ISO 9642-2020 pdf free

04-20-2021 comment

ISO 9642-2020 pdf free.Optics and photonics — Opticaltransfer function — Application.
This document specifies a method of testing telescopes in terms of imaging states aimed at makingvalid optical transfer function (OTF) measurements.
This document includes two annexes (Annex A and B) that provide information on the more recenttechniques for measuring optical transfer function and methods of deriving image quality criteria fromsuch measurements.
For the purposes of this document, the terms and definitions given in IS0 9334 and ISO 14132-1 apply.
The specimens considered are telescopic observational instruments with direct view used for viewingremote objects and include many instruments such as telescopes,binoculars,telescopic sights orspotting scopes.
ldeally, instruments would be best with no astigmatism and no field curvature coupled with goodchromatic correction but frequently compromises as mentioned above shall be tolerated.
Many optical systems include roof prisms to give a compact instrument. However, the image producedby such systems is basically made up of two superimposed images and the accuracy with which theymatch will depend on the accuracy with which the roof edge has been constructed. In such cases theorientation of the roof edge shall be noted (see 5.5).ln use, the eye is coherently coupled to the telescope, so it may be contended that the only valid testwould be one that included the eye: reference is made to the case of cascaded optical systems in theintroduction to ISO 9334.However, in observer tests using telescopes, improved performance has beenobtained with instruments with better measured OTF performance in a variety of tests,includingcontrast sensitivity using sinusoidal grating targets, which confirms the value of OTF tests.OTF tests also enable performance to be compared with that computed by the telescope designer andprovide effective quality assurance tests of production specimens.
When considering the details of tests, some features of the eye need to be borne in mind, especially itsability to accommodate for varying object distances and to adjust the working aperture, varying theiris size, according to the ambient illumination.Thus firstly, unlike the photographic lens testing case,refocusing for off-axis tests is necessary. Secondly, the working aperture of the telescope, i.e.the exitpupil diameter, will need to match the receiving eye pupil, which generally has a range of 7 mm downto 2 mm diameter for different ambient illumination levels.The size of the evaluation pupil for the MTFmeasurement (receiving pupil in the test setup) is specified in the corresponding imaging state tables.ISO 9642 pdf download.

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