IPhone Night Shift

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by Carley Folluo

In iOS 9.3, Apple introduced iPhone users to a feature known as "Night Shift." Night Shift alters the cool light of the iPhone to contain warmer hues, believing that the blue light prevents users from sleeping well at night. This feature can be analyzed by a Fiber Optic UV-Vis Spectrometer. The following experiment compares the resultant emission spectra from each lighting mode to magnified photos of the pixels on the screen. The screen resolution for the iPhone 6 used in this experiment is 326 ppi.

Figure 1. A blank white screen was shown at full brightness intensity on an iPhone 6 equipped with iOS 10.2.1. The wavelengths of light emitted by the screen were recorded with an Ocean Optics Red Tide USB650 UV Spectrometer. The emission spectrum was recorded with and without Night Shift mode enabled.

Figure 2. Magnified photos of a blank white screen at full brightness intensity on an iPhone 6 were taken with a Bodelin PS-HR-BASE ProScope. The left image depicts the iPhone with Night Shift mode enabled; the right image depicts the iPhone with Night Shift disabled.