First… Here is one TOPAN lamp with a diffuser, no 16571. This one is from 1959.
From Louis Poulsens very early catalogue.
Here, Verner used 5 of these Topan lamps in a group. Here you can see it in Louis Poulsens own magazine “LP & CO -NYT” from 1972.
Then we have another Topan lamp. This one is called no 16572.
It has a ALUX reflector wich makes it possible to use bulbs with 100 watts intead of 75.