Image Blurring

This applet shows how an object of a certain angular width and with a some intensity pattern appears as a more or less blurred image when observed with an instrument, such as a radio antenna or an (optical) lens with a given resolving power - expressed as the Half Power Beam Width angle.

• If the object is larger than the instrument's HPBW, one gets a faithful impression of the object's intensity distribution.
• If the HPBW is larger than the object, the resulting intensity profile is nothing but the resolving profile of the instrument.
• If the object's width is comparable to the instrumental profile, the result is something in between, so that the apparent diametre is somewhat larger than the object's true diameter. With the knowledge of the profiles of the source intensity and of the instrumental sensitivity one may correct for this blurring of the image.