A housing for a scattered light detection unit of a smoke detection device, the housing comprising a base (2) fastened to a mounting plate (1), the base comprising guiding channels (8) for mounting and directing optical elements;
- limiting barriers (9) attached to the channels (8), the limiting barriers arranged on an inner end surface (10) of the base (2) and surrounded by an opaque wall (7) that is concentric to a lateral outer wall (6);
- a casing (3) mounted on the base (2), the casing having a lateral portion (13) that encompasses the base (2), the mounting plate (1), and a disc portion (15) that is parallel to the base (2), the disc portion comprising an opening (16) having an edge that is directed towards the base (2) and that is coaxial to the opaque wall (7);
- and a cover element (4) fastened on the casing (3), wherein the casing (3) is fixable on the base (2), thereby fitting the edge of the opening (16) to an edge of the opaque wall (7), wherein the limiting barriers (9) are vertically arranged relative to the inner end surface (10) and opposite to each other, while forming a gap between them, wherein a height of the barriers (9) is not more than a height of the opaque wall (7), wherein the edge of the opening (16) of the casing (3) is directed by an annular protrusion (17) provided on an outer surface of the disc portion (15), the annular protrusion being connected to the edge of the opening (16) by a curved tilted area (18), wherein the cover element (4) comprises a central portion (19) that is closed at one end and faced towards the casing (3) with an open end, a peripheral portion (20) having series of concentrically arranged longitudinal slit-like openings (21), and a lateral portion (22) that is fixable on the lateral portion (13) of the casing (3), wherein an inner end surface of the central portion (19) is curved, while forming a smooth transition to a cone-like protrusion (28) from its edge to its center, and a height of the cone-like protrusion (28) is not more than a half length of the central portion (19), wherein a diameter of the open end of the central portion (19) is the same as a diameter of the opening (16), wherein the peripheral portion (20) of the cover element (4) is divided into sectors by equidistant radial partitions (26), and wherein the lateral portion (22) of the cover element (4) is fixable on the lateral portion (13) of the casing (3), with an annular slit (24) formed between the open end of the central portion (19) and a curved tilted area (18) of the disc portion (15) of the casing (3), and lower portions of the radial partitions (26) of the peripheral portion (20) fit to the disc portion (15) of the casing (3).