Archive for December, 2011

Most drivers get caught speeding at some time during their driving experience. A common scenario occurs when a policeman uses a lidar speed meter to indicate that a car is over the speed limit. When the car is caught and pulled over, the driver shows a surprised innocent face attempting to get away. But when the policeman shows the driver the reading on his lidar speed meter he knows he’s going to have to pay that fine. Can the driver claim that he was within the speed limit, claiming that the lidar instrument is not calibrated recently?

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Measuring the power of scanning lasers such as barcode scanners presents a problem. A bar code laser beam scans back and forth at a very high frequency so an ordinary photodiode power meter will not measure the power in the beam but rather the average power impinging on it, i.e. the power times the fraction of time the beam is on the detector. Therefore, when exposed to a scanned beam, the reading will be much lower than the actual power in the beam. For example, if a scanning laser delivers 2mW to a photodiode sensor and the beam is on the sensor only 1% of the time, the instrument will read only 0.02 mW.

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Many materials processing laser applications, for example cutting, drilling or marking, all involve a machine inside of which there is a laser and an opto-mechanical system which includes beam shaping and focusing optics, a beam delivery system, and perhaps a galvanometer scanner or other moving parts depending on the application. All these parts have to be aligned when the machine is built and have to maintain their alignment over the course of the machine’s operating life time.

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Ophir Photonics Group, the global leader in precision laser measurement equipment, announced a BeamTrack 3A-QUAD, the first high sensitivity thermal detector to combine multiple functions – power, energy, position – in a single, compact laser sensor.
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By Dick Rieley, Sales Manager, Mid Altantic and Southeast Regions, Ophir-Spiricon LLC

The selection of a sensor to accurately measure the power of a laser or energy of a pulsed laser can seem like a simple and easy procedure. However, many times the selection process is limited to choosing a sensor that only meets the range of power or energy to be measured, leaving out several other essential criteria of the laser specifications; that without their consideration, can allow the wrong sensor to be selected, the laser to be measured inaccurately and likely to cause the sensor to fail prematurely.

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