How can I move the selected region of interest without changing its size?
Energy/Power measurements can be made on any area or region of your laser beam. Energy measurements are made on pulsed beams, whereas Power measurements are made on CW beams.
To perform this measurement:
- Select "Flat Top Analysis" in the Data Analysis dialog box accessed from the Data Collection Menu.
The units of the energy/power analysis are also selected under the Data analysis dialog. Units available are: µW, mW, W, for CW beams or µJ, mJ, J, for pulsed beams. When selected, the Energy/Power parameter values will be displayed in the appropriate MKS units.
- Define an area, called the Energy Region of Interest (Energy ROI), using the drawing tools in the Video window. The drawing tools can be accessed either through the Options menu or by using the four yellow icons on the Video window toolbar. If using the menus, select "Overlays" from the Options menu. Another menu will appear. Then, select "Energy ROI" to obtain the final menu where you must select one of the four area types: Circular, Elliptical, Square, Rectangular. If using the icons, simply click on the icon of the desired area type.
- Draw a ROI. Using the mouse, position the cursor at one "corner" of your desired area, hold down the left mouse button and drag the mouse to the opposite "corner". (For circular and elliptical areas, the "corners" are the points at which tangents of the area perimeter, aligned along the principal axes, intersect.) As you draw, you will see a "fat" outline of the area selected. Release the mouse to "freeze" the outline. The ROI can be drawn only inside the Beam Area.
- If the area is not exactly what you want, you can now use the mouse to change the selected area, or you can draw a new area as in Step #3 above.
- Once you are satisfied with the selected area, you must perform steps to validate your selection. You can validate your selection in 2 ways:
- From the Options menu, select "Energy ROI" and click on the area type that was drawn. Or,
- From the toolbar, click on the Area icon for the area you selected.
The energy ROI has now been defined. All Flat Top Analysis will be performed only in this portion of the Video Image.
- You can move the ROI to different locations, and then use the Recompute feature to analyze the energy in the new locations. If you want to use the exact same area used previously, simply select the "drawing" tool, then while pressing the CTRL key on your keyboard, use the mouse to drag the ROI to the new location.
Displaying the Energy ROI in the Video window:
This feature is optional. An overlay of the selected Energy ROI can be displayed on the Video Screen if the user desires; or, the overlay can be left invisible. This option is available under Options, Overlays, Energy ROI.
- Definitions of Uniformity and Flatness:
The beam Uniformity is defined in the ISO Standard as:
The beam Flatness Factor is defined in the ISO Standard as:
Q. How do I automatically follow a moving beam?
To automatically "follow" a moving beam, use the Auto Track feature. This feature is available either under the Data Collection Menu or by clicking the Auto Track icon on the main toolbar. When selected, the software determines an area, called the "Beam Area", in which profile calculations will be performed.
Q. How do I measure the "short and long" beam diameter and determine the beam rotation in an elliptic beam?
To determine the "long" and "short" diameters of your beam, and the rotation of your beam, select "Elliptical Analysis" in the Data Analysis dialog box. When "Elliptical Analysis" is enabled, beam calculations will be performed to determine the major and minor axes, the beam ellipticity (the ratio of the 1/e2 (13.5%) widths of the major and minor axes) and the tilt angle (angle with respect to horizontal) of the major axis. The elliptical parameters can be displayed in the Beam Statistics Parameters dialog.
Q. How do I subtract the background noise?
To subtract background noise, you must first perform a calibration to generate a background calibration factor. This is done through the Calibration dialog box accessed under the Data Collection menu. Also, the system must be operating in the Analysis mode. A new calibration file is generated whenever you perform a calibration.
Two types of background subtractions are available: either "frame" or "mean". The selection is available under the Data Collection menu by selecting "Background Subtraction". The choice is available because some cameras have very non-uniform backgrounds and some ambient background conditions can be very non-uniform. In cases like these, "Frame Subtraction" is recommended. You may also want to use "Frame Subtraction" for very small beams. The choice is yours.
The background in the calibration file is automatically subtracted from your data. It is important to perform calibrations periodically to ensure that the stored background file is appropriate for your present condition. The background can change significantly due to changes in attenuation and room lighting, or for such things as subtle as the brightness of the shirt you wear.
Q. How do I measure my pulsed beam?
There are two ways to measure pulsed beams. The best way is to use the External Trigger Mode, available under the Data Collection menu by selecting Trigger Mode. You must supply an external TTL level signal to the external input pin (PIN 4) of the 15-pin D-subminiature connector on the Image Capture Card. A trigger cable is available from Photon, inc. as Option /TRG or you can make one yourself.
If you cannot provide an external trigger, use the Pulsed Trigger mode, also available under the Data Collection, Trigger Mode sub-menu. When this mode is selected, the software will automatically determine the presence of the beam based on minimum signal amplitude of 32 counts out of 255, i.e., 12.5% full scale. In this mode, the update rate will, in general, be reduced.
Frame Checking is an algorithm performed on pulsed beam data when operating in the Frame and Pulsed modes. The algorithm detects the presence of the so-called "Venetian Blind" effect, where one field of the video image has no data and is black. When observed on a display, an image of this type appears as if you are seeing it through Venetian Blinds, hence the name, "Venetian Blind" effect. This results from the operation of frame transfer cameras and the timing of the arrival of your laser pulse at the camera. In many cases, because the timing is not correct, the video signal has data in only one field, with the second field at the background level.
