Patent ES-2003060-A6 (ES)
Title: Optical alignment maintenance of rotatable reflector
Inventor: MC NEIL JOHN A
IPC: H01S3/10
Filed: 1987-05-07
Abstract: A diffraction grating (15) is rotatable about an axis (24). The rotation produces optical alignment errors of rotation, or the angle beta of tilt between the grating and the axis which is non-zero. - grating bodily near one end of the rotation range and then adjusting, by rotation about the appropriate axis, either the angle alpha only, or the angle beta only, near the other residual error is acceptable. - spectral lines. Stringent machining and assembly tolerances can be dispensed with. (2a/6) DEAB- DE3779405 G A diffraction grating (15) is rotatable about an axis (24). The rotation produces optical alignment errors of rotation, or the angle beta of tilt between the grating and the axis which is non-zero. - grating bodily near one end of the rotation range and then adjusting, by rotation about the appropriate axis, either the angle alpha only, or the angle beta only, near the other residual error is acceptable. - spectral lines. Stringent machining and assembly tolerances can be dispensed with. EPAB- EP-269658 B A method of aligning a rotatable reflecting element (15) comprising a diffraction grating having a normal vector (17) and rulings, with respect to an optical axis (18) of an optical apparatus, said reflecting element (15) having three degrees of freedom, namely aa) a rotation angle theta between said optical axis (18) and said normal vector (17) caused by rotation about a rotation axis (24) parallel to the rulings bb) an alignment angle alpha in th plane of said reflecting element (15) between the rulings and the projection of the rotation axis (24), cc) a tilt angle beta between said rotation axis (24) and the plane of the grating, wherein said alignment is to maintain the rulings of the reflecting element (15) substantially perpendicular to said optical axis (18) when said reflecting element (15) is rotated over a desired rotation range, said method comprises the steps of a) aligning said optical apparatus at a first reference position corresponding to a rotation angle theta substantially defining a first end of said rotation range by using a two-axis angular adjustment of said reflecting element (15), b) rotating said reflecting element (15) to a second reference position corresponding angle theta substantially defining a second end of said rotation range, c) realigning said optical apparatus by adjusting either said alignment angle alpha or alternatively said tilt angle beta to reduce misalignment d) rotating said reflecting element (15) back to said first reference position and again aligning said optical apparatus by using said two-axis angular adjuster to realign said optical apparatus e) readjusting either said alignment angle alpha or said tilt angle beta to further reduce remaining misalignment of said optical apparatus and f) repeating steps (b) through (e) until said optical apparatus is aligned at both said reference positions corresponding to said angular orientations theta0 and theta1. - EP-269658 B A method of aligning a rotatable reflecting element (15) comprising a diffraction grating having a normal vector (17) and rulings, with respect to an optical axis (18) of an optical apparatus, said reflecting element (15) having three degrees of freedom, namely aa) a rotation angle theta between said optical axis (18) and said normal vector (17) caused by rotation about a rotation axis (24) parallel to the rulings bb) an alignment angle alpha in th plane of said reflecting element (15) between the rulings and the projection of the rotation axis (24), cc) a tilt angle beta between said rotation axis (24) and the plane of the grating, wherein said alignment is to maintain the rulings of the reflecting element (15) substantially perpendicular to said optical axis (18) when said reflecting element (15) is rotated over a desired rotation range, said method comprises the steps of a) aligning said optical apparatus at a first reference position corresponding to a rotation angle theta substantially defining a first end of said rotation range by using a two-axis angular adjustment of said reflecting element (15), b) rotating said reflecting element (15) to a second reference position corresponding angle theta substantially defining a second end of said rotation range, c) realigning said optical apparatus by adjusting either said alignment angle alpha or alternatively said tilt angle beta to reduce misalignment d) rotating said reflecting element (15) back to said first reference position and again aligning said optical apparatus by using said two-axis angular adjuster to realign said optical apparatus e) readjusting either said alignment angle alpha or said tilt angle beta to further reduce remaining misalignement of said optical apparatus and f) repeating steps (b) through (e) until said optical apparatus is aligned at both said reference positions corresponding to said angular orientations theta0 and theta1. USAB- US4815820 A The grating aligning method comprises the steps of aligning the optical apparatus at a reference position near one end of the range of rotation, corresponding to an orientation angle theta O, using a solid-body alignment adjustment of the reflecting element of the optical apparatus. The reflecting element is rotated to a second reference position near a second end of the range of rotation, corresponding to an orientation angle theta 1. The optical appts. is re-aligned by adjusting the apparatus to vary the value of an angle alpha to reduce misalignment where the angle alpha is the axial misalignment between an axis coextensive with a reflecting surface of the reflecting element, and the rotational axis. The reflecting element is rotated through angle theta back to the first reference position and again using the solid-body alignment adjustment of the reflecting element of the optical apparatus to realign the optical apparatus. The apparatus is readjusted to further vary the angle alpha to further reduce remaining misalignment of the optical apparatus. The above steps are repeated until the optical apparatus is aligned at both the reference position corresp. to the angular orientation theta O and theta 1.