An aspheric lens reduces spherical aberration by changing its surface slope across the clear aperture, so that each annular zone refracts light by exactly the amount needed to reach one common focus. A spherical surface has the same radius everywhere, which makes the outer zones…
Verifying laser line rejection for Raman spectroscopy means proving three separate things, not one: the optical density at the laser wavelength under the angle and beam geometry the filter actually sees, the spectral distance between the laser line and the point where transmission recovers (expressed…
For a symmetric all-dielectric filter on a non-absorbing substrate, used near normal incidence at low optical power, flipping the part does not change the transmitted spectrum. Transmittance through a non-absorbing multilayer is the same in both propagation directions at the same angle of incidence. Optical…
A filter described as “850 nm,” “550 nm longpass,” or “10 nm bandpass” is not fully specified by those nominal numbers alone. Real optical filters are manufactured and measured against an allowable range. A nominal 850 nm bandpass filter, for example, may require its actual…
The 27th China International Optoelectronic Exposition (CIOE 2026) is being held from September 9–11, 2026, at the Shenzhen World Exhibition & Convention Center. As the exhibition enters its second day, GIAI Photonics continues to welcome visitors at two booths covering different areas of optical technology.…
A machine vision system may use an 850 nm or 940 nm LED, a monochrome camera with good near-infrared sensitivity, and stable exposure settings—yet still produce images whose contrast changes with factory lighting, sunlight, or reflections from nearby equipment. The problem is often not the…
A dichroic mirror is a wavelength-selective optical component designed to reflect one spectral region while transmitting another. Unlike a conventional mirror that is intended to reflect a broad wavelength range, a dichroic mirror uses a carefully designed multilayer dielectric coating to control how different wavelengths…
A ghost image in a beamsplitter is a second, weaker image formed by light that reached the detector along an unintended optical path inside the component. In the large majority of cases the path is a reflection from the second surface of a plate beamsplitter,…
A beamsplitter is often described simply as an optical component that divides one incident beam into transmitted and reflected paths. In an actual optical system, however, an important question comes first: Should the splitting behavior depend on polarization? That question separates two major categories: polarizing…
Edge steepness describes how quickly an optical filter transitions between its passband and its blocking region. It is measured as the wavelength interval between two defined reference points on the transition — for example between the 50% transmission point and the wavelength where transmission drops…
Two narrowband filters may both be described as “850 nm bandpass filters” or “1064 nm narrowband filters,” yet their manufacturing cost can differ substantially. The reason is that center wavelength alone does not define the difficulty of a narrowband filter. A filter becomes more demanding…
An ultra narrow bandpass filter is used when an optical system needs to transmit a tightly defined wavelength region while strongly attenuating light outside that region. Typical ultra narrow bandpass filter applications include laser-line cleanup, LiDAR and active optical sensing, selected fluorescence channels, analytical spectroscopy,…
