A conical frustum shaped optical lens is made of transparent material, the conical frustum shaped optical lens having a long diameter at a first end and a short diameter at a second end and the conical frustum shaped optical lens defined by multiple rotational surfaces and a flat fifth surface. The conical frustum shaped optical lens is configured to create folded light paths within the conical frustum shaped optical lens such that a majority of light from a light source is reflected twice within the conical frustum shaped optical lens before being output. An MR16 form factor LED spotlight including the conical frustum shaped optical lens can achieve a reduced light beam angle and a higher central luminous intensity.

A 1-2nd lens group includes two aspherical resin lenses, and thereby it is possible to perform effective correction in order to suppress aberration fluctuation to be reduced. At this time, a glass lens is disposed between the two lenses, and thereby it is possible to control an incident light angle to the resin lens and to reduce power of the resin lenses, and it is possible to prevent variations of shapes of the resin lens. Even in a case where the second optical group is configured of one mirror, it is possible for a primary image to have appropriate aberration and to hereby reduce aberration for a good image which is finally projected onto a screen through the second optical group.

In a 1-2nd lens group, a reduction-side fixed lens group (first fixed lens group) as a fixed group is disposed on the outermost reduction side, an enlargement-side fixed lens group (second fixed lens group) as a fixed group is disposed on the outermost enlargement side, moving lens groups (lens groups), which move when focusing is performed in response to a magnification change, are disposed between the fixed groups, and thereby it is possible to perform effective correction in order to suppress aberration fluctuation to be reduced. Even in a case where the second optical group is configured of one mirror, it is possible for a primary image to have appropriate aberration and to hereby reduce aberration for a good image which is finally projected onto a screen through the second optical group.

Methods and apparatus for implementing a camera having a depth which is less than the maximum length of the outer lens of at least one optical chain of the camera are described. In some embodiments a light redirection device, e.g., a mirror, is used to allow a relatively long optical chain with a relatively large non-circular outer lens. In some embodiments the light redirection device has a depth, e.g., front of camera to back of camera dimension, which is less than the maximum length of the aperture of the outer lens in the aperture's direction of maximum extent. Multiple optical chains with non-circular outer lenses arranged in different directions may and in some embodiments are used to capture images with the captured images being combined to generate a composite image.

Methods and apparatus for controlling the read out of rows of pixel values from sensors corresponding to different optical chains used to capture portions of the same image area are described. The readout is controlled based on user input and/or determinations with regard to the rate of motion in captured images or portions of captured images. For a low rate of motion i, the readout rate of a sensor corresponding to a small focal length is slowed down while the pixel row readout rate of one or more sensors corresponding to one or more optical chains have larger focal lengths are allowed to proceed at a normal rate. For a high rate of motion, the read out rate of the sensor corresponding to the optical chain having the smaller focal length is allowed to proceed at the normal rate.

Adaptive optical zoom systems and methods are described herein. One example of a system for adaptive optical zoom includes a number of variable focal length elements aligned to receive an image through an aperture, wherein the aperture is smaller than at least one of the number of variable focal length elements, a focal plane array aligned to receive the image, and a computing device coupled to the number of variable focal length elements.

Adaptive optical zoom systems and methods are described herein. One example of a system for adaptive optical zoom includes a number of variable focal length elements aligned to receive an image through an aperture, wherein the aperture is smaller than at least one of the number of variable focal length elements, a focal plane array aligned to receive the image, and a computing device coupled to the number of variable focal length elements.

A zoom lens includes, in the order starting from the object side to the side of an image plane, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having negative refractive power, and a fourth lens group having positive refractive power. The fourth lens group includes, in the order starting from the side closest to the image plane to the object side, a first positive lens, a first negative lens, a second negative lens and a second positive lens. The fourth lens group G4 has a configuration that satisfies the following conditional expression (1) when d.sub.P1 represents an Abbe number of the first positive lens L46 and d.sub.N1 represents an Abbe number of the first negative lens L45:
40<d.sub.P1d.sub.N1<0(1).

A zoom lens includes, in the order starting from the object side to the side of an image plane, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having negative refractive power, and a fourth lens group having positive refractive power. The fourth lens group includes, in the order starting from the side closest to the image plane to the object side, a first positive lens, a first negative lens, a second negative lens and a second positive lens. The fourth lens group G4 has a configuration that satisfies the following conditional expression (1) when d.sub.P1 represents an Abbe number of the first positive lens L46 and d.sub.N1 represents an Abbe number of the first negative lens L45:
40<d.sub.P1d.sub.N1<0(1).

The present application provides a micromechanical (MEMS) based zoom lens system, for use in miniature device applications, such as miniature electronic imaging devices. The MEMS-based zoom lens system comprises at least four optical elements, or two Alvarez or Lohmann lenses, that are configured for passage of optical signals therethrough along an optical signal path. Each optical element is MEMS-driven and displaceable in a direction substantially transverse to the optical signal path. In use, the transverse displacement of the optical elements vary an overall focal length of the MEMS zoom lens system such as to provide an optical zoom function. A method of manufacturing a MEMS zoom lens system is also provided in a further aspect.