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1
COOMET
Project № 277/UA/03
COOMET L.S-1
Conducting of comparisons of comparators
with photoelectric microscopes
Final report
National Scientific Centre "Institute of metrology" (NSC IM)
Coordinator: V. Kupko
NSC "Institute of metrology"
42 Mironositskaya Str.
61002 Kharkov
UKRAINE
Tel.: +38 057 758 73 03
E-mail: [email protected]
Kharkov
2
Report
About the results of comparisons of comparators with photoelectric microscopes
on COOMET Project № 277/UA/03 (COOMET L.S-1)
1. Introduction
The aim of the project is comparison of measurement standard instruments of
measurement technology for determining the uncertainties and providing reliability of
measurement of linear dimensions.
Date of registration of the project "Comparisons of comparators with photoelectric
microscopes" is 6 June 2005.
Type of comparisons – supplementary.
NMIs from three countries were participants of the COOMET project
№277/UA/03.
2. Participants of comparisons:
NMI, address of NMI Сontact person Telephone, e-mail
National Scientific Centre "Institute
of metrology"
address: 42 Mironositskaya Str.
61002 Kharkov
UKRAINE
tel: +38 057 700 34 09
fax: +38 057 700 34 47
Vladimir Kupko tel.: +38 057 758 73 03
e-mail:
Republican governmental enterprise
“Kazakhstan Institute of Metrology”
(KazInMetr)
address: Left bank of the River
Ishim, Orynbor Str., 11, 010000,
Astana, Kazakhstan
Chingis Kuanbaev tel.: +71772 79 33 70
e-mail: e-mail:[email protected]
Federal state unitary enterprise
“D.I.Mendeleyev VNIIM”
address: Russia, St. Petersburg,
190005 Moskovsky pr., 19.
Constantine Chekirda tel.: 7 (812) 323 96 64
e-mail: [email protected]
Ukraine, the coordinator country, developed the program of comparisons and
provided comparison measures.
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3. Organization of comparisons.
3.1 Comparisons are conducted on national measurement standard instruments of
the highest accuracy by means of interference method with the application of
photoelectric microscopes for aiming at the line center.
Comparisons were conducted by means of radial method.
3.2 Dates of conducting of measurements by the participants of comparisons are
shown in table 1.
NSC “Institute of Metrology” October 2008
“D.I.Mendeleyev VNIIM” February 2009
“KazInMetr” February 2010
NSC “Institute of Metrology” September 2010
3.3 Comparison measure in transport box is transferred by messenger service by
aerial or surface kind of transport. Expenses for transporting and clearing from customs
office are covered by member country of the comparisons. Having conducted the whole
phase of comparisons on comparison program member country sends comparison
measure to NSC “Institute of metrology”, Kharkov, Ukraine.
3.4 Comparison measure – length measure of metre of МС 38-02-1000 type,
factory number № 0315-90 manufactured of invarstabil 58 % Ni, overall dimension -
1050*25*30 mm. Mass of comparison measure – 3.13 kg. Comparison measure
represents H-shaped index grating with nominal length of the main scale of 1000 mm.
The length of the interval of the main scale is 1 mm. The width of the strokes of the
scale, marked on the neutral surface of the measure is approximately 5 mkm. On the
measure scale surface there marked 2 longitudinal axial lines with the distance of 2 mm
between them. On the comparison measure there are also two supplementary scales,
located at the beginning and at the end of the main scale. The lengths of supplementary
scales are 1mm, and the length of the interval of main scales is 0.1 mm. On the lateral
surface of a comparison measure there are two marks corresponding to Bessel points (ℓ
4
= 0.22·L, where ℓ– distance from the measure edge to the mark, and L – distance
between measure edges).
Temperature coefficient of comparison measure linear expansion is
αt = 11.36·10-6
К-1
(1)
Measurement standard line comparison measure is placed into original case which
is mounted in plywood package when transporting.
4. Methodology of conducting measurements
Measurand is the shortest distance between the axis (center) “0” of measure line
and the axis (center) of the line of measurable interval. Measuring of interval length
should be conducted in the field between two longitudinal axial lines, marked on the
surface of the scale of comparison measure (see 3.4.).
In table 2 there given nominal values of the intervals, which should be measured.
