A system and method for sensing height above landing surface for an aircraft, processing that sensed height information to provide information useful to the aircraft pilot for assisting with the landing and flare-to-land maneuver, and providing the processed information in a peripheral vision display indicating landing conditions sequentially without interfering with pilot vision and focus on the landing area.

A setpoint adjustment apparatus for a displacement meter (10) includes a determiner (343) to determine whether a measurement value acquired by an acquirer (341) in measurement of a reference workpiece using an applying setpoint, to be used in measurement of the reference workpiece, is within the range of a desired measurement value (352), and a changer (345) to change the applying setpoint. When the measurement value is within the range of the desired measurement value (352), the applying setpoint used in acquisition of the measurement value is employed as an applying setpoint for inspection of a measurement target (1). When the measurement value is out of this range, the applying setpoint used in acquisition of the measurement value is changed to a different applying setpoint, and whether the measurement value from the reference workpiece using this applying setpoint is within the range of the desired measurement value (352) is determined.

A setpoint adjustment apparatus for a displacement meter (10) includes a determiner (343) to determine whether a measurement value acquired by an acquirer (341) in measurement of a reference workpiece using an applying setpoint, to be used in measurement of the reference workpiece, is within the range of a desired measurement value (352), and a changer (345) to change the applying setpoint. When the measurement value is within the range of the desired measurement value (352), the applying setpoint used in acquisition of the measurement value is employed as an applying setpoint for inspection of a measurement target (1). When the measurement value is out of this range, the applying setpoint used in acquisition of the measurement value is changed to a different applying setpoint, and whether the measurement value from the reference workpiece using this applying setpoint is within the range of the desired measurement value (352) is determined.

A distance measurement device includes an emission unit, a detection unit, a first reduction unit that reduces, based on a detection result of the detection unit, influence of variation of an optical axis of the image formation optical system on a subject image received as light by a light receiving section, a second reduction unit that reduces variation of an optical axis of the directional light with respect to the subject based on the detection result of the detection unit, and a control unit that, in the case of operating the first reduction unit and the second reduction unit at the same time, controls the first reduction unit and the second reduction unit to reduce variation of an irradiation position of the directional light in the subject image received as light by the light receiving section.

A distance measurement device includes an emission unit, a detection unit, a first reduction unit that reduces, based on a detection result of the detection unit, influence of variation of an optical axis of the image formation optical system on a subject image received as light by a light receiving section, a second reduction unit that reduces variation of an optical axis of the directional light with respect to the subject based on the detection result of the detection unit, and a control unit that, in the case of operating the first reduction unit and the second reduction unit at the same time, controls the first reduction unit and the second reduction unit to reduce variation of an irradiation position of the directional light in the subject image received as light by the light receiving section.

A distance measurement device includes a detection unit, an optical path forming unit, a common reduction unit that reduces influence of variation of an optical axis of an image formation optical system, and reduces variation of an optical axis of the directional light, an auxiliary reduction unit that auxiliarily reduces at least one of influence of variation of the optical axis of the image formation optical system or variation of the optical axis of the directional light, and a control unit that, in a case of operating the common reduction unit and the auxiliary reduction unit at the same time, controls the common reduction unit and the auxiliary reduction unit to reduce variation of an irradiation position of the directional light in a subject image received as light by a light receiving section.

A distance measurement device includes a detection unit, an optical path forming unit, a common reduction unit that reduces influence of variation of an optical axis of an image formation optical system, and reduces variation of an optical axis of the directional light, an auxiliary reduction unit that auxiliarily reduces at least one of influence of variation of the optical axis of the image formation optical system or variation of the optical axis of the directional light, and a control unit that, in a case of operating the common reduction unit and the auxiliary reduction unit at the same time, controls the common reduction unit and the auxiliary reduction unit to reduce variation of an irradiation position of the directional light in a subject image received as light by a light receiving section.

A distance measurement device includes a detection unit, an optical path forming unit, a first reduction unit, based on a detection result of the detection unit, influence of variation of the optical axis of the image formation optical system, a second reduction unit that is disposed in a different part from a common optical path and reduces variation of the optical axis of the directional light with respect to the subject based on the detection result of the detection unit, and a control unit that, in the case of operating the first reduction unit and the second reduction unit at the same time, controls the first reduction unit and the second reduction unit to reduce variation of an irradiation position of the directional light in the subject image received as light by the light receiving section.

A distance measurement device includes a detection unit, an optical path forming unit, a first reduction unit, based on a detection result of the detection unit, influence of variation of the optical axis of the image formation optical system, a second reduction unit that is disposed in a different part from a common optical path and reduces variation of the optical axis of the directional light with respect to the subject based on the detection result of the detection unit, and a control unit that, in the case of operating the first reduction unit and the second reduction unit at the same time, controls the first reduction unit and the second reduction unit to reduce variation of an irradiation position of the directional light in the subject image received as light by the light receiving section.

A distance measurement device includes an emission unit, a detection unit, a first reduction unit that reduces, based on a detection result of the detection unit, influence of variation of an optical axis of the image formation optical system on the subject image received as light by the light receiving section, a second reduction unit that reduces variation of an optical axis of the directional light with respect to the subject based on the detection result of the detection unit, and a control unit that, in the case of operating the first reduction unit and the second reduction unit at the same time, controls the first reduction unit and the second reduction unit to reduce variation of an irradiation position of the directional light in the subject image received as light by the light receiving section.