A method for optical microscopy by scanning a sample, comprising the steps of - using a first laser beam with light having a first wavelength to excite dye particles contained in a region of the sample, the first laser beam having a first intensity distribution, - using a second laser beam with light having a second wavelength to de-excite a part of the excited dye particles contained in the region, the second laser beam having a second intensity distribution, the first intensity distribution and the second intensity distribution being spatially different when co-aligned, with the first intensity distribution having a maximum in its centre and the second intensity distribution having a minimum where the first intensity distribution has a maximum, - illuminating the region of the sample with only the second laser beam, defining a background signal, - illuminating the region of the sample concurrently with the first laser beam and the second laser beam and detecting a combined emission and background signal, - separating the emission signal from the background signal, characterised in that - the second wavelength is chosen within a wavelength range defined by the full width at half maximum (FWHM) of the emission spectrum of the excited dye particles, and - backscattered laser light of the second wavelength is blocked i. either with at least one ultra-narrow line transmission filter which reflects light not being transmitted, ii. or with an ultra-narrow line absorption filter in combination with a narrowband laser to generate the second laser beam, - wherein the respective filter is adapted to the second wavelength and arranged in the beam path between the sample and a detector. - using a first laser beam with light having a first wavelength to excite dye particles contained in a region of the sample, the first laser beam having a first intensity distribution, - using a second laser beam with light having a second wavelength to de-excite a part of the excited dye particles contained in the region, the second laser beam having a second intensity distribution, the first intensity distribution and the second intensity distribution being spatially different when co-aligned, with the first intensity distribution having a maximum in its centre and the second intensity distribution having a minimum where the first intensity distribution has a maximum, - illuminating the region of the sample with only the second laser beam, defining a background signal, - illuminating the region of the sample concurrently with the first laser beam and the second laser beam and detecting a combined emission and background signal, - separating the emission signal from the background signal, characterised in that - the second wavelength is chosen within a wavelength range defined by the full width at half maximum (FWHM) of the emission spectrum of the excited dye particles, and - backscattered laser light of the second wavelength is blocked i. either with at least one ultra-narrow line transmission filter which reflects light not being transmitted, ii. or with an ultra-narrow line absorption filter in combination with a narrowband laser to generate the second laser beam, i. either with at least one ultra-narrow line transmission filter which reflects light not being transmitted, ii. or with an ultra-narrow line absorption filter in combination with a narrowband laser to generate the second laser beam, - wherein the respective filter is adapted to the second wavelength and arranged in the beam path between the sample and a detector.