pab Gonio-Photometer PG2 for reflection/transmission of materials, BSDF measurements

The next generation in scanning gonio-photometers: Our gonio-photometers measure the angular transmittance/reflectance of arbitrary materials (BSDF) and the angular light distribution of small lamps.
The design and its details are based over 20 years experience in light measurements, providing an efficient combination of precision, angular coverage and speed.

Applications

• out-of-plane, absolute BSDF,BRDF measurements in UV, VIS, near and middle IR, according to ASTM E2387-05
  
• typical sample size 110x110 [mm], largest sample size 0.9m x 1m
  
• measured angular light distribution is known as BSDF, BRDF or BRTF.
  Besides different names used in different fields (Computer Graphics, Architecture, Engineering), this is the same quantity in Physics.
• additionally, the angular distribution of small light sources, e.g. LEDs, can be measured.
• our own measurement services with the PG2 and our consulting work are described at our sister site pab-opto

Videos

More PG2 videos, technical details of the scanning process and examples of measured samples.

Key features

• high dynamic range, 100% angular uniform coverage by design
• combines small-angle-scattering with resolution below 1mrad and full-sphere measurements
• sophisticated control achieves superior angular precision (below 1 mrad)
• unique mechanical concept features unobstructed scan area
• fast measurements on-the-fly with 1kHz sampling rate plus adaptive sampling algorithms.
  This unique scan principle is illustrated in the videos, see link below.
• modular lights sources, detectors and sample mounts cover wide spectral ranges
  radiometric, photometric, and IR measurements
• unattended operation:
  redundant position sensors and integrated fault detection for stand-alone 24h operation,
  optional sample changers offer automatic batch measurements
  integration of sample management using bar-codes
  closely integrated safety devices, interlock standard
• Linux based control system for stable operation
  Integration into external computer infrastructure using standard protocols (DHCP, HTTP, SQL and SSH)
  
• flexible measurements profiles:
  second generation control software with graphical-front-ends (GUI) and programming interface (API), based on years of experience in BRTF/BSDF/BRDF measurements
• optional media supply to sample and detector
• weight: 310kg, minimum space height/width/length: 2.7m/4m/6m, electric: 400V AC 3x16A, 50 or 60Hz, network: Ethernet TP100, detailed parameters upon request
• CE certified, version with UL approved electric components available for US market
• custom designed add-ons available

Details

Light source for transmittance/reflectance measurements

Light sources are mounted on a standard optical bench, including collimating optics and custom baffles. We supply halogen lamps, diode lasers, gas lasers, LEDs or Xenon short arc lamps as standard light source, depending on your measurement requirements. Multiple lamp setups can be mounted in parallel and selected by software. The incident light is typically collimated and focused on the sample centre or the detector, user adjustable.

Sample mounting

Sample mounting is modular and adapted to the type of measurement: Different modules can be mounted on a centre turntable, which supports a maximum weight of 50kg and has a fine angular positioning resolution.

• Shown in above rendering is the automatic sample changer phirot 5, featuring 5 samples with 110mm x 110mm maximum size under full digital control. The active sample can be be rotated around its surface normal providing a second incident angle φ_in. This adjusts the sample for any arbitrary incident direction.
• The phirot2 mount allows two samples of ISO-A4 size and features computer controlled rotation around its surface normal. Minimum guaranteed precision for φ_in is 0.1° .
• The standard manual sample attachment (see 2D drawing) offers a more general attachment, caring for "exotic" sample shapes and sizes.
• A large sample holder (LSH) allows a generic maximum sample size of 0.9m by 1m.

Detector features

Basically the setup consists of a detector, which is moved fast at a constant distance around the sample centre. The detector is mounted at the end of a linkage consisting of two light weight, optimised, booms made of a combination of steel and carbon-fibre. This design ensures rigid design and a maximum coverage of the sphere surrounding the sample, thus allowing unrestricted movement of the detector.

The detector head supports up to four individual channels that measure in parallel using custom designed low-noise, high-speed, wide-dynamic-range electronics. Each channel supports a variety of detector types, given wide spectral coverage.

Dimensions

Measurement setup at customer sites

Realistic Graphics Lab, EPFL, Switzerland installation in 2017 shown here before installation of armB for camera	Competence Centre Envelopes and Solar Energy (CC EASE) Luzern, Switzerland, During installation. The SERIS PG2 followed Prof. Wittkopf's group to Lucerne in July 2014.
SERIS, Singapore Solar Energy Research Institute of Singapore National University of Singapore during construction in 2009, featuring the LSH mount and dual light sources prior to installation of black drapes	Fraunhofer ISE, Germany during installation, shown here before installation of sample changers and large beam lamp
PG2 setup, LBNL, CA, USA Lawrence Berkeley National Laboratory Berkeley, CA, USA	industrial client during installation in 2007 shown here before installation of sample changer and black drapes

All images copyrighted by pab .

Complementary consulting on lab design

Drawing from experiences in setting up numerous labs for gonio-photometers over the years, it will be our pleasure to assists you with designing your measurement setup. Materials like black Molleton, with flame retardant certification (stage material) can be supplied.

Custom add-ons to the basic pgII set-up are a key feature of our service to provide you with the best available solution to your measurement requirements.

Publications on the PG2 gonio-photometer

• High-Power LEDs as Light Source in a Scanning Gonio-photometer for BSDF Scatter Measurements
  MSA2023, Metrology Society of Australasia, Wellington, New Zealand, 21.2.2023
• Flyer with summary of PG2 advantages, installed PG2s and some details
  
• Scanning Goniophotometers Improve Materials Selection
  Photonics Spectra, October 2012
• Räumliche Messung der Lichtstreuung - die BRDF in der Praxis (German text)
  Photonik 3/2011 (or download from us)
• New scanning gonio-photometer for extended BRDF measurements
  Proc. SPIE, Vol. 7792, 77920O (2010); doi:10.1117/12.860889 (or local PDF file, with corrected fig 9)

Contact for detailed parameters

contact by email: info@pab.eu. We'll be pleased to sent you further details, sample data or consult on your specific application and requirements.

Background and earlier work

This work is based on some years of experience, starting with the pab Ltd founder building a gonio-photometer in 1989 at what was to become Europe's largest solar energy research institute Fraunhofer-ISE as diploma (masters) work. This provided the basis of his PhD work. Some publications on this older gonio-photometer of same author:
Designing an apparatus for measuring bidirectional reflection/transmission, Proc. SPIE, Vol. 2255, 697 (1994); DOI link
Enhancing and calibrating a gonio-photometer, Solar Energy Materials & Solar Cells, 1998, 54, pp 309-322 ; DOI link
On the subject of angular units, see personal web-page of author about tachymeters.
After supervising other diploma works and BRDF measurements with the old setup, the new pgII machine had been designed at pab Ltd from scratch. This offered the conversion of experience to an outstanding design, which combines precision, flexibility and reliability. While firstly motivated to be used in-house for project work and consulting jobs, this gonio-photometer is available as a turn-key system to customers and has been installed worldwide.