An imaging lens for use with an operational waveband over any subset of 7.5-13.5 m may include a first optical element of a first high-index material and a second optical element of a second high-index material, that may have a refractive index greater than 2.2 in the operational waveband, an absorption per mm of less than 75% in the operational waveband, and an absorption per mm of greater than 75% in a visible waveband of 400-650 nm. Optically powered surfaces of the imaging lens may include a sag across their respective clear apertures that are less than 10% of a largest clear aperture of the imaging lens. Respective maximum peak to peak thicknesses of the first and second optical elements may be similar in size, for example within 15 percent of each other. Ratios of maximum peak to peak thickness to clear aperture and, separately, to sag are also provided.

The invention relates to chalcogenide glass compositions for use in a lens system to balance thermal effects and chromatic effects and thereby provide an achromatic and athermal optical element that efficiently maintains achromatic performance across a broad temperature range. The glass composition is based on sulfur compounded with germanium, arsenic and/or gallium, and may further comprise halides of, for example, silver, zinc, or alkali metals. Alternatively, is based on selenium compounded with gallium, and preferably germanium, and contains chlorides and/or bromides of, for example, zinc, lead or alkali metals.

Mechanisms for spatially isolating a region of interest (ROI) in a scene. A first sensor generates sensor data that quantifies energy received from a scene within a field of view (FOV) of the first sensor to generate a real-time FOV full motion video. A processor analyzes the sensor data to identify a first ROI during a wait period of a frame period of the first sensor. A first subset of micromirrors in a micromirror array that is directed toward the scene is identified. The first subset of micromirrors receives energy from the first ROI. A micromirror in the first subset is controlled to move from a primary position of the at least one micromirror to a first tilt position of the micromirror to reflect the energy from the first ROI toward a second sensor, the first ROI being spatially isolated from the real-time FOV full motion video.

The imaging lens includes, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power. In a case of changing focus from an object at infinity to an object at the closest distance, the first lens group is immovable, and the second lens group and the fourth lens group are moved in an optical axis direction along different trajectories from each other. In addition, predetermined conditional expressions (1) to (3) are satisfied.

Provided are a laser speckle contrast imaging method, a laser speckle contrast imaging system, and an apparatus which includes the laser speckle contrast imaging system. The laser speckle contrast imaging system includes a laser light source configured to irradiate laser beams toward a subject, the laser beams having a plurality of wavelength bands and different surface transmittances with respect to the subject. An imaging unit is configured to acquire speckle images by capturing images of speckles by using an image sensor, the speckles being formed when the irradiated laser beams are scattered from the subject. A signal processor is configured to convert the acquired speckle images into speckle contrast images and to acquire a compensated speckle contrast image by compensating for a change caused by a movement of the subject.

Optimal angular field mappings that provide the highest contrast images for back-scanned imaging are given. The mapping can be implemented for back-scanned imaging with afocal optics including an anamorphic field correcting assembly configured to implement a non-rotationally symmetric field mapping between object space and image space to adjust distortion characteristics of the afocal optics to control image wander on a focal plane array. The anamorphic field correcting assembly can include one or more mirrors having non-rotationally symmetric aspherical departures.

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 m 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.

An optical imaging lens assembly includes, in order from an object side to an image side: a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element has an object-side surface being concave in a paraxial region thereof. The second lens element has positive refractive power. The third lens element has negative refractive power. The fourth lens element has positive refractive power. The fifth lens element has negative refractive power.

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 dual-band refractive optical system having an eyepiece-type arrangement and configured for mid-wave infrared and long-wave infrared operation. In one example the optical system includes a plurality of lenses, each constructed from a material that is optically transparent in the mid-wave infrared and long-wave infrared spectral bands. The lenses are arranged to receive infrared electromagnetic radiation in an operating waveband that includes at least a portion of the mid-wave infrared and at least a portion of the long-wave infrared spectral bands via a front external aperture stop and to focus the infrared electromagnetic radiation onto a rear image plane, the lenses being positioned between the front external aperture stop and rear image plane. The optical system can further include a corrector plate positioned coincident with the front aperture stop.