A Revolutionary New Type of Lens Focuses All The Colours of The Rainbow Into a Single Point

Science Alert has the article A Revolutionary New Type of Lens Focuses All The Colours of The Rainbow Into a Single Point.

A brand new type of lens called a metalens has just passed a major hurdle. A metalens is a flat surface that use nanostructures to focus light, and it could change optics forever by replacing the traditional bulky, curved lenses we know.

This was an interesting read, but the following stopped me in my tracks.

Making a metalens like this is so tricky because different wavelengths of light move through materials at different speeds. That leads to focusing errors known as chromatic aberrations, which traditional lenses get around through curved surfaces.

And here I thought that lenses used curved surfaces as a way of changing the magnification of an image. In other words the curved surface is what makes it a lens. I went to WikiPedia to see what it had to say in the article Chromatic aberration.

There exists a point called the circle of least confusion, where chromatic aberration can be minimized.[6] It can be further minimized by using an achromatic lens or achromat, in which materials with differing dispersion are assembled together to form a compound lens.

This is the explanation I imagined. Of course, the Wikipedia has much more detail and talks about other techniques of correcting chromatic aberration.

I just think this is an example of what happens when an author with a tenuous understanding of a scientific topic tries to simplify an article to explain science to other people with a tenuous understanding of the topic. Don’t treat as gospel what you read in a news medium that has the word “science” in its name. Actually, such a medium may be no more trustworthy than a medium that makes no claim to be about science.

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