Patent ID: 7016718

Claim:
A method comprising: irradiating laser light via an oscillating wavelength controllable semiconductor laser light source, diagnosing or treating a focus of cancer by causing excitation of a photosensitizer, from said irradiating to a focus, at which the photosensitizer is preliminarily accumulated, the photosensitizer having an affinity to a tumor and having an energy absorption band, controlling the oscillating wavelength of the laser light to within the energy absorption band of the photosensitizer; guiding the laser light irradiated from the semiconductor laser light source to a vicinity of the focus with a light transmission line; guiding, with an image transmission line, a fluorescent light emitted from the photosensitizer accumulated in the focus which has been excited by the laser light to observe the focus and a periphery thereof; extracting only the fluorescent light transmitted in the image transmission line; and picking up and analyzing an image of the extracted fluorescent light, wherein a full width at half maximum of the controllable oscillating wavelength is narrower than a width of an energy absorption band of the photosensitizer in which an energy absorption of the photosensitizer is at least 90% of a maximal energy absorption of the photosensitizer.