Temat: image intensifier - Prolib Integro

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Tytuł:: Subjective measurement of resolution of image intensifier tubes
Autorzy:: Chrzanowski, Krzysztof
Tematy:: image intensifier
IIT
resolution
subjectivity; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/58970391.pdf Link otwiera się w nowym oknie
Opis:: Limiting resolution is traditionally defined as a spatial frequency of smallest resolvable element of a resolution target that can be distinguish by a human observer. This definition and measurement method have been criticized in a series of literature sources due to its subjectivity and low repeatability/accuracy. Such criticism looks reasonable as it is commonly known that results of measurement of resolution of the same tubes carried out by several test teams can differ significantly. This paper presents a detail analysis of classical subjective measurement method of limiting resolution of image intensifier tubes implemented by real test systems. The findings show that in spite of a common opinion, subjectivity of measurement is not the main reason for differences of test results carried out by different test teams. The main reasons are differences in performance of optics of test systems, use of resolution targets of different types and polarity, and inherent spatial non-uniformity of performance of image intensifier tubes. The paper also shows that due to spatial non-uniformity it is very difficult to design automatic test systems that could produce the same results as human observers using classical subjective measurement method.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Objective method of measuring resolution of image intensifier tubes
Autorzy:: Chrzanowski, Krzysztof
Stafiej, Bolesław
Tematy:: image intensifier
IIT
resolution measurement
subjective resolution
objective resolution; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/58973794.pdf Link otwiera się w nowym oknie
Opis:: Image intensifier tubes (IITs) are the most important modules of night vision devices used in huge numbers by military forces worldwide. Resolution is the most important parameter of IITs that presents information about ability of these devices to produce output images preserving information about details of the observed scenery. Despite its importance, it is still a common practice to measure resolution subjectively, by an observer looking at image of a resolution target created by a tested IIT. A series of attempts have been carried out to develop objective methods for accurate resolution measurement of IITs but with limited success. Accuracy of these methods varies depending on the tested IIT. This paper presents detailed analysis of proposed methods for objective resolution measurement. This analysis has shown that significant variability of accuracy of these methods is caused by one main drawback: the methods do not take into account influence of the spatial noise effect on human perception of image of the resolution target. Thus, an improved method taking into account spatial noise and its impact on target detection has been proposed. The method has been validated through experimental verification that shows accuracy improvements compared to other objective methods. This new approach improves accuracy of measurement of resolution of IITs to a level that can be accepted at professional test stations. In this way, this new method has potential to replace the standard subjective method to measure resolution of IITs and fix the biggest flaw of the standard test stations: measurement subjectivity.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: A method for measuring the quality parameters of image intensifier based on projecting phase-shifting gratings
Autorzy:: Sun, S.
Cao, Y.
Chen, C.
Fu, G.
Wang, Y.
Xu, X.
Tematy:: phase measurement
phase-shifting grating
distortion
image intensifier
imaging quality parameter; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/174300.pdf Link otwiera się w nowym oknie
Opis:: A method for measuring the quality parameters of image intensifier based on projecting phase-shifting gratings is proposed. A set of designed phase-shifting gratings are projected into the measuring system orderly to obtain the magnification parameter of the measured image intensifier, and the phase caused by the measured image intensifier. After obtaining the referential phase caused by only the magnification of the measured image intensifier, the phase caused by the distortion of the measured image intensifier is extracted by phase calculating and phase unwrapping. Both the global distortion and the partial distortion of the measured image intensifier can be measured by phase-to-distortion matching at the same time. The experimental results show that the proposed method can measure the multiple quality parameters of image intensifier effectively.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Simulation research of bionic image intensifier based on the retina structure of elephant-nose fish
Autorzy:: Zhang, Hongxia
Jin, Qingwen
Li, Peng
Jia, Dagong
Liu, Tiegen
Tematy:: geometric optical design
micro-optical device
image analysis
low-light night vision
bionic image intensifier; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/1835814.pdf Link otwiera się w nowym oknie
Opis:: Enhancing image brightness under low light conditions is crucial. The traditional night vision technology depends on the development of photoelectric materials and accurate image processing algorithms. Inspired by the structure of elephant-nose fish, we construct a bionic image intensifier (BII) model. The BII is a planar array based on the concentrating principle of the compound parabolic concentrator (CPC). This solution is based on pure optical design and independent. Through light tracing, the simulation results show that the brightness of the image is improved and good image uniformity is obtained. Quantitative analysis of the geometric concentration ratio (GCR) and the image uniformity is used to optimize CPC structure parameters. At the same time, we also discuss the influence of CPC structural parameters on image continuity, uniformity and geometric concentration ratio. The optimization results are as follows: the input port diameter is 50 μm, the output port diameter is 10 μm, the height is 90 μm, the GCR is 5.61, and the image uniformity is 95.30%. The comprehensive performance of the BII achieves the best.
Dostawca treści:: Biblioteka Nauki

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