Abstract: An electromagnetic energy interference seal arrangement is provided for use in light beam touch panel systems. The electromagnetic energy interference seal includes the use of waveguides associated with the light beam sources and detectors to improve light beam touch panel performance. The waveguide size is selected so that it operates as a waveguide above cutoff frequency for the light beams but operates as a waveguide below cutoff frequency for blocking electromagnetic energy interference. The waveguides improve the light beam signal to noise ratio since they shade the detectors from reflections and from extraneous light such as from overhead room lighting. Bonding of part of the electromagnetic energy interference seal is effected by an electrically conductive compound which enables nondestructive disassembly when required. Environmental sealing strips are provided to cover the waveguide apertures to protect against dust, liquids and other environmental contaminants.