Light Source Detection Using the OPT4003-Q1 Ambient Light Sensor
Abstract
Light sensors are becoming more common in many different applications that need to extract lighting information from the surrounding environment. In addition to intensity and color information, the need to detect the type of light source is becoming more important in many systems. The OPT4003-Q1 is a dual-channel ambient light sensor (ALS) that measures the intensity of both visible and near infrared (NIR) light. This application report describes how to use the information provided by the NIR channel to detect different types of light sources.
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1 Introduction
Detecting the type of light that is being produced by a source can be an important feature for different applications. For example, in headlight systems light source detection can be used to distinguish between sunlight and artificial light to more accurately control illumination. Automatic display brightness controls need to adjust differently depending on the type of light in the environment, and it is necessary to distinguish between sunlight and other light sources.
The ratio of visible to NIR light is unique for different light sources, forming the basis of light source detection which is discussed in this report. Figure 1-1 illustrates the various visible to NIR light ratios of common sources. The specific test setup used to collect this data is described in more detail in Section 3.
Figure 1-1 OPT4003-Q1 Visible and NIR
Channel Ratios