Advertisement
Quick Links
Advertisement
Related Manuals for FASTLITE DazScope all
Summary of Contents for FASTLITE DazScope all
- Page 1 DAZSCOPE SYSTEM OPERATING MANUAL 9 september 2008 FASTLITE - info@faslite.com...
- Page 2 CONTENTS 1 Introduction 1.1 What the DazScope is ........1.2 What the DazScope is not .
- Page 3 ........42 FASTLITE-9 september 2008 Table of contents...
- Page 4 (see figure for a typical architecture). The DazScope is based on the pulse-shaping device commercialized by FASTLITE under the trademark Dazzler, and can be provided both as a an add-on for existing Dazzlers or as a stand- alone system.
- Page 5 The pulses delivered by chirped pulse amplification (CPA) laser systems typically verify such specifications. However, a double pulse structure, for example, will not be correctly measured nor corrected. FASTLITE-9 september 2008 Table of contents 4/42...
- Page 6 CHAPTER INSTALLATION To install from scratch, please follow the instructions given in section 2.1, section 2.2 sec- tion 2.3. To install the DazScope on a laser system already including a Dazzler, the reader may go directly to section 2.3. Software The DazScope software is a LabView 8.5 executable file.
- Page 7 (10Hz, kHz lasers). Operational details are described The acoustic propagation time depends on the crystal cut. For 25mm crystals, this is 31 6 s for the WB cut, and 40 6 s for the HR cut. FASTLITE-9 september 2008 Table of contents 6/42...
- Page 8 It is not unusual to set ”position = 800” and to measure amplified pulses at 810-815nm. FASTLITE-9 september 2008 Table of contents 7/42...
- Page 9 The phase coefficients (second order, third order etc) refer to a Taylor expansion of the spectral phase around . If ”auto = 1”, is assumed to be equal to the ”position” amplitude control with a microsecond accuracy at least FASTLITE-9 september 2008 Table of contents 8/42...
- Page 10 The DazScope hardware is the simplest hardware for pulse characterization. It consists of a lens focusing the beam onto a second harmonic generator (typically a 20µm BBO crystal), a refocussing lens and a high-resolution spectrometer (read through a USB link). This optical part is directly FASTLITE-9 september 2008 Table of contents 9/42...
- Page 11 DazScope CD-ROM is plugged in the computer. Start the Dazzler software and in the setup menu, check remote enable. Check that the Dazzler is correctly triggered. Eventually, start the Remote connection though a network is also possible - contact info@fastlite.com for more information. FASTLITE-9 september 2008...
- Page 12 If the spectrometer works on the second order of diffraction (e.g. the spectral range of the spectrometer is 700-900nm): 1. Uncheck the Run button 2. Remove the blue filter 3. Check the Run button FASTLITE-9 september 2008 Table of contents 11/42...
- Page 13 DazScope — manual Chapter 2 : Installation 4. Tweak the input beam direction to maximize the signal 5. Go back to the initial configuration: the SHG signal shouldn’t be far FASTLITE-9 september 2008 Table of contents 12/42...
- Page 14 CHAPTER SOFTWARE OVERVIEW The main part of the DazScope system is an elaborate software that remotely controls the Dazzler pulse shaper to optimize the spectral phase (i.e. make it linear with frequency). Quick start This section gives a rapid overview to be able to carry a first optimization as explained in the next chapter.
- Page 15 DazScope — manual Chapter 3 : Software overview Figure 3.1: Spectrometer initialization windows. Figure 3.2: Spectrometer configuration window. Left: simplified panel. Right: advanced panel. FASTLITE-9 september 2008 Table of contents 14/42...
- Page 16 ASCII and XML files. Figure 3.4: Content of the ”File” menu. Save Measurement Results as... : saves the last completely acquired data to a binary file format. FASTLITE-9 september 2008 Table of contents 15/42...
- Page 17 If the Advanced checkbox is checked, all the spectrometer parameters and options are displayed. When this checkbox is unchecked, the software displays only a minimal set of parameters. FASTLITE-9 september 2008 Table of contents 16/42...
- Page 18 During the chirp scan successive waveforms are defined and sent into the Dazzler and the corresponding SHG spectra are recorded and displayed. All waveforms are strictly identical, but for the chirp value which is scanned over a given interval. This interval is defined as a variation FASTLITE-9 september 2008 Table of contents 17/42...
- Page 19 Residual phase mode: indicates which curves are displayed on top of the experimental data picture and if the user is allowed to correct for the residual phase. Do not correct: displays only the polynomial correction (white curve). No residual phase correction allowed. FASTLITE-9 september 2008 Table of contents 18/42...
- Page 20 (referred to as amplitude) is calculated. If several boxes are selected the amplitude is equal to the product of each individually defined amplitude functions. Dials: supergaussian or gaussian function defined by the displayed dials. Formula (Advanced mode): analytical formula. Numerical Amp: ASCII text file. FASTLITE-9 september 2008 Table of contents 19/42...
- Page 21 Please refer to the Dazzler manual for the description of the controls displayed in the Dials panels, as well as for the Power Settings. In the advanced mode, the panels slightly change. Please contact Fastlite for a complete description of the extended controls (especially for the formulae). Switching to the advanced mode also displays the Security Settings sub-panel (see figure 3.9).
- Page 22 To set a measurement from the loaded measurements list, select the corresponding item in the Algorithm listbox located in the control area and press Run. This updates the display area and opens the related data processing software. a truncated waveform for example. FASTLITE-9 september 2008 Table of contents 21/42...
