This depends on whether you are using a thermal sensor or a photodiode sensor. With our most sensitive thermal sensor, model RM9, one can measure down to about 500nW. With our photodiode sensor heads we have a several types, silicon, InGaAs and Germanium. Each has a spec on minimum power, which can be as low as 10pW
Beam Profiler FAQ’s
Fortunately all of the latest beam profiler software are available from the web site at; https://www.ophiropt.com/laser-measurement-instruments/beam-profilers/se... You do need to fill out a short form and then you're welcome to download any of the software packages. Be sure to identify the correct package for your beam profiling system. Note; The Photon Scanning Slit Profiler software is also posted here along with the latest version of legacy beam profiling products.
This is a known ActiveX issue with Microsoft. You can occasionally get an error message stating, "The system DLL user32.dll was relocated in memory. The application will not run properly. The relocation occurred because the DLL C:\Windows\System32\Hhctrl.ocx occupied an address range reserved for Windows system DLLs. The vendor supplying the DLL should be contacted for a new DLL." There are two ways to get around this. First, you can just run the Setup.exe from the individual folders on the CD. Or second, you can click the below link and then click the Download button to download the WindowsXP-KB935448-x68-ENU.exe file. Run this to install the 935448 hot fix. You will not need to restart the computer. Then you can install the software from the Flash screen.
The answer depends on what information is wanted from the beam width.
- The most representative measurement of a beam width in determining how the beam will propagate is the Second Moment measurement. However, the Second Moment measurement can have problems if there is diffraction in the beam before measurement, which puts a significant amount of energy in the wings. This energy may diverge faster than the rest of the beam, and if it is included in the measurement, it will give a beam width much wider than reality. However, an aperture can be used to limit the beam width measurement to energy inside these diffraction rings.
- A second very good measurement of beam width is the software equivalent knife-edge measurement. This measurement is less sensitive to diffraction in the wings of the beam, although it will give a beam width measurement which is weighted by energy out in the wings. It is less sensitive to noise.
- Sometimes the most important information is not the beam propagation characteristics, but how much energy is near the peak of the beam. In this case, a percent of peak beam width measurement would be more useful.
Try using the back side USB ports. They are generally connected directly to the PC motherboard and work better, whereas front side USB ports are connected through extension cables and may be subject to signal loss interference.
After numerous requests for re-calibration of M2 systems, in 2008 Ophir-Spiricon started a recalibration program for its M2 systems. This program allows the equipment to be sent back to the factory to be inspected, lubricated and re-calibrated. This enables customers to comply with their ISO regulations. Please click the below link to be directed to a section of our web site where you can request an RMA to return your equipment for re-calibration.
Ultracal is a method of calibrating the zero level of the A to D converter precisely to the zero level of the CCD or other type camera. Ultracal has a number of features that make it much more effective than standard background subtraction. Ultracal works as follows:
- All incoming laser radiation is blocked from the camera, allowing any ambient radiation which will enter the camera during measurement, to still impinge upon the camera. (However, ambient radiation should be minimized under all cases.)
- The A to D converter is then set to capture frames from the camera, and adjust the zero level of the A to D converter. The zero level of the converter is adjusted until it and the baseline of the camera are as close as possible to each other. However, the digitizer is set slightly lower than the zero of the camera so that all noise components from the camera are digitized. This is assured by raising the camera DC level until the digitizer does not report any zero counts, i.e., all negative going noise from the camera/digitizer combination is at least one positive count. Once this baseline level is set, the software accumulates and averages 64 frames so that a baseline is obtained that is essentially free of random noise, but contains any offset or shading from the camera.
- In all subsequent laser signal frames this baseline is subtracted pixel by pixel from the signal frame.
- A unique characteristic of Ultracal is its treatment of what we call negative numbers. Consider that a given pixel signal is exactly at the same level as the average background obtained from the 64 frames. When these two are subtracted from each other, the output magnitude will be zero. On the other hand, if a small positive noise spike occurs on a given pixel, of say, 2 counts higher than the average, then the output from that pixel will be a +2. The third case would be when noise drives the pixel signal lower than the average; for example, 3 counts less than the average. When the average is subtracted from this signal, the resultant is -3 counts. Spiricon holds a patent in which these negative 3 counts are retained in the memory subsequent to the A to D converter. In other acquisition systems negative numbers resulting from background subtraction are truncated to zero.
