CN102866482A

CN102866482A - Fisheye infrared lens

Info

Publication number: CN102866482A
Application number: CN2012103964442A
Authority: CN
Inventors: 朱敏; 王国力
Original assignee: Nanjing Wavelength Optoelectronics Technology Co Ltd
Current assignee: Nanjing Wavelength Optoelectronics Technology Co Ltd
Priority date: 2012-10-18
Filing date: 2012-10-18
Publication date: 2013-01-09

Abstract

The invention relates to a fisheye infrared lens which is composed of four germanium lenses. Focal power is distributed according to a sequence of negative, negative, positive and positive. A lens 1 and a lens 2 are both meniscus concave lenses. The lens 1, the lens 2, a lens 3 and a lens 4 form a positive focal power rear group of inverted telephoto lenses, back focal length is controlled to be two to three times of lens effective focal length. The meniscus concave lenses 1 and 2 are used for balancing aberrations of the other two lenses and have prism deviation effects, an incident angle of edge field light on a follow-up optical component is small, deviation angles shared by all lenses are balanced, correction of aberrations is facilitated, aperture stop is arranged on the front surface of the lens 3, a square-similar telecentric beam path is formed, irradiance nonuniformity caused by equal incidence angles of an off-axis image point principal ray at an image surface position is avoided. The front surfaces of the lens 2 and the lens 4 are both aspheric surfaces and used for removing off-axis aberrations such as coma abberation and astigmatism.

Description

A kind of flake infrared lens

Technical field

The present invention relates to optical field, is a kind of flake infrared lens.

Background technology

At present, the thermal camera on the Chinese market mainly is to realize day and night conversion by infrared filter, namely opens optical filter by day the time, enters CCD to stop infrared ray, allows CCD can only sense visible light; Under the bad state of night vision or illumination condition, optical filter quits work, and stops that no longer infrared ray enters CCD, and infrared ray enters camera lens and carries out imaging after the object reflection.

But the daytime picture often can appear clear, the phenomenon that picture but thickens under the infrared light condition in practice.This be because, the wavelength of visible light and infrared light (IR light) is different, the difference of wavelength can cause the position of focal plane of imaging different, thereby the phenomenon of empty burnt, fuzzy pictures occurs.

And fish eye lens is that the modern science and technology field is needed as the special lens that a kind of field angle can reach more than 200 °.Because have ultra-large vision field, therefore, can utilize it to carry out omnibearing imaging, this technology has strong telepresenc and spatial impression; Utilize fish-eye large visual field to take and record continuously the photo of the above cloud layer in local horizon, process compares, thereby the rule that can find cloud layer to change improves the weather forecast accuracy.In addition, the fish eye lens of infrared band has vital role at aspects such as pipe detection, fire prevention supervision, public security, frontier defense warnings; And in national defence and military affairs, they occupy important and irreplaceable status especially, infrared thermal imaging fish eye lens in particular for medium wave and long wave infrared region, because it can realize obtaining of full airspace containment and the real-time information of full-time territory, meet especially modern war to the needs of technology for information acquisition, this is that other photoelectric detection means are beyond one's ability.In view of infrared fish-eye importance, the research that red wave band fish-eye lens is designed has important value.

Summary of the invention

The invention provides a kind of fish eye lens, can allow the people that interested prospect is produced powerful visual impact; And field depth can be from several centimetres to infinity.

