Explain the Photomicrosensors(photointerrupters) wavelength characteristics of emitter and detector


Explain the Photomicrosensors’(photointerrupters’) wavelength characteristics of the emitter and detector.



Typical properties of Omron’s Photomicrosensors(photointerrupters):
The peak wavelength of the emitter: 940 nm
Peak spectral sensitivity wavelength of the receiver (phototransistor): 850 nm
Peak spectral sensitivity wavelength of the receiver (photo IC): 870 nm
For more information, please refer to the datasheet.



Explanation of relative radiant power and relative sensitivity of EE-SX1081 and EE-SX3091/4081 (Omron’s typical Photomicrosensors):
The graph below is infrared LED (GaAs) emitter wavelength and spectral sensitivity wavelength of receiver of EE-SX1081 and EE-SX3091/4081. In some reflective Photomicrosensors and Optical Sensors (example: EE-SF5, B5W series), the front side of emitter/detector is protected by a dust-proof cover to cut the wavelength of visible light.

EE-SX1081: Relative radiant power and relative sensitivity


Quick tips

Most of our reflective Photomicrosensors are carrying infrared LED, so in some cases, some objects might not be detected properly. Even if a “black” object can be identified in the visible light spectrum that the human eye can view, the color might not be identified in the infrared light due to an increase in the reflection rate. For example, reflective Photomicrosensors might not detect a black symbol on a white paper written with dye ink because the reflection rate increases and the S/N ratio decreases. In such cases, please use different ink or reflective Photomicrosensors for red LED (EE-SY169B).


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