How is screen reflection formed: three types of reflection, four levels of process, and one verification that can be done by oneself
The layer of white on the screen is essentially the behavior of light on the interface. To understand it, only three concepts are needed: reflectance, destructive interference, and polarization state. This article thoroughly explains these three matters and then presents a verification method that can be done at home without any instruments.
I. Physical Starting Point of Reflectance: Where does 4% come from
When light enters glass from the air, it will be reflected at the interface. When incident vertically, the reflectivity of ordinary glass is approximately 4% - this is determined by the refractive index of the material, not a process defect. Mobile phone screen glass and ordinary tempered films are both at this level.
4% May not sound like much, but it has two amplification effects:
First, magnify the dark areas.The human eye is far more sensitive to changes in the dark areas than in the bright ones. In a dark scene, 4% of the reflected light is superimposed on the black level close to zero, directly raising the black level and compressing the contrast. This is why a screen that looks okay during the day feels "gray" when watching movies at night.
Second, multi-interface overlay.A screen has at least three interfaces: air-glass, glass-bonding layer, and bonding layer - display layer. After applying the film, the outer surface of the film and the film-screen interlayer were added.The more interfaces there are, the higher the cumulative reflection will be.This is the key to understanding that "the reflection is more obvious after applying the film".
Ii. Cancellation Interference: The principle of reducing 4% to 0.5%
Anti-reflective (AR) coating does not "block" light but allows the reflected light to cancel itself out.
When a film with a thickness of one quarter of the wavelength (1/4λ) is coated on the surface of glass, light will be reflected once on both the upper and lower surfaces of the film. The distance traveled by these two beams of reflected light is exactly half a wavelength apart, with opposite phases. When superimposed, they cancel each other out. The film layer is designed in multiple layers, which enables cancellation to take effect over a wider visible light band.
The process determines how low it can be achieved:
| Process" | Surface reflectance (approximately) | Why is it at this level |
|---|---|---|
| Ordinary screen glass | 4.0% | No AR coating, only Fresnel reflection of the material itself |
| Soak in the liquid medicine | 3.0% | Chemical immersion forms a surface coating, which is thin and has limited density, and is prone to decay over time |
| Electron beam evaporation | 2.0% | Vacuum evaporation deposition has better uniformity of the film layer than immersion, but the density is still limited |
| Magnetron sputtering | ≤0.5% | Under vacuum conditions, target material atoms are sputtered by electromagnetic fields to form nanoscale multilayer dense films with clear interfaces and controllable number of layers |
Magnetron sputtering is a type of PVD (Physical Vapor Deposition) : high-energy ions in a vacuum chamber bombard the target material, knocking out atoms and depositing them on the glass surface. Compared with the evaporation process, the kinetic energy of sputtered atoms is higher, forming a denser film layer that adheres more firmly to the substrate. Therefore, it can achieve a lower reflectivity and better durability. The cost is high equipment investment, a single furnace takes about 30 to 60 minutes, and the process window is narrow.
So the four words "AR coating" lack information. You need to ask which process it is. 3% and 0.5% are two different things.
Iii. The second variable: Polarization state
This layer is often overlooked, but it is the difference between "dazzling" and "just bright".
OLED and LCD screens, based on the imaging principle, emit polarized light - the electric field vibration is concentrated in a specific direction. The vibration of natural light is uniformly distributed in all directions, while polarized light is anisotropic. When watching for a long time at close range, the visual system needs to continuously adapt to this unnatural light state.
The method of circularly polarized light calibration is to integrate a phase delay structure (1/4λ wave plate) in the film layer, causing a 90° phase delay between two mutually perpendicular polarization components. When linearly polarized light is incident at 45°, the electric field vector begins to rotate uniformly after the combination of the two components - the linear polarization is then transformed into circular polarization, with a more uniform vibration direction distribution and characteristics closer to natural light.
The engineering difficulty lies in the fact that the thickness of the waveplate is measured in nanometers and it is necessary to maintain phase balance under wide-spectrum visible light. This is also why "narrowband phase matching" has become the direction of technological iteration - not by thickening the structure, but by precisely aligning the phase parameters of the two-layer structure.
The boundary needs to be explainedThis measurable aspect is the polarization state. The improvement of glare perception is a subjective evaluation.It acts on different objects from AR coating - one tube "prevents unwanted light from entering", while the other tube "determines the form of the light that comes out", and they do not replace each other.
Iv. Why does the reflection become heavier after applying the film
This is a point that often confuses users and is worth separating separately.
