Laser Power Probes

Laser power measurements should be quick and easy. They should not involve time consuming set-up and alignment problems. Ideally, the measurements should also be able to be made at any point in an optical system where losses are likely to occur.

Unfortunately, most laser power meters have sacrificed ease of use to gain continuous power readings. However, in most laboratory and production situations, the usual requirement is for a quick spot-check of power with a minimum of disruption.

Even when tuning up a laser, researchers have found that it is best to tune for a desirable mode pattern using Thermal Image Plates, then briefly check the laser power.

Our Laser Power Probes are calorimeter-type power meters which measure laser power using a timed exposure. Laser Power Probes display average power absorbed on a calibrated readout scale and can be used with continuous or repetitively pulsed lasers ranging from small 2 watt YAG lasers to large 10,000 watt CO2 lasers.

Select Features

• The absorbing head of a Laser Power Probe is conveniently sized. An absorbing head is large enough to be easily used, yet small enough to be inserted between optical components to measure the laser power without disturbing set-up.
• The hand-held laser power probes require only about one minute to make a power measurement.
• The absorbent coating is very tough, resisting mechanical abrasion and water immersion.
• A zero adjustment mechanism has been incorporated into the design to expedite and simplify the power measurement process.
• An accurate and durable all-metal construction has been used to insure a long life.

Taking Measurements

Each Laser Power Probe is a self-contained unit consisting of an absorbing head, a temperature measuring mechanism, a zeroing knob and a readout dial. In operation, the dial is zeroed. Then the absorbing head on the end of the Laser Power Probe is exposed to the laser beam for a specified time interval. After the Laser Power Probe has been removed from the laser beam, the average laser power can be read out on the dial. The process takes about one minute. If it is necessary to make several power measurements in succession, the absorbing head can be rapidly cooled by immersing in a beaker of water between measurements.

The Laser Power Probes have proven to be so popular that we now offer 13 flat and 2 conical models. The models include 8 different power ranges and 2 different absorbing coatings.

• The "Y" series Laser Power Probes have a broad spectral absorption coating which can be used from 0.2 to 11u. These Laser Power Probes are designed for use with the YAG or CO2 lasers. The "C" series Laser Power Probe can only be used with CO2 laser wavelengths.
• The "C" series is recommended for use with CO2 lasers because the coating generally has a higher damage limit than the "Y" series.

For CO2 lasers in excess of 1200 watts, there are two additional laser power probes available based on conical absorbing heads. These conical heads exhibit a higher damage threshold than the standard flat surface heads. However, the conical head laser power probes are thicker and have a smaller target area than the standard flat probe of equivalent power ranges. See the Conical Laser Power Probe data sheet for more information.

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Laser Power Probe Specifications

* Repeatability of all laser power probes is +/-1.5%

Alternate power ranges can be obtained by doubling or halving exposure time and the indicated power. For CO2 lasers, the "C" coating is recommended because this coating can withstand higher laser power than the broad band "Y" coating.

• The accuracy and repeatability of the Laser Power Probes partly depends on the accuracy of the exposure time. The average accuracy of exposures (hand held) has been found to be 0.2 seconds. This amounts to a 1% error for a 20 second exposure time. Many lasers are equipped with a shutter that can produce an exact time exposure.
• 10 second exposure time for 10,000 watts.
• 20 second exposure time for 5,000 watts.

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*Approximate Damage Threshold
For Stationary Probes

*Moving the probe during exposure will increase (up to double) the damage threshold compared to the numbers shown for a stationary probe. To achieve this increase, the head must be moved in a circular motion so that the laser beam does not strike any one area continuously for more than 1.5 seconds.

(1) Exposure time of the laser beam on a power probe head which is rated to accept the indicated power level.