A first look at the SuperCam RMI images aboard Perseverance

2021 ◽  
Author(s):  
Olivier Gasnault ◽  
Cedric Virmontois ◽  
Sylvestre Maurice ◽  
Roger C. Wiens ◽  
Stephane Le Mouelic ◽  
...  
Keyword(s):  
Focal Length ◽  
Attenuation Factor ◽  
Angular Size ◽  
Landing Site ◽  
Image Resolution ◽  
Local Context ◽  
Circular Field ◽  
Flat Field ◽  
Organic Spectroscopy ◽  
Better Than

<p>Starting in February 2021, the <strong>Perseverance rover</strong> will characterize a new landing site, the Jezero crater on Mars, and assemble a returnable cache of samples [1]. Among the remote sensing instruments, SuperCam combines chemical, mineralogical and organic spectroscopy, sound recording and imaging [2, 3, 4]. SuperCam’s <strong>RMI (Remote Micro-Imager)</strong> provides pictures for local context and site imaging at high-resolution.</p><p><br>The 110-mm SuperCam telescope with a focal length of 563 mm allows to take color images of 2048x2048 pixels with a CMOS camera on a bandwidth from ~375 to ~655 nm. The images will be divided by a reference flat-field to correct the attenuation factor of ~5 due to vignetting. The diameter of the circular field-of-view is ~18.8 mrad. The angular size of the RMI pixels is slightly less than 10 microrads, and the effective image resolution is better than 80 microrads, which represents 0.24 mm at 3 m.</p><p><br>Images will be taken at the start and end of the SuperCam raster observations [3] and assembled into annotated mosaics, which will provide information on the nature of the targets at the scale of the SuperCam investigation. Images will also be taken to study remote outcrops. At the time of the conference, Perseverance will have been on Mars for 2 months. Although the first images of the RMI will be used to check the health of the instrument, we also hope to have a first view of the landing site by then.</p><p><br><strong>References:</strong> [1] Farley K.A. et al. (2020) SSR, 216, 142. [2] Maurice S. et al. (in revision) SSR. [3] Wiens R.C. et al. (2021) SSR, 217, 4. [4] Maurice S. et al. (this issue). </p>

An improved stereocamera and control system for close-up photography of the fauna of the continental slope and outer shelf

1976 ◽  
Vol 56 (1) ◽  
pp. 247-257 ◽  
Author(s):  
A. J. Southward ◽  
S. G. Robinson ◽  
D. Nicholson ◽  
T. J. Perry
Keyword(s):  
Control System ◽  
Continental Slope ◽  
Focal Length ◽  
Image Resolution ◽  
Outer Shelf ◽  
Flash Duration ◽  
Natural Size ◽  
And Control ◽  
Better Than

A stereocamera system is described, built-up mostly from commercially obtainable items. Special features include use of standard 55 mm focal length lenses down to 0.5 m focus, adjustable flash duration to improve image resolution, and a visual and audible pinger control for noisy ship conditions. Resolution in tank tests is better than 70 lines/mm, allowing photographs taken in the field to be enlarged to 3 times the natural size of the animals.

scholarly journals On a cassegrain reflector with corrected field

1913 ◽  
Vol 88 (602) ◽  
pp. 188-191
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Straightforward Manner ◽  
Flat Field ◽  
Convex Mirror ◽  
Solution Proceeds ◽  
Characteristic Features ◽  
Working Out ◽  
Essential Problem ◽  
Single Focus

