A: There is a new Microsoft Windows XP update (KB925902) that causes an Illegal System DLL Relocation error with the Pyrocam III. Microsoft is aware that it causes an error with the RelTek Audio control panel, the same way that it causes an error with the Pyrocam III.
Microsoft has released a hot fix for the problem with the RealTek Audio, and the fix also works for the Pyrocam III.
See: http://support.microsoft.com/kb/935448/
This website has a download file: WindowsXP-KB935448-x86-ENU.exe
This executable fixes the Illegal System DLL error with the Pyrocam III PyroCamControl.exe.


Close

A: The LBA-USB cameras pull power from the USB port and do not need a power supply. This is just a backup incase the USB power option has been turned off in the Device Manager or in the computer bios.


Close

A: It’s possible that the USB power option has been turned off in the Device Manager or in the computer bios. Check to see if this has been turned off and if it has not been turned, see the below.

There is also a known problem with the LBA-USB cameras sometimes blowing the USB power connection inside the camera. This is a known manufacturing defect and is covered under warranty. If your camera will not show up in the drop down camera list please contact the Service department for test procedures to verify if the USB power connection is blown inside the camera.


Close

A: The Spiricon products that are compatible with Windows Vista are only tested and recommended for use under Windows Vista Business 32 bit. No 64 bit platforms.

Product	Software Version
LBA-USB	v4.83
LBA-FW	v4.83
LBA-PC	v4.18
M2-200	v4.58
Pyrocam III	v1.89

Close

A: Usually this is because the camera has not been connected correctly. On desktop computers power can be pulled directly over the 6 pin to 6 pin Firewire cable. On laptops, you must use the supplied “Y” power adapter cable. The 6 pin to 6 pin Firewire cable must connect into the back of the camera and then connect into the female connection on the “Y” power adapter cable. Then the male connection of the “Y” power adapter cable is plugged into the laptop computer card. The same configuration is used for laptop computers that have built in IEEE 1394 except the 6 pin to 4 pin connector is used instead of the laptop adapter card. The round power connection must also be connected for the camera to show up in the camera list.


Close

A:(The answer below applies to analog CCD cameras. The rectangular pixels of digital cameras are directly displayed as rectangular pixels.) CCD cameras incorporate a low pass filter in the output video line of about 5MHz bandwidth, which very slightly smoothes the output data in the horizontal axis.

• Therefore, the signal in a horizontal line is not 100% correlated to the pixel width.
• Because of this it is possible to digitize the horizontal video line at any frequency desired.
• Spiricon systems digitize the horizontal line at the same spacing as the vertical pixel pitch.
• This creates a square pixel from a rectangular pixel element

Since the rectangular pixel width is slightly wider than the vertical pixel pitch, the above system samples the data at a rate slightly higher than the pixel pitch. Therefore, no specific pixel information is lost by this technique.

Close

A: Ultracal is a method of calibrating the zero level of the framegrabber 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 available in other framegrabbers. 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 the zero of the framegrabber 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 framegrabber 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 framegrabber 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.

Close

A: Commercially available framegrabbers do not offer the capability described in the question above about Ultracal.

Close

A: 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/framegrabber combination.
• Camera/framegrabber 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.

Close

A: The Dark Gray region in the Pan/Zoom display window depicts the Capture window, i.e., the region on the camera detector where the image is being acquired. Because this relates to how the frame grabber hardware is configured, it is referred to as the Hardware Zoom box. If you Double-left-click inside this box, you will cause this box to Zoom-in by a factor of 2x. If you Double-left-click outside this box you will Zoom-out. Observe that the image resolution will increase as you zoom-in; x4.., x2.., x1.., is in the increasing direction. As you zoom-in the number of pixels in the image remains the same, until the resolution can no longer increase. At this point the number of pixels starts to decrease, making the apparent size of the image larger.The chart below depicts this zooming process. The starting point is based upon how you configured the image size and resolution in the Camera dialog box. First find your resolution factor in the top row. Then drop down to the display width size. In the example below the resolution is x8, and the width is 64 pixels. Each time you zoom in you'll be following the arrows leaving each location and leading to the next. In this example your zoom-in sequence will begin at 64x60x8, then progress to 64x60x4, 64x60x2, 64x60x1, 32x30x1, 16x15x1. You will retrace this route in reverse order as you zoom-out. The center of the hardware Zooming action will be the intersection point of the Cursors. If the Cursors are turned Off, the zoom center will be about the center of the current frame.

