Regular Spectral Transmittance Service

1 Page 1 NIST Measurement Services: Regular Spectral Transmittance NIST Special Publication 250-69 David W. Allen, Edward A. Early, Benjamin K. Tsai, and Catherine C. Cooksey U.S. Department of Commerce Technology Administration... Open at page → 2 Page 2 NIST Special Publication 250-69 NIST MEASUREMENT SERVICES : Regular Spectral Transmittance David W. Allen, Edward A. Early, Benjamin K. Tsai, and Catherine C. Cooksey Optical Technology Division Physical Measurement Labo... Open at page → 3 Page 3 National Institute of Standards and Technology Special Publication 250-69 Nat. Inst. Stand. Technol. Spec. Publ. 250-69, 60 Pages, (March 2011) CODEN: NSPUE2 NIST PRINTING AND DUPLICATING OFFICE GAITHERSBURG, MD: 2011 Open at page → 4 Page 4 1 PREFACE The calibration and related measurement services of the National Institute of Standards and Technology are intended to assist the makers and users of precision measuring instruments in achieving the highest pos... Open at page → 5 Page 5 2 ABSTRACT This document describes measurement services, instrumentation, and techniques for regular spectral transmittance over the spectral range from 250 nm to 2500 nm at the National Institute of Standards and Techno... Open at page → 6 Page 6 3 TABLE OF CONTENTS Abstract ............................................................................................................................................2 1. Introduction .................................... Open at page → 7 Page 7 4 LIST OF FIGURES Figure 1. Schematic of the RTS .......................................................................................................9 Figure 2. Slit-scattering function measured with emission line lam... Open at page → 8 Page 8 5 LIST OF TABLES Table 1. Optical detector choices based on wavelength ................................................................11 Table 2. Geometrical specifications of the RTS ...................................... Open at page → 9 Page 9 6 1. Introduction NIST maintains and operates the reference instrument that establishes the national scale for regular spectral transmittance. It is within the NIST mission to maintain this national scale and disseminate... Open at page → 10 Page 10 7 staff. In general, for calibration service 38061S the customer supplies the test item, which is measured under the spectral conditions specified by the customer. Uncertainty estimates will be given and will depend on t... Open at page → 11 Page 11 8 ),( ),( ),( ),( ),( ),( ),( it ii ii it ii it i        G G S S I I  , (2) where I is the intensity, S is the measured signal, G is the transimpedance amplifier gain, and the subscripts i and t denote... Open at page → 12 Page 12 9 Figure 1. Schematic of the RTS with the systems and components labeled. The light path from source to detector is shaded. The Illuminator system consists of QTH – quartz-tungsten-halogen lamp, D2 – deuterium lamp, AL –... Open at page → 13 Page 13 10 the flux from the source onto the entrance slit of the monochromator at a distance of 570 mm from the source. A light chopper can be placed in front of the entrance mask as needed for use with the extended indium-gall... Open at page → 14 Page 14 11 the current multiplied by 10 6 V/A. The Si detector is temperature-controlled at 26° C with a transimpedance amplifier having gains that are selected manually or remotely. The extended- range InGaAs detector, temperat... Open at page → 15 Page 15 12 543 544 545 546 547 548 549 0.00 0.02 0.04 0.06 0.08 (a) Grating A, 1 mm slits Signal [nA] Wavelength [nm] 540 541 542 543 544 545 546 547 548 549 550 551 552 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 (b) Grating A, 2 mm sl... Open at page → 16 Page 16 13 Table 3. Spectral bandwidth for each slit width, emission line, and grating used to measure the slit-scattering function Slit Width [mm] Lamp Line [nm] Grating Order FWHM [nm] 1 Hg 546.1 A 1 1.6 1 Ar 763.5 B 2 1.4 1 H... Open at page → 17 Page 17 14 Wavelength Calibration The wavelength was calibrated using Hg, Ne, and Ar emission lamps for both gratings and slit widths of 1 mm and 2 mm. The wavelength uncertainty (k = 1) is 0.05 nm for the 1 mm slit width and 0.... Open at page → 18 Page 18 15 200 250 300 350 400 0 50 100 150 200 250 300 D 2 source, PMT detector (a) Signal [nA] Wavelength [nm]  = 0  = 90 200 250 300 350 400 0 200 400 600 800 1000 1200 1400 1600 1800 2000 D 2 source, PMT detector (b) Signa... Open at page → 19 Page 19 16 200 400 600 800 1000 1200 0 2 4 6 8 10 QTH source, Bare Si detector, 1 mm slits (a) Signal [nA] Wavelength [nm]  = 0  = 90 200 400 600 800 1000 1200 0.1 1 10 QTH source, Bare Si detector, 1 mm slits (b) Signal [nA]... Open at page → 20 Page 20 17 200 400 600 800 1000 1200 0 20 40 60 80 100 120 140 160 180 200 QTH source, Bare Si detector, 2 mm slits (a) Signal [nA] Wavelength [nm]  = 