Imaging lens and imaging device

Abstract

An imaging lens is provided with: a first lens with negative power; a second lens with negative power; a third lens with positive power; and a fourth lens with positive power. The cemented fourth lens is formed from an object side lens with negative power and an image side lens with positive power. The thickness of a resin adhesive layer that bonds the object side lens and the image side lens is 20 μm or greater on the optical axis, and when Sg1H is the amount of sag in the image side lens surface of the object side lens and Sg2H is the amount of sag in the object side lens surface of the image side lens. The bonding operation is easy without damage occurring to the cemented surfaces, with a design that takes into account thickness of the resin adhesive layer; therefore various forms of aberration can be corrected.

1 . An imaging device for visible light ray and near infrared ray comprising:
 a cemented lens composed of a negative lens and a positive lens, and an image pick-up device, wherein the negative lens and the positive lens being cemented together with an adhesive layer;   a first cemented surface of the negative lens adjacent the adhesive layer and a second cemented surface of the positive lens adjacent the adhesive layer have different aspheric shapes.   
     
     
         2 . The imaging device according to  claim 1 , wherein the visible light ray has a wavelength of 400 nm to 700 nm, and the near infrared ray has a wavelength of 800 nm to 1100 nm. 
     
     
         3 . The imaging device according to  claim 1 , wherein the image pick-up device is a CCD sensor or a CMOS sensor.