Lesson plan
Diffractive optically variable image device
A diffractive optically variable image device (DOVID) is a type of optical variable device; a security feature based on visual effects created by diffraction. The acronym was coined by Ian Lancaster of Reconnaissance International in 1995. He pointed out that the security print industry was wary of holograms and similar diffractive devices because they were used as decorative, promotional and toy items, proposing the use of DOVID as a means to differentiate security diffractive optical devices from these other uses.
Article summary
A diffractive optically variable image device (DOVID) is a type of optical variable device; a security feature based on visual effects created by diffraction. The acronym was coined by Ian Lancaster of Reconnaissance International in 1995. He pointed out that the security print industry was wary of holograms and similar diffractive devices because they were used as decorative, promotional and toy items, proposing the use of DOVID as a means to differentiate security diffractive optical devices from these other uses.
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.