- By maintaining the use of both positive and negative noise counts for each pixel in the sensor, the negative signals can offset the positive signals, and thus the background averages much closer to zero. This enables much more accurate measurement of beam width and other beam characteristics.
All of the Beam Profiling systems include comprehensive PDF User Guide Manuals. These manuals are provided on the software installation CD and are installed to the folder where the beam profiling software installs as a separate PDF file. In addition to the User Guide Manuals, there are also readme files and support documentation that can be found in the folder where the beam profiling software installs. For example the BeamGage Professional software installs a full hypertext manual for automation in the C:\Program Files\Spiricon\BeamGage Professional\Automation\Documentation folder.
If you are searching just for a PDF copy of a particular beam profiling system manual, they are also available from the web site at; https://www.ophiropt.com/laser-measurement-instruments/beam-profilers/services/manuals
There is no NIST standard laser beam by which beam analyzer results can be compared and verified. Spiricon engineers, however, have generated mathematically derived beams, added mathematically derived random noise to the beam, and then performed various beam measurements. Since the original beam was mathematically derived, the accuracy of the beam measurements can be verified under realistic conditions.
- This process verifies the accuracy of the software, but does not do any verification of the accuracy of the camera/acquisition combination.
- Camera/acquisition system combination verification can be performed by making very accurate measurements of characteristics such as beam width vs. intensity on the camera to verify that the camera is linear. The beam can also be moved about the camera to make sure that it is uniform. This type of measurement must be verified by meticulous measurements.
The BeamGage and NanoScan software are offered in either Standard or Professional versions with corresponding associated cost. The software upgrade from BeamGage Standard to Professional requires a license key and the installation of the Professional version of the software, which is available from the software download section from our website. The NanoScan V2 software upgrade, from Standard to Professional, only requires the license key. To purchase the upgrade please contact us at firstname.lastname@example.org for current pricing. We will need the serial number of the unit(s) for upgrading.
Pyroelectric cameras can acquire data with pulse repetition rates up to 1kHz, but output data at approximately 60Hz.
Shutters enable CCD cameras to split out single pulses out of a pulse train up to 10kHz pulse repetition rate.
We have recently updated our website product pages to include drawings of items. If you are looking for a drawing for an Ophir-Spiricon product, please visit its product page and click on the Drawings tab. Drawings are available in a number of different formats including PDF, SolidWorks, and STEP.
The most reliable synchronization is to have the beam analyzer camera system trigger the laser. Then 100% synchronization is achieved.
- When triggering the laser is not possible, then the camera can sometimes be triggered from the laser. Some beam profilers provide both Trigger In and Trigger Out options, others just Trigger In or Trigger Out. Please see specifications for details.
- A very simple system is Ophir-Spiricon's Video Trigger, in which the camera is free running, and the software simply looks to see if a signal of a pre-determined minimum magnitude is present from a pulse. If it is, then that signal is acquired and displayed. If no signal is present, then that frame is discarded. This video trigger system achieves about 98% reliability.
- An optional optical accessory can also be used to synchronize with the pulsed source. https://www.ophiropt.com/laser--measurement/beam-profilers/products/Accessories/optical-camera-trigger/optical-camera-trigger
Different measurements have different accuracy. The accuracy is also dependent upon the conditions of the signal coming into the camera. Ideal conditions consist of signal that nearly saturates the camera, and the 1/e2 width covers about 50% of the pixels. In this case the error of most measurements is less than 1%, but no greater than 5%. When fewer pixels of the camera are covered by the beam, or when the beam intensity is reduced, measurement accuracy is compromised. However, Ophir-Spiricon's Ultracal system maintains excellent accuracy down to very few pixels and very low intensity. Refer to Ophir-Spiricon's published articles for specific details.
The smallest beam depends on the pixel pitch in the camera.
For 1/1.8" format cameras the pixel pitch is typically 3.7µm or 4.4µm, depends on a model. At least 10 pixels should be illuminated on the camera. This means the beam should be at least 37µm or 44µm to measure effectively.
For focused spots in the range of 10µm, a microscope objective or a re-collimation and refocus with a long focal length lens can be used. Then resolution of the camera can be effectively magnified by about a factor of 10, so that resolution less than 1µm is obtained. Thus a focused spot beam could be as small as 7µm, and an effective measurement could still be made.
The camera works as an integrating device and thus can measure a profile of pulses down to the femtosecond range. In slowly pulsed systems it is always advisable to use a trigger into the camera to synchronize pulses.