Patent ID: 7535012

Claim:
A method comprising: providing first activation radiation to a sample that includes phototransformable optical labels (“PTOLs”) to activate a first subset of the PTOLs in the sample; providing deactivation radiation to the sample to transform activated PTOLs to an unactivated state, wherein the deactivation radiation has a spatially-structured radiation field including intensity minima, such that a second subset of PTOLs located substantially at the intensity minima of the deactivation radiation remain activated, while activated PTOLs exposed to the deactivation radiation outside the minima are substantially transformed into an unactivated form; providing excitation radiation to the sample to excite at least a portion of the activated PTOLs in the sample located substantially at the intensity minima of the deactivation radiation; and detecting radiation emitted from the activated and excited PTOLs with imaging optics.