Patent ID: 7460215

Claim:
A method for optically measuring distance or speed, comprising: providing a transmitting arrangement having at least one microchip laser that is adapted to emit radiation in the form of pulses and a frequency converter that converts a portion of the radiation emitted by said at least one microchip laser to a different wavelength, wherein said transmitting arrangement emits radiation in the form of a common beam toward an object, wherein said common beam being a diffraction-limited Gaussian beam of the at least two wavelengths (λ 1 , λ 2 ), the common beam of the radiation reflected by a surface of an object being received and evaluated, wherein the transmitting arrangement emits at least radiation having a wavelength in the invisible range (λ 1 ), said wavelength in the invisible range and radiation of another wavelength (λ 2 ) simultaneously with the radiation having a wavelength (λ 1 ) wherein the further radiation of another wavelength (λ 2 ) is in the visible range; evaluating together the information available after the at least two wavelengths (λ 1 , λ 2 ) have been received; and monitoring the radiation of visible radiation and switching off at least that part of the transmitting arrangement which emits the invisible radiation if said monitoring determines that the visible radiation is absent.