An imaging lens including a first lens group and a second lens group. Each of the first lens group and the second lens group includes three lenses with refractive power. The first lens group includes two aspheric lenses and a glass lens, and an outermost lens surface of the first lens group facing an object side is a spherical surface. The second lens group includes an aspheric lens and a glass lens, and the second lens group includes a cemented surface. An aperture stop of the imaging lens is disposed between the first lens group and the second lens group.

An imaging lens including a first lens group and a second lens group. Each of the first lens group and the second lens group includes three lenses with refractive power. The first lens group includes two aspheric lenses and a glass lens, and an outermost lens surface of the first lens group facing an object side is a spherical surface. The second lens group includes an aspheric lens and a glass lens, and the second lens group includes a cemented surface. An aperture stop of the imaging lens is disposed between the first lens group and the second lens group.

There are provided an excellent diffractive optical element having a small amount of flare coloring and unaffected optical performance with a decrease in diffraction efficiency minimized and an optical system and an optical apparatus using the diffractive optical element. A diffractive optical element GD used in an optical system OL of a camera 1, which is an optical apparatus, and including a diffraction grating so that the diffractive optical element GD serves as a lens is so configured that the grating height h0 of the diffraction grating in a central region Ac around an optical axis Z is smaller than the grating height hmax of the diffraction grating in a peripheral region Ap.

There are provided an excellent diffractive optical element having a small amount of flare coloring and unaffected optical performance with a decrease in diffraction efficiency minimized and an optical system and an optical apparatus using the diffractive optical element. A diffractive optical element GD used in an optical system OL of a camera 1, which is an optical apparatus, and including a diffraction grating so that the diffractive optical element GD serves as a lens is so configured that the grating height h0 of the diffraction grating in a central region Ac around an optical axis Z is smaller than the grating height hmax of the diffraction grating in a peripheral region Ap.

An imaging lens system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens disposed in order from an object side, and a stop disposed on an image side of one of the first to sixth lenses, and one or more of the second to seventh lenses, disposed on an image side of the stop, each has a positive refractive power and a negative refractive index temperature coefficient.

An imaging lens system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens disposed in order from an object side, and a stop disposed on an image side of one of the first to sixth lenses, and one or more of the second to seventh lenses, disposed on an image side of the stop, each has a positive refractive power and a negative refractive index temperature coefficient.

There is provided converter lens system including a first lens that is a negative lens of which both surfaces are concave, a second lens that is a negative lens of which both an image plane side and an object side are convex toward an object side, and a third lens that is a positive lens of which both sides are convex. The first to third lenses are disposed in this order from the object side, and the converter lens system is inserted and used between an imaging lens and a camera.

There is provided converter lens system including a first lens that is a negative lens of which both surfaces are concave, a second lens that is a negative lens of which both an image plane side and an object side are convex toward an object side, and a third lens that is a positive lens of which both sides are convex. The first to third lenses are disposed in this order from the object side, and the converter lens system is inserted and used between an imaging lens and a camera.

Disclosed herein are an obstacle sensing module and a cleaning robot including the same. The cleaning robot includes a body, a driver to drive the body, an obstacle sensing module to sense an obstacle present around the body, and a control unit to control the driver, based on sensed results of the obstacle sensing module. The obstacle sensing module includes at least one light emitter including a light source, and a wide-angle lens to refract or reflect light from the light source so as to diffuse the incident light in the form of planar light, and a light receiver including a reflection mirror to again reflect reflection light reflected by the obstacle so as to generate reflection light, an optical lens spaced from the reflection mirror by a predetermined distance, to allow the reflection light to pass through the optical lens, and an image sensor, and an image processing circuit.

Disclosed herein are an obstacle sensing module and a cleaning robot including the same. The cleaning robot includes a body, a driver to drive the body, an obstacle sensing module to sense an obstacle present around the body, and a control unit to control the driver, based on sensed results of the obstacle sensing module. The obstacle sensing module includes at least one light emitter including a light source, and a wide-angle lens to refract or reflect light from the light source so as to diffuse the incident light in the form of planar light, and a light receiver including a reflection mirror to again reflect reflection light reflected by the obstacle so as to generate reflection light, an optical lens spaced from the reflection mirror by a predetermined distance, to allow the reflection light to pass through the optical lens, and an image sensor, and an image processing circuit.