A rugged, adjustable optical alignment device well suited for use as a pistol rear sight is adapted for use in a dovetail, as is customarily seen on the slide of an automatic pistol. The sight assembly includes a rear notch, but could just as easily include a peep aperture or other optical alignment structure. The rear sight provides an easy click-detent adjusting mechanism for horizontal translation of the notch, as well as a second click-detent mechanism for vertical translation of the structure defining the notch, thereby providing adjustments for windage and elevation. A base hingedly supports a vertical tilt member. A horizontal slide member mounted on the rear of the vertrical tilt member is horizontally translatable by adjustment of a windage adjustment screw.