Table 2
Nominal length of intervals in mm
0-1 0-6 0-10 0-60 0-100 0-600
0-2 0-7 0-20 0-70 0-200 0-700
0-3 0-8 0-30 0-80 0-300 0-800
0-4 0-9 0-40 0-90 0-400 0-900
0-5 0-50 0-500 0-1000
When measuring the lengths of any scale interval of comparison measure it’s
necessary to apply not less than two measuring techniques – it’s necessary to conduct
measurements under forward and return stroke of the comparator carriage with the
return to the initial line. The mean value of these two measurements is accepted as
measuring result. The measured length of the interval should be reduced to the
temperature of 20° C.
When measuring it’s necessary to place the comparison measure onto the beds in
Bessel points, which are pointed out at the measure (see 3.4.).
The results of comparisons are recorded with the indication of:
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- brief description of the method and the conditions of conducting of the
measurements;
- measured values of lengths of the intervals and their deflection from nominal value
of length of the interval;
- uncertainty budget;
5. Measuring equipment, conditions and measurement results
5.1 NSC “Institute of metrology”, Ukraine
5.1.1. Measuring equipment
The measurements were conducted on an interference comparator, placed in a heat
chamber, by the method of counting of interference lines. Comparator enters into the
composition of national primary measurement standard of length unit – metre of DETU
01-03-98. For aiming at the line centre, photoelectric microscope with scanning slot was
used. As a source of measurement standard emission, He-Ne laser-heterodyne was used,
stabilized under the frequency with He-Ne/J2 laser which wavelength is compared with
the wave of He-Ne/J2 lasers, entering into group measurement standard of a complex of
laser sources of measurement standard emission of primary measurement standard of
length unit of DETU 01-03-98. Relative uncertainty of wavelength of He-Ne laser-
heterodyne is 3·10-10
.
The refractive index of air is calculated with a help of Edlen formula using
measured physical parameters of air: humidity, pressure and temperature.
Air humidity was measured with a help of aspiration psychrometer МV-4М.
Measurement uncertainty of air absolute humidity is 0.29 mm of mercury.
Air pressure was measured with a help of mercury barometer IR. Measurement
uncertainty of air pressure is 0.12 mm of mercury.
Air temperature and comparison measure was measured with a help of copper-
constantan thermocouples cold ends of which are placed on a copper plate.
6
Absolute temperature of copper plate is measured with a help of platinum resistance
thermometer, calibrated through two reference temperature points – water triple point of
0.01 °С and helium melting temperature of 29.7646 °С. Measurement uncertainty of
temperature is 0.006 ˚С.
5.1.2. Conditions of conducting of measurements
Measurements were conducted under following conditions:
-air temperature (20 ± 0,1) ˚С;
-air absolute humidity (10 ± 3) mm of mercury;
-atmospheric pressure (98 – 102) Kpa;
5.13. Measurement results
Measurement results of intervals of comparison measure, conducted at NSC
“Institute of metrology” in October 2008 and 2010 are given in table 3.
Table 3. Measurement results of comparison measurement standard intervals.
nominal of
interval, in
mm
deviation
from
nominal nm,
2008
deviation
from
nominal nm,
2010
nominal of
interval, in
mm
deviation
from
nominal nm,
2008
deviation
from
nominal nm,
2010
1 5 8 60 -55 -47
2 15 19 70 52 62
3 -20 -15 80 -42 -45
4 61 70 90 -7 7
5 9 19 100 37 74
6 -48 -42 200 49 49
7 35 26 300 61 32
8 63 58 400 -52 -165
9 68 74 500 -155 -236
10 39 24 600 -227 -328
20 -26 -21 700 -240 -372
30 39 43 800 -309 -403
40 -34 -39 900 -264 -406
50 54 49 1000 -355 -490
7
The length of intervals of comparison measure, reduced to 20˚С is calculated on
the basis of measurement equation (2)
)T(20Ln/16NL мnomB020
where
L20 – interval length of comparison measure, reduced to 20˚С;
N – interferometer reading;
λ0 – laser emission wavelength in vacuum;
1⁄16 – interferometer constant;
na – wavelength refractive index in air;
Lnom – measurement interval nominal length;
α – measure linear expansion temperature coefficient;
Тм – temperature of measure.