The above example works for all non-interlaced cameras, interlaced Interline transfer cameras, and interlaced Full-Frame transfer cameras. If your camera is an interlaced Frame transfer type, the above example works in CW mode, but works slightly different in any of the Pulsed modes, i.e., Trigger Out, Video Trigger, and Trigger In. These style cameras will only output a pulsed laser image in one field. As a result the x1 resolution is denied, and the x2 resolution is the highest possible setting. Under this scenario, the above example will progress 64x60x8, then 64x60x4, 64x60x2, 32x30x2, 16x15x2.

• Soft Zooming, unlike the above Hardware Zoom, does not effect your data acquisition frame size or resolution. Soft Zooming only impacts the magnification of the displayed image . To initiate a Soft Zoom, Double-right-click inside the Dark Gray box. Observe that a smaller Light Gray box now appears, and that your beam display image has been magnified. You can continue to Soft Zoom-in by Double-right-clicking until your image is magnified to 16x15 pixels. To Soft Zoom-out, double-right-click outside of the Light Gray box. Each soft zoom increases or decreases the image magnification by a factor of 2x.The center of the Soft Zooming action will be the intersection point of the Cursors. If the Cursors are turned Off, the zoom center will be about the center of the current frame. Note: You can not perform Hardware Zoom operations once you have caused a Soft Zoom to occur. To change the Hardware Zoom you must first zoom all the way out of the soft zoom, until the Light Gray box is no longer visible.
• Panning:You can Pan the Dark Gray capture window across the camera's active detector region. Panning works at all zoom and resolution settings. If Soft zooming is activated, then the Panning controls will only pan the Light Gray zoom box.Two scroll bars are provided to allow you to perform the panning operations. The Horizontal scroll bar will allow you to pan Left and Right; the Vertical allows you to pan Up and Down.

Close

A:

• CCD camera manufacturers typically quote a signal-to-noise ratio of 50 to 60db. This refers to the peak signal before saturation divided by the RMS noise. This is a 20 log function, so 60db would be equivalent to a dynamic range of 1000, whereas 50db would be a dynamic range of about 300. However, it should be noted that this is comparing peak signal to RMS noise. The peak-to-peak noise is about 6 times the RMS noise. Therefore, the dynamic range in terms of peak signal to peak-to-peak noise ranges from about 50 to 180. With 8-bit digitizers, i.e., 256 counts, this means that the bottom 2-5 counts in the digitizer are noisy.
• The Pyrocam III pyroelectric camera also has a 60db signal-to-noise ratio. However, this is a worst case pessimistic specification. Typically the dynamic range is about 70db, which means the dynamic range is about 500 relative to peak-to-peak noise. This makes the camera very useful with 10 and 12-bit digitizers

Close

A:The amount of power or energy that the camera can take depends on the type of camera sensor. See Spiricon's Camera Selection Guide for specific details.

• CCD cameras typically saturate at about 0.3µW/cm² CW, and 3nJ/cm² pulsed
• Pyroelectric solid-state cameras typically saturate at 3W/cm² CW and 10mJ/cm² pulsed.

Close

A: Sampling and attenuating the beam is done in a two-step process.

• A high quality beam splitter is used to pass typically 90% of the beam through the beam splitter, and reflect or split typically 10% of the beam 90° away from the input path.
  
  • The beam splitter is typically quartz for the UV to Near IR, and AR coated ZnSe for CO2, or a transmitting or reflecting grating.
  • The beam splitter is typically quartz for the UV to Near IR, and AR coated ZnSe for CO2, or a transmitting or reflecting grating.
  • The splitter can be wedged to eliminate interference from the reflections from two surfaces, or thick enough that the back side reflection does not overlap the front side reflection.
  • The beam splitters are polarization sensitive, and this factor should be considered.
• This sampled beam is then typically attenuated with high quality uniform neutral density filters.
  • ND filters from 450nm to 2µm can be bulk absorbing BK7 glass, and achieve excellent results.
  • In the UV, quartz plates with surface reflecting coatings can be used. However, great care must be taken to minimize interference fringes.
  • At 10.6µm flats of CaF2 absorb about 50% per mm thickness, and can be used to attenuate CO2 beams.
  • Attenuation in the 2mm to 10mm region is difficult, and is best done by multiple beam splitters.

