Why measure gloss?
Gloss is an aspect of the visual perception of objects that is as important as colour when considering the psychological impact of products on a
Objects made from transparent materials are common in everyday life, clear plastic is used in packaging film and drinks bottles, windowpanes and windshields are made from glass, mobile phones are protected by a clear protective display.
The function of transparent materials is often to form a barrier which allows a clear view of a protected object or a scene beyond it. Manufactured products however, are rarely perfectly transparent-inhomogenieties in base material, surface texture caused during manufacture or scratches and abrasion reduce see-through quality.
As these effects can reduce the perceived quality and functionality it is important that they are accurately quantified. Accurate measurement provides opportunities to optimise materials or processes during manufacture.
Materials with high optical quality have low visual impact on objects viewed through them. The material itself is visually unobtrusive and almost invisible to the observer.
A hazy material causes colour seen through the material to appear washed out or faded. The severity of this loss of contrast is often related to the size of the gap between the object and the material.
A material which blurs the view of objects has low sharpness- this effect can be directional causing a visible pattern to be seen in the material.
Materials with poor optical qualities are visually intrusive and can be described as milky or opalescent. Patterns and texture which may be visible in the material drastically blur viewed objects.
The Rhopoint ID measurement technology (patent pending) was jointly developed with Eidgenössische Technische Hochschule (ETH) Zürich.
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Light passes through material covering the graticule and reaches the camera where it is converted into a reading.
Traditional haze-meters measure light scattering, an indirect measurement of appearance that does not fully capture the optical transmission properties of a material.
Rhopoint Haze (H) measurement are compatible with ASTM 1003 measurements made with a traditional transmission haze meter, the most specified parameter for transparent materials.
A backlit, high accuracy, reference target graticule functions as the viewed object, creating a highly defined pattern of light intensities with optimally sharp transitions between the backlit and masked areas.
The camera works like the human eye quantifying changes in the transmission of the light caused by a test material.
Image analysis techniques are used to characterise these effects into parameters which correlate closely with human perceptions.
Haze: quantifies the loss of contrast for objects viewed through a material.
When a material has haze, it changes the appearance of both the material and any objects viewed through it. This can lead to a reduction in perceived quality.
Measure Haze with the Rhopoint ID to ensure visibility of products are at their best and can be seen properly by the customer.
Perception | Description |
---|---|
No Haze |
|
Perfect Sharpness |
|
H = 0%
S = 100%
T = 100%
Perception | Description |
---|---|
Medium Haze |
|
High Sharpness |
|
H = 10.4%
S = 92.32%
T = 92.3%
Perception | Description |
---|---|
High Haze |
|
Low Sharpness |
|
H = 30%
S = 78.8%
T = 89.7%
Haze can be affected by factors such as the choice of resin, the moulding process and any surface textures. Haze can be caused by:
For example, a plastic with an incorrect melt viscosity for a particular process.
Cooling a plastic material too quickly can introduce micro textures onto the surface of the film or structures in the bulk which reduce optical quality.
Wear and tear in moulds, chill rollers and slip dies can induce visible surface defects in the material.
Sharpness quantifies the loss of perceived detail for objects viewed through a material.
When viewed through a material with high sharpness, an object appears sharp and distinct. As material sharpness decreases, the object appears blurry and obscured.
A material can often exhibit optical effects which are directional. These phenomena are often induced in plastic parts by specific processing faults.
Visible texture is a common feature of plastic films and causes a significant reduction in their see- through quality.
The Rhopoint ID is the only instrument that can measure directional effects in materials using the ID laboratory analysis software.
The images to the right show the visual impact of different ID Sharpness (S) values in vertical and horizontal directions.
Measuring directional effects can be used in advanced optical quality control and for adjusting processing parameters to obtain optimal transparency.
Note: Clarity and Sharpness do NOT capture poor optical characteristics associated with wavy/orange peel surfaces.
Quantifies the blurriness of an object when viewed through a material, results are proportionate with Sharpness, but the measurement scale is compressed and the measurement resolution is reduced.
Clarity is a scale used by traditional haze and clarity meters. When measured using the 8mm adaptor plate, Rhopoint ID Clarity data conforms to specifications written for these meters.
Inter-instrument Clarity agreement between Rhopoint ID and traditional sphere instruments for commercial plastic films (<1000μm) is typically <0.4% C (SD).
Inter-instrument Clarity agreement between traditional sphere instruments and Rhopoint ID for thick transparent plastic materials (<6mm) is typically <0.5% C (SD).
Better measurement resolution than clarity.
Compatible measurement with existing measurements.
Waviness is an optical effect caused by large structures (0.1-2mm) on the surface of the material. If the structure is homogeneous it is often described as orange peel – the surface resembles the peel of an orange.
If the effect is anisotropic, visible lines can often be seen when looking through the material.
Unlike sharpness, these larger structures can cause dynamic distortion when the film is moved over a target image/object which has straight edges – the edges appear to distort and wave as the material is moved.
Waviness measures the visible distortion of the ID graticule edges through the material. W is the standard deviation of the edge deformation in μm.
Waviness homogeneity is assessed by comparing W (average waviness) with WH (horizontal waviness) and Wv (vertical waviness) using Rhopoint ID software available with the Rhopoint ID-L version.
