Abstract: Methods and apparatus for monitoring and detecting absorbed infrared radiation endpoint(s) are provided herein. In some embodiments, a method for determining an endpoint of a photoresist removal process may include removing a photoresist from a substrate disposed in a process chamber using reactive species provided to the process chamber from a remote plasma source. Infrared radiation is directed into the at least one of the reactive species or process byproducts while removing the photoresist. A quantity of infrared radiation absorbed by at least one of the reactive species or process byproducts during the removal process is monitored. The photoresist removal process may be ended based upon the monitored quantity reaching a predetermined level.