Close

A: With extremely fast P6 computers the acquisition speed is now limited only by the camera. This is typically 30Hz in the U.S. with the RS-170 standard, and 25Hz in Europe with the CCIR standard.

• 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.

Close

A: 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. The LBA-PC provides both Trigger In and Trigger Out functions.
• A very simple system is 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.

Close

A: 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, Spiricon's Ultracal system maintains excellent accuracy down to very few pixels and very low intensity. Refer to Spiricon's published articles for specific details.

Close

A: For satisfactory operation of your LBA-PC Laser Beam Analyzer, your PC should meet the following minimum requirements:

• A Pentium® or Pentium Pro® or equivalent processor based motherboard, with at least one open PCI bus slot.
• A Windows® 2000, or XP Pro operating environment with at least 64MB of main memory.
• A graphics card that will support a minimum of 1024x768.
• At least 15 MB of free disk space on one hard drive. An extra 100MB of free space if you plan to use Data Logging.
• A CD-ROM Drive.

Close

A:When using a camera with a lens, the operator must perform a spatial calibration to obtain accurate dimensional results. To do this, you must set up the camera lens system to view an object of a known dimension. The object to be viewed must contrast against its background to yield well defined edges. Use the following procedure.

• In the Camera Dialog Box, set the "Pixel Scale" V value to 1.
• In the Beam Display Toolbar Dialog Box check "Cursors" and "Crosshair"
• In the Camera Dialog Box set the "Resolution" to 1X.
• On the Beam Display Toolbar set "Crosshair" to Manual and "Cursor" to Manual.
• Set the LBA-PC into "CW Mode" and start it "Running."
• Place an object containing at least one known dimension into the imaging plane of the camera lens system, and focus the optics. (A good object might be a circular disk with a diameter of 1cm.) The object should be large enough to fill over 50% of the display height. You can hardware zoom to enlarge the object if necessary. Orient the object so that the calibration dimension aligns vertically on the Y axis cursor. You can use the Pan and Cursor controls to achieve a good alignment.
• With the mouse and left button move the cursor to one edge of the object
• With the mouse and left button move the crosshair to the object's opposite edge. The Delta = value on the screen will contain the pixel count between the known calibration dimensions. Divide this number into the calibration dimension to yield the correct "Pixel Scale" value.
• For example, if a 1cm distance produced a delta count of 176, then the "Pixel Scale" value would become .00568cm, or 56.8µm.

Close

A: The largest beam that can impinge directly on the camera depends on the size of the camera sensor.

• Spiricon offers three CCD camera types, 2/3" format, 1/2" format, and 1/4" format. The 2/3" format cameras, such as the COHU-4800 or the Pulnix TM-745 can image beams as large as 6mm. The smaller camera format, such as the COHU-6700 or the Pulnix TM-6 can image beams just under 4mm.
• Beams can be measured in the infrared with the Pyrocam III
• Large format digital cameras are available for high resolution and large area.
• For beams larger than those mentioned above, there are two techniques for measuring the beam.
• One is to use a beam expander in reverse to reduce the beam width by a known factor, so that it does fit onto the camera.
• The second method is to impinge the beam on a scattering reflecting surface, and then image that surface with a lens on the camera. In this case there is no limit to the size that the beam can be.

Close

A: The smallest beam depends on the pixel pitch in the camera.

• For 2/3" format cameras the pixel pitch is typically 13µm. At least 7 X 7 pixels should be illuminated on the camera. This means the beam should be at least 100µm to measure effectively.
• Using small format cameras with pixel pitch as small as 6µm, the beam could be as small as 40µm in width.
• For focused spots in the range of 10µm, a microscope objective or a recollimation 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.

Close

A: 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.

Close

A:The word gain refers to video gain. This implies amplification of the camera signal before the digitizer. The advantage of video gain is to boost the signal before digitizing so that the peak signal is closer to the peak digitizing range. However, noise is also amplified so that the signal-to-noise ratio is not necessarily improved. The biggest advantage of video gain is to maximize the dynamic range of the signal.

• Display Z-axis scaling is effectively a gain after digitizing. It is a process of scaling the image being displayed by 2X, 4X, etc. This is especially useful for observing small or low intensity signal that is in the wings of the laser beam, whereas otherwise the color scale may not differentiate between small changes in the wing energy.