Uncertainty budget, calculated on the basis of formula (2) is shown in table 4.
Table 4. Uncertainty budget.
Sources of
uncertainty
Type of
uncertainty
Distribution
Standard
uncertainty
Influence
coefficient
Contribution to
total uncertainty
nm
Independent on length of the interval
Identification of line
center u(lc)
of type А
normal
9
Form variations of
line u(lf)
of type В
uniform 4 1 4
Dependent on length of the interval
Uncertainty of type
A, dependent on
length of the
interval
of type А
normal
40×L
Wavelength
(relative)
u(λ)
of type В
uniform 3×10–10
L×109 0.3×L
Air temperature u(t) of type В
uniform 0.006 °C 0.947×10
3×L 5.7×L
Air pressure u(p) of type В
uniform
0.12 mm of
mercury 0.364×10
3×L 43.7×L
Air humidity u(e) of type В
uniform
0.29 mm of
mercury 0.056×10
3×L 16.2×L
Calculation method
of refractive index
of air u(n)
of type В
uniform 5×10
-8 L×10
9 50×L
8
Temperature of
measure
of type В
uniform 0.006 °C 11.36×10
3×L 68.2×L
Gradient of measure
temperature
of type В
uniform 0,009°C 11.36×103×L 102.2×L
TKLR uncertainty
of measure when
(20–Т=0.1) ˚С
of type В
uniform 1×10-7
0.1×109×L 10×L
L – length of measuring interval in metres.
Total measurement standard uncertainty of interval length, subject to the
evaluations shown in table 4, consists of:
- total measurement standard uncertainty, independent on the length of the interval:
nm8.949 22 tuu (3)
- total measurement standard uncertainty, dependent on the length of the interval:
nm144)L10102,268,25016,243,75,70,3(40u 2222222222
сз L (4)
Total measurement standard uncertainty of the length of the interval subject to the
dependent and independent on the length components will be of the form:
nm,L)144(8,9)u()(u 222
сз
2
tuc u (5)
where L – length of measuring interval in metres.
Expanded uncertainty U, when confidence probability equals to 0.95, is calculated
by the formula c, ukU 950 with k = 2.
metres.in - L wherenm,)144(8,92 22
95,0 LU (6)
5.2 Federal state unitary enterprise “D.I.Mendeleyev VNIIM”, Russia
5.2.1. Measuring equipment
Measurements were conducted on the interference comparator. The comparator
enters into the composition of national primary measurement standard of length unit –
metre of GET 2-85.
Structure of the interference comparator
1. Frequency-stabilized laser.
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2. Laser interferometer.
3. Carriage movable on a bed.
4. Carriage drive.
5. System of measurement of temperature of measure, including platinum
thermometer and thermocouples.
6. System of thermostating of room.
7. Microscope with CCD camera.
8. Refractometer with vacuum system.
9. Computer with software.
Refractive index of air (n) is determined with a help of refractometer on the basis
of wavelength of laser (λο) in vacuum, length of camera of refractometer (Lref) and
phase shift of interference fringes (φref) when vacuumizing camera by the formula:
ref0 / Lln ref (7)
In the process of calculating the length of intervals of comparison measure,
arithmetic mean value of refractive index of air (na) is used, measured before and after
the measurement. Relative uncertainty of measurement of refractive index of air is
9·10-8
.
Temperature of measure (Тм) is determined with a help of platinum resistance
thermometer and thermocouples. In the process of calculating of length of intervals of
comparison measure, arithmetic mean value (Тм) of temperature of measure is used,
changed before and after the measurement. Uncertainty of measurement of measure
temperature is 0.006 °С.
5.2.2. Conditions of conducting measurements
When measuring the following conditions were respected:
-air temperature (20 ± 0,1) ˚С;
-relative humidity of air (58 ± 5) mm of mercury;
-atmospheric pressure (104 – 106) Kpa;
5.13. Measurement results
10
Measurement results of intervals of comparison measurement standard, conducted
in Federal state unitary enterprise “D.I.Mendeleyev VNIIM” in February 2009, are
shown in table 4.
