Abstract. The imager for Mars Pathfinder (IMP), a stereoscopic, multispectral camera, is described in terms of its capabilities for studying the Martian environment. The camera's two eyes, separated by 15.0 cm, provide the camera with range-finding ability. Each eye illuminates half of a single CCD detector with a field of view of 14.4 x 14.0 ø and has 12 selectable filters. The f/18 optics have a large depth of field, and no focussing mechanism is required; a mechanical shutter is avoided by using the frame transfer capability of the 512 x 512 CCD. The resolving power of the camera, 0.98 mrad/pixel, is approximately the same as the Viking Lander cameras; however, the signal-to-noise ratio for IMP greatly exceeds Viking, approaching 350. This feature along with the stable calibration of the filters between 440 and 1000 nm distinguishes IMP from Viking. Specially designed targets are positioned on the Lander; they provide information on the magnetic properties of wind-blown dust, measure the wind vectors, and provide radiometric standard reflectors for calibration. Also, eight low-transmission filters are included for imaging the Sun directly at multiple wavelengths, giving IMP the ability to measure dust opacity and potentially the water vapor content. Several experiments beyond the requisite color panorama are described in detail: contour mapping of the local terrain, multispectral imaging of the surrounding rock and soil to study local mineralogy, viewing of three wind socks, measuring atmospheric opacity and water vapor content, and estimating the magnetic properties of wind-blown dust. This paper is intended to serve as a guide to understanding the scientific integrity of the IMP data that will be returned from Mars starting on July 4, 1997.
Abstract. The Imager for Mars Pathfinder returned over 16,000 high-quality images from the surface of Mars. The camera was well-calibrated in the laboratory, with <5% radiometric uncertainty. The photometric properties of two radiometric targets were also measured with 3% uncertainty. Several data sets acquired during the cruise and on Mars confirm that the system operated nominally throughout the course of the mission. Image calibration algorithms were developed for landed operations to correct instrumental sources of noise and to calibrate images relative to observations of the radiometric targets. The uncertainties associated with these algorithms as well as current improvements to image calibration are discussed. The primary requirement for mission success was that IMP provide a color panorama of the landing site. Other science goals included contour mapping of the local terrain, multispectral imaging of the surrounding rocks and soils to study local mineralogy, viewing of three windsocks, measuring atmospheric opacity and water vapor content, and estimating the magnetic properties of wind-blown dust.In this paper we review the baseline IMP performance, expanding on the prelanding experiment report [Smith et al., 1997]. We then discuss several experiments that were performed postlaunch that verify the nominal performance of the camera system. Finally, we describe the algorithms used to calibrate raw image data and review the differences between the level of calibration performed during operations versus more current and pending calibration algorithm. Note that this document is primarily intended to review IMP calibration and performance. The full IMP calibration report [Reid et al., 1998] will be archived with the raw data by the Planetary Data System (PDS).
Electrically driven acousto-optic devices that provide beam deflection and optical frequency shifting have broad applications from pulse synthesis to heterodyne detection. Commercially available acousto-optic modulators are based on bulk materials and consume Watts of radio frequency power. Here, we demonstrate an integrated 3-GHz acousto-optic frequency shifter on thin-film lithium niobate, featuring a carrier suppression over 30 dB. Further, we demonstrate a gigahertz-spaced optical frequency comb featuring more than 200 lines over a 0.6-THz optical bandwidth by recirculating the light in an active frequency shifting loop. Our integrated acousto-optic platform leads to the development of on-chip optical routing, isolation, and microwave signal processing.
Optical wave-front propagation in a layered model for the atmosphere is analyzed by the use of diffraction theory, leading to a novel approach for utilizing artificial guide stars. Considering recent observations of layering in the atmospheric turbulence, the results of this paper indicate that, even for very large telescopes, a substantial enlargement of the compensated angular field of view is possible when two adaptive mirrors and four or five artificial guide stars are employed. The required number of guide stars increases as the thickness of the turbulent layers increases, converging to the conventional results at the limit of continuously turbulent atmosphere.
The Imager for Mars Pathfinder (IMP) is a stereo multi-spectral CCD camera designed to support a variety of science experiments from the Martian surface. The camera combines a straightforward imaging system based on a pair of Cooke triplets, fold optics, and a divided 512 x 256 pixel CCD with a complement of spectral and solar filters on two filter wheels. Aluminum and titanium component mountings on an aluminum optical bench provide for a complete pointing and imaging system having a mass of less than 3 kg..The az-el gimbal utilizes gearhead stepper motors to provide a field of regard of 370° in azimuth and 156°i n elevation, in support of stereo and monoscopic panoramas and atmospheric studies. This paper discusses mechanical aspects of the optical component mountings and adjustments, as well as structural and mechanical aspects of the gimbal.
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