Radiance Temperature Laboratory
>> Files for this document are noted by and require
a reader to be loaded for viewing.
[ Get the Adobe PDF Reader ]
Program Objective: This laboratory has as its principal
activity the establishment, maintenance, and dissemination of the
US National Scale of Radiance Temperature. This laboratory is
responsible for temperature measurements above the freezing point
of silver (1234.93 K or 961.78 °C).
The 1990 NIST Radiance Temperature Scale is the NIST
realization of the International Temperature Scale 1990 from
blackbody physics. The radiance temperature of a radiator is
equivalent to the temperature of a blackbody with the same
radiant intensity of the radiator's surface at a fixed wavelength.
Click on the items below to read more about:
Radiance Temperature Laboratory Measurement System
LEGEND |
|
AMP |
|
Amplifier |
|
PS |
|
Power Supply |
DVM |
|
Digital Voltmeter |
|
RS |
|
Room Humidity Sensor |
EM |
|
Environmental Monitor |
|
TC |
|
Thermoelectric Cooler |
GPBB |
|
Gold-point Blackbody |
|
TL |
|
Test Lamp |
GPL |
|
Gold-point Lamp |
|
TS |
|
Temperature Sensor |
PC |
|
Personal Computer |
|
VTBB |
|
Variable Temperature Blackbody |
PMT |
|
Photomultiplier Tube |
|
WSL |
|
Working Standard Lamp
|
- A gold freezing point blackbody (reference standard) and
the Planck radiation law are used to realize and
disseminate the 1990 NIST Radiance Temperature Scale.
The Planck equation:
(1)
(2)
|
|
where
= |
wavelength in air [cm] |
=
|
Spectral emissivity = 1 for ideal blackbody |
c1L
= |
first radiation constant in radiance
form = c1 /
= 1.191 043 x 10-12 [W · cm2] |
c2 = |
second radiation constant = 1.4388 [cm · K]
|
n = |
refractive index of air at 15 °C and 76 cm Hg
using the Cauchy formula ( in
Å) |
|
1 + {2726.43 + [12.288 / (2 x 10-8)] + [0.3555 /
(4 x 10-16)]}
x 10-7 |
= |
1.000 28 for
= 6553 Å |
- The radiance temperature of the working standard is
determined by comparison to the gold point blackbody. A
high stability vacuum lamp operated at approximately
1255 °C is the working standard.
- The NIST Photoelectric Pyrometer (PEP) is the transfer
device used to compare the spectral radiances of the
sources.
- The PEP is a filtered radiometer which uses two
interference filters to select the bandpass. The
bandwidth is 5 nm with a mean effective wavelength
of 655.3 nm. A photomultiplier tube with a S-20
spectral response is used in the DC mode. The measurement
spot size is a 0.6 mm by 0.8 mm rectangle.
NIST Photoelectric Pyrometer
|
|
LEGEND |
|
AS |
|
Aperture Stop |
CL |
|
Collimating Lens |
CPD |
|
Cooled Photomultiplier Detector |
DL |
|
Diverging Lens |
FS |
|
0.6 mm x 0.8 mm Rectangular Field Stop |
GPBB |
|
Gold-point Blackbody |
GPL |
|
Gold-point Lamp |
IF |
|
Interference Filters |
OL |
|
Objective Lens |
TL |
|
Test Lamp |
VTBB |
|
Variable Temperature Blackbody |
WSL |
|
Working Standard Lamp |
|
- The radiance temperature of the test lamp is determined
by comparison to the working standard.
- The variable-temperature blackbody (VTBB) is the transfer
standard used to calibrate test pyrometers. The radiance
temperature of the transfer standard is determined by
comparison to the working standard.
- The blackbody operates between 800 °C and
2700 °C with an estimated emissivity of 0.99. The
blackbody cavity is a single piece of graphite, specially
tapered for temperature uniformity. This graphite tube is
cylindrically hollow on both ends to form two
2.54 cm diameter cavities with a common partition in
the center. One cavity is used for temperature control
and the other as a blackbody source.
