The 3A-P actually absorbs about 85% at 10.6µm and therefore it can be used to measure weak CO2 lasers. Note the low power damage threshold, however, of 50W/cm2.
Power Meters FAQ's
The RM9 is only sensitive to signals chopped at 18 Hz, so placing the chopper as close to the laser source as possible will minimize stray light entering the chopper and being read as part of the signal.
The noise specification is based on a 10 second moving average. Set the power meter to average the measurements for optimal performance.
It is also recommended to zero the sensor before use. This is done by disconnecting the BNC cable between the RM9 sensor and the chopper or turning off the chopper. Then follow the regular instructions for zeroing that can found in your power meter or PC interface manual.
The absorber is calibrated at 532nm, covering the visible and UV region. At 355nm it reads less than 0.5% higher that at 532nm and at 266nm, it reads 1-2% higher.
What are the calibrated wavelength regions of thermal broadband sensors as defined by the laser wavelength regions displayed?
UV: 193 - 350nm, VIS: 350 - 850nm, NIR: 850 - 3000nm, CO2: 10.6um. Newer sensors have the regions explicitly where the laser settings are: <.8µ, .8-6 and 10.6
Why is the P type absorber shown to be completely flat spectrally in the catalog but there are still two wavelength settings in the sensor?
It is flat for <750nm and for >900nm but can vary +/-2-3% between those regions. Since it can vary in either direction, this information cannot be put in the spectral graph.
How is it possible that a thermal sensor can pass the calibration before test, but still need a disc replacement?
The answer to this question is two-fold. First of all the recalibration process accomplishes the recalibration of the sensor and returns it to "as-new" working condition. If there is surface damage on the sensor disc that creates areas of non-uniformity exceeding the uniformity across-the-surface specification, then the disc needs to be replaced, even though the accuracy performance of the sensor is not out-of-tolerance. Secondly, many applications require that sensors be found in-tolerance during the calibration process, or else deviation explanations are required and/or costly recalls may need to be implemented. The calibration process is intended to help maintain the sensors within tolerance if at all possible.
What is the absolute energy accuracy for single-shot energy measurement with a thermal sensor? It does not seem to be included in the specs.
The accuracy is basically +/-5%, but it is complicated and depends on several factors including energy level and range; it therefore cannot be properly specified by a single number for all cases.
Can an unused laser wavelength selection be disabled on a thermal sensor to avoid the possibility of an out-of-tolerance failure at that wavelength during recalibration?
Yes. Thermal sensors are calibrated at 532nm, 1064nm and 10.6µm. If (for example) only 1064nm, the fundamental YAG laser wavelength is used, then the other two laser wavelengths can be disabled and we will only recalibrate at 1064nm. This eliminates the potential for out-of-tolerance failures at the unused laser wavelength selections. If you put this request in the “Special Notes” section of the RMA request checklist form, we will then know to provide this option.
Why wasn’t the firmware upgraded to the latest version when the meter was sent in for recalibration?
Our recalibration process is to not automatically upgrade the firmware in meters when they are sent in for recalibration, unless specifically requested to upgrade it. The reason for this is that we support many companies, such as medical companies, that have equipment validation processes that don’t allow changing the firmware version from the currently validated version. If you do want the latest firmware version installed, we will do that at no additional charge (for meters which are upgraded electronically) if it is specifically requested on the RMA request checklist form. For older meters (such as the Nova) that are upgraded through changing the EEPROM, a nominal fee is added, if firmware upgrade is requested. Note; upgrading the firmware does not affect the calibration.