Is there special surface finish required prior to inspection?
The advantage of Scientific Visual’s scanning technology is that it does not require you to either split a boule nor to provide a special surface finish. The inspection runs on a typical ‘as cut’ or ‘as grown’ surface, notably for HEM boules. The exception is for non-sliced Verneuil-grown carrots covered with a crust – the numerous sub-surface defects inherent in such pieces prevent light from traveling smoothly through them.
We inspect sapphire with baby oil and the naked eye. To what extent would SapphiroScan™ grading match our visual grading?
Scientific Visual’s automatic grading is objective and significantly superior to a human eye. Depending on the quality of your visual expertise you could normally expect to match it by between 90-97%.
The difference results from the subjectivity of human grading. This depends on the expert, as accuracy fluctuates dependent on the inspector’s mood and level of fatigue, etc.
Let us assume sapphire items are graded into two categories: Standard and Failed. For a human grading there will be some borderline cases which could be allocated to either of the two grades, depending on the personal opinion of the inspector. This ‘gray area’ typically covers 5-10% of an inspected batch. In other words, this is the margin of error that can be expected from human inspection, and which Scientific Visual’s technology eliminates.
The SapphiroScan™ grading is objective, therefore the border between the grades is a line, not a gray area. This explains why a 100% match between human and instrument grading is impossible.
Using SapphiroScan™ the borderline between Standard and Fail can be positioned differently, creating various inspection sensitivity or accuracy scenarios.
Therefore, the match between human and SapphiroScan™ grading depends on a width of the ‘human bordercase window’ and the selected SapphiroScan™ settings. This match is normally within 90-97%.
Could you capture a 'smoke'-like defects?
The ‘smoke’ (aka milkiness or microporosity) is a cluster of microbubbles in general in form of lines or a cloud. Individual microbubbles are not distinguishable by a human eye which leads to a cloud-like appearance, typically of a blue shade.
Its detection level could be customized with detection threshold parameters.
Smoke defect in KY sapphire boule.
Smoke defect (not the one depicted above) captured by SapphiroScan in a spinel disk ⌀ 30 mm produced by sintering.
Making automatic ‘Standard / Fail’ decisions based on observed defects is challenging. Could you tell more about the algorithms you use, and what to expect in the near future in terms of technology that addresses improvements in automatic quality grading?
Automatic clarity grading of a non-polished material is challenging, especially if we remember that until now the sapphire items have been graded by human eye. Scientific Visual is continuously working to improve its decision-making algorithms.
Generally speaking a ‘go / no-go’ decision based on the following factors:
1. Defect size
2. Defect shape and morphology
3. Visibility of defect (contrast to the clean material)
4. Location of the defect inside the sapphire pre-form
5. Number of defects in the pre-form
Each factor has different importance for different customers / applications, therefore acceptance thresholds are customized.
SapphiroScan™ workstations allow full automatic sorting based on the above testing criteria. Sensitivity to each factor can be fine-tuned by the operator.
SapphiroScope™ workstations currently rely on operator decision-making. In future, the clarity grading of LED ingots will be more automated with the least possible assistance levels required from the operator. Self-learning algorithms used in conjunction with SapphiroScope™ defect detection technology, are being designed to make the process objective and automatic.
The sapphire community and Scientific Visual are working on establishing industry-wide grades for the sapphire quality. This will make automatic clarity grading even more common and allow industry players to communicate about sapphire quality using a universal language. This means that ingot buyers will know exactly what quality level and characteristics they are about to purchase.
I want to buy a sample of your immersion liquids
Scientific Visual neither sells its immersion liquids off-the-shelf nor does it provide immersion samples for testing. But we are keen to help you, so if you would like to evaluate our technology, please contact us to arrange for a customised test using your own material. We will inspect your samples and send you the results in the form of images or a 3D model of its interior.
What materials could be inspected?
- Germanite and aluminate glasses
- Mineral and Organic Glasses
- Spinel and spinel-type ceramics
What samples sizes could be inspected?
SapphiroScan™ : round disks (polished or non-polished), diameter 24–50 mm, thickness 1.5–5 mm.
SapphiroScope™ : cylinders or bricks (polished or non-polished), diameter 1”–12”, height 1–32 cm, or on request.
SapphiroScope™ for boules : on request.