Using a MMOA Series Mount to Align an OAP

The Reference Flat of an MMOA (Mirror Mount Off Axis) series mount allows quick alignment of the OAP (Off Axis Parabola) into your optical system. During final interferometric analysis of the OAP in its mount, the MMOA series reference flat is aligned perpendicular to the OAP's optical axis. The Reference Flat can then be used for rapid alignment and monitoring of the mounted OAP. The procedure assumes that the mirror is oriented at 3 or 9 o'clock, however, the method could be adjusted to fit other optical layouts. The necessary equipment includes an alignment telescope, an illuminated pinhole, and an adjustable auxiliary flat mirror. Note, the flat should have a diameter large enough to cover the Reference Flat and a portion of the OAP. With a 3" or larger aperture alignment telescope, the auxiliary mirror is no longer needed. .

• Alignment Telescope normal to Reference Flat. Position the alignment telescope such that its projected cross-hair is incident upon the MMOA Reference Flat. Adjust the alignment telescope until the return cross-hair is superimposed on the reference cross-hair. The alignment telescope is now auto-collimated and perpendicular to the Reference Flat, and parallel to the optical axis of the OAP.

• Aligned Auxiliary Flat normal to Alignment Telescope. Insert the auxiliary flat mirror between the alignment telescope and Reference Flat, facing the telescope and obscuring a portion of both the Reference Flat and the OAP behind it. Adjusting only the flat, align it to the telescope. Alignment is achieved when the return cross-hair off the flat is superimposed on the reference cross-hair. The flat mirror now serves as a reference.

• Collimated Beam parallel to OAP Optical Axis. Translate the alignment telescope to the other edge of the flat obscuring the OAP and realign, this time adjusting only the telescope. Remove the flat. A collimated beam, parallel to the optical axis of the OAP, has now been successfully translated from the Reference Flat over to the OAP.

• Optimum OAP Focus. Place a white light illuminated pinhole in the approximate focal location of the OAP and move it around until the pinhole is in focus and aligned in the cross-hair when sighted through the alignment telescope. This is the optimum focus position.

Space Optics Research Labs

7 Stuart Road, Chelmsford, MA 01824

Telephone (978) 250-8640       Fax (978) 256-5605         E-mail to SORL

Back to the top of the page.

Return to The SORL Homepage