A phase-only spatial light modulator (SLM) is a device that is commonly used in various optical applications. Generally, SLM offers great advantages such as low power consumption and compact design. However, due to the manufacturing process, the main drawbacks of the SLM are surface non-uniformity and cross-talk between adjacent pixels, which add undesirable phase modulation. As a result, the SLM’s functionality is impacted, leading to image quality degradation, in terms of the signal-to-noise ratio (SNR), of optical reconstruction in holographic projection, for instance. Therefore, the aim of the current study is to measure and compensate for the surface non-uniformities of the SLM and improve its phase modulation. To achieve this, Shack-Hartmann wavefront sensor (SHWFS) is utilized. At first, a flat constant phase pattern is displayed on the SLM, and its surface phase shape is measured using a plane wave illumination. The reflected wavefront from the SLM is measured using SHWFS and then its phase information has been calculated. Hence, the calculated phase values are converted into a phase-only computer-generated hologram (CGH). The calculated CGH is displayed on the phase-only SLM to compensate for the phase errors of the SLM. The reflected wavefront has been measured after displaying the CGH to evaluate the compensation process. The experimental results reveal that the SHWFS provides high accuracy in the measurement of the phase distortion introduced by the surface of SLM. The SHWFS method is simple, robust, offers real-time performance, and is vibration-insensitive when compared with interferometric approaches.
The present study aims at utilizing holographic projection to reconstruct 3D information of brain tumor progression. The holograms were calculated using an adaptive iterative Fourier transform algorithm and projected using a spatial light modulator.
The measurement of surface roughness of biological tissue at microscale and nanoscale is significant to investigate the surface topography, which has been done through contact or non-contact profilometer. Although the contact profilometers provide quantitative analysis, they can easily scratch the biological tissue. While the noncontact profilometer like optical techniques can provide qualitative nondestructive measurements of the surface topography. Biospeckle imaging is a fast and powerful optical method that can only quantitatively evaluate the structure of the illuminated surface if valuable features are extracted from the biospeckle pattern. This study introduces a new fast biospeckle-based quantitative analysis method to measure the nanoscale average surface roughness of bovine articular cartilage tissue. The proposed method comprises feature extraction through local texture analysis by applying morphological operations by dilation and erosion, at different neighborhoods. The efficiency of the proposed method is evaluated on twelve articular cartilage tissue samples having different average surface roughness values.
The simultaneous production of a set of arbitrary hyperentangled states is crucial for quantum machines running variant quantum protocols concurrently, like universal quantum computers and quantum communication hubs. We present an experimental method to prepare a set of arbitrary path-polarization hyperentangled states concurrently using non-collinear spontaneous parametric down-conversion (SPDC). A cascaded pair of type-I crystals are pumped by 405-nm diagonally-polarized beam to produce a noncollinear stream of photon pairs. Compensation crystals are inserted to correct for the angular slope of the relative phase of the produced polarization entangled state. The pathentangled states are created over four pairs of slits positioned at conjugate locations to the pump beam. The local relative-phases of the path and polarization states can be independently tailored by intercepting the SPDC emission by tiltable birefringent and glass plates. The amplitudes of the polarization states is controlled by the manipulation of the polarization state of the pump. Also, the amplitudes of the path states is accessed by translating the slits over the SPDC cone. Here, while a pure state describes the whole SPDC emission, the produced states can be deemed an independent set by avoiding paths balanced to less than the coherence-length.
Fourier transform Raman and IR spectra are examined for malignant and normal breast tissues. Aside from individual differences that result in normal variations in lipids and glycogen, a clear distinction between normal and malignant tissues can be observed. MIR absorption spectra was observed using FTIR-Raman Spectrometer technique working in the regions Mir, Nir, Fir as well as VIS. Also the system can record Raman Scattering in the region from -2000 to 5600 cm-1 using Nd-Yag laser source of power 1500 mW. The comparison of Mid FTIR spectra from different samples of breast tumors with normal spectra reveals very important features that can be usefulk as diagnostic techniques. An absorption line centered at 3303 cm-1 varies considerably and depends on the nature of the lesion, lipids and proteins composition. The ratio (I3443/I4352) has an average value of 2.4±0.3 for normal tissues while in the case of malignant tissues its average is 4.5±2.8. A broad absorption band was observed in some malignant cases between 2800-3750 cm-1. A good shaped lines at 4259 and 4332 cm-1 is clear in normal spectra, these lines tend to disappear in malignant cases. A normally existing line at 3470 cm-1 increases considerably in malignant cases. When the tumor is not yet malignant it seems that the lines at 4259 and 4320 cm-1 disappears first rapidly. As the tumor turns to be malignant, the band at 3470 cm-1 increases and a new well defined band at 5167 cm-1 appears. Moreover, Raman spectra showed the appearance of a new band at 2900 cm-1 in the case of malignancy. While in normal breast samples this band didn't show up. Datat obtained in the NIR region confirms our observation in the MIR region.
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