Optical arrangement for a light scattering type smoke detector

US4397557A · kind A · utility

Assignee

• Heimann GmbH · DE

Inventors

• Thomas Herwig · Eltville am Rhein, DE
• Ortwin Struss · Nordenstadt, DE

Key dates

• Filing date: Dec 10, 1980
• Grant date: Aug 9, 1983
• Expiry date: Dec 10, 2000

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N21/53
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An optical arrangement for a light scattering type smoke detector has a radiation transmitter and receiver which are each preceded by a lens for obtaining a generally parallel field of view for each of the transmitter and receiver. The radiation is directed at a detection zone which is surrounded by diaphragms and the fields of view for the transmitter and receiver terminate in a light trap for preventing unwanted scattering and reflection. The transmitter and receiver are disposed at an acute angle with respect to each other and the receiver detects only back-scattered radiation from smoke particles in the detection area. This structure allows a relatively short structural length to be utilized along a common optical axis of the transmitter and receiver.