Tree condition meter using optical techniques - detects amount of light passing through foliage at crown of trees

摘要

The meter is carried on a belt (15) worn by the user. The light which is produced by the action of sunlight on particles of dust or moisture filters down through the leaves to the meter as the user walks under the trees. The meter has a housing (10) which is kept level by a counterweight (12) supported below the housing in a universal joint bearing (13). The light passes through an infra-red filter (20), collimator tubes (19) and a glass window (16) to a photoelectric detector. The detector is linked to a processor which has a read-out display (21). The user switches the machine on or off and controls functions of the meter via three switches (22, 23, 24).