A sensor for checking documents, in particular value documents, e.g. for checking the authenticity of the documents, comprising: - an illumination device (1a, 1b) for illuminating a document with one or several excitation light pulses of an excitation light which is suitable to excite the document to emit luminescent light, and - a detector for detecting at least one remission measurement value of the document and at least one luminescence measurement value of the document, and - a detection filter which is located in a detection ray path formed between the document and the detector, and - a control device for controlling the illumination device (1a, 1b) and the detector, wherein the control device is arranged to drive the detector such that the detector detects at least one remission measurement value of the document at at least one point in time at which the document is illuminated with an excitation light pulse of the excitation light, and detects at least one luminescence measurement value of the document at at least one point in time after the end of the respective excitation light pulse, - an evaluation device for checking the document on the basis of the at least one remission measurement value detected by the detector and on the basis of the at least one luminescence measurement value detected by the detector, characterized in that the detection filter is a spectral detection filter whose spectral transmission is selected such that both the luminescent light of the document impinging on the spectral detection filter and at least 0.5% of the excitation light impinging on the spectral detection filter are transmitted through the spectral detection filter. - an illumination device (1a, 1b) for illuminating a document with one or several excitation light pulses of an excitation light which is suitable to excite the document to emit luminescent light, and - a detector for detecting at least one remission measurement value of the document and at least one luminescence measurement value of the document, and - a detection filter which is located in a detection ray path formed between the document and the detector, and - a control device for controlling the illumination device (1a, 1b) and the detector, wherein the control device is arranged to drive the detector such that the detector detects at least one remission measurement value of the document at at least one point in time at which the document is illuminated with an excitation light pulse of the excitation light, and detects at least one luminescence measurement value of the document at at least one point in time after the end of the respective excitation light pulse, - an evaluation device for checking the document on the basis of the at least one remission measurement value detected by the detector and on the basis of the at least one luminescence measurement value detected by the detector, characterized in that the detection filter is a spectral detection filter whose spectral transmission is selected such that both the luminescent light of the document impinging on the spectral detection filter and at least 0.5% of the excitation light impinging on the spectral detection filter are transmitted through the spectral detection filter.