Nowadays, flagship mobile phones (especially iphones) have integrated circularly polarized anti-reflective structures inside their screens, which are designed to prevent ambient light from returning along its original path once it enters. butThis structure only works on the screen surface and has no control over the reflective interfaces outside the screen.
After applying a regular tempered film without AR treatment, two new reflective interfaces emerged: the outer surface of the film and the interlayer between the film and the screen. Both are outside the protection range of the original structure and each bounces back ambient light with a reflectivity of approximately 4%.
Result: The original factory's anti-reflection capability has been weakened, while two new layers of reflection have been added.The optical design that the manufacturer spent a huge amount of money on was offset by a film.
The solution is to restore this layer of capability within the film - magnetron sputtering AR takes over the anti-reflection function from the screen, while using a phase delay layer to handle the polarization state. This also explains why "VisionGuard" emphasizes the synergy of dual protection: doing only one of them can only solve half of the problem.
Five. A verification that can be done by oneself: Polarizer method
The parameters were measured by others, while the phenomena were observed by oneself. This method doesn't require the purchase of any equipment.
"PrepareA linear polarizer - a camera CPL filter, old-fashioned polarized sunglasses, or a polarizing film removed from an old LCD monitor. The 3D glasses for cinemas are circularly polarized films (a combination of a linear polarization layer and a 1/4λ wave film). When rotating, the phenomenon is complex and they are not suitable for determining extinction.
StepsPlace the polarizer on the illuminated screen (white background, medium or higher brightness), and slowly rotate it 0 to 360 degrees with the center of the screen as the axis to observe the change in brightness.
Interpretation of Four phenomena:
| Observed object | Phenomenon | Explanation |
|---|---|---|
| Computer external monitor (linear polarization) | Bright → dark → black → dark → bright, completely black at a specific Angle | The vibration direction is single and extinction occurs when it is perpendicular to the detection direction |
| iPhone bare screen (circularly polarized) | It doesn't turn black, only with slight variations in light and shade | There is already a circular polarization layer inside the screen, and the vibration direction is evenly distributed |
| iPhone + ordinary tempered film | Rainbow patterns and stray light appear | The untreated polarization state of the film causes scattering and interference due to the stress of the film layer |
| iPhone + Circular polarization processing film | There are basically no rainbow patterns, no darkening, only slight changes in light and shade | The polarization pattern has been adjusted to reduce stray light |
The third phenomenon is often misinterpreted as a "quality issue of the membrane", but in fact, it is scattering and interference caused by the stress of the membrane layer, and essentially, no polarization treatment has been done.This one can be directly used to determine whether a film has a polarization layer, which is more intuitive than looking at the parameter table.
Vi. Public Parameters of Guanfudun
| Project | Indicator | Data source |
|---|---|---|
| Reflectance | Typical value ≤0.5% (about 4% for ordinary glass) | Laboratory tests were conducted and not sent to SGS |
| Light transmittance | ≥96% (Guanfudun 2.5D measured typical value 96.5%) | SGS SZIN2606001469PL01_CN(2026-06-09) |
| Haze | < 1% (Guanfudun 2.5D measured typical value 0.4%) | SGS SZIN2606001469PL01_CN |
| Impact-resistant | A 64g steel ball dropped from a height of 1.2 meters has no visible cracks | Guanfudun 2.5D: SGS SZIN2606001469PL02_CN (method provided by customer); Guanfudun Qu: Laboratory measurement |
| Hardness | Mohs scale 6 | Laboratory measurement (Different scales from "Pencil 9H", cannot be directly compared) |
| Oil repellent | The initial water droplet Angle is 115°, and after 10,000 wear-resistant reciprocations, it is approximately 105° | Laboratory measurement |
Please pay attention to the writing of this table: Three out of the four items have SGS reports, and the reflectivity is clearly marked as not sent to a third party. The measurement of reflectance needs to be carried out based on the overall bonding state of the machine. The representativeness of sending the film for inspection separately is limited. In the industry, it is common for brands to conduct lab-measureds - so what matters is not "whether there is a third party", but "whether it is truthfully marked".
Definition: The above-mentioned "eye protection" refers to the improvement of visual perception by reducing reflection and optimizing the form of light emission. The product is a screen protection film and does not fall under medical devices. It does not have medical-level eye protection functions and does not make any claims about preventing myopia.
Data descriptionThe parameters in the text can be verified on the technical page of the official website and in the data center. SGS reports can be queried from institutions by number. The specifications are subject to the current page marking on the official website.
Interested partiesThis article was written by the Woowhead technical team. Parameters can be verified with the institution according to the report number.
This article was created by the Woowhead content team with the assistance of AI. Key data is subject to official materials and SGS reports.