The purpose of this memoir is to discover an optical appliance which shall correct in a practical manner the faults in the field of a Cassegrain reflector, while leaving unimpaired its achromatism and the characteristic features of its design, which gives a focal length much greater than the length of the instrument, combined with a convenient position of the observer. The question touches an investigation by Schwarzschild as to what can be done with two curved mirrors the figures of which are not necessarily spherical. With these be corrects spherical aberration and coma, but in order to secure a flat field he is led to a construction in which the second mirror, which is between the great mirror and its principal focus, is concave, and therefore shortens the effective focal length, in place of increasing it. The deformations from spherical figures are also so great, especially for the great mirror, as to leave it doubtful whether the construction discussed could ever be the model for practicable instruments. If we keep to the Cassegrain form, spherical aberration and coma may equally be corrected by deformations of the mirrors which through large, are less extreme, but there remains a pronounced curvature of the field. For this reason I am led, in the present memoir, to consider more complicated systems produced by the interposition of systems of lenses, achromatism can be preserved completely for a single focus if there are three lenses of focal length determined when their position are given, and if all are made of the same glass. One of these lenses, which I call the reverser, is silvered at the back and replaces the convex mirror; the other two are placed close together in the way of the outcoming beam, about one third of the distance from the great mirror to the reverser; the members of this pair, which I call the corrector, are of nearly equal but opposite focal lengths, introducing very little deviation in the ray but an arbitrary amount of aberration, according to the distribution of curvatures between the two faces of each lens. All the surfaces are supposed spherical except that of the great mirror, The essential problem is to bring the necessary work into a form that will allow unknown quantities which express the distribution of curvature between the faces of each lens to be carried forward algebraically. The methods employed are those of a recent memoir by the author,* and a part of the paper is occupied in working out expressions to which this theory leads, for thin lenses, systems of thin lenses, mirrors, reversers and the like, and it may be regarded as an expansion and working illustration of that memoir. Ibis part does not lend itself to summary, When the expressions are obtained the solution proceeds in a straightforward manner, by approximation, which is somewhat complicated owing to the number of considerations which it is necessary to keep in view, but is not otherwise difficult. The solution is completed at the stage where the unextinguished aberrations are considered negligible.

scholarly journals Research on Focal Length Measurement Scheme of Self-Collimating Optical Instrument Based on Double Grating

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2718
Author(s):  
Wenchang Yang ◽  
Zhiqian Wang ◽  
Chengwu Shen ◽  
Yusheng Liu ◽  
Shaojin Liu ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Focal Length ◽  
Optical Path ◽  
Good Resolution ◽  
Mean Square ◽  
Optical Instrument ◽  
Moiré Fringes ◽  
Measurement Resolution ◽  
Designed Experiment ◽  
Better Than

In this paper, we propose a scheme for measuring the focal length of a collimating optical instrument. First, a mathematical model for measuring the focal length of a collimator with double gratings is derived based on the moiré fringe formula and the principles of geometric optics. Mathematical simulation shows that a slight difference in the focal length of two collimators has an important influence on the imaging law of moiré fringes. Our solution has a good resolution ability for focal length differences within 5‰, especially in the small angle range below 4°. Thus, the focal length of collimators can be measured by the amplification of the slight difference. Further, owing to the relative reference measurement, the measurement resolution at the symmetrical position of focal length is poor. Then, in the designed experiment, a corresponding moiré image at different angles is acquired using collimators with known focal length. The experimental results indicate that the root mean square error (RMSE) of the collimator corresponding to grating angles of 2°–4° is better than 4.7‰, indicating an ideal measurement accuracy of the proposed scheme. This work demonstrates that our proposed scheme can achieve an ideal accuracy in the measurement of a symmetrical optical path.

scholarly journals NuSTAR observations of rotation-powered pulsars and magnetars

2012 ◽  
Vol 8 (S291) ◽  
pp. 331-336
Author(s):  
V. M. Kaspi ◽  
H. An ◽  
M. Bachetti ◽  
E. Bellm ◽  
A. M. Beloborodov ◽  
...  
Keyword(s):  
Point Source ◽  
Angular Resolution ◽  
Focal Length ◽  
Effective Area ◽  
X Ray ◽  
Large Effective Area ◽  
Better Than

AbstractNASA's NuSTAR observatory is the first focusing hard X-ray telescope. Launched in June 2012, NuSTAR is sensitive in the 3–79 keV range with unprecedented ~17″ FWHM angular resolution above 12 keV, a result of its multilayer-coated optics and 10-m focal length. With its large effective area (900 cm2 at 10 keV), NuSTAR has point-source sensitivity ~100 times better than previous hard X-ray telescopes. Here we describe NuSTAR and its planned work on rotation-powered pulsars and magnetars during its nominal 2-yr baseline mission that has just commenced.