When this occurs, the data is corrupted by the dark field. When the Frame Checking Algorithm detects this condition, the data is ignored. This ensures capturing only valid data.
Q. How do I draw/measure a Gaussian fit?
A Gaussian fit can be calculated by selecting "Gaussian 1D" in the Data Analysis dialog box. The fit is calculated according to the ISO Standard. Once the fit calculation is enabled, an overlay can be drawn over the beam profiles in the Profile window. This is accomplished either through the Profile window option menu or by clicking on the "Gaussian Fit Overlay" 
on the Profile window toolbar. The Gaussian Fit Parameter can be reported in the Beam Statistics window.
Q. How do I measure peak intensity?
To measure peak intensity, open the Beam Statistics Parameter dialog box, available under the options menu for the Beam Statistics window option menu, or by clicking the "Parameter" 
icon on the Beam Statistics window toolbar. Select "Peak" to display the peak intensity (in counts) in the Beam Statistic Parameter dialog.
Q. How do I set or display beam area?
The Beam Area is set in one of two ways. The simplest way is to click on the beam area drawing tool icon on the Video window toolbar. Then use the mouse to draw a rectangular region in the Video window. (Note that the software must first be operating in the Analysis mode). To draw, place the mouse at one corner of your desired area; then hold down the left mouse button and drag the mouse to the opposite "corner". As you draw, you will see a "fat" outline of the area selected. Then, to set the area, click the beam area icon again. The Beam Area outline will now appear as a thin line. The second method is to select the Beam Area drawing tool from the Options menu of the Video window.
Displaying the beam area is optional. To display the beam area, select "Beam Area" from the Overlays sub-menu in the Options menu.
Q. How do I know the size of the beam area?
The size of the Beam Area used for all computation is displayed on the Status Bar at the lower right corner of the screen. The upper left coordinate and size of the rectangle are shown in micron.
Q. How do I monitor my laser over long periods?
There are two ways to monitor your laser over long periods of time. This is done using either the Beam Statistics window or the Time Statistics window. (You can open up to 15 Time Statistic windows) You can select the windows under the windows menu or by clicking the icon on the main toolbar. You must define the parameter that you wish to display. This can be done in the Parameter dialog box, accessed either from the Options menu or by clicking on the on the local toolbar.
Q. How do I add my notes to the data that I just collected?
Notes can be appended to your data by using the Notes window. The Notes window can be opened either through the windows menu or by clicking on the Notes window icon from the main toolbar. Use the Notes window like any text editor!
Q. How can I print the data I collected?
There are several ways to print hard copies of your data. You can either use the Print feature under the File menu or you can save your screen as a bitmap file and copy it to another program and print.
Q. What options do I have for saving and outputting data?
There are many ways to save your data. You can save screens with data, save screens as bitmaps, raw pixel data files, or you can log data to files. The save options are available from the "Save" or "Save As" selection under the file menu. The data logger options are accessed from the Beam Statistics Parameter dialog box under the Options menu of the Beam Statistics window.
Q. Can I average the data?
Yes; select Profile Averaging in the Data Collection menu.
Q. What statistics can be calculated?
Statistical quantities available are the Mean, Min, Max and Standard Deviation. These selections are made through the Beam Statistics Parameters dialog box available under the Options Menu of the Beam Statistics window.
Q. How do I profile through a different cross Chapter?
You can profile through a different cross Chapter by moving the Cross Hairs in the Video window (the profiles are displayed in the Dual Aperture Profile window). This is done with the mouse by grabbing the cross hair (click on the left mouse button) and dragging to a new location.
Q. How do I profile through a different cross hair rotation?
To change the rotation of the cross hair, the system must be operating in the Elliptical Analysis mode available from the Data Analysis dialog box under the Data Collection menu. Grab one of the axes by left clicking on the mouse, and while simultaneously holding down the "Ctrl" key; use the mouse to drag the cross hair to a different rotation.
Q. Why can't I see the cross hairs?
If the cross hairs are not visible in the Video window, then the cross hair display feature has been turned off. They can be displayed from the Options menu under the Overlays sub-menu by selecting "Cross Hairs".
Q. How do I remove the cross hairs?
To turn off the cross hair display in the Video window, go to the Options menu under the Overlays sub-menu and "deselect" the "Cross Hairs" option.
Q. How can I change the clip levels?
Clip levels of 13.5%, 36.8%, 50%, 60.7% and one user level are available under the Beam Statistics Parameter dialog box, available by selecting the clip level of choice under "Beam Width". If you selected "User %", then you must also enter the clip level value.
Q. How do I customize the screen?
You can customize the screen in the usual Windows feature by sizing and arranging window or by using the Cascade and Tile Feature available under the Windows menu.
Q. How do I zoom in on the beam?
You can "Zoom In" on the beam displayed in the Video window by selecting "Zoom" under the Options Menu. Choices available are: 1x, 2x, 4x, 8x and 16x.
Q. How do I customize the color scheme?
The color scheme of various displays can be customized under the Clip Level dialog box available under the options menu for each applicable window.
Q. How do I normalize the graphs?
The profiles displayed in the Profile window can be normalized (expand the display to show a peak value of 100%) either from the options menu or by clicking on the Normalize Icon on the local toolbar.
Q. How can the toolbar buttons save me time?
The toolbar buttons save you time by affording you immediate access to selected features. They eliminate the time required to access these features through the various menus and sub-menus.