Close

A: The Pyrocam III needs a window for protection against foreign objects entering the camera, and destroying the crystal. This could happen by someone poking a brush or Q-tip to clean off lint, etc. The window also protects the sensor from the effects of humidity. The window must have anti-reflection coating, or the two surfaces of the window will create interference fringes from a collimated light source which show up on the sensor as ripples in the beam. With anti-reflection coating the reflections, and thus the interference fringes, are minimized, and the sensor sees only the beam energy.

Close

A: A computer is required. The prices mentioned above do not include a computer. The computer required is an IBM PC compatible. The fastest P6 style is recommended, as the price of these computers has become very low.

Close

A: Cameras can be included with the system or can be purchased separately. The system can be purchased without a camera if the user already has one.

Close

A: Almost all monochrome cameras can be used with the Spiricon system. This is particularly true of all CCIR and RS-170 monochrome cameras. Also, digital cameras can be configured for the LBA-400PC and LBA-500PC digital input.

Close

A:

• The wavelength response depends primarily on the camera used, but also on the optics used for beam sampling.
• CCD cameras can see 266nm to 1.1µm
• Pyroelectric solid-state cameras can see 190nm to >100µm
• Other cameras are available for some specific wavelength regions, especially in the near IR

Close

A: Yes. The SP-LTA PCI to PCMCIA Adapter supports the system on a laptop. The LBA-PC runs on the PCI slot in standard computers. It also runs on laptops with the laptop mounted to a docking station that has a PCI slot.

Close

A: The software is not open to add options. However, the data files from the software are available in a number of formats such as ASCII, so that the data can be loaded into other programs for additional processing. An ActiveX server provides LBA-PC data, results, and beam image. You can also tell the LBA-PC to Start, Stop, Calibrate and load a configuration via ActiveX. The ActiveX server works locally or over a network. Examples are provided for LabVIEW, Excel and Visual Basic.

Close

A: No. The LBA-PC is designed specifically to use with our own framegrabber card, because it has features that are necessary for beam analysis that are not available in other framegrabber cards.

Close

A: No. However, all files from Spiricon's earlier beam analyzer, the LBA-100A, can be imported into the LBA-PC system.

Close

A: Most items are available off-the-shelf. Some specialized CCD cameras are ordered as required, and have 4-8 week delivery.

Close

A: Yes, it is possible to print the literature information page by page from our web site at www.spiricon.com by using your web browser's print function.

Close

A: Yes, our system mounted in a computer becomes a LabView virtual instrument, and can be controlled by a remote computer through GPIB, or onboard the same PC via ActiveX. All functions of our system are available via GPIB from the controlling computer. An ActiveX server provides LBA-PC data, results, and beam image. You can also tell the LBA-PC to Start, Stop, Calibrate and load a configuration via ActiveX. The ActiveX server works locally or over a network. Examples are provided for LabVIEW, Excel and Visual Basic.

Close

A: There are no current plans for making higher resolution in the Pyrocam III.

Close

A: M2 measurments are supported with the M2-200, available as an automatic accessory or manually with software only.

Close

A:

• 10 and 12 bit systems are useful with new, low noise 10 and 12 bit digital cameras for viewing and measuring low level structure.
• 10 or 12 bits give better signal-to-noise ratio.
• This is especially useful when there is significant low level structure in the wings of a laser beam.
• Even with 8 bit cameras, when summing or averaging is required to bring the signal out of noise, 10 or 12 bit digitizers divide the noise into finer increments for more accurate processing.

Close

A: No. The LBA-100A is no longer provided. A trade-in allowance is provided for users who wish to trade-in an LBA-100A towards an LBA-300/400/500PC.

Close

A: Digital cameras can be interfaced into the optional digital input of the LBA-400PC and the LBA-500PC.

Close

A:

• Spiricon's Ultracal system that gives precise camera baseline setting to enable precise beam measurements. (See Number 16 in Questions to Customer Service.)
• Spiricon's 10 and 12 bit digitizer systems
• Spiricon's high resolution, up to 1024 X 1024 capability
• Spiricon's never ending innovation and instrument improvements.
• Spiricon's total dedication to customer service.

