The Metrology team focuses on

• Development of a new generation gloss meter
• Near field goniometry
• Integrating sphere measurements
• Absolute radiometry, photometry and colorimetry (calibration)
• Quantum efficiency of wavelength conversion
• BRDF
• Measurement accuracy

We are developing new measurement set-ups and try to improve existing measurement approaches.

Description

In 2010 the light and lighting laboratory purchased three near field photogoniometers with financial support of the Hercules foundation. This goniometers allow the measurement of the luminous intensity pattern, luminous flux and complete ray data sets of all kinds of light sources with dimensions from a couple of mm to 1.8 m. The goniometers are equipped with three sensors: a photo meter, a luminance camera and a spectrometer. The sensors rotate at a short distance around the fixed test object. The classic ‘far field intensity distribution’ is derived from the measured ‘near field intensity distribution’.

Possibilities

• Determination of the intensity pattern with an angle resolution of 0.1°x0.1°
• Determination of luminous flux (lm)
• Measurement of a ray data set
• Measurement of the spectrum of the light source
• Determination of colour coordinates, correlated colour temperature (CCT) and CRI

Calibration source

• LMT calibration source (PTB, Germany): calibrated for the luminous flux

Norms

• CIE 121-1996 The Photometry and Goniophotometry of Luminaires
• CIE 15-2004 Photometry
• TC2-62 Imaging-photometer-based near-field goniophotometry (draftversie)
• EN 13032-1: Light and lighting - measurement and presentation of photometric data of lamps and luminaires - part 1: Measurement and file format
• EN 13032-2: Light and lighting - measurement and presentation of photometric data of lamps and luminaires - part 2: Presentation of data for indoor and outdoor work places
• CIE 15 "Colorimetry"
• CIE 63 "The spectroradiometric measurement of light sources"
• IES LM-79 "Electrical and Photometric measurement of solid-state lighting Products"

Links

• General information on the three goniophotometers

Description

In 2000, a goniophotometer was designed to determine retro reflective properties of traffic signs and verify whether they satisfy the regulations. Soon, this setup was modified to allow characterization of traffic lights and light sources in general as well. The test object is mounted in the goniophotometer which can rotate the object in all directions. At a distance of 9 m from the object, the TOP100 luminance probe detects the emitted (or reflected in the case of retro reflective measurements) light in one direction. The luminance probe is connected with a spectrometer with CCD to allow spectral analysis. This allows the determination of the spectral radiant intensity pattern of light sources.

Possibilities

• Measurement of the spectral radiance [W/(sr.m².nm)] or radiant intensity [W/(sr.nm)] of a light source
• Determination of the spectrum, luminance (Cd/m²) and luminous intensity (Cd) of a light source
• Determination of the  intensity pattern in 4 planes (C0, C90, C180 and C270) with y-interval of 2.5°
• Determination of retro reflection of films and traffic signs

Calibration source

• Bentham SRS8 calibration source: calibrated for spectral radiance and radiant intensity (by NPL) for the visible wavelength range (380 to 780 nm).

Norms

• European norm for traffic lights (EN12368)
• European norm for variable message signs (prEN12966)
• CIE 121-1996 The Photometry and Goniophotometry of Luminaires
• CIE 15-2004 Photometry

Different spectrometer are available in the light & lighting laboratory.

Oriel Instruments 74055 MS260i

This spectrometer has three (exchangable) grating, which can all be optimized for a different wavelength range. The spectrometer is equipped with a Andor iDUS 420 CCD (suited for the visible spectrum), but can be accommodated with a second CCD. Within the laboratory, an Andor DU490A-1.7 InGaAs CCD is available for measurements in the near-infrared.

The spectrometer offers great flexibility and has no fixed wavelength range or bandwidth. It is i.a. used for spectral radiance measurements, can be connected to the goniometer CIE Type 1, it can be used for spectral radiant flux measurement with an integrating sphere, and in combination with the QE measurement setup.

Ocean Optics QE65000

This spectrometer is compact (18,2 x 11 x 4,7 cm) and equipped with a built-in Hamamatsu FFT-CCD. This spectrometer has a fixed grating, the wavelength range is from 350 to 950 nm. The compact dimensions of this spectrometer allow for measurements on location. The unit is i.a. used for spectral irradiance measurements.

In addition, there are some Red Tide USB-650 plug-and-play spectrometers from Ocean Optics for demonstration and lab exercises.

 

 

Description

The P9710 Optometer is an instrument which can be used for illuminance (lux) or irradiance (W/m²) measurements, depending on the connected sensor. These sensors convert a detected optical signal to an electrical current. This current is measured and converted to the desired quantity and presented on the display of the P9710. The optometer can be used manually or can be controlled with a computer through a RS-232 connection. The device can be connected to an oscilloscope to visualize the input current. The battery autonomy is approximately 5 hours.

Specifications

• LCD-display: 2x16 chars, LED backlight
• Battery: 6 V / 0.5 Ah, 5 hours autonomy with backlight, 12 hours without backlight
• Power supply: 7.5 - 8.0 VDC / min. 250 mA
• Detector connector: 9pin DSUB
• Calibration data: stored in the EEPROM of the detector connector
• Remote interface: RS-232 (9600 Baud, 8 data bit, 1 stop bit, no parity)

Description

The BSDF setup allows the spectral measurement of the angular reflection and transmission pattern of a material under different irradiation geometries.

