A white Light interferometer, used e.g. in the context of low-coherence interferometry, is an interferometer, typically a Michelson interferometer, which works with a white light source, i.e., with a Light Source with broad optical bandwidth.

The light Source is not necessarily operating in the visible spectral range, really generating white light. Its temporal Coherence has to be rather small, while a high spatial coherence is normally needed. The high spatial coherence combined with a broad Bandwidth can most easily be obtained by launching light from a bulb into a single-mode fiber, but this leads to a very small launched power. The brightness can be increased by many orders of magnitude by using a superluminescent source such as e.g. a superluminescent diode. In some cases, wavelength-swept Tunable Lasers are used.