We can take advantage of this to create high density optical storage of images that can be accessed at ultra-high speeds, which we do in our HOC project. Furthermore, because of the mechanism through which they are formed, holograms can be stacked at the same location, allowing for multiple gratings to occupy the same space. The exact properties of the grating can be tailored depending on the writing characteristics, allowing for custom input/output angles, diffraction efficiencies, peak wavelengths, etc. Because the recording was formed through an interference pattern, it will contain the amplitude and phase information of the beams that were used to create it, forming a grating. In a mechanic similar to that of old analog photographs, the light reacts with the material and creates a recording (often in 3D in the case of thick holograms).
Holograms are formed when beams of light interfere inside a photosensitive medium. To achieve scale and rotation invariance, we incorporate the polar Mellin transform, which produces unique signatures for each input image. Due to the properties of FTs, this is inherrently shift invariant. The resulting signal is subsequently sent back to the optical domain using a spatial light modulator, where it can be FT'd to produce the 2D cross-correlation of the input images. These signals are detected and transferred into the electronic domain, being added, subtracted, and multiplied using an FPGA on a pixel-by-pixel basis. To capture the phases of these images, we employ PID-controlled auxiliary plane waves to interfere with the FTs. The magnitudes can be directly measured using focal plane arrays (FPAs). The HOC uses optics to perform real-time 2D Fourier Transforms (FTs) of arbitrary images. The maximum operating speed for this device is estimated to be on the order of 5μs, which would allow it to function as an input filter for more resource intensive image processing systems. We have shown that it is capable of producing shift, rotation, and scale invariant target recognition. The Hybrid Optoelectronic Correlator (HOC) was proposed and demonstrated at LAPT. And recently we believe that the passive version of a subluminal laser, which is a passive cavity with slow light medium inside, can be useful for dark matter detections. We have demonstrated different approaches such as Raman gain combined with DPAL and Raman laser. But we are more interested in those where group velocity is much smaller than the speed of light in vacuum. Due to the nature of the gain medium, most of the regular lasers are subluminal lasers. Subluminal lasers are lasers inside which the group velocity is smaller than the speed of light in vacuum. gravitational wave detection, rotation sensing, and measurement of strains. The passive version of a superluminal laser, which is also known as the white light cavity (WCL), are widely used in different areas, e.g. This property makes superluminal lasers ideal for metrological devises such as gyroscopes and accelerometers. We also showed that such lasers have enhanced sensitivity in perturbation in cavity length, which is also equivalent to rotation in ring lasers. Previously, we showed different approaches for realizing superluminal lasers, such as Raman depletion combined with Diode-Pumped Alkali Laser (DPAL), double Raman gain, Raman gain and Raman depletion in both isotopes of Rb vapor, and EIT in Raman gain. To create the fast light condition inside the laser cavity, a negative dispersive gain medium is necessary.
A superluminal laser is a laser inside which the group velocity of laser field is larger than the speed of light in vacuum.
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