Phase-randomized laser illumination for microscopy

Abstract

A simple apparatus is described that phase randomizes the output of a continuous argon ion laser, so that it may be used as a source of high intensity, monochromatic light for microscopy. The phase-randomizing device can be used with any laser, polarized or unpolarized, and of any desired power output and wavelength, including dye lasers for spectral studies. The randomizing system can be adapted to any light microscope and any optical system including bright-field, phase-contrast, Nomarski differential-interference, dark-field, and split-beam interference systems such as the Jamin-Lebedeff System. It can be used for a variety of photometric and photographic studies. The 514-nm wavelength appears to be relatively harmless to a variety of cells.

Characterization of very narrow spectral lines with temporal intensity interferometry

“…These microspheres serve as scattering centers undergoing Brownian motion at room temperature. The resultant phase randomization causes the laser light to exhibit pseudo-thermal photon bunching behavior (Martienssen & Spiller 1964;Arecchi 1965;Scarl 1966Scarl , 1968Estes et al 1971;Hard et al 1977). The coherence properties of light leaving the suspension depend on the temperature of the suspension, the viscosity (ratio of water to microspheres), and beam focus (Dravins & Lagadec 2014); these parameters were not fully characterized, but a combination of a beam waist of roughly 1 mm, with beads-concentration of approximately 0.1% solids [weight/volume] at room temperature (23 degrees Celsius) lead to Doppler-broadened light we could investigate with our technique.…”

Lasing from Micro- and Nano-Scale Photonic Disordered Structures for Biomedical Applications

“…Several optical and computational techniques have been developed to suppress these coherent artefacts so that lasers can be used for wide-field imaging [130,131]. The most commonly used techniques involve vibrating multimode fibers, scanning micromirrors, and phase randomization techniques [132][133][134][135][136][137][138]. However, all of these methods are sequential decorrelation techniques producing time-varying independent speckle patterns that are to be averaged over many images.…”

Plasmonic random laser enabled artefact-free wide-field fluorescence bioimaging: uncovering finer cellular features

“…Several techniques such as phase randomisation using rotating diffusers, spatial light modulators, and nematic liquid crystal devices, vibrating multimode bers, and scanning micromirrors are used to reduce the coherence of lasers. [15][16][17][18][19][20][21] However, all these are sequential decorrelation techniques that create time-varying independent speckle patterns, which are eventually averaged out by acquiring a large number of images. The long acquisition times required for reducing the speckle contrast to human perception level, the post-processing requirements, and the vibration noise introduced by the movement of mechanical parts restrict the usability of these techniques for real-time and in vivo wide-eld uorescence imaging applications and in cases that require dynamic imaging.…”