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Instrumentation

Custom-made software to draw illumination patterns for photo-excitation.
The software integrates the tool-box of a classical graphic editor to draw desired illumination patterns. Target intensity can also use a camera-captured fluorescence image to match automatically the shape of an object, with a user-defined detection threshold, in a selected region of interest. Then, the software calculates the corresponding phase profile to address onto the LC-SLM.

Custom-made software to draw illumination patterns for photo-excitation. The software integrates the tool-box of a classical graphic editor to draw desired illumination patterns. Target intensity can also use a camera-captured fluorescence image to match automatically the shape of an object, with a user-defined detection threshold, in a selected region of interest. Then, the software calculates the corresponding phase profile to address onto the LC-SLM.

Example of phase profile generated by IFTA algorithm.
In the past few years, a key element in the group has been the development of a custom-made software that could be used within the different projects of the team. This program named “WaveFront Designer IV” (WfdIV) is now a tried and tested software.

Example of phase profile generated by IFTA algorithm.

In the past few years, a key element in the group has been the development of a custom-made software that could be used within the different projects of the team. This program named “WaveFront Designer IV” (WfdIV) is now a tried and tested software.
 
As a chief requirement, the system had to be accessible and easy-to-use when dealing with biological research projects. To achieve real-time control of the optical beams, phase profiles have to be generated and transmitted to the SLM instantaneously. To this end, various algorithms were implemented, including: Iterative Fourier Transform Algorithm (IFTA) to design illumination shapes [1] - 3D display of multiple diffraction-limited spots [2] – Generalized Phase Contrast (GPC) method invented by J. Gluckstad [3]. In order to precisely place excitation spots in the sample, WfdIV can grab images in real-time from a CCD camera or load pre-recorded image. It can communicate with microcontrollers (Michrochip/PIC) to synchronize devices - such as illumination lamps, lasers or cameras - to take measurements or to process loop control for adaptive optics.
 
This software has been written in C++ with different libraries (graphic library Qt, Fourier transforms library fftw, CUDA library for massive data processing,…). Some modules developed in our group have been implemented into SlideBookTM, software commercialized by our partner Intelligent Imaging Innovations (3i) https://www.intelligent-imaging.com

References:

  1. F. Wyrowski, O. Bryngdahl "Iterative Fourier-transform algorithm applied to computer holography"J. Opt. Soc. Am. A 5, 1058-1065 (1989)
  2. R. Di Leonardo, F. Ianni, G. Ruocco "Computer generation of optimal holograms for optical trap arrays", Opt.Express 15 1913–1922 (2007)
  3. J. Gluckstad, "Phase contrast image synthesis", Opt. Commun. 130 225–230 (1996)