scholarly journals Active athermalization of dual-infrared zoom lenses

2020 ◽  
Vol 44 (6) ◽  
pp. 931-936
Author(s):  
G.I. Greisukh ◽  
I.A. Levin ◽  
S.V. Kazin
Keyword(s):  
Thermal Imaging ◽  
Entire Range ◽  
Optical Axis ◽  
Focal Length ◽  
Dual Band ◽  
Length Variation ◽  
Simple Design ◽  
Optical Components ◽  
Long Wavelength ◽  
Single Lens

For medium- and long-wavelength dual-band infrared refractive and refractive-diffractive thermal imaging zoom lenses of simple design, we show that it is possible to maintain superb and practically unchanged optical characteristics across the temperature range from –40 to +40°C in the entire range of focal length variation. Athermalization for any focal length is achieved by moving one double-lens component or a single lens along the optical axis of the lens. Considering that these optical components are not involved in the zooming process, it becomes possible to both compensate for thermal defocusing and focus the lens on the object of interest using the same focusing mechanism, while maintaining the size and tightness of the optical system.

On the construction and use of single achromatic eye-pieces, and their superiority to the double eye-piece of Huyghens

1843 ◽  
Vol 4 ◽  
pp. 194-195 ◽  
Keyword(s):  
Entire Range ◽  
Single Lens

The author observes, that experience has shown it to be impracticable to make a telescope even approach to achromatism, by employing the same object-glass with an astronomical, as with a terrestrial eye-piece: for if the focus of the blue rays from the object-glass be thrown forwards, as it must be in order to make it impinge upon the focus of the blue rays of the terrestrial eye-glass, then there will be produced a great over-covrection for the astronomical eye-glass; and vice versa . Hence it appears that the application of Huyghenian eye-pieces to refracting telescopes, is incompatible with the conditions of achromatism, throughout the entire range of magnifying power; and that in reflecting telescopes they unavoidably introduce dispersion, because they are not in themselves achromatic. These defects the author proposes wholly to obviate, by substituting for the Huyghenian eye-pieces, single achromatic lenses of corresponding magnifying power; consisting of the well-known combination of the crown-lens, and its correcting flint-lens, having their adjacent surfaces cemented together; thus avoiding internal reflections, and enabling them to act as a single lens. The achromatic eye-pieces which he uses were made by Messrs. Tulley and Ross, and are of the description usually termed single cemented triples .

scholarly journals DoF-Dependent and Equal-Partition Based Lens Distortion Modeling and Calibration Method for Close-Range Photogrammetry

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5934
Author(s):  
Xiao Li ◽  
Wei Li ◽  
Xin’an Yuan ◽  
Xiaokang Yin ◽  
Xin Ma
Keyword(s):  
Optical Axis ◽  
Focal Length ◽  
Calibration Method ◽  
Depth Of Field ◽  
Model Parameters ◽  
Lens Distortion ◽  
Camera Model ◽  
Distortion Model ◽  
Manual Adjustment ◽  
Close Range

Lens distortion is closely related to the spatial position of depth of field (DoF), especially in close-range photography. The accurate characterization and precise calibration of DoF-dependent distortion are very important to improve the accuracy of close-range vision measurements. In this paper, to meet the need of short-distance and small-focal-length photography, a DoF-dependent and equal-partition based lens distortion modeling and calibration method is proposed. Firstly, considering the direction along the optical axis, a DoF-dependent yet focusing-state-independent distortion model is proposed. By this method, manual adjustment of the focus and zoom rings is avoided, thus eliminating human errors. Secondly, considering the direction perpendicular to the optical axis, to solve the problem of insufficient distortion representations caused by using only one set of coefficients, a 2D-to-3D equal-increment partitioning method for lens distortion is proposed. Accurate characterization of DoF-dependent distortion is thus realized by fusing the distortion partitioning method and the DoF distortion model. Lastly, a calibration control field is designed. After extracting line segments within a partition, the de-coupling calibration of distortion parameters and other camera model parameters is realized. Experiment results shows that the maximum/average projection and angular reconstruction errors of equal-increment partition based DoF distortion model are 0.11 pixels/0.05 pixels and 0.013°/0.011°, respectively. This demonstrates the validity of the lens distortion model and calibration method proposed in this paper.

DESIGN AND PERFORMANCE OF TRISH, A BINOCULAR ROBOT HEAD WITH TORSIONAL EYE MOVEMENTS

1993 ◽  
Vol 07 (01) ◽  
pp. 51-68 ◽  
Author(s):  
EVANGELOS MILIOS ◽  
MICHAEL JENKIN ◽  
JOHN TSOTSOS
Keyword(s):  
Optical Axis ◽  
Automatic Gain Control ◽  
Focal Length ◽  
Vertical Component ◽  
Gain Control ◽  
Vertical Axis ◽  
Stereo Pair ◽  
Robot Head ◽  
And Performance ◽  
Stereo Processing

We present the design of a controllable stereo vision head. TRISH (The Toronto IRIS Stereo Head) is a binocular camera mount, consisting of two fixed focal length color cameras with automatic gain control forming a verging stereo pair. TRISH is capable of version (rotation of the eyes about the vertical axis so as to maintain a constant disparity), vergence (rotation of each eye about the vertical axis so as to change the disparity), pan (rotation of the entire head about the vertical axis), and tilt (rotation of each eye about the horizontal axis). One novel characteristic of the design is that each camera can rotate about its own optical axis (torsion). Torsional movement makes it possible to minimize the vertical component of the two-dimensional search which is associated with stereo processing in verging stereo systems.

scholarly journals JUSTIFICATION OF REQUIREMENTS FOR INFRARED RANGE LENSES STATIONED AT AIRCRAFT

2020 ◽  
Vol 6 (1) ◽  
pp. 173-180
Author(s):  
Julia S. Kiseleva ◽  
Tatiana N. Khatsevich
Keyword(s):  
Thermal Imaging ◽  
Infrared Range ◽  
Single Lens ◽  
Infrared Materials

The article discusses the requirements for the lens of thermal imaging devices, and formulates special requirements for their placement on aircraft. Thermooptic aberrations of a single lens made of various infrared materials are analyzed. The values of the thermooptic constant for some materials are given. A condition for eliminating thermal refocusing for a single lens is given.

scholarly journals Improved detector performance rendering in the optical spectral ranges to provide accurate image.

2019 ◽  
Vol 29 (4) ◽  
pp. 106
Author(s):  
Basaad Hadi Hamza
Keyword(s):  
Thermal Imaging ◽  
Imaging System ◽  
Imaging Systems ◽  
Sensor Systems ◽  
Thermal Detector ◽  
Detector Performance ◽  
Long Wavelength ◽  
Ir Imaging ◽  
Thermal Imaging System ◽  
Spectral Ranges

Modern sensor systems have complex sensor assemblies with performance depending on variety of factors. An algorithm presented in this work to provide accurate image rendering in the optical spectral ranges of IR imaging systems. From the images output notice that in long wavelength bandwidth of IR (8-12) µm the image was more clarity without noise. This mean S/N ratio and the Efficiency of detector is bigger than band (1-3) µm. Recommend that this method can be used to improve the performance of the thermal detector which uses in thermal imaging system in any package of wavelength. This algorithm can be store as a code in the cart storage of IR imaging system.

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