Abstract: An image compression method comprises the following steps applied to at least one image: decorrelating the image by applying thereto a mathematical transform to obtain a set of coefficients, decomposing the image into blocks and, for each block of the image, quantizing the coefficients using a dead-zone uniform scalar quantizer having a semi-dead zone of size T and a quantization step size ?, and coding the quantized coefficients, the size T of the semi-dead zone of the scalar quantizer being determined by minimizing the difference between an estimated quantization distortion D(T), dependent at least on size T, and a target quantization distortion Dc.

Abstract: A method for producing a mirror comprising a plurality of optical surfaces, the method comprises: a step of producing elements, step of assembling the elements with each other from the rear, a step of fixing the elements from the rear onto a supporting structure of the mirror, and a step of polishing subsequent to the step of fixing the elements in order to obtain the optical surfaces of the mirror and correct the residual positioning defects of the optical surfaces and polish them.

Abstract: An image compression method comprises the following steps applied to at least one image: decorrelating the image by applying thereto a mathematical transform to obtain a set of coefficients, decomposing the image into blocks and, for each block of the image, quantizing the coefficients using a dead-zone uniform scalar quantizer having a semi-dead zone of size T and a quantization step size ?, and coding the quantized coefficients, the size T of the semi-dead zone of the scalar quantizer being determined by minimizing the difference between an estimated quantization distortion D(T), dependent at least on size T, and a target quantization distortion Dc.

Abstract: A method for producing a mirror comprising a plurality of optical surfaces, the method comprises: a step of producing elements, step of assembling the elements with each other from the rear, a step of fixing the elements from the rear onto a supporting structure of the mirror, and a step of polishing subsequent to the step of fixing the elements in order to obtain the optical surfaces of the mirror and correct the residual positioning defects of the optical surfaces and polish them.

Abstract: An autonomous spontaneous deployment deployable mast includes at least one elementary structural unit having a longitudinal deployment axis X and two platforms parallel to a plane YZ orthogonal to the axis X. The elementary structural unit includes N stages stacked above one another parallel to the longitudinal deployment axis X, where N is greater than 1. Each stage includes at least three longitudinal flexible tape-springs, the N stages being fixed to one another two by two by means of connecting platforms parallel to the plane YZ and two contiguous lower and upper stages being offset angularly relative to each other by rotation about the deployment axis X, the tape-springs of the lower stage being interleaved between the tape-springs of the upper stage.

Abstract: In the field of optic instruments comprising at least one optical architecture, a photoreception assembly and means for acquisition and analysis of the images arising from the said photoreception assembly, the acquisition and analysis means comprising an algorithm of phase diversity type, an optical architecture comprises an optical plate of low or zero optical power arranged in the vicinity of the photoreception assembly and disposed so as to form on all or part of the said assembly a first focused image and a second image defocused by a first predetermined value and shifted by a second predetermined value with respect to the first image. The optic instrument can advantageously be a space telescope.

Abstract: An autonomous spontaneous deployment deployable mast includes at least one elementary structural unit having a longitudinal deployment axis X and two platforms parallel to a plane YZ orthogonal to the axis X. The elementary structural unit includes N stages stacked above one another parallel to the longitudinal deployment axis X, where N is greater than 1. Each stage includes at least three longitudinal flexible tape-springs, the N stages being fixed to one another two by two by means of connecting platforms parallel to the plane YZ and two contiguous lower and upper stages being offset angularly relative to each other by rotation about the deployment axis X, the tape-springs of the lower stage being interleaved between the tape-springs of the upper stage.

Abstract: A scanning multispectral telescope comprises an optical architecture arranged so as to focus the image of an object in the vicinity of a photodetection assembly, the area of focus being an image plane. The photodetection assembly comprises a number of parallel rows of photodetectors, each row being dedicated to a particular spectral band, each spectral band being centered on a mean wavelength. The telescope comprises means for acquiring and analyzing the images obtained from the rows of photodetectors using a phase diversity algorithm. Finally, the telescope comprises optical or mechanical means arranged in such a way that at least one of the rows of photodetectors is offset by a fraction of the mean wavelength which corresponds to it on an axis perpendicular to the image plane.

Abstract: In the field of optic instruments comprising at least one optical architecture, a photoreception assembly and means for acquisition and analysis of the images arising from the said photoreception assembly, the acquisition and analysis means comprising an algorithm of phase diversity type, an optical architecture comprises an optical plate of low or zero optical power arranged in the vicinity of the photoreception assembly and disposed so as to form on all or part of the said assembly a first focused image and a second image defocused by a first predetermined value and shifted by a second predetermined value with respect to the first image. The optic instrument can advantageously be a space telescope.

Abstract: A scanning multispectral telescope comprises an optical architecture arranged so as to focus the image of an object in the vicinity of a photodetection assembly, the area of focus being an image plane. The photodetection assembly comprises a number of parallel rows of photodetectors, each row being dedicated to a particular spectral band, each spectral band being centred on a mean wavelength. The telescope comprises means for acquiring and analyzing the images obtained from the rows of photodetectors using a phase diversity algorithm. Finally, the telescope comprises optical or mechanical means arranged in such a way that at least one of the rows of photodetectors is offset by a fraction of the mean wavelength which corresponds to it on an axis perpendicular to the image plane.

