encoder-led optical encoding with LEDs

Optical encoding with LEDs

What are optical rotary encoders?

Rotary encoders can be classified into two types: magnetic/electric induction type and optical type. The optical type detects rotation angles by detecting the on/off signals of light. This is achieved by placing a code wheel with fine pitch slits between a light emitter (e.g., LED) and photosensor (e.g., photodiode) and blocking and transmitting light.


High accuracy detection requires several features. For the photosensor Si photodiode, a chip arrangement that supports complicated slip patterns and high-speed response are required. For the light-emitting LED, uniform irradiation is required. Hamamatsu provides light emitters and photosensors for both transmissive and reflective encoders.


See below to learn more about our LEDs for optical encoders. Click here to learn more about our photodiodes for optical encoders.

Transmissive encoder | Reflective encoder

Features of LEDs for encoders

Unique semiconductor process

Thin-film crystal growth under ultra-high vacuum in MBE equipment | This-film crystal growth with MOCVD equipment

Using our unique semiconductor process technology, Hamamatsu manufactures high-output, highly reliable LEDs that are suitable light emitters for encoders.

Extensive product lineup

LED for encoder - product lineup

We produce and provide various types of LEDs for a wide variety of applications including automotive, industrial, and consumer.

For optical encoders, we provide collimated LEDs that can irradiate low-focus/dispersion, uniform collimated light suitable for constructing high accuracy encoders.

Improved reliability by refining the crystal structure

Higher reliability than those of previous confinement type LEDs was achieved by refining the crystal structure of the LED chip. Further, it is possible to design light emission diameters that meet customer needs. (Hamamatsu LEDs are normally provided as packaged products. Bare chip products are provided separately. If you require them, please contact us.)

Example of a confinement type LED chip design (unit: μm)

Example of a confinement type LED chip design (unit: μm)

Example of confinement type LED

Example of a confinement type LED

Recommended products

Infrared LEDs

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