Insights on Amorphous Silicon Nip and MIS 3D Position Sensitive Detectors

2006 ◽  
Vol 514-516 ◽  
pp. 13-17 ◽  
Author(s):  
Rodrigo Martins ◽  
Daniel Costa ◽  
Hugo Águas ◽  
Fernanda Soares ◽  
António Marques ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Image Resolution ◽  
Mis Structure ◽  
Silicon Thin Film ◽  
One Dimensional ◽  
Operation Conditions ◽  
Plane Image ◽  
Position Sensitive ◽  
Position Sensitive Detectors ◽  
Better Than

This work aims to report results of the spatial and frequency optical detection limits of integrated arrays of 32 one-dimensional amorphous silicon thin film position sensitive detectors with nip or MIS structure, under continuous and pulsed laser operation conditions. The arrays occupy a total active area of 45 mm2 and have a plane image resolution better than 15 m with a cut-off frequency of about 6.8 kHz. The non-linearity of the array components varies with the frequency, being about 1.6% for 200 Hz and about 4% for the cut-off frequency (6.8 kHz).

Stokes Mechanism of Drag Reduction

2005 ◽  
Vol 73 (3) ◽  
pp. 483-489 ◽  
Author(s):  
Promode R. Bandyopadhyay
Keyword(s):  
Drag Reduction ◽  
Attenuation Factor ◽  
Viscous Sublayer ◽  
Wall Region ◽  
Mean Velocity ◽  
Turbulence Suppression ◽  
Maximum Drag Reduction ◽  
The Mean ◽  
Stokes Second Problem ◽  
Better Than

The mechanism of drag reduction due to spanwise wall oscillation in a turbulent boundary layer is considered. Published measurements and simulation data are analyzed in light of Stokes’ second problem. A kinematic vorticity reorientation hypothesis of drag reduction is first developed. It is shown that spanwise oscillation seeds the near-wall region with oblique and skewed Stokes vorticity waves. They are attached to the wall and gradually align to the freestream direction away from it. The resulting Stokes layer has an attenuated nature compared to its laminar counterpart. The attenuation factor increases in the buffer and viscous sublayer as the wall is approached. The mean velocity profile at the condition of maximum drag reduction is similar to that due to polymer. The final mean state of maximum drag reduction due to turbulence suppression appears to be universal in nature. Finally, it is shown that the proposed kinematic drag reduction hypothesis describes the measurements significantly better than what current direct numerical simulation does.

scholarly journals BIFOCAL STEREO FOR MULTIPATH PERSON RE-IDENTIFICATION

2017 ◽  
Vol XLII-2/W8 ◽  
pp. 37-44 ◽  
Author(s):  
G. Blott ◽  
C. Heipke
Keyword(s):  
Focal Length ◽  
Image Resolution ◽  
Field Of View ◽  
Eye Lens ◽  
Single Camera ◽  
Identification Performance ◽  
Stereo Cameras ◽  
Working Distance ◽  
3D Information ◽  
Fish Eye

This work presents an approach for the task of person re-identification by exploiting bifocal stereo cameras. Present monocular person re-identification approaches show a decreasing working distance, when increasing the image resolution to obtain a higher reidentification performance. We propose a novel 3D multipath bifocal approach, containing a rectilinear lens with larger focal length for long range distances and a fish eye lens of a smaller focal length for the near range. The person re-identification performance is at least on par with 2D re-identification approaches but the working distance of the approach is increased and on average 10% more re-identification performance can be achieved in the overlapping field of view compared to a single camera. In addition, the 3D information is exploited from the overlapping field of view to solve potential 2D ambiguities.

