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US 12,209,860 B2Granted
Method and device for analog in situ laser process monitoring
AssigneeUniversitaet Bayreuth
InventorGeorg Herink
Life of this patent
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Abstract
Disclosed is a method and a device for in situ process monitoring and control down to a single pulse measurement during laser processing, like ablation, laser printing additive manufacturing and modification of refractive index. The disclosure relates to laser material processing and to an integrated process monitoring using interference effects of a laser beam or laser pulse.
Claims15
A method for in situ process monitoring during laser processing comprising at least the steps of:
- a. emitting at least one ultrashort pulse laser beam by an ultrashort pulse laser;
- b. splitting the at least one ultrashort pulse laser beam by a beam splitter into at least one main pulse laser beam and at least one reference pulse laser beam;
- c. reflecting or transmitting said at least one main pulse laser beam by a target object and reflecting said at least one reference pulse laser beam by a reference mirror;
- d. providing at least one combined pulse laser beam by superposing the at least one reflected or transmitted main pulse laser beam and the at least one reflected reference pulse laser beam;
- e. coupling the at least one combined pulse laser beam into a dispersive element;
- f. interfering the at least one combined pulse laser beam with itself due to temporally stretching the frequency content by the dispersive element;
- g. converting at least one interference beam to an electrical signal,
- whereby the at least one interference beam is a result and an emission of the dispersive element with inversely proportional amplitude/intensity modulation of the spectrum and respective temporal waveform after time-stretch in the dispersive element to the time delay between the at least one reflected or transmitted main pulse laser beam and the at least one reflected reference pulse laser beam;
- h. filtering a specific frequency and/or a specific range of frequencies of the electrical signal;
- and
- i. rectifying the filtered electrical signal to an output signal for control functions and as measurand;
- wherein the electrical signal is processed in an analog electric domain.
9 more elements
A device for processing and in situ process monitoring comprising:
- a. an ultrashort pulse laser which is configured for emitting at least one ultrashort pulse laser beam;
- b. a beam splitter which is configured for splitting the at least one ultrashort pulse laser beam into at least one main pulse laser beam and at least one reference pulse laser beam;
- c. a target object to be processed by the at least one main pulse laser beam and partly reflecting or transmitting the main pulse laser beam to the beam splitter and
- d. a reference mirror which is configured for reflecting the at least one reference pulse laser beam to the beam splitter and superposing the at least one reflected or transmitted main pulse laser beam and the at least one reflected reference pulse laser beam to at least one combined pulse laser beam;
- e. a dispersive element which is configured for being passed through by the at least one combined pulse laser beam and for providing at least one interference beam with an amplitude/intensity modulation inversely proportional to the time delay between the at least one reflected or transmitted main pulse laser beam and the at least one reflected reference pulse laser beam;
- f. a detecting element which is configured for converting the at least one interference beam into an electrical signal;
- g. a frequency filter which is configured for filtering a specific frequency and a specific range of frequencies of the electrical signal;
- and
- h. a rectifier which is configured for rectifying the filtered electrical signal to an output signal for control functions and/or as measurand;
- wherein the electrical signal is processed in an analog electric domain.
7 more elements
Dependencies are inferred from the claim text.