Bright wide-angle infrared lens

• US 6,507,432 B1
• Filed: 07/11/2000
• Issued: 01/14/2003
• Est. Priority Date: 07/26/1999
• Status: Expired due to Term

• Current Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Inventors: Watanabe, Fumio
• Primary Examiner(s): CHANG, AUDREY Y
• Application Number:
  US09/613,835
• Time in Patent Office: 917 Days
• Field of Search: 359/355, 359/356, 359/357, 359/642, 359/784, 359/785, 359/757, 359/649
• US Class Current: 359/356
• CPC Class Codes: G02B 13/14 for use with infrared or ultraviolet radiation G02B13/008, G02B13/16 take precedence

Abstract

A bright wide-angle infrared lens, suitable for a wavelength band of 8 to 12 μm, having favorable imaging performances comprises, successively from the object side, a first lens L₁ made of a positive meniscus lens having a convex surface directed onto the object side and an image-side surface formed aspheric, a second lens L₂ made of a negative meniscus lens having a convex surface directed onto the object side, and a third lens L₃ having a positive refracting power with a convex surface directed onto the object side.

Claims

1. A bright wide-angle infrared lens comprising, successively from an object side, a first lens made of a meniscus lens having a positive refracting power with a convex surface directed onto the object side, a second lens made of a meniscus lens having a negative refracting power with a convex surface directed onto the object side, and a third lens having a positive refracting power with a convex surface directed onto the object side, at least one surface of said first lens being formed aspheric.

2. A bright wide-angle infrared lens according to claim 1, satisfying the following conditional expressions (1), (2), and (3):

3. A bright wide-angle infrared lens according to claim 1, wherein the image-surface-side surface of said first lens is formed aspheric.

4. A bright wide-angle infrared lens according to claim 1, wherein said first, second, and third lenses are formed from germanium and are used for a wavelength band of 8 to 12 μ

m.

5. A bright wide-angle infrared lens according to claim 1, wherein the object-side surface of said third lens is formed aspheric.