Search results
Results from the WOW.Com Content Network
Speckle imaging and eye testing using speckle also use the speckle effect. Speckle is the chief limitation of coherent lidar and coherent imaging in optical heterodyne detection . In the case of near field speckles, the statistical properties depend on the light scattering distribution of a given sample.
The optical arrangement is the same as for out-of-plane displacement above. The object is vibrated at a specific frequency. Those parts of the object which do not move will continue to be speckled. It can be shown that parts of the object which vibrate with amplitudes of nλ/4 have higher speckle contrast than those parts which vibrate at (n+½ ...
The size of each speckle pattern should smaller than the photodetector's pixel size to avoid the decrease of contrast. The minimum speckle diameter for an LSCI system depends on the wavelength of light, imaging system magnification, and imaging system f-number: d min ≈ 1.2 ( 1 + M ) λ f / # {\displaystyle d_{\min }\thickapprox 1.2(1+M ...
The introduction of the CCD into astronomy, which captures more than 70% of the light, lowered the bar on practical applications by an order of magnitude, and today the technique is widely used on bright astronomical objects (e.g. stars and star systems). Many of the simpler speckle imaging methods have multiple names, largely from amateur ...
In 1995, Guerra [4] published results in which he used a "form of optical heterodyning" to detect and image a grating with frequency many times smaller than the illuminating wavelength, and therefore smaller than the resolution, or passband, of the microscope, by beating it against a local oscillator in the form of a similar but transparent ...
In physics, dynamic speckle is a result of the temporal evolution of a speckle pattern where variations in the scattering elements responsible for the formation of the interference pattern in the static situation produce the changes that are seen in the speckle pattern, where its grains change their intensity (grey level) as well as their shape along time.
Speckle variance optical coherence tomography (SV-OCT) is an imaging algorithm for functional optical imaging. Optical coherence tomography is an imaging modality that uses low-coherence interferometry to obtain high resolution, depth-resolved volumetric images.
One way to categorise the numerous PUF concepts is by how the source of variation within each PUF is measured. [1] For instance some PUFs examine how the source of uniqueness interacts with, or influences, an electronic signal to derive the signature measurement while others examine the effects on the reflection of incident light, or another optical process.