1、 Reference number ISO 14490-4:2005(E) ISO 2005INTERNATIONAL STANDARD ISO 14490-4 First edition 2005-11-01 Optics and optical instruments Test methods for telescopic systems Part 4: Test methods for astronomical telescopes Optique et instruments doptique Mthodes dessai pour systmes tlescopiques Parti
2、e 4: Mthodes dessai pour tlescopes astronomiques ISO 14490-4:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and install
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5、ase inform the Central Secretariat at the address given below. ISO 2005 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writin
6、g from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reservedISO 14490-4:
7、2005(E) ISO 2005 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member b
8、ody interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electro
9、technical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted
10、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 bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent r
11、ights. 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 photonics, Subcommittee SC 4, Telescopic systems. ISO 14490 consists of the following parts, under the general title Optics and optical instr
12、uments Test methods for telescopic systems: Part 1: Test methods for basic characteristics Part 2: Test methods for binocular systems Part 3: Test methods for telescopic sights Part 4: Test methods for astronomical telescopes Part 5: Test methods for transmittance Part 6: Test methods for veiling gl
13、are index Part 7: Test methods for limit of resolution The following part is under preparation: Part 8: Test methods for night-vision devices INTERNATIONAL STANDARD ISO 14490-4:2005(E) ISO 2005 All rights reserved 1 Optics and optical instruments Test methods for telescopic systems Part 4: Test meth
14、ods 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 documents are indispensable for the application of this document. F
15、or 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 its presentation ISO 14132-1:2002, Optics and optical instruments Voc
16、abulary 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 14490-1:2005, Optics and optical instruments Test methods for telescopi
17、c 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 telescopes Typical test methods are shown here, and other similar methods
18、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 telescopes or that of the main mirror of reflecting telescopes by mean
19、s 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 collimator on the eyepiece side, project the exit bundle of rays from the ob
20、jective onto a screen perpendicular to the optical axis and measure its diameter. ISO 14490-4:2005(E) 2 ISO 2005 All rights reservedc) Using a piece of ground glass let diffuse light be incident on the eyepiece side of the telescope or the finder telescope, and measure the minimum value of the apert
21、ure 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 objective and eyepiece shall be as given in 4.2.1 or 4.2.
22、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 collimator lens (item 3) on an optical bench (item 6). Place a reti
23、cle (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 collimator. Measure the focal length f in accordance with 4.2
24、.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). While adjusting the microscope (item 5) so that the reticle (i
25、tem 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 movement of the image. 4.2.1.2 Remove the alignment reticle (ite
26、m 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 clearly. Set the rear nodal plane of the lens under test to
27、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 the microscope on the optical bench. 4.2.1.3 The equivalen
28、t 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. ISO 14490-4:2005(E) ISO 2005 All rights reserved 3Key 1 light source 2 collimator reticle 3 collimator lens 4 alignment reticle 5 microscope with numerical aperture
29、 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 ISO 14490-4:2005(E) 4 ISO 2005 All rights reserved4.2.2 Focal l
30、ength of objective mirror (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
31、microscope with illuminator (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 t
32、he 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 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
33、 the objective mirror 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
34、b of the microscope 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 t
35、he readings of the positions of the microscope with illuminator in positions 4.2.2.2 and 4.2.2.3, (e.g. 0,5 a b ). ISO 14490-4:2005(E) ISO 2005 All rights reserved 5Key 1 rotary table 2 mirror under test 3 microscope having the numerical aperture 0,1 or higher, with illuminator 4 light source 5 reti
36、cle 6 optical bench C centre of curvature of the mirror under test Figure 2 Measurement of focal length of objective mirror ISO 14490-4:2005(E) 6 ISO 2005 All rights reserved4.3 Resolution The resolution shall be measured by the following method. 4.3.1 Resolution of main telescope For measurement of
37、 the resolution of the telescope, a well-designed eyepiece should be used by a 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
38、in the target should be in accordance with the Rayleigh criterion defined in ISO 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-de
39、signed eyepiece for measurement with an exit pupil diameter of 0,5 mm. A test target 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
40、 of the collimator objective for testing the main telescope and finder telescope 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 144
41、90-7 for the measuring method of the resolution for the finder. Values in seconds of arc d min= 0,002 mm ISO 14490-4:2005(E) ISO 2005 All rights reserved 7 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
42、 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 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 abou
43、t the test arrangement and/or procedure, if required and/or if different from those specified in this part of 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. ISO 14490-4:2005(E) 8 ISO 2005 All rights reservedBibliography 1 ISO 14490-7, Optics and optical instruments Test methods for telescopic systems Part 7: Test methods for limit of resolution ISO 14490-4:2005(E) ICS 37.020 Price based on 8 pages ISO 2005 All rights reserved
