Length of minor tick marks

Hi !

I would like to modify the length of the minor tick marks in my IDL
plot. For Major tick marks there is the "ticklen" keyword. Is there a
"minorTicklen" keyword? How could I obtain a minorTicklen=1.0 (i.e.
minor tick mark for one side to the other on my plot, similar to
ticklen=1.0) on my plot, especially in log scale.

Thanks for your consideration.
Noah