Table 4. Measurement results of intervals of comparison measurement standard
nominal of
interval,
мм
deviation from
nominal nm,
2009
nominal of
interval,
мм
deviation from
nominal nm,
2009
1 -8 60 -63
2 28 70 30
3 -28 80 -88
4 50 90 -16
5 -11 100 15
6 -79 200 24
7 -3 300 48
8 30 400 -73
9 59 500 -196
10 -33 600 -261
20 -35 700 -273
30 8 800 -330
40 -58 900 -287
50 40 1000 -407
The length of intervals of comparison measure, reduced to 20˚С, is calculated on
the basis of measurement equation (8):
)20()/)((/)( мBinterf0Bint020 TnnL erf (8)
where
L20 – length of interval, reduced to 20°С;
λο – length of wave of laser emission in vacuum;
φinterf – phase shift of interference fringes in interferometer in the process of
moving the carriage with microscope;
na – refractive index of wave length in air;
α – temperature coefficient of linear expansion of measure;
11
Тм – temperature of measure.
Uncertainty budget calculated on the basis of formula (8) is shown in table 5.
Table 5. Uncertainty budget.
Sources of uncertainty Type of
uncertainty
Distribution
Measurement
standard
uncertainty
Influence
coefficient
Contribution to
total uncertainty
nm
Independent on length of the interval
Identification of line
center
of type А
normal
6
Inaccuracy of
manufacturing of optics
of type В
uniform 5 1 5
Nonlinearity of
interferometer
of type В
uniform 1 1 1
Vibration of line edge of type В
uniform 5 1 5
Dependent on length of the interval
Evaluation of Type A at
maximum interval
(vibration, wavelength,
electronic noise)
of type А
normal
30×L
Uncertainty of laser
wavelength
(relative)
of type В
uniform 2×10–8
L×109 20×L
Refractive index of air
(relative)
of type В
uniform 9×10
–8 L×10
9 90×L
Temperature of measure
°C
of type В
uniform 0.006 11.36×10
3×L 68.2×L
Gradient of temperature
of measure°C
of type В
uniform 0,006 11.36×103×L 68.2×L
Uncertainty TKLR of
measure when
(20–Т=0.1) ˚С
of type В
uniform 1×10-7
0.1×109×L 10×L
L – length of measurable interval in metres.
Total measurement standard uncertainty of interval length, with a glance of
evaluations shown in table 5, consists of:
- total measurement standard uncertainty independent on interval length:
nm3,95156 2222
tu u (9)
- total measurement standard uncertainty, dependent on interval length:
nm137)106868902030( 2222222
сз LLu (10)
12
Total measurement standard uncertainty of interval length with a glance of
dependent and independent on the length of components will be like
nm,)137(9)()( 222
сз
2
tuс Luuu (11)
where L – length of measurable interval in metres.
Expanded uncertainty U with confidence probability equivalent to 0.95, is
calculated with a help of the formula U0,95 = k·uc when k = 2.
metres.in wherenm,)137(92 22
0,95 LLU (12)
5.3 Republican governmental enterprise “Kazakhstan Institute of Metrology” (KazInMetr)
5.3.1 Measuring equipment
Measurements were conducted by absolute interference method on interference
comparator. Comparator enters into the composition of national primary measurement
standard of length unit – metre. Into the composition of national primary measurement
standard of length unit also enters He-Ne/J2 with relative frequency instability of
2.5·10-11
.
Interference comparator consists of:
- optic-mechanical system;
- frequency-stabilized He-Ne laser of LGN-303 type;
- system of measurement of air parameters – temperature, pressure, humidity.
Relative uncertainty of wavelength of He-Ne laser is 2·10-8
, uncertainty of
measurement of temperature of measure equals to 0.012 °С, uncertainty of measurement
of air parameters are:
- temperature 0.012 °С;
- pressure 0.09 mm of mercury;
- humidity 0.2 mm of mercury;
5.3.2 Measurement conditions
When measuring the following conditions were respected:
- air temperature (20 ± 0.1) ˚С;
13
- relative humidity of air (20 ± 5) %;
- atmospheric pressure (980 ± 10) Kpa.
5.3.3 Measurement results
Measurement results of comparison measurement standard intervals, conducted at
Republican governmental enterprise “Kazakhstan Institute of Metrology” (KazInMetr)
in February 2010, are shown in table 6.