The setup consists of two parts: the irradiation section and the detection section. The irradiation section consists of a Xe lamp (250 W). Using a collimating mirror, a parallel beam is created, which is directed towards the sample. A filter wheel with neutral density filters can be inserted in the path of light to enhance the dynamic range of the setup. The sample is positioned in a sample holder, which allows rotation around two axes (vertical and horizontal). This allows the selection on any incident direction of the beam on the sample. The detection part consists of a bench which can be rotated (using stepper motors) around two axes. This allows the selection of any viewing angle. A detector is positioned at the end of the bench, which is connected to a spectrometer with CCD with an optical fiber.

Specifications

• Xe light source (300 W)
• Filter wheel with 3 neutral density filters, dynamic range > 6 decades
• Full 3D range (reflection and transmission)
• Angular resolution: 1.8°
• Spectrometer with CCD: spectral measurements
• Wavelength range VIS CCD: 360-800 nm
• Spectral bandwidth: 3.5 nm

Two kinds of luminance measurement devices are available in the Light & Lighting Laboratory: the Eldim Muratest luminance camera and two Minolta LS-100 hand luminance meters. Both luminance meters are ‘mobile’ (and can be used on location) but differ significantly in accuracy and ease of use.

Eldim Muratest

The Eldim Muratest luminance camera performs detailed luminance measurements of light sources and reflective surfaces. For each measurement an image is created and results in the luminance value per pixel. The Muratest camera can also be used to measure spatially resolved colour coordinates.

 

Minolta LS-100

The Minolta LS-100 hand luminance meter is a mobile device, which allows quick luminance measurements. The luminance meter returns the average luminance of one measurement area.

 

 

 

Description

The Hunterlab UltraScan Pro colorimeter can be used for colour measurements in both reflection and transmission. A spectral measurement over the wavelength range from 350 nm to 1050 nm is done and allow the determination of the colour characteristics of the test object. The measurements are performed in d/8° geometry.

Specifications

• Calibrated D65 light source
• Resolution: 5 nm
• Wavelength range: 350 – 1050 nm
• Geometry: d/8°

Norms

The Hunterlab UltraScan Pro meets the requirements for colour measurements according to:

• CIE
• ASTM
• USP

General info Hunterlab UltraScan Pro

The Quantum Efficiency (QE) setup was designed in the light & lighting laboratory and consists of a Xenon lamp, an integrating sphere (GigaHertz Optik, met ODM98 coating) and a spectrometer (Oriel Instruments 74055 MS260i). The selection of the excitation wavelength is done using an interference filter. The integrating sphere is equipped with a central mount sample holder, which allows the measurement of samples of 4 by 4 cm. The setup allows for the determination of the absorption at excitation wavelength, the emission spectrum, and the quantum efficiency of fluorescent materials.
The calibration of the setup is done using a halogen en deuterium irradiance standard (purchased from Bentham, calibrated by the National Physical Laboratory (NPL), UK).

Yokogawa WT3000

The light & lighting laboratory has with the precision power meter WT3000 from Yokogawa one of the most accurate power analyzers on the market. The WT3000 combines power measurements with high accuracy with a frequency range from 0.1 Hz to 1 MHz. The device has three independent input channels (with a 30 A current shunt). Using the G6 option for advanced calculations allows to perform broadband harmonic distortion measurements.

More information

Voltech PM1000

The PM1000 from Voltech can be used for accurate determination of electrical characteristics such as current, voltage and power. The device also allows the determination of the total harmonic distortion and power factor of the voltage and current.

When performing light measurements on light sources, it is important to have a stable and controlled electrical supply. The luminous flux can be highly influenced by a variable voltage supply (variations in amplitude, harmonic distortion…). Most norms require a perfect sinusoidal voltage supply with a specific amplitude and frequency for light measurements.

Several controlled power supplies are available in the Light & Lighting Laboratory.

Voltage supply Agilent, type 6813B

Specifications

• Maximum ratings: 1750 VA, 300V rms, 13 A rms, crest factor 6 TEST
• Frequency range: DC and AC from 45 Hz to 1 kHz
• Possibility to create a specified non-sinusoidal wave form.
• Possibility to create controlled voltage drops, transients…

DC-bron SM120-13 (Delta Elektronika)

Description

The DC-supply SM120-13 from Delta Elektronika is a stable current and voltage supply. The voltage can be set between 0 and 120 V, the current between 0 and 13 A.

Elgar CW901P sinusoidal voltage supply

Description

The Elgar, type CW801P (800 VA) is a single phase voltage supply which creates a stable sinusoidal voltage.

TracePro®  is a ray tracing software package which can be used for general optical simulations and more specific for the design of luminaires. When a light source and a 3D CAD model of a luminaire are available, TracePro® can be used to investigate the optical properties of the system. To this end, rays are traced through the 3D CAD model, taking absorption, reflection, refraction, and scattering into account.

The software allows to calculate radiometric and photometric data, such as irradiance, radiant intensity pattersn, radiance…

Computer simulations are only reliable if the input parameters are determined sufficiently accurate. In the Light & Lighting Laboratory, a lot of measurement equipment is available to allow accurate determination of these input parameters:

• Measurement of BRDF and BTDF of materials
• Optical characterization of light sources, which can be implemented as ‘ray files’ in the ray tracing software. The ray files can be obtained using the Near-field goniophotometers.
• Measurement of intensity patterns of luminaires
• Measurement of luminance of surfaces
• ...