0  = 90 200 400 600 800 1000 1200 0.1 1 10 100 QTH source, Bare Si detector... Open at page → 21 Page 21 18 200 400 600 800 1000 1200 0 2 4 6 8 10 QTH source, Si detector with sphere, 2 mm slits (a) Signal [nA] Wavelength [nm]  = 0  = 90 200 400 600 800 1000 1200 0.01 0.1 1 10 QTH source, Si detector with sphere, 2 mm sli... Open at page → 22 Page 22 19 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 0 5 10 15 20 25 QTH source, InGaAs(ext) detector, 2 mm slits (a) Signal [nA] Wavelength [nm]  = 0  = 90 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 0.01 0.1 1 10... Open at page → 23 Page 23 20 and is determined by the double-aperture method [6]. All that is required is that the detection system is linear over the full range of light possible through the monochromator with maximum slit width and without the... Open at page → 24 Page 24 21 program to acquire and analyze the data. For each polarization and wavelength, a signal is measured, which is proportional to the efflux. To cancel the effect of source drift to first order, an average of the clear re... Open at page → 25 Page 25 22 average of both polarizations as a function of wavelength. The calculation procedure is detailed in Section 3.5 below. The combined file (*.cmb) calculates an average repeat transmittance value based on multiple scans... Open at page → 26 Page 26 23 Reducing the data to final values for multiple source and detector combinations is usually accomplished using the combined files and a spreadsheet program. In general, each sample is measured once over a specified wav... Open at page → 27 Page 27 24       2/1 22 22222 0 RPD RPD RPT RPT DGR DGR DRR DRR DL DL)()(                                                            uu uuuuuu       ,... Open at page → 28 Page 28 25 Table 7. Sources of uncertainty and typical uncertainty contributions at 0.5 transmittance Source of Uncertainty Standard Uncertainty Uncertainty Contribution Wavelength (λ) 0.05 nm 0.0001 Detector Linearity (DL) 0.05... Open at page → 29 Page 29 26 room temperature and sample dimensions are provided as reference and are not intended to be certified values. A plot of the data is also provided. The scale displayed on the plot may not be the best representation for... Open at page → 30 Page 30 27 4.2 Instrument Calibration Validation of the instrument operation is achieved by performing tests with the validation programs which are part of the instrument’s software package. These tests are run every year or bef... Open at page → 31 Page 31 28 blank sample holder is blocked with an opaque material for the 0 % transmittance baseline. A zero-baseline correction can either be calculated automatically by the software or manually by the user. 4.4 Data Analysis T... Open at page → 32 Page 32 29 References 1. P. Y. Barnes, E. A. Early, and A. C. Parr, “Spectral Reflectance,” NIST Spec. Pub. 250-48, U. S. Dept. of Commerce (1998). 2. M. E. Nadal, E. A. Early, and E. A. Thompson, “Specular Gloss,” NIST Spec. Pu... Open at page → 33 Page 33 30 Appendix A: Transmittance Theory and Measurement Equation When radiant flux (optical radiation) interacts with matter, it may be reflected, absorbed, or transmitted. For purposes of the regular spectral transmittance... Open at page → 34 Page 34 31 which regular transmittance is measured, the object is semi-transparent and non-conducting, the following equations are applicable for a homogeneous dielectric, linear, isotropic, and non- magnetic medium. For the bou... Open at page → 35 Page 35 32 ttii ttii icos)(cos)( cos)(cos)( )s,,(  nn nn r   and (A7) tiit tiit icos)(cos)( cos)(cos)( )p,,(   nn nn r    . (A8) The angle of the transmitted ray can be eliminated from Eqs. (A7) and (A8... Open at page → 36 Page 36 33      m )( d d  . (A15) Expressing the spectral attenuation coefficient as a product of the concentration c of the absorbing medium and the medium’s extinction coefficient (λ) yields Beer’s law form of Eq. (1... Open at page → 37 Page 37 34 Although the luminous transmittance is not often requested, sometimes it is needed. The luminous transmittance V for CIE standard illuminant C and for both the CIE 1931 (2º) standard observer color-matching function... Open at page → 38 Page 38 35 The above formulas neglect coherence effects important when the coherence length of the incident light,     n L 2 , (A27) is on the order of or larger than the sample thickness. For λ = 1000 nm, Δλ = 1.5 nm, and... Open at page → 39 Page 39 36 t cos mm2 d . (A30) The transmittance as a function of incident angle for s and p polarizations and for unpolarized incident radiant flux is shown in Fig. A3. 