Maximum effect of the present invention is that angular field of view is large, and the visual angle generally can reach 220 ° or 230 °, this be shooting at close range on a large scale Landscape Creation condition; Fish eye lens can cause very strong transparent effect when taking near object, emphasize the contrast that object is near big and far smaller, makes the picture of taking the photograph have a kind of stirring appeal; Fish eye lens has the quite long depth of field, is conducive to show the long Deep Canvas of photo.Fish-eye imaging has two kinds, and a kind of as other camera lenses, imaging is full of picture; Another kind is imaged as circle.No matter which kind of imaging, with the picture that fish eye lens is taken the photograph, distortion is quite severe, and it is strong that perspective converges sense.So it is often used as the special-effect camera lens, one stretches to fish-eye arm, can seem than one times of original length.The retrofocus type optical texture is adopted in design of the present invention, is positioned at the camera lens outside as square principal plane, has long reach.The focal power of camera lens the place ahead optical module is for negative, and the focal power of rear mirror group is for just.Off-axis ray passes through after the dispersing of front group of negative lens, so that the angle of itself and optical axis obviously diminishes, the aberration correction that is conducive to rear set of pieces, in addition, the decay of the illumination of optical system field of view edge illumination and field of view center, for large visual field optical system, edge-light illumination reduces can be very serious, adopts instead to take the photograph structure far away because of the large barrel distortion of group negative power generation before it, so that field angle of image reduces, can effectively slow down edge illumination and descend, illuminance of image plane is more even.

Description of drawings

Fig. 1 is system architecture schematic layout pattern of the present invention

Fig. 2 is that the present invention passes the letter schematic diagram

Fig. 3 is the curvature of field of the present invention and distortion schematic diagram

Embodiment

As shown in Figure 1, the present invention is by

germainium lens

1,2,3,4, protecting window 5, detector 6 forms, focal power by negative, negative, positive, just distribute.Lens 1, lens 2 are negative meniscus; With lens 3, lens 4 form instead far to be organized behind the positive light coke of object lens, distance is between two to three times of camera lens effective focal length after the control,

negative meniscus

1,2 is except being used for balance in addition the aberration of two lens, has the effect of prism deflection, make the people firing angle of edge field rays on the subsequent optical element less, so that the angle of deviation that each lens is shared is balanced, be beneficial to the correction that differs, aperture diaphragm is positioned on the front surface of lens 3, form approximate telecentric beam path in image space, eliminate the irradiance unevenness that off-axis image point chief ray causes greatly in the incident angle at image planes place etc.Wherein, lens 2, lens 4 front surfaces are aspheric surface, are used for better eliminating coma, the off-axis aberration such as astigmatism.

Fish eye lens system parameter of the present invention is: operating wavelength range 8um to 14um, 180 ° at full visual angle, effective focal length 6.05mm, full visual field image height 18mm, entrance pupil diameter 6mm, be that the F1 number reaches 1, optical length from lens 1 front surface S 1 to image planes is 70mm, operating distance from lens 4 to image planes reaches 14mm, the external diameter diameter of germainium lens is 46mm to the maximum, and the general assembly (TW) of four germainium lens is 100 grams, therefore, not only volume weight is little for it, and extremely is convenient to the installation of focus planardetector and optical filter.

Fig. 2 is fish eye lens of the present invention at the modulation transfer function curves at five even row's field angle places, its in length and breadth coordinate represent respectively mtf value and image planes place spatial frequency, as can be seen from Fig. 2, the picture element in camera lens 0.8 visual field is near diffraction-limited.

Fig. 3 provides the curvature of field and distortion figure, and systematical distortion is by linear change.

Claims

1. flake infrared lens is characterized in that it mainly is comprised of four germainium lens and protecting window and detector, focal power by negative, negative, positive, just distribute.

2. a kind of flake infrared lens according to claim 1 is further characterized in that lens 1, and lens 2 are negative meniscus; With lens 3, lens 4 form instead far to be organized behind the positive light coke of object lens, and control is rear apart between two to three times of camera lens effective focal length.

3. a kind of flake infrared lens according to claim 1 and 2 is characterized in that operating wavelength range 8um to 14um, 180 ° at full visual angle, effective focal length 6.05mm, full visual field image height 18mm, entrance pupil diameter 6mm.

4. according to claim 1,2,3 each described a kind of flake infrared lens, it is characterized in that field depth can be from several centimetres to infinity.