A-A-52036B
3. SALIENT CHARACTERISTICS.
3.1 Accuracy. Accuracy shall be certifiable, for the life of the level, to permit not greater than
1.54 seconds of error (1st order) for class 1 instruments; and not greater than 3.07 seconds of error (2nd order) for class 2 instruments.
3.2 Level types.
3.2.1 Tilting level. A tilting instrument (type I) shall require manual leveling prior to use and periodic checking for maintenance of a level horizontal line of sight during use. The instrument shall be provided with a circular spirit level, or similar device, for initial coarse leveling and a graduated leveling readout device and leveling screws for precise leveling. The type I, style A level shall be equipped with a parallel-plane optical micrometer that allows the operator to measure horizontal distances, within instrument limits. The type I, style B level shall not be equipped with an optical micrometer.
3.2.2 Self-leveling. A self-leveling instrument (type II) shall automatically maintain the telescope in a level position, until no longer needed, once the instrument has been manually brought to a defined approximation of level. Type II instruments shall have provisions for measuring horizontal distances. The type II, style A instrument shall have provisions for horizontal full circle angle measurement; the style B instrument shall not. Type II levels shall be equipped with an automatic compensator, with a working range of not less than ±15 seconds of arc, that shall maintain a true horizontal level line of sight at all telescope positions. After telescope rotation, the instrument shall return to true level in not greater than 5 seconds.
3.3 Optical system. The optical system of either type instrument shall be aberration free,
provide a clear, bright, high contrast, and sharp image throughout the focusing range and field of view. The image may be erect or inverted. Optical properties shall be as follows:
a. Magnification: Not less than 30 diameters at an accuracy of ±5 percent b. Objective lens effective aperture: Not less than 39 millimeters (mm)
c. Minimum focus distance: Not greater than 3.7 meters
d. Minimum field of view: Not less than 60 minutes of arc e. Resolution: Not less than 4 seconds of arc
f. Eye relief distance: Not less than 7 mm
3.3.1 Reticle. The reticle shall be a pattern of permanent opaque lines, on a distortion free, optically transparent medium. It shall be adjustable for precise positioning of the cross hairs, in the horizontal and vertical planes, about the central line of sight axis of the telescope. The reticle shall be positioned in the eyepiece focus and so as to eliminate distortion during collimation. Horizontal and vertical stadia lines shall be a minimum of 5 minutes of arc in length, parallel to the corresponding cross lines, and spaced at standard stadia line intervals of 1 to 100. The width of all reticle lines shall be 3 seconds of arc, + 0.0 seconds, -0.5 seconds.
3.3.2 Stadia constant. When horizontal distance is measured using the stadia method the difference shall not be greater than ±0.3 percent when compared to the verified distance.
3.3.3 Optical micrometer. When provided, the parallel plate optical micrometer shall measure the interval between the horizontal reticle line and the nearest rod graduation directly to 1 mm.
2
For Parts Inquires submit RFQ to Parts Hangar, Inc.
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business