Close

A: Our wedge beam splitters have no coatings so they have a high damage threshold.
The damage threshold of the beam splitter was tested at higher than >5J/cm2 for 10ns pulses.
The determining damage threshold is usually that of the C-mounted ND filters immediately in front of the camera, 50W/cm2 or 1J/cm2, or on other accessories after a beam splitter, such as the UV plate. For estimating power densities after the beam splitters, you have to do the arithmetic, including any beam reduction or expansion required along the way.
Close

A: The FX cameras connect to the computer via a standard Firewire IEEE 1394a port.
If a DESKTOP PC already has a 6 pin Firewire port installed, then this is usually OK.
If a customer does not have a Firewire port and needs to add a Firewire port to his computer, Ophir can supply a PCI Firewire card for DESKTOP PC's , or a PCMCI Firewire Cardbus for NOTEBOOKs + power supply.
Note: A power supply and adaptor is required for the camera with notebooks.
Close

A: Yes. The BeamStar software is supplied with the FX cameras and is freely available for distribution. It can be downloaded from our website Downloads section.
The BeamStar software will analyse data only from Ophir profiler cameras or video data files recorded with the BeamStar.
Close

A: For the latest version of the BeamStar application, you can freely download the BeamStar installation from our website, either as a demo or as a software version upgrade:
http://www.ophiropt.com/laser-measurement-instruments/beam-profilers/software/beamstar
For updating a previous version of BeamStar, you only need to download the first item on the download webpage.
Installation of the latest version will step you through uninstalling the previous BeamStar application, but will leave your saved data files intact in their original directories.
Close

A: All of our FX cameras are digital cameras. As such, there is exact 1 to 1 registration between the pixels in the CCD and the pixels in the computer. Therefore the width dimension depends mainly on one thing - the physical spacing of the pixels in the CCD. The CCD manufacturer's published pixel spacing for the CCD we use is more accurate than will be any calibration procedure involving a standard laser. There can be no drift over time. Temperature will have an effect according to the thermal coefficient of expansion of silicon.
(To achieve greater confidence or greater accuracy, one could use a microscope and accurate measurement slide to measure the CCD pixel spacing in microns directly).
The software does have a provision for entering a calibration factor. This is used particularly for the various magnifying or de-magnifying Optical Accessories. Overall scaling factor and separate factors for X and Y are supported.
Close

A:	1.	The noise level of the BeamStar FX 33 and 50 series cameras at 635nm on their most sensitive setting is ~10nW/cm2 (100µW/cm2 for saturation level). For other wavelengths, see graph below.
	2.	On a particular setting, the dynamic range on the screen is about 1000:1 (10 bit)
	3.	The shutter speed can vary from 1/frame rate to 1/8,000th s, a dynamic range of ~500:1
	4.	The camera gain can be varied from the screen from 0dB to 14dB, a dynamic range of 25:1
	5.	3 additional filters are provided with the BeamStar FX, 2-NG1 and 1-NG9. The transmission vs. wavlength is given below (upper curve NG9, lower curve NG1) The filters give a dynamic range of at least 50x50x10:1 = 25000:1 and as much as 200x200x20=8E5 depending on wavelength.
Thus with all of the above factors together: For CW lasers, the total dynamic range is >1000 x 500 x 25 x 25000 = 3E11:1 For pulsed lasers, the total dynamic range is >1000 x 25 x 25000 = 6E8:1

Close

A:	1.	Continuous lasers:
		a.	For CW radiation, with no filters installed, the damage threshold is about 10W/cm2. The damage threshold of the filters is ~50W/cm2.
		b.	On the shortest shutter opening (1/8,000th s) and lowest gain (0dB), the CCD saturates at ~0.4mW/cm2 for 635nm and correspondingly higher or lower for other wavelengths depending on if the sensitivity is lower or higher.
	2.	Pulsed lasers:
		a.	For nanosecond pulses, with no filters installed, the damage threshold to the CCD surface is ~1mJ/cm2. The damage threshold of the filters is ~1J/cm2.
		b.	For nanosecond pulses on the lowest gain setting (0dB), the CCD saturates at ~ 50 µJ/cm2 at 1064nm.

