MURAKAMI - Avian Optics and Spectroscopy Group

MURAKAMI

Color Research Laboratory

11-3 Kachidoki 3-Chome Chuo-Ku Tokyo 104 Japan Tel: +81 3 3532 3011 Fax: +81 3 3532 2056

GCMS-3 GONIOSPECTROPHOTOMETER SYSTEM GSP-1 Main

System Overview The colour and surface appearance of materials illustrated by pearlescent paint, changes depending on the incident and viewing angles of the light.. This phenomenon is commonly called the “Flop Effect”. The GCMS-3 GonioSpectrophotometric Colour Measurement System permits the user to automatically vary the incident and viewing angles over a broad range, thus building a multi-angle reflectance profile for the specimen under evaluation. The system comprises the GSP-1 Optical Measurement Unit operated in conjunction with GCMS-Win Software running on a Windows™-based PC. The GSP-1 optical sensor features a true dual-beam design wherein the reflectance from the specimen is compared continuously against that of a reference plate. This offers very high stability and measurement precision. This facility also provides automatic correction for the variation in intensity, and the area of illumination / viewing, as a consequence of rotating the specimen in the light path. The GSP-1 features a highspeed detection system to derive spectral information, which reduces the measurement time particularly at high angular resolutions. The GCMS-Win Software is an interractive package allowing the user to create defined setups to speed up routine and repetitive tests. In each named setup, the measurement mode, incident angle and receiving angle range may be entered with a selection of spectral and tristimulus data tables, and a wide range of graphical displays illustrating the colorimetric distribution. Avian Group USA/ P.O. Box 822/Wilmington.Ohio 45177 USA

www.aviangroupusa.com

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Data may be readily transferred from GCMS-Win into other Windows-based software applications such as spreadsheets, for further analysis. Data is captured from the GSP-1 sensor unit and stored in spectral form which enables the user to alter the colour scale, illuminant and observer function retrospectively, without the need to re-measure the sample. The software automatically detects a connection to the GSP-1 and if not present, enters “data recall” mode – data files stored in the PC may be re-opened for further processing and display. Applications The GCMS-3 is suitable for evaluating the angular colour and lightness distribution of a wide range of materials including: ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦

Pearl-mica and metallic paints Anodised and metallised coatings and inks Hair treatments – colorants and conditioners Coated Glass Plastics Retro-reflective, coated and pearl-effect textiles Cosmetics Lquid-crystal displays

Avian Group USA/ P.O. Box 822/Wilmington.Ohio 45177 USA


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GSP-1 Optical Measurement Unit – Principle of Operation

The sample to be measured (5) is clamped into place on the sample stage with manuallyadjustable tilt (“flapping”) angle (3). This stage accepts samples up to 195 x 220 mm and has a broad aperture to allow a wide range of incident and viewing angles. Fine adjustment of the flapping angle can be made by the micrometer assembly (4). During calibration, the sample is replaced by a barium sulphate-coated white standard plate. The reference white plate (6), similarly barium sulphate-coated, is positioned in its receptacle and remains in place throughout routine measurements. The entire sample platform (2) rotates in accordance with the parameter settings made in the software, between limits of -80° and +80° from the normal (perpendicular to the sample plane). The lamp housing (1) incorporates a single tungsten halogen source lamp which is divided into two identical beams via mirrors, lenses and heat filters. The sample beam (1S) and reference beam (1R) exit through apertures. The lamp housing rotates on the same axis as the sample platform to provide a variable incident angle, again within the range of ± 80° from the normal. The light reflected from the sample, and that from the reference white plate enter the sample receptor (7S) and reference receptor (7R) respectively. Each beam is directed to the fixed detection system via a mirror and through a beam chopper assembly. The chopper alternately directs the reference beam and the sample beam to the monochromator via a lens system. The light from the monochromator is dispersed into each wavelength via a diffraction grating and then is photoelectrically converted by the elements of a photodiode array. The electrical signals are amplified by a wavelenth-independent amplifier, transformed to digital signals by an A/D converter, and then transmitted to the PC via a GP-IB IEEE interface for processing into the userselected colour scales and displays. Avian Group USA/ P.O. Box 822/Wilmington.Ohio 45177 USA


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The raw data comprises spectral reflectance and angular locus of the lamp housing and sample stage relative to the fixed detector. In the case of highly-reflective or glossy sample surfaces, the light reflected from the sample close to the specular angle may approach the saturation level of the detection system. To counteract this, the sample and reference receptors incorporate a filter wheel. A series of neutraldensity (mesh) filters are automatically introduced into the receptor light path until the detection system is no longer light-saturated. The reflectance data is then compensated by the transmittance of the appropriate filter used. Below is a functional schematic:

Filter wheel

Fixed Detector Housing

Flapping angle δ° (manually-adjusted)

Chopper

Sample

Receiving angle R° Incident angle I °

Polychromator/ Diode Array

Reference plate (barium sulphate)

Lamp housing / beam splitter

Specimen table

Setting I° + R°

Sample Stage and Lamp Housing Common Rotational Axis



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Setting R°

Specifications GSP-1 Optical Sensor Unit Measurement System

Dual-Beam Optics with Reference Plate

Light Source

12V 100W Halogen Lamp

Lamp Life

1000 hrs Nominal

Monochromator

Concave Diffraction Grating

Detector

Silicon Photodiode Array

Wavelength Range

390 – 730 nm

Wavelength Interval

10 nm

Spectral Bandpass

approx. 10 nm

Wavelength Accuracy

± 1 nm @ 560nm

Wavelength Repeatability

± 0.1 nm

Measurement Ranges: Incident (illumination) Angle - 80º to + 80º Receiving (viewing) Angle - 80° to + 80° (except when incident angle + receiving angle ≤ 12° as lamp housing obstructs receptor) Angular Accuracy

within ± 0.5°

Angular Resolution

0.1° (resolution of absolute encoder)

Viewed Area

approx. 8 x 16 mm at 0° receiving angle approx. 8 x 94mm at 80° receiving angle (with flapping angle = 0°)

Aperture Angles: Source image angle Receptor aperture

± 1.05° in plane of measurement ± 2.10° perpendicular to plane of measurement ± 1° in circle

Neutral Density Filter Range

Reduces sample to 30, 10, 3, 1, 0.3, 0.1, or 0.03%

Measurement Duration

approx. 3 seconds per angle increment

Measurement Accuracy

within ± 0.5%

Repeatability

0.05% SD ( white tile measured 45°/0° at 560nm)

Dimensions (mm) / Weight

566 (W) x 972 (D) x 922 (H) / 86kg

Power Requirements

100V AC, 50/60 Hz, 4A (for Europe, 220 - 240V AC, 1KVA transformer recommended)

Computer Interface

GP-IB (PC) F by Contec Ltd



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GCMS-Win Software Tool Bar Functions Start Scale Display Print Save

Begin, Pause or Continue Measurement Sequence Select and Configure Colour Scales and Graphical Displays Begin Screen Output of Measured or Stored Data Print Pre-Selected Display Windows Manually Store Data in User-Specified File

Menu Functions File Setup Colour Difference Calibration Measurement menu

Window Maintenance

Open Saved Data File, Save Setups, File Conversion, Quit Global , Screen Display, Printer, Sensor and Calibration Data Selecting Product Standards Execute using White Reference Tile, Enter New Cal. Tile Data. Measurement Mode selection R-Scan - Incident and Inclination (Flapping) angles fixed I -Scan - Receiving and Flapping angles fixed F-Scan – Incident and Receiving angles fixed Selection of Incident angle or range and increment size Receiving angle or range and increment size Flapping angle or range and increment size Saving as Named Measurement Setup Tile, Cascade, Arrange Lamp Setup and Diagnostic Functions

Colorimetric Calculations Spectral Reflectance Colour Scales Illuminants Observer Functions

Radiance Factor (%) , 10nm Intervals, 390 – 730 nm CIE XYZ, CIE L*a*b*,C*ab, h* ab, Yxy,Hunter Lab, CIE L*U*V*, AN-40 A, C, D65, D50, D55, D75, F 2°, 10°

Tabular and Graphical Displays Data Tables

Spectral Distribution v. Angle ( I, R, F ) Tristimulus Data (user-defined)

Graphs (auto or manual scaling)

Spectral Distribution v. Angle ( 2-D ) Spectral Distribution v. Angle ( 3-D ) L,a,b Change v. Angle ( 2-D ) ab Chromaticity Change v. Angle ( 3-D animated ) xy Chromaticity Change v. Angle ( 2-D ) Optional Data v. Angle ( 2-D , XY and Polar )

( Right-hand mouse button opens COPY / PASTE menu selection to other Windows applications )

Computer Requirements

Pentium™ 433 or higher 64Mb Ram or higher 100Mb free hard disk space 17in SVGA monitor or larger recommended, > 32,000 colours 1 free ISA / PCI card slot Windows™ 95 or 98 (NT4.0 in future)



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Examples of GCMS-Win Screen Displays



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