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US 4,902,963 AGranted
Method and arrangement for recording periodic signals with a laser probe
OwnerHans D. Brustinventor
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OwnerHans D. Brustinventor
Estimating the term…
Method and arrangement for recording periodic signals with a laser probe. The application of stroboscopic methods in laser metrology requires the synchronization of the measuring arrangement (scanning laser microscope) with the periodic signal excited in the electronic component to be investigated. Since short laser pulses are very difficult to generate in response to a trigger signal, an attempt is made to derive the module clock from the pulse repetition rate of the laser. This type of synchronization requires complex apparatus particularly when the required clock frequency lies above the pulse repetition rate of the laser. In accordance with the present invention, therefore, a synchronization of the measuring arrangement and of the component is eliminated. In order to assign the proper point in time within the period of the signal to the measured values, the chronological spacing of the laser pulses allocated to the measured values are identified relative to a trigger signal that is synchronous with the signal to be recorded.
A method for recording periodic signals with a laser probe, whereby the laser probe is pulsed and is directed onto at least one point of a specimen carrying a first signal, and whereby a secondary signal triggered on the specimen by the laser probe is detected and is converted into a measured signal (g(t)), comprising asynchronously gating the laser probe;
A arrangement for recording periodic signals with a laser probe, having a means for generating a pulsed laser probe, having a lens system for focusing the laser probe onto a specimen, having a means for positioning the laser probe to at least one point of the specimen that carries a first signal, having a means for detecting a secondary signal (PE) generated on or within the specimen by the laser probe, having an evaluation electronics connected to a means for generating a measured signal (g(t)), said means for generating having an input connected to an output of said means for detecting, and having a recording unit having at least a first input connected to an output of said means for generating, comprising a means for measuring a time difference (.DELTA.t) that has an output connected to a second input of the recording unit, a first input of said means for measuring receiving a second signal (CLK) synchronous with said first signal and a radiation detector whose output signal (SDA) is received by a second input of the means for measuring the time difference (.DELTA.t), the radiation detector receiving on an input thereof the pulsed laser probe.
Dependencies are inferred from the claim text.