Dual-band lens

Abstract

A single lens or optical system is used to image two different optical bands, for example visible and infrared, with the same possible adjustments in zoom and / or focus. A dual band singlet is formed of a first, larger, optical element, suitable for operating on light of a first optical band, with an aperture cut out of it. A smaller element, suitable for operating on light of a second optical band, is secured in, or on either side of, the aperture cut through the larger optical element, thus forming a dual band singlet that can operate on two different wavelength bands. Combinations of dual band lenses, lens elements, and lenses with cut-out apertures are used to form dual-band optical systems, including systems with dual-band focus and zoom.

Description

FIELD OF THE INVENTION [0001] 1. Field [0002] Embodiments relate to the field of optics and in particular to imaging lenses. [0003] 2. Related Art [0004] Different cameras, sensitive to different optical wavelength bands, are commercially available for a variety of applications. For example, visible cameras and infrared cameras are used in industrial, security, and rescue applications. Infrared and Ultraviolet cameras are used in fire detection. It can be advantageous to have two different cameras, sensitive to two different wavelength bands, observe the same scene. For example, a visible camera could be combined with an infrared camera. The visible camera would show a typical image of a scene, so that an operator could see normally. Meanwhile, the infrared camera would show the operator where there were hot-spots. [0005] One approach to providing dual waveband viewing is to mount two separate cameras on a common base. Another approach is to use a shared reflective optical system, b...

AI Technical Summary

Problems solved by technology

However, there are problems with both approaches.

However, as aperture increases, a larger and larger beam-splitter is required.

As beam-splitter size increases, so does cost and difficulty of manufacture.

Further, if the two cameras have adjustable focus or zoom, matching focus or zoom changes between the two separate systems can be difficult.

This could make it difficult to recombine the images on a single display, or perform data fusion or other image processing.

Two separate systems also have more mass and take up more space than a single camera.

However, reflective systems are difficult to focus by element motion, typically take up more space than refractive systems, and are difficult to design with zoom features.

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