Calibration
Contact Persons
Dr. Daniel Schläpfer |
Keywords
Bidirectional Effects, Goniometry, Spectral Radiometry, BRDF, Laboratory
Abstract
The Calibration Pool contains of different instruments for calibration purposes and therefore provides the reliability of the whole measurement equipement. The calibration devices are:
- Integrating Sphere
- Irradiance Source
- Spectralon Panel
- Wavelength Standard
Instruments
Integrating Sphere
Parameter | Description |
Manufacturer | Optronic Laboratories Inc., Orlando (FL) USA |
Spere Diameter | 8 inches (4, 6, 12 or 18 inches are also available) |
Exit Port Diameter | 2 inches (1, 1.5, 3 or 6 inches respectively) |
Luminance Uncertainty (relative to NIST) | ± 2 % |
Spectral Radiance Calibration | ± 3 to ± 6 % |
Color Temperature Range | 2000 - 3000 K |
Color Temperature Uncertainty | ± 25 K |
Luminance Stability | ± 0.5 % |
Maximum Luminance at 2856 K | 3000 fL |
Maximum Luminance at 3000 K | 5000 fL |
Minimum Luminance | 0.001 fL |
Size, Weight | 42.55 x 26.04 x 26.04 cm / ?? |
Shutter | open / close |
Light Source | 150 W tungsten quarz-halogen lamp |
Purpose:
The Integrating spheres are widely used to calibrate spectroradiometric measurement devices. Several types of measurements such as diffuse reflectance, specular reflectance and diffuse transmittance can be performed using an integrating shere. In general an integrating shere is a hollow shere which has its interior coated with a substance that is nearly perfectly diffuse or lambertian. For accurate radiance calibration of a spectroradiometer, the sphere as a source of uniform radiation as a secondary is discussed.
This Integrating Sphere (OL Series 455-8-2) consists of a source module/optics head and a separate electronic display console/power supply (OL 450 Controller). This enables remote location of either unit which facilitates anlignment or positioning of the source with respect to the device to be calibrated. This Integrating Sphere can also be obtained with calibrations of spectral radiance over 350 to 2500nm wavelength region.
Irradiance Source
Parameter | Description |
Manufacturer | |
Elements | QTH Power Supply |
Spectral Range | 450-2500 nm |
AC Input | 95-130 VAC/18 A, 190-260 VAC/9 A, 50/60 Hz |
DC Output | 0-10 A, 0-130 V, 0-1100 W |
Max. T. for QTH | 40° |
Weight of QTH | 22 kg |
Size of Lamp Housing | 222 x 216 x 444 mm |
Condenser material | Borosilicate Crown Glass and Fused Silica |
Axial Transmittance | 70-75 % (coated ~80%) |
Norm f (at 589 nm) | 51,7 mm |
Norm BFL (at 589 nm) | 25,3 mm |
Bulb Diameter | 40 mm |
Operating Environment | under construction |
Purpose | Simulation of Sunlight (energy and spectral range) in the laboratory for inside measurements comparable to field measurements. |
Spectralon Panel
Parameter | Description |
Manufacturer | Labsphere Inc., North Sutton (NH) USA |
Spectral Range | 250 - 2500 nm |
Intended purpose | UV - VIS - NIR |
Generally reflectance | > 99 % from 400 - 1500 nm, > 95 % from 250 - 2500 nm |
Reflectance variance | < 5 % from 250 - 2500 nm |
Material | Thermoplastic resin |
Density | 1.25 -1.5 g/cm³ |
Size, Weight | ?? |
Damages due to weathering | None |
Thermal stability | Decomposes at >400° C |
Purpose:
Spectralon diffuse reflectance standards are calibrated and traceable to The National Institute of Standards and Technology (NIST). They are available individually and in sets consisting of a diffuse white standard, and a selection of diffuse gray standards. Each is supplied with diffuse reflectance data from 250mm to 2500mm, in 50 mm increments. Optional intervals are available. Spectralon diffuse white standards offer the highest diffuse reflectance values of any known substance. These durable, chemically inert and washable standards have typical reflectance values of 95% to 99% and are spectrally flat over the UV-VIS-NIR spectrum. All Spectralon materials are typically flat to +/- 4% over the range of 250 to 2500 nm and +/- 1% over the photopic region of the spectrum.
Spectralon reflectance standards and materials are highly lambertian over their effective spectral range. Spectralon SRM-99 reflectance material is the most lambertian reflector available for use over the wavelength range from 250 - 2500 nm.
Wavelength Standard
Parameter | Description |
Manufacturer | Labsphere Inc., North Sutton (NH) USA ID - number: |
Spectral Range | 250 - 2500 nm |
Intended purpose | UV - VIS - NIR |
Generally reflectance | ?? |
Reflectance variance | ?? |
Material | ?? |
Density | ?? |
Diameter | 5 cm |
Damages due to weathering | ?? |
Thermal stability | ?? |
