Concept Trees for the RP Photonics Encyclopedia

When one learns about a technical term, it is often helpful to know where it lives in the bigger picture. Is it a special case of a broader phenomenon? Does it have important subtypes? What are its “siblings” in the taxonomy? To make this structure clear, we now display concept trees in article headers.

A concept tree is a compact diagram showing how the current article connects to more general and/or more specific terms — most of which are covered in other articles of the Encyclopedia.

For example, on the right side you see the concept tree for the article on gas discharge lamps. It makes it very easy to realize various relevant details:

• Gas discharge lamps are a type of light sources — a term also covered in the Encyclopedia.
• The Encyclopedia also has articles on various other types of light sources, such as incandescent lamps, light-emitting diodes, etc.
• Further, there are more specific types of gas discharge lamps such as arc lamps, flash lamps, fluorescent lamps, etc.

Previously, we only listed broader and narrower terms in plain text. The new concept trees convey this structure much more clearly — and they are more visually appealing. The only downside is that they take up a little more space, requiring some extra scrolling. We think that’s a small price to pay for the clarity they add.

Note that not all articles can have such a tree, because not in all cases we can group terms into such a structure. For example, the f-number of a photographic objective is at the moment more like an isolated concept — but probably not forever: We might introduce an article on “properties of objectives”, referring to other properties such as focal length, magnification, numerical aperture, field of view — there are already plenty such articles! So this will probably happen soon, just as it has already happened in other cases: RP already made various brief overview articles on topics like optical elements to better connect the articles.

The advantages are clear: Concept trees make it easier for readers to see how a topic is embedded in the field and what related articles are available. Graphical representations are simply quicker to grasp than text lists.

We also expect concept trees to encourage more exploration. While quick fact-checkers may rely on search engines or AI summaries, those who want to really learn a subject benefit from the depth and reliability of the RP Photonics Encyclopedia. And that's exactly what the trees highlight: the breadth and interconnectedness of our coverage.

Our advertisers also value this continuous investment in the platform. With regular new articles, ongoing improvements to existing content, and new features such as these concept trees, we are making the Encyclopedia ever more useful for the photonics community — and our sponsors and advertisers make this work financially sustainable.

We at RP Photonics work really hard, as you can see, to continuously improve this learning resource, which has long been used by much of the photonics community. And we are grateful for all support, without which this would not be possible:

• First of all, we warmly thank our sponsors, which we list at the end of this article.
• Second, all other advertisers, i.e., suppliers using our Advertising Package for effective sales lead generation.
• Third, we need our huge user community, which spans a substantial part of the whole photonics community! There is a large number of Encyclopedia fans who probably very often start their search in the Encyclopedia straight away, not relying on Google/AI where results are more mixed and less reliable.

All are needed, and together we can get great things done!