- Calibration reports are
issued giving the radiance temperature of the blackbody
at 655.3 nm versus scale reading, output current, or
output voltage
-
Test No. |
Measurement Description |
35010C |
Radiance Temperature Standard,
Disappearing Filament Optical Pyrometer (1 pyrometer
range, 4 to 12 points, 800 °C to 2400 °C) |
35020C |
Radiance Temperature Standard,
Disappearing Filament Optical Pyrometer (per additional
range up to 4200C with Test no. 35010C only) |
35040C |
Radiance Temperature Standard,
Disappearing Filament Optical Pyrometer (3 or fewer
points, 800 °C to 4200 °C) |
- Calibration reports are
issued giving the radiance temperature at 655.3 nm versus
direct current
-
Test No. |
Measurement Description |
35050C |
Radiance Temperature Standard, Ribbon
Filament Lamp (6 to 16 points, 800 °C to
2300 °C) |
35060C |
Radiance Temperature Standard, Ribbon
Filament Lamp (5 or fewer points, 800 °C to
2300 °C) |
- Test reports are issued
giving the radiance temperature of the blackbody at
655.3, 900, or 1000 nm versus the indicator reading,
output current, or output voltage
-
Test No. |
Measurement Description |
35070S |
Special Tests of Radiation Thermometers |
- The expanded uncertainty (coverage factor k = 2) is a
two standard deviation estimate.
-
Standard |
Temperature
Range |
Expanded
Uncertainty |
Ribbon filament lamp |
800 °C to
1600 °C
1600 °C to 1900 °C
1900 °C to 2300 °C |
0.7 °C
1.0 °C
1.5 °C |
Leeds & Northrup Model 8000 series
Disappearing filament optical pyrometer |
800 °C to
1600 °C
1600 °C to 2100 °C
1900 °C to 2300 °C
2400 °C to 2700 °C
2700 °C to 3200 °C
3200 °C to 4200 °C |
4 °C
5 °C
7 °C
8 °C
17 °C
25 °C |
Pyrometer Instrument Model 95
Disappearing filament optical pyrometer |
800 °C to
1400 °C
1400 °C to 1800 °C
1800 °C to 2400 °C
2400 °C to 2700 °C
2700 °C to 3200 °C |
3 °C
4 °C
5 °C
8 °C
12 °C |
Infrared radiation thermometer |
800 °C to
2000 °C
2000 °C to 2700 °C |
2 °C
3 °C |
This laboratory's quality system is based on the ANSI/NCSL
Z540-1-1994 standard and the ISO/IEC Guide 25.
- Prepare a purchase order with the following:
- Company name and address
- Contact person's name and phone number.
- Billing address
- Service ID number requested (include range and
points)
- Test fee
- Address to ship test item
- Return shipping instructions (prepay and add,
COD, charge to account with shipper)
- the test fee does not include shipping
costs
- customers are responsible for all
shipping costs
- If no instructions are given, NIST will
return the test item by common carrier,
collect, and uninsured.
- Send the purchase order to:
- National Institute of Standards and Technology
- Calibration Program
- Building 820, Room 232
- Gaithersburg, MD 20899-0001
-
- Tel.: (301) 975-2002
- FAX: (301) 869-3548
- E-mail: calibrations@enh.nist.gov.
- Send the test item(s) to:
- Charles Gibson
- NIST
- Building 221 / Room B208
- Gaithersburg, MD 20899-0001
-
- Tel.: (301) 975-2329
- FAX: (301) 869-5700
- E-mail: cgibson@nist.gov.
Radiance temperature calibrations are performed in February,
May, August, and November. Requests for calibration services are
scheduled after the receipt of a purchase order.
NIST policy requires prepayment of all calibration services
performed for non-U.S. organizations. Please contact Denise
Lockard of the Calibration Program office to arrange payment. The
Fax number is 301-869-3548. The e-mail address is calibrations@nist.gov.
- Aerospace industry
- Industrial users including aluminum, glass, and steel
manufacturers
- NASA
- National standards laboratories
- Pyrometer and blackbody manufacturers
- Research universities
- US military service calibration laboratories
OTD Home Page |
Site Comments
Online: September 1997 - Last updated: May 2003
|