Many materials exhibit a variation of transparency depending on whether the material is in contact with a viewed object, or separated by an ‘air gap’ distance between them.
Matching the material exactly to the application allows quality improvements and production cost savings.
To match a specific material application the Rhopoint ID can measure ID Haze at any distance within 0–40 mm.
Using the ID it is possible to identify the air gap distance at which maximum Haze is obtained (typically <25 mm).
The images below show the effect of air gap distance for a hazy plastic film held in front of an image.
Direct measurement of haze from transmission image contrast
Measured in contact or at user-defined distance between material and object (0–40 mm)
Measures distance dependence on the same scale as ASTM Haze
Direct measurement of transparency via contrast of black and white areas on target graticule
Measure and understand distance dependent haze
When considering how material is perceived by a consumer it is important to consider how bright an object viewed through it will appear.*
*Traditional hazemeters measure total transmission which is related to light absorption not visual perception
The Rhopoint ID has been designed to measure samples for haze, transmittance and sharpness quickly and safely.
Eliminates risk of mechanical failure
Small footprint reduces space required in laboratory
Easy to move in the laboratory or production line
Made from durable, recyclable materials
The Rhopoint ID is suitable for laboratory or production use.
ID-L | |
---|---|
Measures Haze, Transmission, Sharpness and Clarity | ✓ |
Operate in stand-alone mode | ✓ |
Measure (ID) with the sample material in contact with test target | ✓ |
Measure non contact distance haze and transmittance up to 40mm | ✓ |
Measure Waviness | ✓ |
Measure curved parts - bottles, tubes and pipes | ✓ |
Detailed analysis software | ✓ |
Anisotropic Sharpness measurement | ✓ |
Live view makes it easy to position test sample and locate specific areas of interest | ✓ |
The Rhopoint ID-L analysis software enables detailed visual analysis of the sample using LIVE VIEW. Statistical analysis of multiple test results is shown for each measured parameter. • Saves all the results as a CSV file
Sharpness | Haze | Clarity | Transmission | |||
---|---|---|---|---|---|---|
Range | 0-100% | 0-10% | 10-100% | 0-100% | ||
Resolution | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | |
Repeatability SD | 0.1 | 0.05 | 0.05 | 0.03 | 0.05 | |
Reproducibility SD | 1 | 0.2 | 0.5 | 0.3 | ||
Inter-instrument Agreement Rhopoint ID vs Traditional Haze & Clarity Instrument SD* | N/A | 0.2 | 0.5 | 0.4 | N/A | |
Effective Operating Range | Materials T > 50% | Materials T > 50% | Materials T > 50% |
*Typical values – packaging film <1000µm
Instrument Information | ID-L |
---|---|
Measurement Mode | Contact and Non Contact |
Non Contact Distance | Up to 40mm |
Material Thickness | <30mm |
Software | Rhopoint ID-Analysis |
Connection | Ethernet LAN |
Spatial Resolution | 12μm |
Imaged Area | 20mm x 20mm |
Minimum measurement area (Haze, Sharpness) | 6x2mm |
Minimum measurement area (Transmittance) | 2x2mm |
Image Format | 16 Bit Tiff |
Image Sensor Size | 1280x1024 |
Operating Temperature | 10-40°C |
Dimensions h x Ø | 470 x 125 mm |
Weight | 3.95 Kg |
Packed Weight | 6.7 Kg |
Power | 110/230V |
Product | Included Accessories | Order Code |
---|---|---|
Rhopoint ID-L | 1 x USB drive (contains software / manual ) • 1 x checking standard • 1 x calibration certificate 1 x 8mm spacer (ASTM) • 1 x 5mm spacer • 1x LAN cable and 1x USB2 to LAN adaptor | A3100-001 |
Optional accessories for ID-L | Order Code |
---|---|
Abrasion adaptor | B3100-002 |
Surface roughness adaptor | B3100-003 |
20mm distance haze pack | B3100-001 |
Rhopoint transmission check standard - 25% | B3100-012 |
Rhopoint transmission check standard - 50% | B3100-011 |
Rhopoint transmission check standard - 70% | B3100-008 |
Order code | ||
---|---|---|
20mm distance haze pack
|
B3100-001 | |
Abrasion adaptorAllows Taber abraded samples to be mounted on the Rhopoint ID-L |
B3100-002 | |
Surface roughness adaptorAllows the roughness of the film on each side to be isolated and measured without submersing the material in oil |
B3100-003 |
Free extended 2 year warranty: Requires registration at www.rhopointinstruments.com/help-services/forms-feedback/instrument-registration/ within 28 days of purchase. Without registration, 1 year standard warranty applies.
Fast and economic service via our global network of accredited calibration and service centres. Please visit www.rhopointinstruments.com/help-services/calibration-servicing/ for detailed information.
Gloss is an aspect of the visual perception of objects that is as important as colour when considering the psychological impact of products on a
Identify the surface that you wish to measure. Is it a flat surface? If so, it can be measured with a traditonal glossmeter. Curved surfaces
RSpec is the peak reflectance measured over a very narrow angular band in the specular direction (+/-) 0.0991º. RSpec is very sensitive to any texture
Please note, this is NOT a quotation, just a confirmation of the price when purchased in the UK exclusive of VAT/duties
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