The ornamental design for an expansionunit for an optical analyzer, as shown and described.
FIG. 1 is a perspective view of an expansion unit for an optical analyzer, showing the new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines shown are included for the purpose of illustrating portions of the expansion unit for an optical analyzer that form no part of the claim.