(a) Alternative leak detection technology--Technology other than that specified by the United States Environmental Protection Agency Method 21, including optical gas imaging technology, designed to detect emissions of air contaminants.(b) Imaging--A means or process of making emissions visible that may otherwise be invisible to the naked eye.(c) Leak--For purposes of this subchapter, a leak is any emissions imaged by an optical gas imaging instrument, as defined in this section.(d) Optical gas imaging instrument--An instrument that makes emissions visible that may otherwise be invisible to the naked eye.(e) Repair--The adjustment or alteration of a component in order to eliminate a leak.(f) Supplemental detection method--Any leak detection method that supplements or adds to an existing technology approved by the executive director such as 40 Code of Federal Regulations Part 60, Appendix A-7, Method 21 monitoring program.