Question

The following source is used to inspect 50 mm thick Al plate:

100 kV; max. tube current 6 mA; the square spot size 2.2 x 2.2 mm2.

The distance from the source to the front of the plate is 500mm.

Image magnification M=3.

3 mm diameter flaw is located on the middle of the plate, on the centerline from the

source. Sketch this inspection arrangement, indicating the image size on the film and the

umbra and penumbra. Calculate the geometric unsharpness for these conditions.

Answer 1

An NDE is a disciplinary field of study that is concerned with the development of analysis techniques and measurements.the umbra and penumbra are distinct part of shadow, created by light source. An umbra is the innermost and darkest part of shadow, where the light source is completely blocked and a penumbra is the region in which a portion of the light source is obscured.Penumbra is the region where some of all the light source obscured.

Geometric unsharpness or the size of penumbra(Ug) shown in the image below can be calculated with this following equation,

Ug = f*t/d

Where f is squre spot size

t is thickness of material

d is distance from source to the front of the plate

Gievn, thickness = 50 mm, M=3

The distance from the source to the front of the plate =500 mm

A square pot size = 2.2 x 2.2 mm^2

Ug = 2.2*2.2*50/500

= 0.484mm^2.