Optical Testing — A Practical Introduction for Scientists, Engineers, Optical Designers, Students and Optical Workshop Personnel is written for those working in optics with a practical introduction to optical testing methodologies, instrumentation, and procedures, and assist in the development of their professional careers. No optical component or system should be built without a prior specification which defines base parameters, tolerances, and system performance. Optical testing is done to verify whether the specification and performance criteria have been met. Customers need to make sure that they get what they pay for. Providers are bound both by moral and contractual obligations to provide what the customer ordered at the price quoted. Thus, the need for optical testing is incumbent upon both sides of the transaction, and both should have sufficient testing capabilities to validate the resulting optical product.