Table 6. Measurement results of comparison measurement standard intervals
nominal of
interval,
мм
deviation from
nominal nm,
2010
nominal of
interval,
мм
deviation from
nominal nm,
2010
1 -34 60 -29
2 45 70 7
3 -4 80 -70
4 69 90 -29
5 -8 100 80
6 -54 200 80
7 -30 300 100
8 51 400 -130
9 39 500 -530
10 30 600 -501
20 -26 700 -640
30 49 800 -740
40 -80 900 -710
50 80 1000 -620
Length of comparison measurement standard intervals, reduced to 20˚С is calculated
on the basis of measurement equation (13):
)20()/)((/)( мainterf0aint020 TnnL erf (13)
where
L20 – length of interval, reduced to 20°С;
λο – laser emission wavelength in vacuum;
14
φinterf – interference lines phase shift in interferometer in the process of moving
carriage with microscope;
na – wavelength refractive index in air;
α – measure linear expansion temperature coefficient;
Тм – temperature of measure.
Uncertainty budget calculated on the basis of formula is shown in table 7.
Table 7. Uncertainty budget
Uncertainty components
Type of
uncertainty
Distribution
Standard
uncertainty
Influence
coefficient
Contribution to
total uncertainty
nm
Independent on length of the interval
Identification of center of
line u(цш)
Of type А
normal 10
Nonidealness of optics Of type В
uniform 10
Nonlinearity of
interferometer
Of type В
uniform 2 1 2
Variations of line edges Of type В
uniform 5 1 5
Dependent on length of the interval
Uncertainty of type A,,
when measuring big
intervals
Of type А
normal
40×L
Laser wavelength
(relative)
Of type В
uniform 2×10
–8 L×10
9 20×L
Edlen formula
(relative)
Of type В
uniform 5×10
–8 L×10
9 50×L
Air pressure
mm of mercury
Of type В
uniform 0.09 0.364×10
3×L 32.8×L
Air temperature °C Of type В
uniform 0.012 0,947×10
3×L 11.4×L
Air humidity
mm of mercury
Of type В
uniform 0.2 0.056×10
3×L 11.2×L
Gradient of measure
temperature ˚С
Of type В
uniform 0.012 11.36×10
3×L 136×L
Temperature of measure
˚С
Of type В
uniform 0.012 11.36×10
3×L 136×L
TKLR uncertainty of
measure when (20–Т=0.1)
˚С
Of type В
uniform 1×10-7
0.1×109×L 10×L
L – length of measurable interval in metres.
15
Total measurement standard uncertainty, with a glance of uncertainty evaluations
of type A and B, independent on interval length, equals to:
nm15251010 2222
tu u (14)
Total measurement standard uncertainty, with a glance of uncertainty evaluations
of type A and B, dependent on interval length, equals to:
nm207)101361362,114,118,3250200(4 2222222222
сз LLu (15)
Then total measurement standard uncertainty will be equivalent to:
nm,)207(15)()( 222
сз
2
tuс Luuu (16)
Expanded uncertainty U, when confidence probability equals to 0.95 is calculated
with a help of formula U0,95 = k·uc when k = 2.
metres.in wherenm,)207(1522 22
с0,95 LLuU (17)
6. Analysis of measurement results when conducting comparisons.
Total time on comparisons is 2 years. During this time comparison measure was
transported for 2 times at rather significant distances. At figures 1, 2 and 3 measurement
results of comparison measure in 2008 and 2010 are shown. At these figures there are
given deviations of measured intervals from their normal value, with corresponding to
them expanded uncertainties. From given data one can make a conclusion that stability
of comparison measure for these 2 years is satisfactory.
At figures 4, 5 and 6 results obtained from 3 national metrology centers,
participants in conducting comparisons were given. Each organization presented its
calculation of uncertainties of type A and of type B, which are given in corresponding
tables.
16
Measuring of comparison measure of NSC “Institute of metrology”
17
Measurement result obtained by Member countries
Figure 6 : Interval 100 -1000 мм -1200 -1100 -1000
-900 -800 -700 -600 -500 -400 -300 -200 -100
0 100 200 300 400
0 100 200 300 400 500 600 700 800 900 1000 1100
мм
нм Russia Kazakhstan Ukraine