Pointable optical system with coude optics having a short on-gimbal path length

A coude gimbal structure comprising:

• a two-axis gimbal system including
• an outer gimbal pivotable about a first rotational axis, and
• an inner gimbal supported on the outer gimbal and pivotable about a second rotational axis which is perpendicular to the first rotational axis and which intersects the first rotational axis at an intersection point;
• and
• a reflective coude optical system consisting essentially of only three powered mirrors and only two flat fold mirrors,
• said only three powered mirrors comprising a positive-optical-power primary mirror mounted to the inner gimbal, wherein the primary mirror lies along a third axis passing through the intersection point and lying perpendicular to the first rotational axis and perpendicular to the second rotational axis, and
• wherein said only two flat fold mirrors comprise an intersection flat fold mirror at the intersection point.

A coude gimbal structure comprising:

• a two-axis gimbal system including
• an outer gimbal pivotable about a first rotational axis, and
• an inner gimbal supported on the outer gimbal and pivotable about a second rotational axis which is perpendicular to the first rotational axis and which intersects the first rotational axis at an intersection point;
• and
• a reflective coude optical system including
• a positive-optical-power primary mirror mounted to the inner gimbal, wherein the primary mirror lies along a third axis passing through the intersection point and lying perpendicular to the first rotational axis and perpendicular to the second rotational axis, and
• an intersection flat fold mirror at the intersection point,
• wherein the reflective coude optical system further comprises
• the positive-optical-power primary mirror, a negative-optical-power secondary mirror, a positive-optical-power tertiary mirror, a first flat fold mirror, and the intersection flat fold mirror,
• wherein the primary mirror and the secondary mirror lie on the third axis, and wherein a beam path parallel to the third axis is reflected from the primary mirror to the secondary mirror, and
• wherein the tertiary mirror lies on the second rotational axis,
• the first flat fold mirror redirects the beam path reflected from the secondary mirror to the tertiary mirror, and
• the intersection flat mirror redirects along the first rotational axis the beam path reflected from the tertiary mirror.