Shot Noise in Digital Holography

We discuss on noise in heterodyne holography in an off-axis configuration. We show that, for a weak signal, the noise is dominated by the shot noise on the reference beam. This noise corresponds to an equivalent noise on the signal beam of one photoelectron per pixel, for the whole sequence of images used to build the digital hologram

In vivo laser Doppler holography of the human retina

The eye offers a unique opportunity for non-invasive exploration of cardiovascular diseases. Optical angiography in the retina requires sensitive measurements, which hinders conventional full-field laser Doppler imaging schemes. To overcome this limitation, we used digital holography to perform laser Doppler perfusion imaging of the human retina in vivo with near-infrared light. Wideband measurements of the beat frequency spectrum of optical interferograms recorded with a 39 kHz CMOS camera are analyzed by short-time Fourier transformation. Power Doppler images and movies drawn from the zeroth moment of the power spectrum density reveal blood flows in retinal and choroidal vessels over 512 $\times$ 512 pixels covering 2.4 $\times$ 2.4 mm$^2$ on the retina with a 13 ms temporal resolution.Comment: 5 pages, 5 figure

Pulsatile microvascular blood flow imaging by short-time Fourier transform analysis of ultrafast laser holographic interferometry

We report on wide-field imaging of pulsatile microvascular blood flow in the exposed cerebral cortex of a mouse by holographic interferometry. We recorded interferograms of laser light backscattered by the tissue, beating against an off-axis reference beam with a 50 kHz framerate camera. Videos of local Doppler contrasts were rendered numerically by Fresnel transformation and short-time Fourier transform analysis. This approach enabled instantaneous imaging of pulsatile blood flow contrasts in superficial blood vessels over 256 x 256 pixels with a spatial resolution of 10 microns and a temporal resolution of 20 ms.Comment: 4 page

Pemodelan Sistem Pengelolaan Bahan Baku Pada PT. Japfa Comfeed Indonesia, Tbk Unit Makassar untuk Mendukung Perencanaan Produksi

PT. Japfa Comfeed Indonesia, Tbk Unit Makassar merupakan salah satu perusahaan yang bergerak di bidang industri pakan ternak daerah Sulawesi Selatan. Bahan baku yang dikelolah untuk menjadi pakan ternak adalah jagung. Kegiatan proses pengelolaan bahan baku dilakukan sangat ketat dalam pengelolaannya untuk menghasilkan pakan ternak berkualitas. Pengadaan bahan baku memperhatikan mutu jagung sebelum pembelian tahapan pertama dilakukan perusahaan dalam memastikan kualitas bahan baku yang akan diterima. Setelah dilakukan pembelian, dilakukan proses pengeringan dan pengendalian kualitas yang Quality Control lakukan secara ketat dan teliti dalam memastikan mutu jagung sebelum disimpan sesuai standar perusahaan. Yang terjadi pada PT. Japfa Comfeed Indonesia, Tbk Unit Makassar terjadi penurunan kualitas bahan baku dalam penyiapan yang dapat menghambat perencanaan produksi. Penelitian ini peneliti menggunakan metode spiral boehm karena perlu analisis secara lebih mendalam permasalahan terjadi pada PT. Japfa Comfeed Indonesia, Tbk unit makassar dalam mendukung poses produksi. Penelitian ini termasuk kedalam penelitisn studi kasus (Case Study) peneliti menganalisa kondisi aktivitas kedalam penelitian ini kemudian memodelkan ssistem pengelolaan bahan baku untuk perusahaan yang dapat membentu dalam perencanaan dan pengendalian bahan baku sehingga mendukung proses produksi. Hasil penelitian ini menghasilkan pemodelan sistem pengelolaan bahan baku PT. Japfa Comfeed Indonesia, Tbk Unit Makassar dalam perencanaan produksi

Heterodyne detection of multiply scattered monochromatic light with a multipixel detector

International audienceA new technique is presented for measuring the spectral broadening of light that has been multiply scattered from scatterers in motion. In our method the scattered light is detected by a heterodyne receiver that uses a CCD as a multipixel detector. We obtain the frequency spectrum of the scattered light by sweeping the heterodyne local oscillator frequency. Our detection scheme combines a high optical etendue (product of the surface by the detection solid angle) with an optimal detection of the scattered photons (shot noise). Using this technique, we measure, in vivo, the frequency spectrum of the light scattered through the breast of a female volunteer

Detection of the tagged or untagged photons in acousto-optic imaging of thick highly scattering media by photorefractive adaptive holography

We propose an original adaptive wavefront holographic setup based on the photorefractive effect (PR), to make real-time measurements of acousto-optic signals in thick scattering media, with a high flux collection at high rates for breast tumor detection. We describe here our present state of art and understanding on the problem of breast imaging with PR detection of the acousto-optic signal

Theoretical study of Acousto-optical coherence tomography using random phase jumps on US and light

Acousto-Optical Coherence Tomography (AOCT) is variant of Acousto Optic Imaging (called also ultrasonic modulation imaging) that makes possible to get z resolution with acoustic and optic Continuous Wave (CW) beams. We describe here theoretically the AOCT e ect, and we show that the Acousto Optic tagged photons remains coherent if they are generated within a speci c z region of the sample. We quantify the z selectivity for both the tagged photon eld, and for the M. Lesa re et al. photorefractive signal

Correlations between critical current density, j(sub c), critical temperature, T(sub c),and structural quality of Y1B2Cu3O(7-x) thin superconducting films

Correlations between critical current density (j(sub c)) critical temperature (T(sub c)) and the density of edge dislocations and nonuniform strain have been observed in YBCO thin films deposited by pulsed laser ablation on (001) LaAlO3 single crystals. Distinct maxima in j(sub c) as a function of the linewidths of the (00 l) Bragg reflections and as a function of the mosaic spread have been found in the epitaxial films. These maxima in j(sub c) indicate that the magnetic flux lines, in films of structural quality approachingthat of single crystals, are insufficiently pinned which results in a decreased critical current density. T(sub c) increased monotonically with improving crystalline quality and approached a value characteristic of a pure single crystal. A strong correlation between j(sub c) and the density of edge dislocations ND was found. At the maximum of the critical current density the density of edge dislocations was estimated to be N(sub D) approximately 1-2 x 10(exp 9)/sq cm