Speckle Illumination Research Articles

Non-scanning confocal fluorescence microscopy using speckle illumination

An arrangement in which a diffuser may be utilised to provide full field speckle illumination in a fluorescence microscope is described. The design requires that the conventional image of the speckle-illuminated object and a separate image of the speckle pattern are recorded or processed in real time. An alternative design could utilise a light valve. An analysis of the performance of the proposed microscope is given which shows that with adequate averaging the microscope response is equivalent to that of a scanning confocal arrangement. A computer simulation is used to demonstrate the enhanced lateral resolution and depth discrimination and also to assess the amount of averaging required for high fidelity imaging.

Wide field amplitude and phase confocal microscope with speckle illumination

This communication describes a wide field phase sensitive confocal optical microscope based on correlation between speckles. We show both experimentally and theoretically that the system operates as a wide field amplitude and phase confocal system; and demonstrate unique modes of operation such as extended focus phase measurement, which have, hitherto, only been demonstrated on scanning systems. Some potential applications of the system are discussed.

Contouring by Electronic Speckle Pattern Interferometry Employing Divergent Dual Beam Illumination

Abstract For contouring of large object surfaces by means of electronic speckle pattern interferometry divergent illuminations were used. A method to shift dual illumination beams was employed to obtain contour fringes. The relationship between the fringes and object depth does not have the same form as in the case of collimated illuminations. It shows that the original measurement data can be corrected. Theoretical analysis and experimental results are presented which are in agreement with each other.

Experimental Study on the Spatial Correlation Properties of Speckled Speckles Using Digital Speckle Photography

This paper experimentally investigates the spatial correlation properties of the speckled-speckle pattern produced from a cascade of two diffusers under laser beam illumination. The experiments were conducted by means of digital speckle photography. The experimental results show that the spatial correlation state of the speckled speckles depends not only on the surface roughness of the diffuser used to produce the speckle illumination but also on the distance z between two diffusers. As such, the dependency can be fairly well interpreted by introducing the concepts of the specular beam and the speckle beam to the illuminating speckle field which consists of the specular and diffuse components.

Velocity dependence of image speckles produced by a moving diffuser under dynamic speckle illumination

The velocity dependence has been investigated experimentally for the image speckles produced by a moving diffuse object under illumination of a dynamic speckle pattern. The boiling motion of the illuminating speckle pattern has little influence on the resultant speckle intensity fluctuations at the image plane if it is detected through a lens having a large pupil. In this case, the time-correlation length of speckle intensity fluctuations is inversely proportional to the object velocity. For the case where a translating speckle pattern illuminates the diffuser, its motion strongly affects the autocorrelation function of resultant speckle intensity fluctuations. The relationship between the pupil size of the imaging lens and the temporal behavior of image speckles is also considered.

Properties of light scattered by a diffuse object under dynamic speckle illumination and their application to the roughness distribution measurement

The properties of the scattered light which depends on the surface roughness of the diffuse object under a dynamic speckle illumination have been investigated. From these properties, a new method to measure the spatial roughness distribution by means of the dynamic speckle illumination is proposed.

Time-average readout of speckle photographs by laser illumination from a vibrating optical fiber

The time-averaging effect on fringes produced from a specklegram under time-varying speckle illumination, by which undesirable speckle noise is successfully reduced, is studied. In this method, a specklegram is illuminated by laser speckles emerging from a vibrating multimode optical fiber. The characteristics of time-averaged fringes are revealed theoretically and experimentally by taking into consideration the deformation of speckles recorded on the specklegram and the correlation area of speckles from the multimode optical fiber.