scholarly journals Synthetic aperture imaging in acoustic microscopy

2021 ◽  
Author(s):  
Golafsoun Ameri
Keyword(s):  
Image Resolution ◽  
Acoustic Microscopy ◽  
Synthetic Aperture ◽  
Lateral Resolution ◽  
Depth Of Field ◽  
Single Element ◽  
Focal Region ◽  
Array Transducer ◽  
Small Depth ◽  
Better Than

Acoustic microscopy (AM) provides micro-meter resolution using a highly focused single-element transducer. A drawback in AM is a relatively small depth of field, resulting in poor resolution outside the focus. Synthetic aperature focusing technique (SAFT) can be used to improve the image resolution throughout the field of view. SAFT mathematically synthesizes the effect of an array transducer and produces dynamic focusing and depth-independent resolution. SAFT in time domain with and without apodization, TD-SAFT and ATD-SAFT, respectively, and in frequency domain (FD-SAFT) were implemented and tested using simulated and experimental radio-frequency data from an acoustic microscope at 400 MHz. Lateral resolution of all the SAFT reconstructed images were better than those of the conventional B-mode images. While TD-SAFT and FD-SAFT permformed better than ATD-SAFT in improving the lateral resolution, ATD-SAFT provided lower side lobes. In conclusion, SAFT improves resolution in AM outside the focal region.

High Resolution Balloon-Borne Spectrograph for the Near Solar Ultraviolet

1971 ◽  
Vol 41 ◽  
pp. 263-270 ◽  
Author(s):  
P. Lemaire
Keyword(s):  
Spatial Resolution ◽  
Focal Length ◽  
Solar Spectrum ◽  
Image Plane ◽  
Solar Image ◽  
Balloon Flight ◽  
Aperture Ratio ◽  
Cassegrain Telescope ◽  
Solar Ultraviolet ◽  
Better Than

In order to obtain the solar spectrum of the Mgii lines at 2795.5 Å and 2802.7 Å, we built a balloon instrument which consisted of a Cassegrain telescope, with an aperture ratio of F/20 and a focal length of 300 cm to give a solar image on the slit of a spectrograph. The theoretical spectral resolution is better than 10 mÅ. In the laboratory, we measured a spatial resolution of 10 μ in the image plane of the spectrograph, which corresponds to 1 arc sec in this mounting. During a balloon flight of 1969, April 30, which used a biaxial pointing system, we obtained a spatial resolution better than 10 arc sec, limited by the accuracy of the pointing system. Lastly, on 1970 June 24, the same instrument with a servosystem inside the telescope, was launched and spectral and spatial resolutions of 25 mÅ and about 3 arc sec, respectively, were obtained.

SEM and microdiffraction study of the reduction of metal oxides in a STEM instrument

1988 ◽  
Vol 46 ◽  
pp. 516-517
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Electron Beam ◽  
Metal Oxides ◽  
Structural Information ◽  
Image Resolution ◽  
Secondary Electrons ◽  
Additional Information ◽  
Reduction Processes ◽  
Exit Surface ◽  
Reduction Of Metal Oxides ◽  
Better Than

It has been reported that under electron beam irradiation maximally valent metal oxides can be reduced to lower oxides and under some circumstances even to metals due to the preferential loss of oxygen. The electron beam induced reactions can be conveniently studied in a STEM instrument equipped with a field emission gun and a chamber vacuum pressure about 5x10-9 Torr.. Microdiffraction patterns obtained from areas about 1.0-1.5 nm in diameter can be used to deduce the structural information of the reduction products. The recently attached SE detector in our HB5 STEM instrument can collect secondary electrons at the exit surface of the sample and the image resolution is better than 1 nm3. Since SE signals carry information about the surface and sub-surface of the studied material and SE emission is sensitive to surface modifications (both geometric and electronic) such as the change of work function due to the formation of new phases on the specimen surface, high resolution SE imaging can provide additional information about the reduction processes of metal oxides under electron beam bombardment. The combination of SE imaging with the microdiffraction technique proves to be a powerful tool for studying surface reactions.

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