Patent ID: 7417211

Claim:
A laser scanning microscope comprising: a first laser scanning optical system which is operable to irradiate coherent excitation light for exciting fluorescence and to scan a sample with the excitation light, from a first side of the sample; a second laser scanning optical system which is operable to irradiate coherent stimulation light for giving optical stimulation to the sample and to scan the sample with the stimulation light, from a second side of the sample that is opposite to the first side of the sample; an observation light detector which is provided on a path branched from the first laser scanning optical system, and which receives the fluorescence which has been generated from the sample by irradiation of the excitation light and which has returned to the first laser scanning optical system; and a light invasion preventing section which prevents the stimulation light from invading the observation light detector; wherein the light invasion preventing section comprises a control section which stops laser irradiation of the stimulation light by the second laser scanning optical system while continuing the irradiation of the excitation light by the first laser scanning optical system when the first laser scanning optical system scans, with the excitation light, a region in which an observation scanning area to be scanned with the excitation light by the first laser scanning optical system and a stimulation scanning area to be scanned with the stimulation light by the second laser scanning optical system overlap each other, and wherein the control section performs control to resume irradiation of the stimulation light to the sample by the second laser scanning optical system when the first laser scanning optical system scans, with the excitation light, a region within the observation area that does not overlap the stimulation scanning area.