Large Aperture Camera Research Articles

Large aperture camera lens with minimalistic refocus for smartphone portraiture photography

This paper describes the design of a small form-factor lens for use in portraiture photography. The current general requirement of mobile cameras having good all-round performance results in a typical, familiar, multi-lens design. Such designs have little room for improvement, in terms of the available degrees of freedom and highly-demanding target metrics such as low F-number and wide field of view (FoV). However, the specific application of the proposed portraiture lens relaxes the requirement of an all-round high-performing lens, allowing improvement of certain aspects at the expense of others. With a main emphasis on reducing depth of field (DoF), the current design takes advantage of the simple geometrical relationship between DoF and pupil diameter. To achieve high resolution in object space, the design has a large aperture of 4 mm, for which a typical F/2 lens would have a relatively large focal length compared to z-height, requiring refractive–reflective elements; hence, FoV is reduced. The system is folded perpendicular to the optical axis using two 45∘ plane mirrors, with a 4:3 aspect ratio for the FoV maximising use of available space. Inverse sensitivity analysis was used to show that the lens has acceptable tolerancing limits. A minimalistic refocus mechanism supplements reduction of energy consumption from digital bokeh post-processing to give a low-energy, low-DoF, high-performing lens for future use in a multi-camera setup.

Observations of Near-Earth Optical Transients with the Lomonosov Space Observatory

The results of observations with the MASTER-SHOK robotic wide-field optical cameras onboard the Lomonosov Space Observatory carried out in 2016 are presented. In all, the automated transient detection system transmitted 22 181 images of moving objects with signal-to-noise ratios greater than 5 to the Earth. Approximately 84% of these images are identified with well-known artificial Earth satellites (including repeated images of the same satellite) and fragments of such satellites (space debris), according to databases of known satellites. The remaining 16% of the images are relate to uncatalogued objects. This first experience in optical space-based monitoring of near-Earth space demonstrates the high efficiency and great potential of using large-aperture cameras in space, based on the software and technology of the MASTER robotic optical complexes (the Mobile Astronomical System of TElescope-Robots (MASTER) global network of robotic telescopes of Lomonosov Moscow State University).

Ultrathin cameras using annular folded optics

We present a reflective multiple-fold approach to visible imaging for high-resolution, large aperture cameras of significantly reduced thickness. This approach allows for reduced bulk and weight compared with large high-quality camera systems and improved resolution and light collection compared with miniature conventional cameras. An analysis of the properties of multiple-fold imagers is presented along with the design, fabrication, and testing of an eightfold prototype camera. This demonstration camera has a 35 mm effective focal length, 0.7 NA, and 27 mm effective aperture folded into a 5 mm total thickness.

A Monte Carlo study of the acceptance to scattered events in a depth encoding PET camera

We present a Monte Carlo study of the acceptance to scattered events in a depth encoding large aperture camera (DELAC), a hypothetical PET scanner with the capacity to encode the depth-of-interaction (DOI) of incident /spl gamma/-rays. The simulation is initially validated against the measured energy resolution and scatter fraction of the ECAT-953B scanner. It is then used to assess the response to scattered events in a PET camera made of position encoding blocks of the EXACT HR PLUS type, modified to have DOI resolution through a variation in the photopeak pulse height. The detection efficiency for 511 keV /spl gamma/-rays, as well as for those that scattered in the object or left only part of their energy in the block, is studied for several combinations of DOI sensitivities and block thicknesses. The scatter fraction predicted by the simulation for DELACs of various ring radii is compared to that of the ECAT-953B as a function of the energy threshold. The results indicate that the poorer discrimination of object scatters with depth sensitive blocks does not lead to a dramatic increase of the scatter fraction.

Design studies of a depth encoding large aperture PET camera

The feasibility of a wholebody PET tomograph with the capacity to correct for the parallax error induced by the depth-of-interaction of /spl gamma/-rays is assessed through simulation. The experimental energy, depth, and transverse position resolutions of BGO block detector candidates are the main inputs to a simulation that predicts the point source resolution of the depth encoding large aperture camera (DELAC). The results indicate that a measured depth resolution of 7 mm (FWHM) is sufficient to correct a substantial part of the parallax error for a point source at the edge of the field-of-view. A search for the block specifications and camera ring radius that would optimize the spatial resolution and its uniformity across the field-of-view is also presented. >

Fast large aperture camera and data acquisition system with applications in astrophysics, particle physics and nuclear medicine

A fast large aperture multielement imaging camera has been developed to record Cherenkov light spots produced in the atmosphere by cosmic ray showers. The camera may have possible applications in other branches of astrophysics, in particle physics and in nuclear medicine. The camera is capable of simultaneously digitizing the transient outputs (20 ns) of 37 phototubes, each into an 8 bit byte while also capturing a further 27 bytes of system housekeeping data. The 64 bytes are written onto magnetic tape in 114 μs. The throughout rate of the camera is therefore very high. The hardware of the imaging system and its associated data acquisition devices are described in detail.

Waves in the OH emissive layer: photogrammetry and topography

The waves in the OH emissive layer, which appear on photographs of the sky in the near IR taken with large aperture cameras, are distorted by atmospheric refraction and by a perspective effect. Two methods have been developed to allow restitution of the topography of the waves in a simple way. In the first method a grid is computed, which is superimposed on an enlargement of the original 24 x 36-mm negative frame. In the second method the image is projected on an aspherical surface that is tilted with respect to the enlarger beam. The topography of a wave display, photographed from the Pic du Midi Observatory during the night of 19-20 November 1976, is obtained using both methods. The photometric aspect of the photographs may be interpreted under the simple assumption that the emissive layer has a constant thickness and is ruffled like the wavy surface of the sea.

Photometry of Compact Galaxies

Photometric histories of the N galaxies 3C 390.3 and PKS 0521-36. Four other compact galaxies, Markarian 9, I Zw 92, 2 Zw 136, and III Zw 77 showed no evidence of variability. The photometric histories were obtained from an exhaustive study of those plates of the Harvard collection taken with large aperture cameras. The images of all galaxies reported were indistinguishable from stars due to the camera f-ratios and low surface brightness of the outlying nebulosities of the galaxies. Standard techniques for the study of variable stars are therefore applicable.