Browse Prior Art Database

Improved Beamsplitter for Optical Alignment

IP.com Disclosure Number: IPCOM000103324D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Doany, FE: AUTHOR [+2]

Abstract

Disclosed is a beamsplitter to combine optical beams from two directions for optical alignment purposes. The beamsplitter is insensitive to misorientation about two of the three rotation axis.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 91% of the total text.

Improved Beamsplitter for Optical Alignment

      Disclosed is a beamsplitter to combine optical beams from two
directions for optical alignment purposes.  The beamsplitter is
insensitive to misorientation about two of the three rotation axis.

      The beamsplitter arrangement is shown in FIG. 1.  It is easily
made from readily available penta prisms 1 and 2, a right angle prism
3 and a beamsplitter cube 4.

      Ray tracing of rays 5 and 6 entering from opposite directions
in one line shows that a slight rotation of the prism assembly about
an axis perpendicular to the plane of the paper will not change the
angle of the beams exiting the assembly.  A slight shift in the
position of the beams will result, which will be of no consequence if
the light 5 and 6 comes from objectives with infinity correction.

      Rotation about the axis of the incoming light will rotate both
exiting beams together through the same angle. The relative
orientation of the positions of the alignment marks viewed by beams 5
and 6 will not change, although the position of each mark will appear
to shift when viewed with an eyepiece or television camera 7.

      Rotation about an axis parallel to the exiting beams will cause
each beam to rotate in opposite directions, and lead to an apparent
misalignment of the alignment marks.

      However, this arrangement means that the prism assembly must be
adjusted using only one parameter instead of two. The prism assembly
is a...