When Optics Specifications Break the Laws of Physics


At Ross Optical, we are proud to provide components and designs that meet our customers' unique needs. Sometimes, though, customers request solutions that would violate the laws of physics. Below we give three examples of laws that we cannot break, and ways we can work around these barriers.

We cannot break the "Diffraction Limit."

The diameter of a lens dictates the diameter of its focal point. Generally speaking, a smaller focal point requires a larger-diameter lens. The size of an optical system is therefore inextricably tied to its resolution.

What we can do: When the required system volume conflicts with the required system resolution, a compromise is required. Our designers can balance your designs to optimize performance.

We cannot break “Conservation of Energy.”

It is not possible to make a single light source brighter. In optics, "brightness" goes by the technical term "radiance." Conservation of radiance dictates that a large light source and a small light source can only have the same brightness if the smaller light source shines into a broader angle. This means it is impossible for a broad-angle source, such as a LED, to focus without loss to a small spot with a small angle, such as the tip of a fiber.

What we can do: Ross Optical engineers study proposed designs for this kind of "law breaking" and can propose alternate methods to achieve the desired results.

We cannot eliminate “Dispersion.”

A material's "refractive index" determines how it bends light. The laws of subatomic physics rule that a material's refractive index cannot be the same for all colors of light. That said, the inclusion of additional optical elements of differing materials can minimize chromatic aberrations to within specifications.

What we can do: Our designers' expertise regarding lens and material availability greatly reduces the cost of dispersion correction.

All of these physical laws constrict optical systems, but our optical engineers can adjust designs and requirements to keep them "legal." Contact Lisa Yang at lisa@rossoptical.com or 915-595-5417 x18 to discuss your design needs.

Furthermore, without these laws and restrictions, the universe would be a very different place to live. The diffraction limit relates to the response of an eye's pupil, conservation of energy keeps us from being cooked by the sun, and dispersion is responsible for rainbows. That's not a bad deal when you think about it.

Download our Tolerancing Guide for tips on choosing the right specifications.

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