1、BRITISH STANDARD BS ISO 14490-4:2005 Optics and optical instruments Test methods for telescopic systems Part 4: Test methods for astronomical telescopes ICS 37.020 BS ISO 14490-4:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 12 January
2、 2006 BSI 12 January 2006 ISBN 0 580 47136 5 National foreword This British Standard reproduces verbatim ISO 14490-4:2005 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee CPW/172, Optics and optical instruments, which has the
3、 responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. A
4、 list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Corre
5、spondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not
6、of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii and iii, a blank page, pages 1 to 8, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when
7、 the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 14490-4:2005(E)INTERNATIONAL STANDARD ISO 14490-4 First edition 2005-11-01 Optics and optical instruments Test methods for telescopic systems Part 4: Test methods for astronomical telescope
8、s Optique et instruments doptique Mthodes dessai pour systmes tlescopiques Partie 4: Mthodes dessai pour tlescopes astronomiques BS ISO 14490-4:2005ii BS ISO 14490-4:2005 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
9、 member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, gover
10、nmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC D
11、irectives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member
12、bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 14490-4 was prepared by Technical Committee ISO/TC 172, Optics and photoni
13、cs, Subcommittee SC 4, Telescopic systems. ISO 14490 consists of the following parts, under the general title Optics and optical instruments Test methods for telescopic systems: Part 1: Test methods for basic characteristics Part 2: Test methods for binocular systems Part 3: Test methods for telesco
14、pic sights Part 4: Test methods for astronomical telescopes Part 5: Test methods for transmittance Part 6: Test methods for veiling glare index Part 7: Test methods for limit of resolution The following part is under preparation: Part 8: Test methods for night-vision devices blank1 Optics and optica
15、l instruments Test methods for telescopic systems Part 4: Test methods for astronomical telescopes 1 Scope This part of ISO 14490 is applicable to amateur astronomical telescopes. For general optical test methods of telescopic systems see ISO 14490-1. 2 Normative references The following referenced
16、documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 8596, Ophthalmic optics Visual acuity testing Standard optotype and it
17、s presentation ISO 14132-1:2002, Optics and optical instruments Vocabulary for telescopic systems Part 1: General terms and alphabetical indexes of terms in ISO 14132 ISO 14132-4:2002, Optics and optical instruments Vocabulary for telescopic systems Part 4: Terms for astronomical telescopes ISO 1449
18、0-1:2005, Optics and optical instruments Test methods for telescopic systems Part 1: Test methods for basic characteristics 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 14132-1 and ISO 14132-4 apply. 4 Optical test methods for astronomical telesco
19、pes Typical test methods are shown here, and other similar methods are acceptable. 4.1 Clear aperture of objective The clear aperture of the objective shall be measured by one of the following methods. a) Measure the unobstructed diameter of the objective lens of refracting telescopes and finder tel
20、escopes or that of the main mirror of reflecting telescopes by means of an appropriate linear measuring instrument. b) Set the focus of the optical system of the telescope or finder telescope to infinity using a dioptric tester. Set a bundle of parallel rays at zero incidence angle using a collimato
21、r on the eyepiece side, project the exit bundle of rays from the objective onto a screen perpendicular to the optical axis and measure its diameter. BS ISO 14490-4:2005BS ISO 14490-4:2005 2 c) Using a piece of ground glass let diffuse light be incident on the eyepiece side of the telescope or the fi
22、nder telescope, and measure the minimum value of the aperture of the objective by using a travelling microscope parallel to the optical axis in object space, which can be moved across the diameter of the objective. 4.2 Focal lengths of objective and eyepiece The test methods for the focal lengths of
23、 objective and eyepiece shall be as given in 4.2.1 or 4.2.2. 4.2.1 Focal length of objective lens and eyepiece (nodal slide method) Refer to Figure 1. Arrange the rotary table (item 8 in Figure 1) (nodal slide stand), so that the axis of rotation is perpendicular to the optical axis of the collimato
24、r lens (item 3) on an optical bench (item 6). Place a reticle (item 2) at the focal plane of the collimator. On the rotary table, a slide stand (item 7) is moving in the direction of the optical axis of the microscope (item 5), which has its optical axis approximately coinciding with that of the col
25、limator. Measure the focal length f in accordance with 4.2.1.1 to 4.2.1.3. 4.2.1.1 Install the alignment reticle (item 4 in Figure 1) on the slide stand (item 7) so that the alignment reticle (item 4) coincides with the axis of the rotation of the rotary table (item 8), as shown in Figure 1 a). Whil
26、e adjusting the microscope (item 5) so that the reticle (item 4) can be seen clearly, read out the position of the microscope on the optical bench (item 6) and stop when the position of the reticle (item 4) is such that, when it is slightly rotated about its vertical axis, there is no lateral moveme
