Evelyn: Hi Stephen, I recently purchased a new red dot sight with an aspheric lens, and I wonder what’s so special about the aspheric lens, can you lecture me about it?

Stephen: Sure! Before we start talking about the aspheric lens, Evelyn, do you know much about its contrast the spheric lens?

Evelyn:  The spheric lens refer to traditional simple lens right? It usually has one or both sides concave/convex.

Stephen:  Yes, spherical lenses are commonly made by grinding and polishing, with either one or both sides being concave/convex or one surface being flat. spheric lenses have a uniform curvature across their surface, which is typically spherical.

Evelyn: I see. And what about aspheric lenses?

Stephen: In contrast to spherical lenses, aspheric lenses have a non-spherical lens surface. And unlike conventional spherical lenses, aspheric lenses have varying curvatures across their surface, allowing for improved optical performance. 

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Evelyn: Got it! So a red dot sight with an aspheric lens would offer a better optical performance?

Stephen: Yes, Aspheric lenses help minimize various optical aberrations such as spherical aberration, coma, and astigmatism. Red dot sights with aspheric lenses can provide clearer and more distortion-free images, improving overall optical performance.

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Evelyn: Understood, and what other advantages do aspheric lenses offer?

Stephen: Aspheric lenses can achieve comparable or superior optical performance with fewer lens elements. This reduction in elements results in a lighter and more compact red dot sight. Aspheric lenses also optimize light transmission, allowing more light to reach the user's eye. While some designs minimize parallax, they may require advanced processing. Aspheric lenses are particularly suitable for red dot sights with a short focal length.

Evelyn: I see, but are there any limitations of aspheric lenses?

Stephen: Yes, aspheric lenses tend to be more difficult to manufacture using conventional processes such as grinding and polishing. This is because aspheric lens elements are more complex than spherical ones. As a result, this can increase the production cost of red dot sights.

Evelyn: And what about spheric lenses? The optical performance of them are not so good as aspheric lenses, right?

Stephen: Yes, compared to aspheric lenses, spheric lenses are more prone to optical aberrations such as spherical aberration. This can result in reduced image quality and potential distortion of the red dot projection. Additionally, spheric lenses may require a thicker lens profile, resulting in a heavier red dot sight compared to those with aspheric lenses.

Evelyn:  And do they have their own set of advantages as well?

Stephen: Yes, Spheric lenses are generally less expensive to manufacture compared to aspheric lenses. This cost-effectiveness makes spheric lenses more accessible and widely used in many red dot sight models.

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Evelyn: To sum up, Aspheric lenses offer superior optical performance, a lightweight design, and a wider field of view, albeit at a higher cost. On the other hand, spheric lenses provide a cost-effective solution with proven technology, although they may sacrifice some optical quality and result in a bulkier design.

Stephen:  Yes, you are a fast learner!