- Page 23 CHAPTER OPTIMIZING THE PULSE DURATION USING CHIRPSCAN Optimization Once the ChirpScan algorithm is started, the software acquires several spectra and displays all the acquired spectra in a 2D map (see figure 4.1). A dialog panel then pops up and prompts the user to proceed to the next step which can either be: keep the current waveform without any modifications (Keep Ref.WF as is.) compensate for the measured spectral phase (Apply these corrections to Ref.WF).
- Page 24 As the phase corrections are expressed in terms of phase coefficients, it is not straightforward to evaluate how big the corrections are or might be. Table gives some typical values for the first FASTLITE-9 september 2008 Table of contents 23/42...
- Page 25 4.2), the optimization is done and the pulse is compressed as best as possible. For orders 3 and 4, these values have been minored to take into account the extension of the pulse in the feet. FASTLITE-9 september 2008 Table of contents 24/42...
- Page 26 CHAPTER THEORY Most techniques for characterizing the phase of short pulses can be divided into three successive steps: a linear filter, a non linear interaction (e.g. SHG) and a spectral measurement of the output. In the case of Frequency Resolved Optical Gating (FROG), the linear filtering consists in generating two time-shifted replica of the original pulse.
- Page 27 3 000fs to +3 000fs onto four different optical pulses: one Fourier transform (ie purely linear spectral phase) (Figure 5.2), one with a pure second order only +1 000fs (Figure 5.3), FASTLITE-9 september 2008 Table of contents 26/42...
- Page 28 The determination by the center of symmetry is robust to noise and requires very few points (11 points per scan is enough for optimization process). It is especially efficient on the wings of FASTLITE-9 september 2008 Table of contents 27/42...
- Page 29 1000 2000 3000 Added second order (fs Added second order (fs Figure 5.4: Chirp scan - pure third order phase. White dots: second order derivative of the spectral phase as a function of wavelength. FASTLITE-9 september 2008 Table of contents 28/42...
- Page 30 Sinusoidal phase Sinusoidal phase -3000 -2000 -1000 -3000 -2000 -1000 1000 2000 3000 1000 2000 3000 Added second order (fs Added second order (fs Figure 5.6: Chirp scan - sinus phase. FASTLITE-9 september 2008 Table of contents 29/42...
- Page 31 This sets a maximum number of all possible time and spectrally independent and successive sub- pulses. For a purely chirped pulse (ϕ (ω) = cte), this maximum number if equal to the full spectral width multiplied by the square root of the chirp coefficient. FASTLITE-9 september 2008 Table of contents 30/42...
- Page 32 2ω . As a result, I (ω) can be described by the formula (5.1): (ω) (ω) ϕ (ω) This result can be derived more rigorously by using the stationary phase approximation theory. FASTLITE-9 september 2008 Table of contents 31/42...
- Page 33 CD drive where the fastlite software CD has been inserted, b) this note applies only for the CD delivered with an “Installers” directory, earlier distributions were operating differently.
- Page 34 Dazzler system. However, fastlite will endeavour to help with that installation whenever possible. fastlite will only help with the installation of non fastlite software provided that this ex- ternal software is necessary to operate the Dazzler system. fastlite will not guarantee operation if the original operating system has been tampered with, or its parameters modified...
- Page 35 2. installation of the application program: setup-V400a-exe.exe where the name will vary with the different releases. The CD may have several releases, be sure to liaise with fastlite to know which version is suitable for your system. By default, executing the file, will define a directory where the executable files and working files will be installed.
- Page 36 Parameters In case your parameters have been lost, you might find a useful set on the CD-ROM under cdrom:/Fastlite-ONLY/parameters hoard. The system reference appears on the back of the gen- erator, just under the exhaust fan grille. FASTLITE-9 september 2008...
- Page 37 DazCurrent.txt settings optionally saved upon exit rw wave.txt current waveform parameters Files marked ro (read only) are factory settings and should NOT be changed without consul- tation with Fastlite. The other files are read and written by the application program to optionally...
- Page 38 For example, the software uses this file to determine if the generator has the T 2, or T unable options implemented. This file has been created by Fastlite and should never be changed. Otherwise, the generator and software might completely stop working.
- Page 39 To allow the software to start automatically using your set of parameters, you should then click once on ”Make Default”. When the window looks like Figure B.2, just click ”OK”. The software should then start normally using the selected parameters. Figure B.2: Parameters Directory Selected FASTLITE-9 september 2008 Table of contents 38/42...
- Page 40 This software should have been installed by fastlite on your computer prior to shipment. If you cannot find it for any reason, please reinstall it : this is free software that you can find on the web.
- Page 41 The following note describes the procedure to align and calibrate the crystal for the case of a Dazzler operating at the output of a seed oscillator. The principles described here can be readily extended to other implementation cases, with some modifications in the measurement procedures . In case of difficulty, contact Fastlite. Alignment The diagram on Figure C.1...
- Page 42 Verify that the calibration remains valid for other wavelength positions of the hole feature. Alternatively, for small calibration errors of order 1 nm, it is possible to adjust the crystal angle, i.e. deviate slightly from perpendicularity to the input face, by rotating around the y axis. FASTLITE-9 september 2008 Table of contents 41/42...
- Page 43 100nm. Extend the signal to cover the full range of delays, by adjusting the second order phase coefficient. Use the full power. Observe the drop of signal on the scope. The maximum drop should be at least 50% for a laser source of bandwidth smaller than 100nm. FASTLITE-9 september 2008 Table of contents 42/42...