Synthesis Of Coherence Function Research Articles

Low-coherence interferometry with synthesis of coherence function

Synthesis of a coherence function by manipulation of the spectral phase of low-coherent light with a segmented liquid-crystal phase modulator and its application in a low-coherence interferometry are described. Effects of space-time coupling caused at diffractive gratings and second-order dispersion at the spatial light modulator on the coherence function synthesis are theoretically and experimentally verified. Various coherence functions can be shaped with phase-only masks designed by simulated annealing optimization algorithm. We utilized this technique for a novel optical low-coherence reflectometry without any mechanical movement for scanning optical delay.

Real-time optical image processing by synthesis of the coherence function using real-time holography

We have proposed an optical information processing technique by synthesis of the optical coherence function utilizing direct frequency modulation of a laser diode. In the former system, however, a silver halide holographic plate was used, so wet developing process was required. In this letter, real-time holography is adopted by using a liquid crystal spatial light modulator, which enables real-time processing. This system does not require any mechanically moving part nor electrical calculation in the processing procedure. Selective extraction of a 2-dimensional image from a 3-dimensional object is successfully demonstrated in real-time.

Optical Information Processing by Synthesis of the Coherence Function–Selective Masking of 2-D Information by Synthesis of Notch-Shaped Coherence Function–

We have proposed an optical information processing system adopting synthesis of the optical coherence function by using direct frequency-modulation of a laser diode.1’ Optical coherence function having notch shape is discussed theoretically and experimentally. Applying the notch shaped coherence function to this system, to mask selectively a two-dimensional (2-D) information from a three-dimensional (3-D) object can be carried out. After showing the experimental results on selective masking, the performance deterioration factors are discussed in detail.

Optical information processing by synthesis of the coherence function

We propose an optical parallel information processing technique adopting synthesis of the optical coherence function by using direct frequency modulation of a laser diode. The optical coherence function having a delta-function-like shape can be synthesized by modulating the laser frequency with an appropriate waveform. In this optical parallel information processing system, selective extraction of two-dimensional information from a three-dimensional semitransparent object, and other operations between two-dimensional information, can be carried out. This manner has no mechanical moving part, and there is no need for calculation by combining with holographic method. In this paper, the method to synthesize the optical coherence function is studied in detail. The manner to improve the suppression ratio of unnecessary subpeaks in the delta-function-like coherence function is studied both in theory and experiments. Moreover, notch-shaped optical coherence function is also studied. Selective extraction and selective masking of a two-dimensional information from a three-dimensional object was successfully performed in basic experiments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Optical information processing by synthesis of coherence function

Optical information processing by synthesis of coherence function

Optical coherence domain reflectometry by synthesis of coherence function

Reflectometry by synthesis of optical coherence function using a laser diode as a light source for high resolution measurements of optical systems and waveguide devices is proposed. This method has no mechanical moving parts. The oscillation frequency of the laser diode is controlled by the injection current with an appropriate waveform and the coherence function, which corresponds to the time-averaged spectrum shape, is synthesized. The principle that includes three types of synthesized coherence function is presented. The basic experiments of the three methods have been successfully carried out and the resolution about 10 mm in air is demonstrated using an ordinary Fabry-Perot-type single-mode laser diode. The performance deterioration factors of the most promising method are also discussed, in which a coherence function with a delta-function-like shape along the optical path is synthesized to obtain the reflectivity distribution directly.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Selective extraction of a two-dimensional optical image by synthesis of the coherence function

We propose a novel manner for optical ranging and imaging by adopting a synthesis of the optical coherence function. The optical coherence function with a periodic delta-function-like shape can be synthesized in the sense of time averaging by modulating the laser frequency with an appropriate waveform, in which the direct frequency-modulation characteristic of a semiconductor laser diode is used. This method does not require either mechanically driven references or Fourier-transform calculations. Selective extraction of a two-dimensional image from an object was successfully performed in a basic experiment.

Optical coherence domain reflectometry by synthesis of coherence function: improvement of the resolution with non-linearity compensation in frequency modulation

Optical coherence domain reflectometry by synthesis of coherence function: improvement of the resolution with non-linearity compensation in frequency modulation