Abstract: A new broadband discrete spectrum light source comprising a gain medium placed in a feedback cavity is disclosed. A design for a feedback cavity including reflectors having raised-edge reflectivity is presented. Bandwidth enhancement is achieved by selectively enhancing the intensity of the discrete emission lines near the band edges of the gain medium spectrum. The bandwidth of a broadband discrete spectrum light source is further enhanced by digitally applying a spectral correction to each detected signal according to a predetermined correction profile. A combined effect of using a broadband discrete spectrum light source and applying spectral correction to the detected signal in an imaging system such as a Spectral Domain Optical Coherence Tomography (SD-OCT) imaging system, results in a desired spectral profile and a bandwidth necessary to achieve higher depth resolution for obtaining high quality diagnostic images.

Abstract: A new broadband source having a discrete set of spectral emission lines having high peak power in each line is provided by placing a gain medium in a reflective cavity comprising reflective front and back surfaces. A cavity feedback factor less than unity is achieved by providing reflectivity of one surface substantially lower than the reflectivity of the other surface such that spontaneous emission in the gain medium is linearly amplified just below the lasing threshold. In an alternative arrangement, a movable external back surface placed at a prescribed distance from the gain medium provides a means to achieve a free spectral range and finesse of the emission lines to match a pitch of a detector array in a SD-OCT system. By simultaneously providing high power to each detector element of the array, sensitivity and imaging speed of SD-OCT system are significantly improved.