An optical imaging system includes five lens elements, the five lens elements being, in order from an object side to an image side: a first lens element having positive refractive power; a second lens element having negative refractive power; a third lens element having positive refractive power; a fourth lens element having positive refractive power; and a fifth lens element having negative refractive power.

An imaging apparatus includes an imaging optical system that has a light transmission characteristic of transmitting near-infrared light in a near-infrared light wavelength range including 1550 nm, and an imaging sensor that outputs an imaging signal by imaging the near-infrared light transmitted through the imaging optical system, the imaging sensor has sensitivity to heat radiation from a subject, and the imaging signal includes information regarding a heat radiation image by the heat radiation.

The application discloses an optical imaging lens. The optical imaging lens sequentially includes from an object side to an image side along an optical axis: a first lens having a focal power; a diaphragm; a second lens having a focal power; a third lens having a focal power, and provided with an object-side surface and an image-side surface, the object-side surface is convex surface, the image-side surface is a concave surface; a fourth lens having a positive focal power, and provided with an object-side surface and an image-side surface, the object-side surface is a concave surface, the image-side surface is a convex surface; and a fifth lens having a negative focal power; at least one aspherical mirror surface is included in an object-side surface of the first lens to an image-side surface of the fifth lens; the optical imaging lens meets the following relational expressions: f/EPD<1.5, and 2 mm<ImgH*EPD/f<3 mm.

An infrared optical system having a spectral range for achieving a fog penetration distance of at least 2.75 Runway Visibility Range (RVR) is provided herein. The optical system may include a single set of optical elements designed to have a wavelength range extending beyond 1.2 μm toward shorter wavelengths and comprising a short-wavelength infrared (SWIR) range and at least one of: a middle-wavelength infrared (MWIR) range and a long-wavelength infrared (LWIR) range, to enhance a detection range of the infrared optical system, wherein the single set of optical elements is laid such that the both the SWIR range and the at least one of the MWIR range and the LWIR range of infrared radiation pass through all of the optical elements.

An iris image acquisition system comprises an image sensor comprising an array of pixels including pixels sensitive to NIR wavelengths; at least one NIR light source capable of selectively emitting light with different discrete NIR wavelengths; and a processor, operably connected to the image sensor and the at least one NIR light source, to acquire image information from the sensor under illumination at one of the different discrete NIR wavelengths. A lens assembly comprises a plurality of lens elements with a total track length no more than 4.7 mm, each lens element comprising a material with a refractive index inversely proportional to wavelength. The different discrete NIR wavelengths are matched with the refractive index of the material for the lens elements to balance axial image shift induced by a change in object distance with axial image shift due to change in illumination wavelength.

A zoom lens system includes: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a positive refractive power; a fifth lens group having a positive refractive power; and a sixth lens group having a positive refractive power, wherein the first to sixth lens groups are sequentially arranged along an optical axis from an object side to an image plane side, and zooming is performed by moving at least one of the second lens group, the fourth lens group and the fifth lens group along the optical axis. A distance between a focal point of light having a first wavelength and a focal point of light having a second wavelength is about 50 μm or less at a wide-angle position and a telephoto position. The first wavelength corresponds to green light, the second wavelength corresponds to near infrared (NIR) light.

A rigid-scope optical system includes: an image-formation optical system that causes an image in each of wavelength bands to be formed in a predetermined imaging device, the wavelength bands including a fluorescence wavelength band and a visible light wavelength band; and a color-separation-prism optical system having a dichroic film that separates an optical path of light to be imaged into an optical path of the visible light wavelength band and an optical path of the fluorescence wavelength band, in which the image-formation optical system causes the respective images to be formed in a fluorescence imaging device and a visible light imaging device, the fluorescence imaging device and the visible light imaging device being disposed to cause an amount of misalignment to correspond to a difference between an optical path length of fluorescence and an optical path length of visible light.

A zoom lens is provided. The zoom lens includes a first lens group, a second lens group, a third lens group and an aperture stop. The second lens group is disposed between the first lens group and the third lens group. The aperture stop is disposed between the first lens group and the second lens group. When the zoom lens zooms, the aperture stop is fixed without moving and the first lens group correspondingly moves.

Provided is an optical system including, in order from an object side to an image side, a first lens unit having a negative refractive power, an aperture stop, and a second lens unit having a positive refractive power, in which an average value θIR(G2p).sub.AVE of partial dispersion ratios of materials of positive lenses included in the second lens unit and an average value θIR(G2n).sub.AVE of partial dispersion ratios of materials of negative lenses included in the second lens unit are appropriately set, provided that BF and F are a backfocus and a focal length of the optical system at a wavelength of 1050 nm, respectively, and a partial dispersion ratio of a material is θ=(Ns−Nm)/(Ns−Nl), where Ns, Nm, and Nl are refractive indices of the material at wavelengths of 400 nm, 1050 nm, and 1700 nm, respectively.

A zoom lens system with a large zoom ratio is disclosed, which operates in a broad spectral range, including visible and infrared spectra. The zoom lens system comprises, in order from the object side to the image side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a detection system, wherein zooming from a wide-angle end to a telephoto end is performed by axially moving the second and third lens groups. The system has a relatively long back focal length, and satisfies the following conditions: 0.2<|f2|/(f.sub.W*f.sub.T)½<2, 1<f4/|f2|<8, 0.3<|f2|/f3<1.5, where f.sub.W is the system focal length at the wide-angle end, f.sub.T is the system focal length at the telephoto end, (f.sub.W*f.sub.T).sup.1/2 is the geometric mean of the two focal lengths, and fi is the focal length of the i-th lens group.