Close

A: The BeamStar FX cameras are carefully designed to reduce or eliminate interference effects as follows:
1.	The removable filter windows are all angled at 2 degrees so as not to interfere with each other.
2.	The filter windows are made of high quality optically flat polished glass so as not to distort the beam.
3.	The windows are large in size so they will be easy to clean and remove dust.
4.	All standard cameras have the window removed from the CCD. The BeamStar FX 66 does not have the window removed since it is primarily for large sized beams where interference effects are less serious.
5.	For almost total elimination of interference effects, use the variable attenuator (Ophir P/N 1Z17012) instead of the screw on ones. These attenuators are wedges so they completely eliminate interference effects.

Close

	A: The BeamStar FX variable attenuator allows continuous adjustment of beam attenuation while at the same time almost completely eliminating any interference effects due to its wedge design. The dynamic range of attenuation is shown below as a function of wavelength, where the blue line is the transmission in its most transmissive setting and the red line in its most attenuating position.

Close

A: In normal (CW) operation, the CCD is automatically triggered to start a measurement. At the end of the integration time, the voltage for each pixel is read out of the CCD serially and converted by the A-to-D into a 12-bit digital value When the PLD has finished reading all the pixels of the CCD it signals to the PC that data is ready to be read. After the PC has finished reading the data, the next available measurement of the CCD is again stored and the cycle continues.

In Pulsed Mode for Long Pulses ( >5µs ), the CCD is triggered by the trigger circuit instead of automatically as for CW mode. As the pulses are long, their intensity can be read by the CCD after it is triggered, by setting the appropriate shutter time for the length of pulses.

In Pulsed Mode for Short Pulses ( <5µs ), the same method as for long pulses cannot be used because once the circuit is triggered, the pulse has already finished. Therefore, the CCD is triggered automatically as with the CW mode, but after each measurement of the CCD, the PLD checks to see whether the trigger circuit received a pulse while the CCD was measuring. If so, the data is and the cycle continues as normal; otherwise a new CCD measurement is made.

In most cases of pulsed light sources, CW operation will be sufficient (and the intensity can be adjusted by adding filters or reducing the Shutter Time). In that case, the Shutter Time should be adjusted to capture a few pulses of light for each CCD integration, to avoid having 'empty' measurement cycles where no light is captured by the CCD. In the case that the pulses are slow, and/or the Shutter Time would have to be excessively long to guarantee capturing at least one pulse each time, the Pulse Mode operation can be used instead.

Close

A: What determines this is the amount of power getting through the slit of size 5µm x 3mm so as long as the light source is larger than 3mm to overfill the slit, the power density is what determines this.

At a typical wavelength of 670nm, the reading reaches full scale where the exposure time x power density ~ 2E-7 Watts * sec / cm2.

Since the longest exposure time is 7s, and we can easily read 1/100th of full scale, the lowest power density on the slit will be ~ 0.5nW/cm2. If the input is from a fiber, you can use the SMA fiber input accessory (Ophir P/N 1Z08205) with focusing lens (Ophir P/N 1G01236) to focus the fiber output onto the slit.

Since the shortest exposure time is 28µs, the highest power density we can read is ~ 1mW/cm2. In practice, we can always spread the beam as much as we want or reflect it off of a diffusing surface into the WaveStar so there is really no limit to how high a power we can measure.

Close

A: For 905nm the single shot energy threshold is ~ 100nJ/cm2 falling on the input slit of 5um x 3mm. At 1030 - 1100nm the sensitivity will probably be 10 to 100 times less.

Close

A: Not exactly known but far far more than the saturation intensity so you will never reach it if set up properly.

Close

A: The relative spectral sensitivity is given in the accompanying graphs. Note that the WaveStar corrects for differences in spectral sensitivity.





Close

A: In response to growing customer demand, WaveStar is being upgraded to include ActiveX controls. This will allow other applications (such as LabVIEW, LabWindows, Visual Basic, Visual C++) to control WaveStar parameters and collect measurements in real time. This will be included in the next release of WaveStar (February 2002).

Close

A: When the power calibration of the WaveStar is activated by pressing the P icon, the software puts in a calibration factor for each wavelength which compensates for the variations in sensitivity of the WaveStar at various wavelengths and produces a spectral curve which has the correct relative intensity values. For instance, if the light at one wavelength has twice the intensity of another, the display will show a relative height difference between the two wavelengths of a factor of 2.

The correction curve is generated by exposing the WaveStar to a NIST traceable calibrated wide band light source. The software compares the known relative intensity values of the lamp spectral curve with the values produced by the WaveStar and generates a correction curve.

Close