A system is provided for boresighting a laser to a passive sensor using a fluorescent conversion material. A passive sensor, such as a FLIR, is aligned with a boresight module using a test pattern on a fluorescent conversion material. Laser energy is then emitted onto the fluorescent conversion material at a first wavelength which is beyond the passive sensor's operating waveband. The fluorescent conversion material then radiates the laser energy at a second wavelength which is within the passive sensor's operating waveband. The location where the laser energy is radiated on the fluorescent conversion material is used as a reference in boresighting the laser to the passive sensor.