ISO TR 14999-3-2005 Optics and photonics - Interferometric measurement of optical elements and optical systems - Part 3 Calibration and validation of interferom.pdf

1、 Reference number ISO/TR 14999-3:2005(E) ISO 2005TECHNICAL REPORT ISO/TR 14999-3 First edition 2005-03-01 Optics and photonics Interferometric measurement of optical elements and optical systems Part 3: Calibration and validation of interferometric test equipment and measurements Optique et photoniq

2、ue Mesurage interfromtrique de composants et systmes optiques Partie 3: talonnage et validation des quipements dessai interfromtrique ISO/TR 14999-3:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but

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7、org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reservedISO/TR 14999-3:2005(E) ISO 2005 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Terms and definitions. 1 3 Systematical investigation of test equipment, test set-up and test environment for source

8、s of errors. 2 3.1 General. 2 3.2 Sources of uncertainty . 2 3.3 Combination of uncertainties 3 4 Separation of errors into rotationally symmetric and non-rotationally symmetric terms. 4 4.1 General. 4 4.2 Principle . 4 4.3 Apparatus. 6 4.4 Procedure. 6 5 Measurement relying on the quality of a phys

9、ical reference surface . 6 5.1 Planes. 6 5.2 Spheres 9 5.3 Aspheres 12 5.4 Homogeneity testing. 24 5.5 Optical systems in transmission. 25 6 Optical test procedures for achieving absolute calibration . 28 6.1 General. 28 6.2 Flats 29 6.3 Spherical surfaces 35 6.4 Cylindrical surfaces 41 6.5 Windows

10、in transmission. 42 Bibliography . 44 ISO/TR 14999-3:2005(E) iv ISO 2005 All rights reservedForeword 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

11、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, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO

12、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 Directives, Part 2. The main task of technical committees is to prepare Internationa

13、l 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 bodies casting a vote. In exceptional circumstances, when a technical committee has

14、 collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does

15、not have to be reviewed until the data it provides are considered to be no longer valid or useful. 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. IS

16、O/TR 14999-3 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 1, Fundamental standards. ISO 14999 consists of the following parts, under the general title Optics and photonics Interferometric measurement of optical elements and optical systems: Part 1: Terms, def

17、initions and fundamental relationships (Technical Report) Part 2: Measurement and evaluation techniques (Technical Report) Part 3: Calibration and validation of interferometric test equipment and measurements (Technical Report) Part 4: Interpretation and evaluation of tolerances specified in ISO 101

18、10 ISO/TR 14999-3:2005(E) ISO 2005 All rights reserved vIntroduction A series of International Standards on Indications in technical drawings for the representation of optical elements and optical systems has been prepared by ISO/TC 172/SC 1, and published as ISO 10110 under the title Optics and pho

19、tonics Preparation of drawings for optical elements and systems. When drafting this standards series and especially its Part 5, Surface form tolerances, and Part 14, Wavefront deformation tolerances, it became evident to the experts involved that additional complementary documentation is required to

20、 describe how the necessary information on the conformance of the fabricated parts with the stated tolerances can be demonstrated. Therefore, the responsible ISO Committee ISO/TC 172/SC 1 decided to prepare an ISO Technical Report on Interferometric measurement of optical wavefronts and surface form

21、 of optical elements. When discussing the topics which had to be included or excluded into such a Technical Report, it was envisaged that it might be the first time, where an ISO Technical Report or Standard is prepared which deals with wave-optics, i.e. that is based more in the field of physical o

22、ptics than in the field of geometrical optics. As a consequence only fewer references than usual were available, which made the task more difficult. Envisaging the situation, that the topic of interferometry has so far been left blank in ISO, it was the natural wish to now be as comprehensive as pos

23、sible. Therefore there was discussion, whether important techniques such as interference microscopy (for characterizing the micro-roughness of optical parts), shearing interferometry (e.g. for characterizing corrected optical systems), multiple-beam interferometry, coherence sensing techniques or ph

24、ase conjugation techniques should be included or not. Other techniques, which are related to the classical two-beam interferometry, like holographic interferometry, Moir techniques and profilometry were also mentioned as well as Fourier transform spectroscopy or the polarization techniques, which ar

25、e mainly for microscopic interferometry. In order to complement ISO 10110, the guideline adopted was to include what nowadays are common techniques used for the purpose of characterizing the quality of optical parts. Decision was made to complete a first Technical Report, and to then update it by su

26、pplementing new parts, as required. It is very likely that more material will be added in the near future as more stringent tolerances (two orders of magnitude) for optical parts and optical systems become mandatory, when dealing with optics for the EUV range (wavelength range 6 nm to 13 nm) for mic

27、rolithography. Also, testing optics with EUV radiation (the same wavelength as they are later used, e.g. at-wavelength testing) can be a new challenge, and is not covered by any current standards. This part of ISO 14999 should cover the need for qualifying optical parts and complete systems regardin

28、g the wavefront error produced by them. Such errors have a distribution over the spatial frequency scale; in this part of ISO 14999 only the low- and mid-frequency parts of this error-spectrum are covered, not the very high end of the spectrum. These high-frequency errors can be measured only by mic

