A laser processing system for processing a workpiece with a laser beam , comprising: a processing head , and a measuring device for determining a distance between a laser processing head and a workpiece, comprising: an optical coherence tomograph configured to determine a distance between the processing head and the workpiece , wherein said optical coherence tomograph comprises a measuring arm for guiding measuring light reflected from said workpiece and a reference arm with more than two reference stages (210, 220; 310, 311, 312, 313, 314) having different optical path lengths; and an evaluation unit configured to determine the distance based on a superposition of measuring light from said measuring arm and measuring light from said reference arm , wherein said reference arm comprises a beam splitter assembly for splitting the measuring light into said more than two reference stages (210, 220; 310, 311, 312, 313, 314), characterized in that said beam splitter assembly is configured to split the measuring light, in substantially equal parts, into said more than two reference stages (210, 220; 310, 311, 312, 313, 314), and said more than two reference stages (210, 220; 310, 311, 312, 313, 314) are arranged sequentially. a processing head , and a measuring device for determining a distance between a laser processing head and a workpiece, comprising: an optical coherence tomograph configured to determine a distance between the processing head and the workpiece , wherein said optical coherence tomograph comprises a measuring arm for guiding measuring light reflected from said workpiece and a reference arm with more than two reference stages (210, 220; 310, 311, 312, 313, 314) having different optical path lengths; and an evaluation unit configured to determine the distance based on a superposition of measuring light from said measuring arm and measuring light from said reference arm , wherein said reference arm comprises a beam splitter assembly for splitting the measuring light into said more than two reference stages (210, 220; 310, 311, 312, 313, 314), characterized in that said beam splitter assembly is configured to split the measuring light, in substantially equal parts, into said more than two reference stages (210, 220; 310, 311, 312, 313, 314), and said more than two reference stages (210, 220; 310, 311, 312, 313, 314) are arranged sequentially. an optical coherence tomograph configured to determine a distance between the processing head and the workpiece , wherein said optical coherence tomograph comprises a measuring arm for guiding measuring light reflected from said workpiece and a reference arm with more than two reference stages (210, 220; 310, 311, 312, 313, 314) having different optical path lengths; and an evaluation unit configured to determine the distance based on a superposition of measuring light from said measuring arm and measuring light from said reference arm , wherein said reference arm comprises a beam splitter assembly for splitting the measuring light into said more than two reference stages (210, 220; 310, 311, 312, 313, 314), characterized in that said beam splitter assembly is configured to split the measuring light, in substantially equal parts, into said more than two reference stages (210, 220; 310, 311, 312, 313, 314), and said more than two reference stages (210, 220; 310, 311, 312, 313, 314) are arranged sequentially. <EOS>