physics

Photon sieve

Photon sieve is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Photon sieve rather than just read about it. In short: A photon sieve is a device for focusing light using diffraction and interference. It consists of a flat sheet of material full of pinholes that are arranged in a pattern which is similar to the rings in a Fresnel zone plate, but with the ability to bring light to much sharper focus.

Key takeaways

Photon sieve belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Photon sieve to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Photon sieve from memory before moving on to harder problems.

Reference excerpt

A photon sieve is a device for focusing light using diffraction and interference. It consists of a flat sheet of material full of pinholes that are arranged in a pattern which is similar to the rings in a Fresnel zone plate, but with the ability to bring light to much sharper focus. The sieve concept, first developed in 2001, is versatile because the characteristics of the focusing behaviour can be altered to suit the application by manufacturing a sieve containing holes of several different sizes and different arrangement of the pattern of holes. Photon sieves have applications to photolithography and are an alternative to lenses or mirrors in telescopes and terahertz lenses and antennas.

When the size of sieves is smaller than one wavelength of operating light, the traditional method mentioned above to describe the diffraction patterns is not valid. The vectorial theory must be used to approximate the diffraction of light from nanosieves. In this theory, the combination of coupled-mode theory and multipole expansion method is used to give an analytical model, which can facilitate the demonstration of traditional devices such as lenses and holograms.

Alternative explanation When following a radial path on a Fresnel zone plate, the transmission varies from 0 to 1 to 0 etc. The transition from 0 to 1 and back again is immediate—it is a square wave. A square wave can be constructed from an infinite series of sinusoidal curves. Within a Fresnel zone plate, each of these sinusoidally curved transmission patterns creates a different focus, so a standard Fresnel zone plate creates a rather messy primary focus as shown in figure 4 of reference 1. If the transmission function could be made to vary radially as a single sinusoid, then there would be just one focus. This and the following are explained in detail in reference 8 especially chapter 2 summarised in equation 2.95 and Table 1 therein. However a perfectly sinusoidal transmission pattern may be difficult to manufacture and can be closely approximated by having the average transmission at a given radius (i.e. averaging all the way around a circle at that radius) from the centre vary sinusoidally. This can be achieved by punching holes of appropriate size at calculated locations as in a photon sieve. Holes are easy to manufacture and allow one to use a binary pattern that varies radially and around each circle to make on average a sinusoidal variation, thereby eliminating other foci.

References

Andersen, Geoff (2005). "Large optical photon sieve" (PDF). Optics Letters. 30 (22): 2976–8. Bibcode:2005OptL...30.2976A. doi:10.1364/OL.30.002976. PMID 16315693.

Illustrations

Worked examples

Example 1 — a first encounter with Photon sieve

Start with the simplest possible case. Write down what Photon sieve claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Photon sieve before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Photon sieve ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Photon sieve

In research: Photon sieve appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Photon sieve in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Photon sieve is common in secondary-school and first-year university syllabi. It links to neighbouring topics Optical devices, so understanding it makes those chapters shorter.
In everyday life: Look for Photon sieve outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Photon sieve in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Photon sieve means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Photon sieve out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Photon sieve in simple terms?

Why does Photon sieve matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Photon sieve?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Photon sieve.