Sep. 04, 2026

Why Does a Concave Lens Form a Virtual Image?

A common optical design problem occurs when engineers, students, or buyers expect a concave lens to project an image onto a screen but obtain no focused image. The underlying cause is not a manufacturing defect: a concave lens makes transmitted light diverge, so the rays do not physically meet on the opposite side of the lens. Instead, the eye traces those diverging rays backward and perceives

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Sep. 04, 2026

Effective Focal Length vs. Back Focal Length: What Is the Difference?

1/f = (n − 1)(1/R1 − 1/R2)

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Sep. 03, 2026

What Is Laser-Induced Damage Threshold in Optical Lenses?

What Is Laser-Induced Damage Threshold in Optical Lenses? Laser-Induced Damage Threshold (LIDT) is the maximum laser fluence or power density an optical lens can withstand before its coating, surface, or bulk material shows permanent damage. It is usually expressed in J/cm² for pulsed lasers or W/cm² for continuous-wave (CW) lasers. In practical applications, LIDT helps engineers select a safe

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Sep. 03, 2026

Achromatic Doublet vs. Spherical Singlet: Which Produces Better Images?

Choosing between an achromatic doublet vs. spherical singlet is not simply a question of buying the more expensive part. A Spherical Lens may be adequate for a low-cost sensor, collimator, or relaxed-focus lighting system, while a doublet is usually the safer choice when users need sharper color images across a visible wavelength band. The practical questions are familiar: Why do red, green, and

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Sep. 02, 2026

Sapphire vs. Fused Silica Lenses for Harsh Environments

For an optical spherical lens manufacturer, the most important question is not which material is universally better. The correct choice depends on wavelength, temperature, abrasion, chemical exposure, optical precision, service life, and total system cost. This guide compares sapphire and fused silica lenses for industrial imaging, laser systems, sensors, medical equipment, aerospace instruments,

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Sep. 02, 2026

How to Choose the Right Wavelength Range for an Achromatic Lens

Choosing the correct wavelength range is essential for achieving sharp images, low chromatic aberration, and stable optical performance. At Sunday Optics, we help engineers select an achromatic lens by matching the lens design, glass combination, coating, and operating spectrum to the real application. In this guide, I will show you how to define the wavelength band, verify optical

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Sep. 01, 2026

How to Choose a Focusing Lens for a High-Power Fiber Laser

An optical spherical lens manufacturer can help you select a focusing optic that matches your laser wavelength, power, beam quality, working distance, and cutting or welding process. This guide explains how to choose the lens step by step, which tools and specifications you need, and which purchasing mistakes can cause poor focus, thermal damage, or inconsistent processing. Sunday Optics supplies

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Sep. 01, 2026

Bi-Concave vs. Plano-Concave Lenses for Beam Expansion

Choosing a Spherical Lens for a laser beam expander is not simply a question of selecting the cheapest negative lens. Engineers comparing the best negative lens for laser beam expansion, a bi-concave lens for collimated beam expansion, and a plano-concave lens beam expander must evaluate spherical aberration, focal length, and divergence angle under the paraxial approximation, while also checking

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Aug. 20, 2026

Equal-Radius vs. Unequal-Radius Bi-Convex Lenses

Choosing the right Spherical Lens is not simply a matter of selecting a larger diameter or shorter focal length. Designers comparing an equal-radius bi-convex lens, an unequal-radius bi-convex lens, and a custom solution from an optical spherical lens manufacturer must consider the radius of curvature, refractive index, and lensmaker’s equation.

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Aug. 20, 2026

How Lens Diameter, Focal Length, and F-Number Affect Spot Size

When a focused beam produces a spot larger than expected, the cause is usually not mysterious: a Spherical Lens may have the wrong aperture, the focal length may not match the working distance, or diffraction may be limiting the result. This guide explains spherical lens spot size calculation, the relationship between lens diameter, focal length, a

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Aug. 19, 2026

Germanium vs. Silicon vs. ZnSe: Choosing an Infrared Lens Material

Choosing the right infrared lens material affects image quality, system size, battery life, thermal stability, durability, and total ownership cost. Germanium, silicon, and zinc selenide, commonly called ZnSe, are all widely used for infrared optics, but they are not interchangeable.

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Aug. 19, 2026

How to Match Optical Lens Material to UV, Visible, and IR Wavelengths

Choosing a Spherical Lens for UV, visible, or infrared work is not simply a matter of selecting the clearest glass. The correct choice depends on the wavelength range, optical transmission, refractive index, absorption coefficient, operating temperature, coating, and beam power. Engineers searching for an optical spherical lens manufacturer, a UV visible IR spherical lens selection guide, or a

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