| 摘要 |
A rear aperture sight for use in conjunction with a front sight post sight on a rifle. The front sight post has a horizontal top edge and vertical side edges. The rear aperture sight comprises a rear sight adapted to be mounted on the rifle. The rear sight has a horizontally elongated aperture formed therein having height and width dimensions. The width dimension is greater than the height dimension. The aperture is defined by two circular segments s1 and s2 having chords c1 and c2, respectively, defined by included angles &thetas;1 and &thetas;2, respectively, of circles having radii R1 and R2, respectively. The chords c1 and c2 have heights h1 and h2, respectively. Radii R1 and R2 and angles &thetas;1 and &thetas;2 are selected such that chords c1 and c2 are of equal length. The circular segments are positioned such that chords c1 and c2 are co-linear and oriented horizontally. In another aspect, the rear sight has at least one aperture plate having an aperture formed therein which defines an entrance pupil for an eye of a shooter of the rifle. The entrance pupil is horizontally elongated having a height h and a width w, the width w being at least about 125% of the height h, the height h being smaller than a diameter of a pupil of the eye of the shooter and of such a value that the entrance pupil is adapted to cause the horizontal top edge of the front sight post and a horizontal edge of a target to be more sharply focused than if viewed by an unaided eye, the width w being of such a value that an area defined by the entrance pupil is greater than an area defined by a circular entrance pupil having a diameter equal to the height h, thereby permitting more light to pass through the entrance pupil than through the circular entrance pupil, and causing the front sight post and the target to appear brighter than if viewed through the circular entrance pupil.
|
