Utilizing a Thin-Film ALD Design as Anti-Reflective Coating Alternative for Minimizing Ghost Images and Flare

Today’s most modern and robust camera modules, trusted in consumer technologies like mobile phones and self-driving vehicles, continue to suffer from unwanted ghost images and flares. These optical phenomena result from the reflection and scattering of ambient light from the several material interfaces present in multi-lens camera systems. Traditional anti-reflective coatings (ARC) are used to mitigate these imaging problems; however, very thick optical stacks (≥1 μm) are typically required and lead to long and expensive coating processes.  

At Beneq, we have developed a next-generation ARC with atomic layer deposition (ALD) technology using our P-series thermal batch ALD system. Using Beneq ALD, we utilized a gradient-index and low-temperature (100°C) process to produce an ARC with a total thickness of ∼150 nm, a fraction of the thickness of traditional ARCs. 

Beneq ALD Anti-reflective coating compared with traditional ARC
Figure 1

Figure 1 presents the measured reflectance of the designed ARC on D263 glass with an angle of incidence (AOI) of 7°. As a reference, we also display the simulated reflectance for a traditional TiO2-SiO2 ARC with a total thickness of ∼1μm. 

With Beneq’s ALD-ARC, we obtain very low reflectance of approximately 0.05% at around 410 nm and 550 nm. In addition, we observe wide bandwidth ARC performance with ∼0.07% average reflectance between 380-620 nm. By tuning the optical design, the average reflectance can be shifted towards longer or shorter wavelengths for targeted applications. 

Beneq’s ALD-ARC can be applied to several types of substrates ranging from nanostructured components to highly curved lenses and domes. Utilizing a thin design and the Beneq batch ALD system’s ability to house extremely large volumes of components enables extremely low-cost production of ARCs on glass and polymer components without the addition of plasma. This process paves the way for the mass-production of optical coatings for camera lens systems used in emerging applications. 

Learn more about optical coatings with Beneq ALD.

Learn more about the Beneq P400A Thermal Batch ALD System.

A comparison of lenses coated with conventional PVD methods and lenses coated with Beneq’s ALD antireflection coatings. For coatings optimized in the visible and visible to near IR ranges, ALD drastically decreases the amount of lens flare compared to traditional AR coatings.
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