directed to the object side and having positive refractive power, in this order from the object side.
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