VCSELs can provide high efficiency, reliability, and precision in optical sensors based on reflection, transmission, absorption, scattering, interference, self-mixing, and other techniques. For example, VCSELs are ubiquitous in applications that use reflective sensors and either specular, imaging, or scattering techniques to detect objects or objects in motion.

Sensor applications where VCSELs may provide greater precision and efficiency in a compact form factor include:

• Self-mixing incorporating signal feedback to create instability in the laser that can be used to determine position, direction, and relative velocity in a completely touchless manner that avoids wear issues common to mechanical systems
• VCSELs have been demonstrated to have achieved precision turbidity sensing with resolution to 2 NTU
• Particle detection in liquids
• Speckle sensing for tracking motion using statistical measurements

VCSELs can be surface mounted, enabling direct replacement in LED-based applications such as photoelectric control. With its focused, coherent light, a VCSEL is 10X more efficient than an LED in similar packaging. For example, a VCSEL-based photoreflective sensor detecting black and void consumes only 6 mA compared to 55 mA with an LED. VCSELs provide increased discrimination to background light (i.e., contrast), improved precision in determining object location and velocity, and offer lower power dissipation.

The efficiency and reliability of VCSELs also enables them to be constructed in a sealed module and placed in a remote location for reliable operation over several years on a single battery (e.g., CSAC atomic clocks for geographical mapping of the ocean floor).

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