27、nt of the image. 4.2.1.2 Remove the alignment reticle (item 4) and mount the objective lens (item 9) under test on the slide stand (item 7) in front of the collimator. Adjust the microscope (item 5) until the sharp image of the collimator reticle (item 2) formed by the lens under test can be seen cl
28、early. Set the rear nodal plane of the lens under test to coincide with the axis of rotation of the rotary table (item 8), as shown in Figure 1 b), i.e. when the rotary table is slightly rotated about its vertical axis, the image of the collimator reticle is stationary. Read out the new position of
29、the microscope on the optical bench. 4.2.1.3 The equivalent focal length f of the objective lens to be measured is the difference between the positions of the microscope in 4.2.1.1 and 4.2.1.2. 3Key 1 light source 2 collimator reticle 3 collimator lens 4 alignment reticle 5 microscope with numerical
30、 aperture 0,1 or higher 6 optical bench 7 slide stand 8 rotary table 9 objective lens or eyepiece under test 10 green filter (max. transmittance about 0,55 m) f focal length Figure 1 Measurement of the focal lengths of objective lens or eyepiece BS ISO 14490-4:20054 4.2.2 Focal length of objective m
31、irror (method using a microscope with illuminator) The test method described below does not apply to objective mirrors with central obscuration. Let the axis of rotation of the rotary table be perpendicular to the optical axis and lie in the same plane as the optical axis of the microscope with illu
32、minator (item 3) as shown in Figure 2, and measure in accordance with the following procedures. The rotating mechanism of the rotary table shall be used for alignment of the optical axis of the objective mirror (item 2) under test with that of a microscope with illuminator. Let the axis of rotation
33、of the rotary table be perpendicular to the optical axis and lie in the same plane as the optical axis of the microscope with illuminator and place the reticle (item 5) in the object plane of the microscope, parallel to the axis of rotation. 4.2.2.1 As shown in Figure 2 a), mount the objective mirro
34、r to be measured on the rotary table in front of the microscope with illuminator. 4.2.2.2 Move the microscope with illuminator to the position where the image of the reticle can be seen clearly and read out its position a on the optical bench. 4.2.2.3 Next, read out the position b of the microscope
35、with illuminator on the optical bench, where the image of the reticle, which has been reflected at the centre of the objective mirror, can be seen clearly, as in Figure 2 b). 4.2.2.4 The focal length of the objective mirror to be measured is equal to half the difference between the readings of the p
36、ositions of the microscope with illuminator in positions 4.2.2.2 and 4.2.2.3, (e.g. 0,5 a b ). BS ISO 14490-4:20055Key 1 rotary table 2 mirror under test 3 microscope having the numerical aperture 0,1 or higher, with illuminator 4 light source 5 reticle 6 optical bench C centre of curvature of the m
37、irror under test Figure 2 Measurement of focal length of objective mirror BS ISO 14490-4:20056 4.3 Resolution The resolution shall be measured by the following method. 4.3.1 Resolution of main telescope For measurement of the resolution of the telescope, a well-designed eyepiece should be used by a
38、person with good eyesight (compensated visual acuity of 1,0 or over, measured in accordance with ISO 8596). A test target with two pinholes should be observed through a collimator. The separation between the two pinholes in the target should be in accordance with the Rayleigh criterion defined in IS
39、O 14132-4, taking into account the focal length of the collimator and of the instrument under test. The resolution is determined when the images of the two pinholes are observed as just resolved. Use an excellent, well-designed eyepiece for measurement with an exit pupil diameter of 0,5 mm. A test t
40、arget of double pinholes shall be as shown in Figure 3. In order to maintain accuracy, the diameter d of the test pinholes relative to their separation s should be small, d u 0,5 s. It is recommended that the focal length of the collimator objective for testing the main telescope and finder telescop
41、e be greater than 2 000 mm. It is recommended to measure and state the usable image plane diameter of the objective alone to where the resolution drops twice to axial. 4.3.2 Resolution of finder telescope Refer to ISO 14490-7 for the measuring method of the resolution for the finder. Values in secon
42、ds of arc d min= 0,002 mm BS ISO 14490-4:20057 Pinhole separations of test target (collimator focal length: 2 500 mm) Seconds of arc s mm 0,4 0,005 0,5 0,006 0,7 0,008 1,0 0,012 1,5 0,018 2,0 0,024 2,5 0,030 3,0 0,036 3,5 0,042 Figure 3 Test target and example of resolution test of main telescope 5
43、Test report A test report shall be presented including the test results and the following information: a) test method; b) date of test; c) identification of the test specimen; d) details about the test arrangement and/or procedure, if required and/or if different from those specified in this part of
44、 ISO 14490; e) reference to this part of ISO 14490, i.e. ISO 14490-4:2005; f) name of the test laboratory; g) name of the examiner. BS ISO 14490-4:20058 Bibliography 1 ISO 14490-7, Optics and optical instruments Test methods for telescopic systems Part 7: Test methods for limit of resolution BS ISO
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