Showing papers on "Night vision published in 1973"

The evolution of the eye in trilobites

Abstract: Clarkson, E .N.K.19 7 5 0 7 1 5 : The evolution of the eye in trilobites. Fossils and Strata, No. 4, pp . 7-3 1 , Oslo. ISSN 0300-949 1 . ISBN 8 2-00-04963-9. The earliest trilobites have fully differentiated compound eyes, and the subsequent evolution of the eye seems to have been controlled by only three factors: ( 1 ) Changes in proportion, surface curvature, etc ., through differential relative growth. ( 2 ) Paedomorphosis, which was probably the main factor in the origin of the schizochroal eye. (3 ) Incorporation of cuticular sensillae into discrete sensory zones peripheral to the eye. Cam­ brian eyes are rarely preserved due to the functional ocular suture. In post­ Cambrian trilobites, the visual surface is normally intact, and an analysis is presented of its growth and form (controlled by a logarithmic spiral genera­ tive zone ), different systems of lens-packing, and visual ranges. The schizochroal eye is shown to have had an internal muscular system, and may have been an organ for night vision.

Illuminated gun sights

Abstract: Battery powered illuminated gun sights for facilitating accurate aiming of a gun in the dark. The sight illumination is furnished by miniature shock-resistant light emitters, such as light emitting diodes, which are energized from batteries contained in the gun by operation of a switch on the gun. The sights are preferably illuminated with red light to avoid degrading of the user''s night vision and in such a way that the illuminated portions of the sights are not visible from the front and sides of the gun and hence do not reveal the user''s location. The front and rear sights may be distinguished by illumination of different intensity or color to facilitate proper alignment of the sights when aiming.

Carbon monoxide and driving skills.

Abstract: Eighty milliliters of carbon monoxide (CO) or 80 ml of air was administered doubleblind to 50 adults (32 men, 18 women). Blood carboxyhemoglobin (COHb) levels increased by 3.4% in those receiving CO. Brake reaction time, night vision, glare vision, glare recovery, hand-steadiness, and depth perception all showed small and individually insignificant deterioration in the group receiving CO; grouping data in a nonparametric analysis, the performance difference became significant (P < .005). During operation of a driving simulator, the CO-exposed group showed a highly significant deficit in “careful driving” skills (P < .005), with a statistically insignificant facilitation of emergency-type movements. Since a 3.4% increase of COHb level is sufficient to prejudice safe driving, there is a need to revise the permitted eight-hour industrial CO exposure level of 50 ppm.

Advances in night vision technology. A pocketscope for patients with retinitis pigmentosa.

Abstract: Thirteen patients with retinitis pigmentosa and two patients with stationary night blindness with myopia had marked improvements in visual thresholds under scotopic conditions with the aid of a Generation II night vision pocketscope. The symptom of night blindness could be effectively eliminated in these patients. All had visual acuities under scotopic conditions that were comparable to their best visual acuities under photopic conditions. Eleven of the 13 patients with retinitis pigmentosa reported thresholds lower than those obtained from normal dark-adapted subjects tested without the pocketscope. Patients with central fields greater than 10° reported that the pocketscope improved their mobility under scotopic conditions. Advantages of this Generation II pocketscope over a previously described Generation I device are discussed.

Modular, Biocular Eyepiece Display For Thermal Systems

Abstract: Many high quality biocular magnifier eyepieces for two-eye viewing have been designed and fabricated for use with image intensifier direct view systems. These eyepieces provide outstanding imagery across a large exit pupil. The phosphor screen of the image intensifier tube has sufficient brightness (10 to 100 foot lamberts) to allow for very comfortable two-eye viewing. The great advances of the Far Infrared (FIR) technology which detects temperature differences and displays that thermal image in the visible spectrum now provide a new dimension to night vision systems. Those FIR systems that use a cathode ray tube (CRT) display can capitalize on the biocular eyepieces designed for image intensifier systems. However, the majority of FIR systems use Light Emitting Diodes (LED) which are reflected off the back side of the FIR scan mirror so as to avoid the complexity of multiplexing inherent in CRT displays. The scanned LED displays typically use visible relay optics which are slow (approx f/9) and present a real image to an eyepiece lens. One cannot use the afore-mentioned biocular eyepieces since most biocular eyepieces have an f/number less than f/1.0. Therefore, current FIR systems with LED displays use only monocular eyepieces and often cause most observers to "squint" at the thermal picture. This paper proposes a solution to that situation which uses a "diode tube" consist-ing simply of a photo-emitting cathode, proximity focussed on a phosphor screen, which provides a lambertian source of increased brightness located at the reticle plane of the visual optics relay and thereby allows for use of existing image intensifier biocular eyepieces. Measured performance parameters of the biocular eyepiece and diode tube are presented.© (1973) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Pocket Size Night Vision Aid

