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Testing surveillance thermal imagers under simulated real work conditions

Chrzanowski Krzysztof

Opto-Electronics Review

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2023

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Vol. 31, No. 1

art. no. e145327

EN

Thermal imagers often work in extreme conditions but are typically tested under laboratory conditions. This paper presents the concept, design rules, experimental verification, and example applications of a new system able to carry out measurements of performance parameters of thermal imagers working under precisely simulated real working conditions. High accuracy of simulation has been achieved by enabling regulation of two critical parameters that define working conditions of thermal imagers: imager ambient temperature and background temperature of target of interest. The use of the new test system in the evaluation process of surveillance thermal imagers can bring about a revolution in thermal imaging metrology by allowing thermal imagers to be evaluated under simulated, real working conditions.

2

Measurement of sensitivity of solar blind UV cameras to solar light

Chrzanowski Krzysztof, Stafiej B.

Opto-Electronics Review

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2021

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Vol. 29, No. 2

45--58

EN

Solar blind UV cameras are not theoretically supposed to be sensitive to solar light. However, there is practically always some sensitivity to solar light. This limited solar sensitivity can sometimes make it impossible to detect the weak emission of a corona target located on the solar background. Therefore, solar sensitivity is one of the crucial performance parameters of solar blind UV cameras. However, despite its importance, the problem of determining solar sensitivity of solar blind UV cameras has not been analysed and solved in the specialized literature, so far. This paper presents the concept (definition, measurement method, test equipment, interpretation of results) of measuring solar sensitivity of solar blind UV cameras.

3

Measurement of eyepiece diopter of direct view imagers

Chrzanowski Krzysztof

Opto-Electronics Review

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2020

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Vol. 28, No. 4

213--219

EN

This paper presents a detailed review on a present confused situation related to defining and measurement of the eyepiece diopter range of optical/electro-optical devices to be used for a direct observation by human observers. On the basis of this review three precise definitions of a direct view imagers eyepiece diopter are presented. One of these definitions is determined as optimal fit to describe the perception of human observers. Further on, design and measurement uncertainties of diopter meters are discussed and rules of accurate measurements are formulated. Finally, recommendations for the maximum acceptable errors of the diopter scale of eyepieces of classic types of direct view imagers are presented, as well.

4

Virtual MRTD – an indirect method to measure MRTD of thermal imagers using computer simulation

Chrzanowski Krzysztof, Hong Viet Nguyen

Optica Applicata

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2020

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Vol. 50, nr 4

671--688

EN

Minimum resolvable temperature difference (MRTD) is considered as the most important parameter of thermal imagers. A new method of MRTD measurement without drawbacks of other methods is presented in this paper. Proposed MRTD measurement method coded as virtual MRTD is based on a three steps measurement concept using semi-automatic objective measurements and computer simulation. First, objective parameters of the tested thermal imager are measured. Second, software simulates this tested thermal imager and generates the image of 4-bar target of specified spatial frequency (size) and contrast (temperature difference). Third, a human observer analyses the images of the 4-bar target generated by the software on the screen of PC set and measures MRTD of the simulated thermal imager at specified set of spatial frequencies. The proposed method offers higher measurement speed, lower cost and typically better accuracy in comparison with the typical MRTD measurement method.