What does OT stand for?

OT stands for Optical Techniques

This definition appears somewhat frequently

Other Resources: Acronym Finder has 92 verified definitions for OT

Samples in periodicals archive:

Precision products and services for industrial metrology. Learn more about “Optical Tooling Techniques” from Brunson Instrument.

If you want to learn how to use Photoshop to create an optical illusion effect, this Deke's Technique is for you. Using only Photoshop, you'll learn how to create an optical illusion effect in just a few steps.