ISSN:0030-3909    

DOI:10.1080/713819047

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

MTF measurements have recently been carried out in a number of European laboratories on a typical wide-angle photographic lens. While showing smaller differences than those occurring in earlier intercomparisons, the results still exhibited a greater variation than is desirable if the MTF is to be adopted universally in the specification and assessment of lens performance. However, a detailed analysis of the results has indicated probable reasons for many of the differences, and when corrected in accordance with the results of this analysis the spread of MTF values has been greatly reduced, never exceeding ± 0·07 and usually amounting to less than ± 0·03. These residual differences are almost certainly smaller than anything which could be detected as a difference of picture quality.

ISSN:0030-3909    

DOI:10.1080/713819048

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819042

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The Effective Instantaneous Field of View (EIFOV) is a new specification for defining system performance that takes into account the system MTF and provides a convenient way to specify and compare the performance of imaging and radiometric systems. The use of EIFOV is illustrated by two examples of first-order designs, each using ƒ/3·5 optics having a diffraction-limited MTF over the spatial frequency range of interest. The systems are to detect reflectance differences of 0·01 with an EIFOV of 30 m in a wavelength interval of 600 to 700 nm from an altitude of 1000 km. One system uses a solid-state array having a noise equivalent signal of 1·0 μJ/m2and elements 15 by 15 μm in size; the other uses aerial film with a diffuse RMS granularity of 0·008. These examples serve to point out the basic differences between electro-optical and photographic systems for imaging through the atmosphere. Assuming they are of the same size, an electro-optical system is preferred when radio-metric measurements of the imagery are needed and a photographic system is preferred when the imagery is to be examined visually.

ISSN:0030-3909    

DOI:10.1080/713819041

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Since it is generally known for which image receptor optical systems are used and what sort of objects will be imaged, a system of optical transfer functions guaranteeing optimum image formation can always be given. Starting from this situation, the paper studies problems when lenses should be corrected automatically with the aid of a system of OTF's or other OTF-based criteria. Summarizing the work of Hopkins and King, the usefulness for practical application is discussed. The cost of computation has been the most important restriction preventing a widespread use of well-known techniques, but with the development of cheaper and quicker computers there is no reason for not designing optical systems of desired quality for the envisaged application. It is emphasized that the final average OTF value which is used as a criterion for optimizing the design can also be used to specify the image quality by a number and can be compared by measuring the real OTF values with the optical system produced later on according to the best constructional data found.

ISSN:0030-3909    

DOI:10.1080/713819040

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

X-ray image intensifiers are applied where low dose X-ray images have to be observed. The modulation transfer function, the veiling glare figure and the noise power factor are important characteristics of the performance of X-ray image intensifiers. The relationship between noise and sharpness can fruitfully be used to measure the sharpness in terms of the spatial noise equivalent bandwidth. Methods are described for measuring MTF, spatial bandwidth, veiling glare and noise power factor of X-ray image intensifiers. Suggestions are made for the use of these imaging characteristics in the development of X-ray image intensifiers and X-ray image intensifying systems.

ISSN:0030-3909    

DOI:10.1080/713819045

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819039

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Instruments are described for measuring the MTF, line-spread function and axial transmission factor of optical systems at wavelengths in the range 2 to 14 μm. Assessment of the homogeneity of infra-red transmitting materials and of the veiling glare of thermal imaging systems is briefly discussed.

ISSN:0030-3909    

DOI:10.1080/713819049

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The ACOFAM combines an optical method of frequency analysis with electronic data unit and display to obtain a fast and accurate measurement of the Modulation Transfer Function of lenses and complete systems in the visible range. Some extra devices are described in order to convert the standard ACOFAM to the infra-red spectral range (5–20 μm). Results of measurements on a 50 mmF/1 developed by the Optical Division of Engins MATRA are shown.

ISSN:0030-3909    

DOI:10.1080/01629779100000441

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713819043

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor