DOCTER DOCTER®nightvision 1x24 - Manual (Page 25)

Distinction level Degree of recognition
Room frequency
[Lp/m] for objects with
a size of 0.5m
Detection The presence of an object is perceived. 4
(12.5cm broad stripes)
Allocation The object is symmetric (or not), and
orientation is possibly detectable
5.6
(9cm broad stripes)
Recognition To recognise the type of the object. 16.0
(3.1cm broad stripes)
Identification The object can be identified in details. 25.6
(2cm broad stripes)
Defects within the field of view
What is at stake here are features that describe the number, position, and size of bright
and dark spots within the field of view. These features are assessed by viewing a
standardised object that lights uniformly. The requirements of the military standard MIL-
I-49428 are complied with. This standard comprises the following specification:
400µm
300µm
250µm
150µm
75µm
Inner circle Ø 5.6mm; centre circle Ø 14.7mm; outer circle Ø 19mm
Size of defects
[µm]
Number of defects
in range 1
Number of defects
in range 2
Number of defects
in range 3
400 or bigger 0 0 0
300 to 400 0 1 2
250 to 300 0 3 3
150 to 250 1 6 9
75 to 150 3 10 14
up to 75 not specified not specified not specified
The aberrations are caused by smallest contaminations in the manufacturing process of
the image intensifier and, therefore, occurring in various kinds. To keep the costs of an