Medical researchers use various optical devices for diagnosis, detection, treatment, and therapy. In some embodiments, they do not have the equipment necessary to determine how much light is emitted by the optical device or how far it penetrates tissue. The present invention provides for a method and apparatus for characterizing light from an optical device by using a tissue phantom. The method includes coupling light from an optical source into a device, transmitting the light through a tissue phantom, detecting a transmitted light, optionally electrically processing the detected output, and displaying the corresponding optical characterization. In some embodiments, the apparatus obtains input light from an optical source, and may include a tissue phantom, an optical detector, an electrical processing unit, and a display for displaying the corresponding optical characterization.