microPROFILER 1.2

The microPROFILER consists of hardware and software components. The dedicated software is capable of rapid as well as very precise analysis of beam profiles of excimer and femtosecond lasers. Beam profiles in the spectral range from 190 to 800 nm (optionally to 1500 nm or 10,6 µm) can be acquired by means of the microPROFILER.
 
The microPROFILER features outstanding user friendliness, software control, and ever-available comments on the particular command (via a "help" feature). Therefore, usage of the microPROFILER system is readily learnable.

Hardware and Data Acquisition 
Hardware and collection of data
Monochrome CCD cameras with diverse chip sizes (e.g., 1/3", 1/2", and 2/3") can be used to record and display beam profiles in real time. Feeding of the video signal is accomplished using frame grabbers allowing for optimal data analysis. By default, a frame-grabber card supplied by the company IDS is employed. Both, this frame grabber as well as the microPROFILER itself support to interface up to 16 different cameras among which the software can switch over. Using the latter feature, for example, the real beam shape can be monitored and analysed after various optical beam-shaping components.
 
Performance
The real-time display of the beam profile is accomplished as a 3D plot with 256 selectable grey levels or colors. In addition, a color table with assigned numerical values is shown in the graph. In order to facilitate the usage by wearers of laser-protection glasses, 3D beam-profile plots can be displayed in green, yellow or in an arbitrary color. The beam-profile graph can be freely rotated on the display in 3D thus enabling the clearest possible presentation. If required, e.g. for the demonstrative display of low-intensity profiles, the plot can be scaled along the Z axis in several steps. Within one camera readout, the software admits to define regions of interest (ROI) that can be independently analysed. A maximum of eight ROI's can be chosen by the operator.

Data processing
The pivotal algorithm contained in the microPROFILER software is the "Levenberg & Marquardt-Algorithm" for the analysis of Gaussian-shaped beam profiles. In addition, top-hat beam profiles can be analysed. The algorithm is capable of a highly precised in-depth beam-profile analysis. Inevitable data noise and camera drift are cautiously and correctly treated thus enabling the operator to measure beam-shape parameters independent of changing experimental conditions. This is achieved by introducing two cutting planes mutually rotated by 90° in the beam-profile model. The azimuthally orientation of these planes can be individually chosen to attain optimum adaptation to the beam profile under consideration.

Analysis
Using the zooming tool, parts of the beam profile can be arbitrarily zoomed in and details inspected. A Gaussian-shaped curve is fitted on data taken from the cutting planes of the Gaussian beam profile in the course of analysis. Subsequently, an assessment of the Gaussian distribution is feasible using this curve. Moreover, beam diameters according to various definitions (at FWHM, 1/e, and 1/e2) are calculated. Top-hat profiles evaluated with respect to edge steepness and smoothness. Additionally, minimal, maximal, and average errors and standard deviation are determined and compiled in a table. The latter calculations are performed both for the cutting planes as well as for the whole beam profile. Numerical values are determined according to DIN ISO standard 13694.

Documentation and data output
The microPROFILER features a facility for charting and documenting the laser-beam stability (‚Pointing Stability'). For this purpose, beam center and peak are recorded and displayed in a graph. Camera-acquired beam profiles can be converted into bit-map files, saved to disk, and reloaded for subsequent analysis. Numerical data recording is logged in ASCII files and can hence be read by other computer programs for the generation of specific diagrams. The analysis results, alternatively as graphical presentation and/or in numerical form can be saved. For specific recordings, this can also become automated.

System requirements

• IBM-compatible PC Pentium 200 MHz, Pentium III 800 MHz or faster (recommended)
• OpenGL graphics board
• IDS Frame-Grabber (Falcon or Eagle series), others upon request
• Windows NT 4.0, 2000, XP operating system