0 153045607590 0.0 0.2 0.4 0.6 0.8 1.0 Polarization Tran... Open at page → 40 Page 40 37 position signals. Since the beam emerging from the collimating mirror is not completely polarized, measurements are made for two orthogonal polarizations of the illumination beam, and the resulting transmittances are... Open at page → 41 Page 41 38 ),(),(),( iiiii  RI  , (A36) ) ,(),,(),,( ttittit  RI , (A37) ) p,()p,,()s,()s,,()t,,( ititit  RRI  , (A38) )p,()p,()s,()s,()u,( iii  RRI  , (A39) and .)p,()p,p,()s,()s,p,(... Open at page → 42 Page 42 39 ),( )t,,( )t,,( ii it i  I I  , (A44) where the current from the optical detector It(, i, t) includes both polarizations of the transmitted radiant flux. The transmittance for unpolarized incident radiant fl... Open at page → 43 Page 43 40  .)t,p,()t,s,( 2 1 )p,( )t,p,( )s,( )t,s,( 2 1 )t,u,( i t i t              I I I I (A48) If the receiver is sensitive to polarization, but the ratio of the responsivities to the two orthogonal li... Open at page → 44 Page 44 41 GIS  ),(),(  , (A52) where G [V/A] is the gain of the transimpedance amplifier. For the RTS, the receiver is insensitive to the polarization of the radiant flux, so the total transmitted flux is measured. Sets o... Open at page → 45 Page 45 42 ),( ),( ),( ),( ),( ),( ),( ii it it ii ii it i        S S G G S S  , (A59) because for most calibrations, the gains, G t(λ, σ) ~ G i(λ, σ), do not vary much. Open at page → 46 Page 46 43 Appendix B: Sample Report REPORT OF CALIBRATION 38061S Regular Spectral Transmittance for Six Neutral Density Filters Submitted by: Any Company, Inc. Attn.: Ms. Jane Doe 123 Calibration Street Measurement City, MD 208... Open at page → 47 Page 47 44 proportional to the incident and transmitted radiant fluxes, respectively. Net signals for the clear and sample positions are obtained by subtracting the dark position signals. Individual items were cleaned with an ai... Open at page → 48 Page 48 45 linearity, which was determined in the characterization of the RTS facility, includes effects from both the detector and the signal electronics. All uncertainty components were assumed to have normal probability distr... Open at page → 49 Page 49 46 Figure B1. Regular spectral transmittance as a function of wavelength  of neutral density filters. 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 360 410 460 510 560 610 660 710 760 Wavelength [nm] Transmittance F1-0... Open at page → 50 Page 50 47 Table B1. Regular spectral transmittance as a function of wavelength  of a neutral density filter, serial number F1-001.  [nm]   [nm]  380 0.9067 580 0.9123 390 0.9077 590 0.9124 400 0.9082 600 0.9125 410 0.90... Open at page → 51 Page 51 48 Table B2. Regular spectral transmittance  as a function of wavelength  of a neutral density filter, serial number F1-002.  [nm]   [nm]  380 0.7956 580 0.8367 390 0.7999 590 0.8376 400 0.8034 600 0.8386 410 0.806... Open at page → 52 Page 52 49 Table B3. Regular spectral transmittance  as a function of wavelength  of a neutral density filter, serial number F1-003.  [nm]   [nm]  380 0.6582 580 0.6694 390 0.6600 590 0.6697 400 0.6612 600 0.6700 410 0.662... Open at page → 53 Page 53 50 Table B4. Regular spectral transmittance  as a function of wavelength  of a neutral density filter, serial number F2-001.  [nm]   [nm]  380 0.7931 580 0.8330 390 0.7973 590 0.8341 400 0.8008 600 0.8351 410 0.8... Open at page → 54 Page 54 51 Table B5. Regular spectral transmittance  as a function of wavelength  of a neutral density filter, serial number F2-002.  [nm]   [nm]  380 0.7384 580 0.7999 390 0.7451 590 0.8015 400 0.7504 600 0.8029 410 0.7... Open at page → 55 Page 55 52 Table B6. Regular spectral transmittance  as a function of wavelength  of a neutral density filter, serial number F2-003.  [nm]   [nm]  380 0.5337 580 0.5059 390 0.5323 590 0.5053 400 0.5307 600 0.5047 410 0.5... Open at page → 56 Page 56 53 Table B7. Uncertainty contributions and expanded uncertainty (k = 2) of the regular transmittance of a neutral density glass filter, serial number F1-001. Source of Uncertainty Standard Uncertainty Uncertainty Contrib... Open at page → 57 Page 57 54 Table B10. Uncertainty contributions and expanded uncertainty (k = 2) of the regular transmittance of a neutral density glass filter, serial number F2-001. Source of Uncertainty Standard Uncertainty Uncertainty Contri... Open at page → 58 Page 58 55 Appendix C: Sample Data Figure C1. Transmittance as a function of wavelength of the color filters. Figure C2. Transmittance, on a logarithmic scale, as a function of wavelength of the MAP (Measurement Assurance Progra... Open at page → 59 Page 59 56 Table C3. Nominal transmittance values at 548.5 nm and materials for the MAP filters. Filter No. Nominal  Material 1-1 0.9 Borosilicate crown glass 1-2 0.7 Schott NG-11 1-3 0.5 Schott NG-11 1-4 0.25 Schott NG-4 1-5 0... Open at page → 60 Page 60 57 Appendix D: How to Request Regular Spectral Transmittance Calibrations 1. Prepare a purchase order with the following (discuss with technical contact prior to submitting a formal request): a. Service ID number request... 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