29、roscopy, measurement of the scattered light or by non-optical probing of the surface. A similar statement can be made regarding the wavelength range of the radiation used for testing. ISO 14999 considers test methods with visible light as the typical case. In some cases, infrared radiation from CO 2

30、 -lasers in the range of 10,6 m is used for testing rough surfaces after grinding or ultraviolet radiation from excimer- lasers in the range of 193 nm or 248 nm is used for at-wavelength testing of microlithography optics. However, these are still rare cases, which are included in standards, that wi

31、ll not be dealt with in detail. The wavelength range outside these borders is not covered. TECHNICAL REPORT ISO/TR 14999-3:2005(E) ISO 2005 All rights reserved 1Optics and photonics Interferometric measurement of optical elements and optical systems Part 3: Calibration and validation of interferomet

32、ric test equipment and measurements 1 Scope This part of ISO 14999 discusses sources of error and the separation of errors into symmetric and non-symmetric parts. It also describes the reliance of measurements on the quality of a physical reference surface and the development of test procedures capa

33、ble of achieving absolute calibration. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 perfect shape mathematically represented figure of the optical surface 2.2 surface error deviation from the perfect shape of the surface under test, includ

34、ing the influence of gravity and support 2.3 wavefront error error of the interferometric wavefront corresponding to the surface error 2.4 absolute test method, which gives the wavefront error of the test piece with respect to a perfect shape, not to a bodily reference 2.5 quasi-absolute test method

35、 which gives the wavefront error, limited to special error types, of the test piece with respect to a perfect shape, not a bodily reference ISO/TR 14999-3:2005(E) 2 ISO 2005 All rights reserved3 Systematical investigation of test equipment, test set-up and test environment for sources of errors 3.1

36、 General The objective of a measurement is to determine the value of the measurand, that is the specific quantity subject to measurement. In the general context of testing and calibration laboratories, the measurand may cover many different quantities, but in the context of this Technical Report it

37、is an optical parameter, such as wavefront shape, associated with optical elements or optical systems. A measurement begins with an appropriate specification of the measurand, the generic method of measurement and the specific detailed measurement procedure. No measurement is perfect and the imperfe

38、ctions give rise to error of measurement in the result. Consequently, the result of a measurement can only be an approximation to the value of the measurand and it is only complete when accompanied by a statement of the uncertainty of that approximation. Because of measurement uncertainty the true v

39、alue can never be known. Uncertainty of measurement comprises many components. Some may be evaluated from the statistical distribution of the results of a series of measurements and can be characterized by experimental standard deviations. The other components are based on experience or other inform

40、ation and are evaluated from assumed probability distributions. They are also characterized by (equivalent) standard deviations. Random errors arise from random variations of the observations, due to random effects from various sources affecting measurements taken under nominally the same conditions

41、 These produce a scatter around the mean value of a series of measurements. They cannot be eliminated but the uncertainty due to their effect can be reduced by increasing the number of observations and applying statistical analysis. Systematic errors arise from systematic effects, that is an effect

42、 on the measurement result arising from a quantity that is not included in the measurement specification of the measurand but influences the result. These remain unchanged when the measurement is repeated under the same conditions. Examples might be drifts during measurements or since the last calib

43、ration of a measuring instrument, zero errors in scales, errors in assumed expansion coefficients, etc. Their effect is to introduce a displacement, or bias, between the value of the measurand and the experimentally determined mean value. They cannot be eliminated but may be reduced by making correc

44、tions for the known extent of an error due to a recognized systematic effect. The total uncertainty of measurement is a combination of all identified component uncertainties. Careful consideration of each measurement involved in the test or calibration is required to identify and list all the factor

45、s that contribute to the overall uncertainty. This is a very important step that requires a good understanding of the measurement equipment, the process of the test or calibration and the influence of the environment. Having identified the component uncertainties, the next step is to quantify them b

46、y appropriate means. An initial approximate quantification can be valuable in identifying components that are negligible, less than one fifth the largest component, and not worthy of more rigorous evaluation. Uncertainties from random sources, classified as Type A, may be quantified by calculation o

47、f the standard deviation of repeated measurements. Uncertainties from systematic sources, classified as Type B, require an exercise of judgement by the metrologist, using all relevant information on their possible variability, to evaluate effective standard deviations. Subsequent calculations are ma

48、de simpler if, wherever possible, all components are expressed in the same way, e.g. as a proportion, or in the same units as used for the reported result. 3.2 Sources of uncertainty There are many possible sources of uncertainty, which will depend on the technical discipline involved. However, the

49、following general points will apply to many areas of optical testing and calibration: incomplete definition of the test; the requirement may not be clearly described in sufficient detail; ISO/TR 14999-3:2005(E) ISO 2005 All rights reserved 3 imperfect realization of the test procedure; even when the test conditions are clearly defined, it may not be possible to produce the theoretical conditions in practice due to imperfections in the systems used; personal bias in the reading of analogue instruments and scales; inst