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Line Laser Profiling System

Posted by Loren Jones on 11/3/2016 to General

Introduction

DataRay has always been committed to providing accurate and reliable solutions for characterizing a wide range of laser beams. We take pride in listening to customer requests and working to expand our product line to meet their needs. DataRay is happy to announce our new Line Laser Profiling System (LLPS) with the capability to provide direct measurements of line lasers up to 200 mm in length and down to 55 microns in thickness.

Overview

The Line Laser Profiling System uses the full-featured free DataRay software to automatically move our flagship WinCamD-LCM4 beam profiling camera across the length of the line laser output using our M2DU-200 linear stage. The software will calculate the ideal exposure time for the scan, then automatically complete a full scan to capture and analyze the line laser output. A full image of the line laser intensity distribution will be shown along with a vertical centroid plot, line width plot, intensity plots, and several other useful metrics. The Line Laser Profiling System is enabled in software versions 8.0B16 and later.


Figure 1: Line laser with edges physically blocked to reduce it to 28 mm in length. The diffraction seen near the edges is due to the physical blocking of the line laser; this can be observed with the DataRay software (Figure 3).

Software Features

The Line Laser Profiling System Dialog provides access to the new line laser measurement capabilities of the free DataRay software. The dialog is shown in Figure 2 and demonstrates the interface to perform scans and record line laser measurements.


Figure 2: Line Laser Profiling System Dialog

Results

The Results box displays statistics for the Y centroids, width (thickness) of the line, length of the line, and tilt of the line.

Y Centroid Plot

The Y Centroid plot displays the Y-position centroid for each column against its X-position. This plot may be displayed as absolute data or as an offset from a linear fit.

Width Plot

The Width Plot plots the width (thickness) of the line laser along the axis of camera movement, measured in accordance with the chosen clip width level.

Normalized Summed Intensity

This plots the normalized sum of the pixel intensities in each column against X position.


Figure 3: The characteristic pattern of edge diffraction from our physically truncated line laser in Figure 1 can be viewed in the Normalized Summed Intensity plot

Normalized Peak Intensity

This plots the normalized peak value of the pixel intensities in each column against X position.

Data Output

The Line Laser Profiling System Dialog includes several options to save and export data. The built-in PDF report generator outputs a concise summary of the data including the four plots, an image of the intensity distribution, and custom notes. Export to Excel will export the raw data from each plot to an Excel document, and the Export to CSV option will export this raw data to a CSV file using Notepad. There is also an option to save a file with all current data that can be reopened later in the DataRay software.


Figure 4: Auto-generated PDF Report

Residual Sensor Tilt Compensation

Due to manufacturing limitations or imprecise custom mounting, there is a possibility of slight roll of the sensor along the optical axis. In most cases this effect will not be noticeable, but even just a few milliradians of sensor tilt may cause a “zigzag” effect in the intensity distribution. An exaggerated diagram demonstrating the effect as the sensor moves across the stage is shown below in Figure 5.


Figure 5: The left shows four captures from the camera, the right shows the image of these four captures that the computer will display. Slight rotation of the sensor will result is a "zigzag" effect since the computer assumes the sensor is perfectly aligned.

The DataRay software can optionally remove this effect without affecting the overall tilt measurement of the entire line.


Figure 6: The plots on top show the Y centroids without Residual Sensor Tilt Compensation for a sensor with <0.5 degrees tilt. The plots on the bottom show the Y centroids with Residual Sensor Tilt Compensation.

Conclusion

Line lasers that are too long to be measured on a single stationary sensor can still be directly measured using DataRay’s Line Laser Profiling System. The full-featured free software provides simple and powerful controls for the measurement and analysis of line lasers. Should you have any questions about any of our beam profiling products, please contact us at support@dataray.com. We have years of experience in the field of laser beam profiling and look forward to finding a solution for your system.