SCHOTT solutions no. 2/2012 > Filter Glass

Top performance under tough conditions: during endurance testing at 85 °C and 85 % relative humidity, the surface of coated blue glass remained transparent for hundreds of hours. Photo: SCHOTT/C. Costard

Blue Glass for Digital Eyes


A new, climate-resistant filter glass from SCHOTT produces brilliant photographs with modern smartphone cameras.


Oliver Frederik Hahr

Spontaneously capturing that special moment without much effort has never been easier with today’s smartphones. Starting with 8 megapixels of resolution – standard in most smartphone cameras and tablet PCs – image quality has already nearly reached that of compact cameras. Blue glass from SCHOTT has made an important contribution to this
developmen. It protects the digital ”retina,” the sensitive image sensor, against overexposure in the infrared wavelength range and delivers flawless color pictures.

”Improving image quality really poses a challenge. The resolution of smartphones is getting better and better while the photo sensor remains the same size. This results in increasingly smaller dimensions of the pixels,” explains Dr. Steffen Reichel from Application Development at SCHOTT Advanced Optics. ”The sensors record light from a wider angle of incidence. The filters made of coated glass that have been used in the past resulted in falsified colors and ghost images. Now, these types of image defects can be avoided with the new blue glass filter glass from SCHOTT,” Reichel adds. It basically puts a pair of sunglasses on the photo sensors and makes these sensors nearly as sensitive to color as the human eye.
More and more people are discovering their love for photography now that compact digital cameras and smartphones come equipped with high resolution cameras. Blue optical filters deliver flawless image quality when the same sized image sensors are used. Photo: thinkstock
Another advantage: whereas with coated glasses the surfaces of the filters can corrode and become hazy when they are exposed to heat and humidity, while going on vacation to Rio’s Copacabana or rainy London, for example, blue glass from SCHOTT is extremely climateresistant.

Even when it is subjected to endurance tests under 85 °C and 85 percent relative humidity, similar to the conditions that a smartphone must endure, the surface of the blue glass filter
remains completely transparent for hundreds of hours and permanently retains its high image quality. ”The filter glasses used in smartphones are extremely small, only around 5 mm x 0.3 mm, and sometimes only 0.21 mm thick. For this reason, we offer blue glass filters with various transmission properties. The standard version is designed to accommodate a thickness of 0.3 mm. Yet another type of blue glass was recently introduced for even thinner filters. After all, smartphones offer very little space,” explains Dr. Marc Clement from Launch Management at SCHOTT Advanced Optics. ”In addition, we also offer customized solutions that improve the quality of the cameras despite increasingly smaller dimensions,” he adds.
Optical glasses from SCHOTT are used in single-lens reflex cameras and color prisms for digital, high-end projectors, for example. Photo: SCHOTT/C. Costard
The market for camera sensors has been booming for years. They can be found in smartphones, tablets, cell phones with cameras, notebook webcams, digital cameras and camcorders. Other fast-growing niche markets include security and driving assistance systems (rearview cameras) and medical technology (endoscopes). Analysts at Yole Devéloppement estimate that 2.1 billion ”digital eyes” were shipped in 2012 and expect this figure to rise to more than three billion by 2015. According to estimates from the German Imaging Industry Association, 143 million digital cameras will be sold in 2012 (2011: 140 million). However, the ability to connect devices and users via the Internet and mobile communications appears to be what really mobilizes the masses. 75 percent of all image sensors are already being integrated into multifunctional mobile devices. 700 million smartphones (2011: 450 million) were purchased in 2012 and are exciting completely new customer segments for photography. <|

Visionary development – pragmatic manufacturing
Digital camera: from 0.01 to 41 megapixels