Filter screen

A filter screen having a plurality of slots, each slot having a longest principal axis A1 that has a length L, and each slot having a second axis A2 that is perpendicular to A1 and that has a length W, wherein the slots are arranged so that

• all the axes A1 are parallel to each other;
• the slots are disposed in a plurality of rows, wherein within each row the axes A2 are collinear;
• wherein the distance between center points of adjacent slots in the direction of the axes A2 is XP;
• wherein XP is greater than W;
• the slots are disposed in a plurality of columns, wherein within each column the axes A1 are collinear;
• wherein the distance between nearest circumference points of adjacent slots in the direction of the axes A1 is YP;
• wherein L is 1600 micrometers or less;
• wherein XP is 180 micrometers or less.