Geometrical instruments – Straight-line light ray type – Level
Reexamination Certificate
1998-07-30
2001-03-20
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Straight-line light ray type
Level
C033S286000, C033S287000, C033S293000
Reexamination Certificate
active
06202314
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to measurement systems and, in particular, to a particularly effective calibration system for measuring with greater precision when optical comparison to a calibration is used for measuring.
BACKGROUND OF THE INVENTION
Surveying is as old as the art of civil engineering itself and predates even recorded history. One of the primary objectives of surveying is accuracy and precision in measurements made. In measuring an elevation, for example, a calibrated reference is placed at a point of interest while a scope is placed at a second point of reference. The second point of reference, and thus the scope, has a known elevation. The scope is leveled and aimed at the calibrated reference. A horizontal reference line is positioned within the view through the scope such that visual comparison of the reference line as viewed through the scope to the calibrated reference provides a measurement of the difference in elevation between the first and second points of interest.
At times, the distance between the first and second points of reference is considerable and accurate optical comparison between the reference line and the calibrated reference is difficult. For example, conventional calibration systems mark centimeters and perhaps half centimeters such that millimeters are merely estimated by a surveyor. Despite high quality optical magnification within the scope, comparison of the reference line within the scope to marked half-centimeters to estimate a measurement to the nearest millimeter is quite difficult. However, simply marking the calibrated reference with reference marks spaced by one millimeter is ineffective. Specifically, reference marks so close to one another appear as a single, indistinguishable mark from a distance notwithstanding high quality optical magnification.
Another problem with current surveying calibration references is that the view of the scope frequent has insufficient information to make a complete assessment of a current measurement. For example, it is common that only half-centimeter marks of the calibrated reference are visible through the scope at a particular measurement. Such generally requires that the scope be panned up and/or down to view markings which indicate absolute measurements such that the relation between the originally viewed half-centimeter marks and the absolute measurement markings can be determined. Only then can a measurement be made by comparison of the reference line to the half-centimeter marks which would otherwise lack context.
What is needed is a calibration system by which more precise and accurate measurements can be made and by which such measurements can be made without reference to distant portions of a calibrated reference.
SUMMARY OF THE INVENTION
In accordance with the present invention, a measuring system includes an optical site reference, such as a reference line within a scope used in surveying, and a calibrated reference scale which provides measurements by optical comparison to the optical site reference. The calibrated reference scale includes centimeter sections which in turn include upper and lower stepped sections. The upper and lower stepped sections are symmetrical with respect to one another such that the upper and lower stepped sections can be easily distinguished from one another from significant distance. Each of the steps of each stepped section indicates a specific, corresponding offset within the stepped section. In particular, each stepped section includes a long reference section which is adjacent to a short reference section along an adjacent edge of the long reference member. The short reference member is substantially less wide than the long reference member so as to expose a significant portion of the adjacent side. Thus, the exposed portion of the adjacent edge of the long reference member easily visible from significant distances and alignment of the optical site reference with the exposed portion of the adjacent edge can be easily recognized. The symmetry of the upper and lower stepped sections is in the relative positions of the long and short reference members. For example, the long reference member is above the short reference member in the upper stepped section and the long reference member is below the short reference member in the lower stepped section.
The long and short reference members have uniform heights such that edges of the long and short reference members opposite the adjacent edge, as well as the adjacent edge itself, provide references for predetermined offsets within the calibrated reference scale. Some of the advantages of the upper and lower stepped sections are best appreciated in the context of an illustrative example. Consider the lower stepped section in which (i) the bottom, non-adjacent edge of the long reference member is spaced two millimeters from a reference point on the calibrated reference scale, (ii) the height of the long reference member is one millimeter such that the top, adjacent edge of the long reference member is spaced three millimeters from the reference point, and (iii) the height of the short reference member is also one millimeter such that the top, non-adjacent edge of the short reference member is spaced four millimeters from the reference point. In this illustrative example, the top and bottom edges of the long reference member provide two- and three-millimeter references, respectively, relative to the reference point, and the top edge of the short reference member provides a four-millimeter reference relative to the reference point. As a result, references are provided with a precision of one-millimeter. To accomplish references separated by one-millimeter using simple tick marks would either result in marks which are too thin to see from significant distances notwithstanding high-quality optics or in marks which are too close together to distinguish from significant distances. Even if the marks are visible and distinct, determining with which mark the optical siting reference is aligned is difficult since the marks would look similar. Thus, the stepped sections provide references which are close to one another yet are easily recognizable and distinguished, even from significant distance.
Further in accordance with the present invention, the calibrated reference scale includes a number of digit reference sections. A digit reference section is spaced a predetermined distance from a reference point along the calibrated reference scale and includes an alphanumeric representation of that predetermined distance. The alphanumeric representation has a predetermined height such that the alphanumeric representation itself provides a reference for offsets from a base of the alphanumeric representation. In particular, those alphanumeric representations which have horizontal components place those horizontal components so as to provide relatively evenly spaced references which the digit reference section. Such horizontal components have a uniform, predetermined height and are spaced from one another by the same uniform, predetermined height. The following example is illustrative.
A digit reference section whose base is eight centimeters from a reference point along the calibrated reference scale includes an alphanumeric representation of the numeral eight. The digit reference section is one centimeter in height, and the alphanumeric representation is approximately one centimeter in height so as to provide a representation of the entire height of the digit reference section. The alphanumeric representation has top, middle, and bottom horizontal members which define two spaces therebetween, namely, an upper space between the top and middle horizontal members and a lower space between the middle and bottom horizontal members. Each of the horizontal members and the spaces between has a height of two millimeters. Thus, the tops and bottoms of each of the horizontal members and spaces between provides a reference corresponding to an offset within the digit reference section of an even number of millimeters.
Doan Quyen
Fulton Christopher W.
Ivey James D.
LandOfFree
Calibration system for use with measuring systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Calibration system for use with measuring systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Calibration system for use with measuring systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2457805