Abstract: The earliest U.S. electro-optical work to remove the cover of darkness centered around the development in the 1950's of an infrared image tube. This infrared image tube detected targets illuminated by covert infrared search-lights and converted their images to visible displays. The best known device using this technology was the "sniperscope" which had the obvious disadvantage of being an active system. That is, the IR search-light was needed to covertly illuminate the target and could be rather easily detected by a sophisticated enemy.

Low-contrast vision under mesopic and photopic illumination

Abstract: THE OBJECTIVE OF THIS RESEARCH WAS TO OBTAIN NORMATIVE DATA FOR 3 MEASURES OF VISUAL ABILITY UNDER SIMULATED NIGHT-DRIVING LUMINANCE (MESOPIC) AND ORDINARY LIGHTING (PHOTOPIC) CONDITIONS, TO COMPARE THE PERFORMANCE OF DIFFERENT AGE GROUPS, AND TO COMPARE RESULTS WITH THOSE OF A PREVIOUS STUDY. A TOTAL OF 371 SUBJECTS AGED 16 TO OVER 60 WERE GIVEN THE TITMUS STANDARD ACUITY TEST AND A TITMUS LOW-CONTRAST TEST AT PHOTOPIC (34 FT-L) AND MESOPIC (0.4 FT-L) BACKGROUND LUMINANCE, THE LATTER SIMULATING NIGHT-DRIVING CONDITIONS. THEY WERE ALSO GIVEN THE ALLEN NIGHT VISION PERFORMANCE TEST WITH A 10 PERCENT CONTRAST TARGET AT 10 AND 0.2 FT-L. COMPARISONS WERE MADE WITH A PREVIOUS STUDY IN WHICH THE NVPT TARGET WAS 50 TO 60 PERCENT. AVERAGE SCORES (THRESHOLDS) WERE HIGHER (POORER) ON THE ALLEN TEST WITH THE 10 PERCENT CONTRAST TARGET THAN WITH THE 50 TO 60 PERCENT, BUT LOWER CONTRAST TARGETS WERE SEEN ON THE LOW-CONTRAST TITMUS TEST. THE RESULTS SEEM TO INDICATE THAT THE ALLEN TEST WITH A 10 PERCENT CONTRAST TARGET MEASURED ABILITY TO SEE LOW-CONTRAST TARGETS AGAINST GLARE IN BOTH PHOTOPIC AND MESOPIC LUMINANCE AND THE TITMUS LOW-CONTRAST TEST MEASURED LOW-CONTRAST VISION OF A DIFFERENT TYPE. AVERAGE LOW-CONTRAST VISUAL DISCRIMINATION DECREASED WITH AGE. HOWEVER, SOME SUBJECTS IN ALL AGE GROUPS EXHIBITED POORER VISUAL PERFORMANCE THAN MOST OF THEIR OWN AND OTHER AGE GROUPS, AND PERFORMANCE BY MOST OLDER SUBJECTS WAS AS GOOD AS THAT OF A LARGE PROPORTION OF YOUNGER SUBJECTS.

Evaluation of PbSnTe detector fabrication procedures

Abstract: The PbSnTe alloy is used to fabricate infra-red detectors that are sensitive over the spectral range from 3 to 14 microns. Electronic characteristics of these detectors are very sensitive to fabrication procedures and in order to optimize detector performance, it is necessary to determine the effects of the various processing steps. In this paper, a technique is described for the examination of PbSnTe after fabrication procedures by using an Auger Electron Spectrometer. Data is presented correlating surface treatment of PbSnTe with final device performance.