There is provided herein an optical system for a tip section of a multi-sensor endoscope, the system comprising: a front-pointing camera sensor; a front objective lens system; a side-pointing camera sensor; and a side objective lens system, wherein at least one of said front and side objective lens systems comprises a front and a rear sub-systems separated by a stop diaphragm, said front sub-system comprises, in order from the object side, a first front negative lens and a second front positive lens, said rear sub-system comprises, in order from the object side, a first rear positive lens, an achromatic sub-assembly comprising a second rear positive lens and a third rear negative lens, wherein the following condition is satisfied: f.sub.(first rear positive lens)≤1.8f, where f is the composite focal length of the total lens system and f.sub.(first rear positive lens) is the focal length of said first rear positive lens.

The present disclosure discloses an optical imaging system including, sequentially from an object side to an image side along an optical axis, a first lens having a negative refractive power with a concave object-side surface and a concave image-side surface; a stop; a second lens having a refractive power; a third lens having a negative refractive power; a fourth lens having a refractive power with a convex object-side surface, and a convex image-side surface; and a fifth lens having a refractive power. Half of a maximal field-of-view Semi-FOV of the optical imaging system satisfies 45.0°≤Semi-FOV<65.0°, and an effective focal length f2 of the second lens and a center thickness CT2 of the second lens along the optical axis satisfy 2.5≤f2/CT2≤3.0.

The present disclosure discloses an optical imaging system including, sequentially from an object side to an image side along an optical axis, a first lens having a negative refractive power with a concave object-side surface and a concave image-side surface; a stop; a second lens having a refractive power; a third lens having a negative refractive power; a fourth lens having a refractive power with a convex object-side surface, and a convex image-side surface; and a fifth lens having a refractive power. Half of a maximal field-of-view Semi-FOV of the optical imaging system satisfies 45.0°≤Semi-FOV<65.0°, and an effective focal length f2 of the second lens and a center thickness CT2 of the second lens along the optical axis satisfy 2.5≤f2/CT2≤3.0.

A camera optical lens includes first to fifth lenses. The camera optical lens satisfies: 1.50≤(R5+R6)/(R5−R6); 0.40≤d4/d6≤1.25; 1.00≤TTL/IH≤1.30; and 1.00≤(R3+R4)/(R3−R4)≤2.40, where R3 and R4 denote curvature radiuses of an object side surface and an image side surface of the second lens, respectively; R5 and R6 denote curvature radiuses of an object side surface and an image side surface of the third lens, respectively; d4 denotes an on-axis distance from the image side surface of the second lens to the object side surface of the third lens; d6 denotes an on-axis distance from the image side surface of the third lens to an object side surface of the fourth lens; IH denotes an image height of the camera optical lens; and TTL denotes a total optical length. The camera optical lens has good optical performance while satisfying design requirements for ultra-thin, wide-angle lenses having large apertures.

A camera optical lens includes first to fifth lenses. The camera optical lens satisfies: 1.50≤(R5+R6)/(R5−R6); 0.40≤d4/d6≤1.25; 1.00≤TTL/IH≤1.30; and 1.00≤(R3+R4)/(R3−R4)≤2.40, where R3 and R4 denote curvature radiuses of an object side surface and an image side surface of the second lens, respectively; R5 and R6 denote curvature radiuses of an object side surface and an image side surface of the third lens, respectively; d4 denotes an on-axis distance from the image side surface of the second lens to the object side surface of the third lens; d6 denotes an on-axis distance from the image side surface of the third lens to an object side surface of the fourth lens; IH denotes an image height of the camera optical lens; and TTL denotes a total optical length. The camera optical lens has good optical performance while satisfying design requirements for ultra-thin, wide-angle lenses having large apertures.

A folded camera that includes two light folding elements such as prisms and an independent lens system, located between the two prisms, which includes an aperture stop and a lens stack. The lens system may be moved on one or more axes independently of the prisms to provide autofocus and/or optical image stabilization for the camera. The shapes, materials, and arrangements of the refractive lens elements in the lens stack may be selected to capture high resolution, high quality images while providing a sufficiently long back focal length to accommodate the second prism.

A folded camera that includes two light folding elements such as prisms and an independent lens system, located between the two prisms, which includes an aperture stop and a lens stack. The lens system may be moved on one or more axes independently of the prisms to provide autofocus and/or optical image stabilization for the camera. The shapes, materials, and arrangements of the refractive lens elements in the lens stack may be selected to capture high resolution, high quality images while providing a sufficiently long back focal length to accommodate the second prism.

An optical system includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a first focus lens unit having a negative refractive power, and a second focus lens unit having a positive refractive power. The first lens unit is fixed during focusing. The first focus lens unit and the second focus lens unit move so that a distance between the first focus lens unit and the second focus lens unit changes during focusing. The first lens unit includes a single lens which is disposed closest to an object and has a negative refractive power. A predetermined condition is satisfied.

A lens group is provided, which includes a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4), and a fifth lens (L5) that are sequentially arranged from an object side to an image side, and a relative refractive index temperature coefficient β of at least one lens meets: −9×10.sup.−5≤β≤9×10.sup.−5. A temperature drift coefficient of the lens group falls within a small range, a temperature effect of the lens group is low, and a defocus phenomenon generated because the lens group changes with a temperature is weak. According to the application, a design difficulty of a voice coil motor in a lens can be reduced and user experience is improved.

A lens group is provided, which includes a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4), and a fifth lens (L5) that are sequentially arranged from an object side to an image side, and a relative refractive index temperature coefficient β of at least one lens meets: −9×10.sup.−5≤β≤9×10.sup.−5. A temperature drift coefficient of the lens group falls within a small range, a temperature effect of the lens group is low, and a defocus phenomenon generated because the lens group changes with a temperature is weak. According to the application, a design difficulty of a voice coil motor in a lens can be reduced and user experience is improved.