Abstract: The present invention relates to a relay lens system, wherein all image aberrations are corrected. This permits modular use with no stand-alone lenses or lenses with great focal distance. The relay lens system comprises at least two subsystems, wherein at least one positive lens and at least one negative lens are placed in at least one subsystem near the intermediate image, and the refractive index N(+) of at least one positive lens and the refractive index N(-) of at least one negative lens and the total focal distance F(FLD) of the lenses of the subsystem near the intermediate image correspond to the following relations:N(+)>N(-)and F(FLD)>0.

Abstract: There is disclosed an objective or compound lens with high speed and large field angle for applications using infrared radiation. Preferred embodiments of the lens system have a useful spectral bandpass in the 2-2.5 .mu.m and 1.5-2.5 .mu.m region. These embodiments are constructed to have low resolution, a speed up to F/0.7 and a total field angle up to 60 degrees. Two embodiments comprise only 4 spherical lenses. By simple calculations the disclosed objectives or compound lenses may be matched to lens materials for use within other ranges of the infrared spectrum as well.

Abstract: A magnifier lens has a focal length f and a distance of at least 0.58f between the exit pupil (EXP) and the last lens (L.sub.5) vertex. This magnifier lens comprises, successively from the object-side to the eye-side, a lens, such as a meniscus lens (L.sub.1) with its concave side facing the object, a positive lens (L.sub.2) and a negative lens (L.sub.3) as well as a meniscus lens (L.sub.4) and a positive lens (L.sub.5), defining the last lens, separated by an air space (d.sub.7). The meniscus lens (L.sub.4) faces the eye with its concave side. The use of thin lenses permits a short overall length of a preferred embodiment of only 1.27f, and a sum of the lens thicknesses of 0.89f. Three large lenses (L.sub.2, L.sub.3, L.sub.4) may be made of so-called light-weight glass (SKL15 and SFL11) instead of regular glass. This results in a handy magnifier of short length and low weight with low cost of manufacture due to the small number of lens elements.

Abstract: This invention provides a high speed catadioptric objective system of F/1.2. The lens system comprises, in accordance with the advance of the light rays, a front or first single lens, a main mirror lens, a counter mirror and a field lens system. The counter mirror is mounted in front of the front lens in order to achieve a short overall length and a good correction of sphero-chromatic aberration. The counter mirror may serve as a focussing element or it may be fixedly mounted to the front lens. The present lens system is distinguished over similar prior art systems by its overall length, which has been reduced by 30 percent, sunshade included. The same type of glass is used for almost all lenses of five preferred embodiments in order to eliminate the secondary spectrum and to enable the objective to be used within a very broad spectral range.

Abstract: This invention provides a high speed compact catadioptric, i.e. reflecting-refracting objective system of F/1.2.The lens system comprises, in accordance with the advance of the light rays, a positive lens with a convex surface toward the object, a lens with front and back surface concave toward the object and with a main mirror surfaced on the peripheral portion of said back surface. A counter-mirror is surfaced to the central portion of said positive lens and a field lens is cemented to the central portion of said lens with the main mirror surfaced thereon. Small zonal errors of spherical aberration, economical production and a reduced sensitivity to machining and mounting errors result from employing only two optical members which carry the mirrors and lens elements.

Abstract: This invention provides a high speed catadioptric objective system of F/1.2. The lens system comprises, in accordance with the advance of the light rays, a front or first single lens, a main mirror lens, a counter mirror and possibly a field lens system. The counter mirror is mounted in front of the front lens in order to achieve a short overall length and a good correction of sphero-chromatic aberration. The counter mirror may serve as a focussing element or it may be fixedly mounted to the front lens. The present lens system is distinguished over similar prior art systems by its overall length, which has been reduced by 30 percent, sunshade included. The same type of glass is used for almost all lenses of five preferred embodiments in order to eliminate the secondary spectrum and to enable the objective to be used within a very broad spectral range.

Abstract: This invention provides a high speed catadioptric system of F/1.2. The lens system comprises, in accordance with the advance of the light rays, a front lens, a main mirror lens, a counter mirror surfaced to the central portion of the front lens, and a field lens system. The field lens system is composed of the unsilvered central portion of the main mirror lens and additional lenses immediately adjacent to the main mirror lens at its object- and image side. The same glass is used for the front lens and the main mirror lens. This glass is light, cheap and rather resistant to chemical attack. Three preferred embodiments present a rather high state of correction for the wavelength range from 400 nm to 1000 nm, providing a high contrast image with good detectability of poor-contrast objects. Such lens systems, in spite of their good performance, are of rather simple construction bringing about a lower price of manufacture than known systems.

Abstract: This invention provides a high speed compact catadioptric, i.e. reflecting-refracting objective system of F/1.2.The lens system comprises, in accordance with the advance of the light rays, a positive lens with a convex surface toward the object, a lens with front and back surface concave toward the object and with a main mirror surfaced on the peripheral portion of said back surface. A counter-mirror is surfaced to the central portion of said positive lens and a field lens is cemented to the central portion of said lens with the main mirror surfaced thereon. Small zonal errors of spherical aberration, economical production and a reduced sensitivity to machining and mounting errors result from employing only two optical members which carry the mirrors and lens elements.