Abstract: A device supporting a first and a second element of a piece of space equipment. The device includes at least two deployable flexible arms each having a first end and a second end, the ends are secured respectively to the first and second elements and each designed to adopt at least one initial position folded in curves and an unfolded final position, in which positions they hold the first element away from the second element by first and second chosen distances respectively, the second distance being greater than the first.

Abstract: An optical space observation system comprises a primary mirror, a secondary mirror, a supporting base containing the primary mirror, on which a mechanical structure bearing a support of the secondary mirror is positioned, and an optical measurement means, said mechanical structure comprising a plurality of mechanical arms. The system also has a system comprising a plurality of actuators positioned on the supporting base, said actuators being connected to the lower ends of said mechanical arms and the upper ends of said mechanical arms being connected to the support of the secondary mirror on the periphery of the support. A space telescope is intended to be loaded in a launcher and put into orbit. The invention is intended in particular for a telescope having a deployable secondary mirror and means for active control of the optics.

Abstract: A deployable reflector (RP), for a space observation instrument is disclosed. The deployable reflector has a chosen number of deployable reflecting elements (E1a-E3b) suitable, once deployed in a first position, for together defining a reflecting area in the form of a so-called Reuleaux triangle (RD) with closed convex curve whose width is constant as a function of direction.

Abstract: A device (D) for compressing digital image data by wavelet transform, the device including a processor (PM) having i) a module (M1) for transforming image data into wavelet coefficients distributed in sub-bands, ii) a module (M2) for estimating for each coefficient, first and second sets of prediction parameters, associated respectively with so-called north-south and west-east directions, based on values of wavelet coefficients of its north or south neighbors, iii) a module (M3) for quantifying the wavelet coefficients, and iv) an entropy coding module (M4) for determining for each coefficient prediction values of expectation and of the width of a Laplace function representing its probability density, based on the first and/or second sets of prediction parameters and on the wavelet coefficient quantified by its north neighbor or its west neighbor, and for entropy coding of the wavelet coefficients quantified via specific associated expectations and widths.

Abstract: A deployable reflector (RP), for a space observation instrument is disclosed. The deployable reflector has a chosen number of deployable reflecting elements (E1a-E3b) suitable, once deployed in a first position, for together defining a reflecting area in the form of a so-called Reuleaux triangle (RD) with closed convex curve whose width is constant as a function of direction.

Abstract: A remote sensing instrument using optical aperture synthesis comprises at least two independent remote sensing devices each comprising at least two light collecting means delivering light beams and having a selected field of view and a selected resolution and further comprising recombination means adapted to recombine interferometrically the light beams delivered by said devices so as to deliver a final light beam associated with a resolution better than or equivalent to the lowest resolution of said devices and/or a field of view less than or equal to the largest field of view of said devices.

Abstract: A device (D) is devoted to supporting a first (M1) and a second (M2) element of a piece of space equipment, such as a telescope for example. This device (D) comprises at least two deployable flexible arms (O11 to O32) each comprising a first end (EX1) and a second end (EX2) which ends are secured respectively to the first (M1) and second (M2) elements and each designed to adopt at least one initial position folded in curves and an unfolded final position, in which positions they hold the first element (M1) away from the second element (M2) by first and second chosen distances respectively, the second distance being greater than the first.

Abstract: The invention concerns a method of compressing and transmitting digital data, in particular images, at a constant bit rate, the method comprising the following steps: splitting input data into blocks of data, applying an orthogonal or bi-orthogonal transform (12) to each block, quantizing (14) the coefficients obtained by applying the transform, entropically coding (20) the quantized coefficients, temporarily saving the data resulting from coding in a buffer memory (18), removing a particular number of bits from the memory for each block of digital data, and adjusting the quantizing step by applying a control function (50) to obtain, after coding, a number of bits close to the number of bits removed from the memory for each block of data. The control function (50) takes account of the data bit rate measured for at least the preceding block.

Abstract: The invention concerns a method for compressing data, in particular images, by transform, in which method this data is projected onto a base of localized orthogonal or biorthogonal functions, such as wavelets. To quantize each of the localized functions with a quantization step that enables an overall set rate Rc to be satisfied, the method includes the following steps: a probability density model of coefficients in the form of a generalized Gaussian is associated with each subband, the parameters ? and ? of this density model are estimated, while minimizing the relative entropy, or Kullback-Leibler distance, between this model and the empirical distribution of coefficients of each subband, and from this model, for each subband, an optimum quantization step is determined such that the rate allocated is distributed in the various subbands and such that the total distortion is minimal.

Abstract: A device (D) for compressing digital image data by wavelet transform, the device including a processor (PM) having i) a module (M1) for transforming image data into wavelet coefficients distributed in sub-bands, ii) a module (M2) for estimating for each coefficient, first and second sets of prediction parameters, associated respectively with so-called north-south and west-east directions, based on values of wavelet coefficients of its north or south neighbors, iii) a module (M3) for quantifying the wavelet coefficients, and iv) an entropy coding module (M4) for determining for each coefficient prediction values of expectation and of the width of a Laplace function representing its probability density, based on the first and/or second sets of prediction parameters and on the wavelet coefficient quantified by its north neighbor or its west neighbor, and for entropy coding of the wavelet coefficients quantified via specific associated expectations and widths.