Abstract: A method for adjusting an optical axis of an imaging optical system is provided. The imaging optical system includes: a first lens element; a right-angle prism; and a lens group, and is incorporated in a lens barrel including: a first holding member positioning and fixing the first lens and the right-angle prism; and a second holding member incorporating the lens group. The method includes: when assembling the first holding member and the second holding member, positioning the first holding member relative to the second holding member; making inspection light incident into the first lens; and changing a relative position of the first holding member to the second holding member so that an image obtained from the inspection light takes a reference position, so as to coincide an optical axis of the subject light emerged from the right-angle prism with an optical axis of the lens group.

Abstract: A lens frame is contained in a lower lens barrel and moves in a direction of an optical axis as guided by a guide shaft. An adjusting lever is provided with a lever body having a bearing for supporting the lower end of the guide shaft and an opening into which an adjusting pin is inserted, and a holding portion extended from near the opening of the lever body to outside the lower lens barrel. A length between an edge of the holding portion and a center of the opening is longer than the length between the center of the opening and a center of the bearing. The lever moves around the adjusting pin in a plane orthogonal to the optical axis to adjust the position of the guide shaft.

Abstract: A method for adjusting an optical axis of an imaging optical system is provided. The imaging optical system includes: a first lens element; a right-angle prism; and a lens group, and is incorporated in a lens barrel including: a first holding member positioning and fixing the first lens and the right-angle prism; and a second holding member incorporating the lens group. The method includes: when assembling the first holding member and the second holding member, positioning the first holding member relative to the second holding member; making inspection light incident into the first lens; and changing a relative position of the first holding member to the second holding member so that an image obtained from the inspection light takes a reference position, so as to coincide an optical axis of the subject light emerged from the right-angle prism with an optical axis of the lens group.

Abstract: A lens frame is contained in a lower lens barrel and moves in a direction of an optical axis as guided by a guide shaft. An adjusting lever is provided with a lever body having a bearing for supporting the lower end of the guide shaft and an opening into which an adjusting pin is inserted, and a holding portion extended from near the opening of the lever body to outside the lower lens barrel. A length between an edge of the holding portion and a center of the opening is longer than the length between the center of the opening and a center of the bearing. The lever moves around the adjusting pin in a plane orthogonal to the optical axis to adjust the position of the guide shaft.

Abstract: A zoom lens device has a first lens holding barrel, a second lens holding barrel, the first lens holding frame and the second lens holding frame, all of which is assembled in a fixed barrel. The second lens holding frame holds a fourth lens group. The second lens holding frame is provided with a hole and a long hole, which fit to a first guide shaft and a second guide shaft respectively. The first and second guide shafts are disposed inside the fixed barrel. A first end of the first guide shaft slidably fits on the second lens holding barrel, while a second end is temporarily fixed to the fixed barrel so as not to move in a direction of an optical axis but to move in a direction substantially perpendicular to the optical axis L. By moving the temporarily fixed second end in the direction substantially perpendicular to the optical axis L, the second lens holding frame can move and a decentering adjustment of the fourth lens group will be made.

Abstract: A zoom lens device has a first lens holding barrel, a second lens holding barrel, the first lens holding frame and the second lens holding frame, all of which is assembled in a fixed barrel. The second lens holding frame holds a fourth lens group. The second lens holding frame is provided with a hole and a long hole, which fit to a first guide shaft and a second guide shaft respectively. The first and second guide shafts are disposed inside the fixed barrel. A first end of the first guide shaft slidably fits on the second lens holding barrel, while a second end is temporarily fixed to the fixed barrel so as not to move in a direction of an optical axis but to move in a direction substantially perpendicular to the optical axis L. By moving the temporarily fixed second end in the direction substantially perpendicular to the optical axis L, the second lens holding frame can move and a decentering adjustment of the fourth lens group will be made.

Abstract: An improvement of a valve mechanism for brake booster is disclosed. According to the invention, a valve mechanism for booster comprises a first valve seat formed on a valve body, a first valve element adapted to be seated upon the first valve seat, a second valve seat formed on a rear side of a valve plunger, and a second valve element adapted to be seated upon the second valve seat. The first valve element is urged rearwardly by a first spring, whereby a rear end of the first valve element is maintained in abutment against the second valve element while maintaining a hermetic seal therebetween. The second valve element is urged toward the second valve seat by a second spring having a resilience greater than that of the first spring. The diameter of a first seat area S1 where a contact occurs between the first valve seat and the first valve element is substantially equal to the diameter of a second seat area S2 where a contact occurs between the second valve seat and the second valve element.