Question

Describe the operation of a whiskbroom scanner with the help of a diagram. Explain how it is different from push broom scanner.

Answer 1

Whiskbroom Scanners: The whiskbroom scanners are made up of a rotating mirror and a single detector. The mirror is so oriented that when it completes a rotation, the detector sweeps across the field of view between 90° and 120° to obtain images in a large number of narrow spectral bands ranging from visible to middle infrared regions of the spectrum. The total extent of the oscillating sensor is known as the Total Field of View (TFOV) of the scanner. While scanning the entire field, the sensor’s optical head is always placed at a particular dimension called the Instantaneous Field of View (IFOV). Figure given below depicts the scanning mechanism of whiskbroom scanners.

• In whiskbroom scanner, a single mirror is used to reflect light onto a single detector. The mirror moves back and forth to collect measurements from one pixel in the image at a time whereas in push broom scanner a line of detectors arranged in perpendicular to flight direction are used. The image is collected one line at a time with all of the pixels in a line measures simultaneously.
• A pushbroom scanner receives stronger signal than whiskbroom scanner because it looks at each pixel area for long.
• Pushbroom scanner is more sensitive than whiskbroom scanner. So it is needed to perfectly calibrate.

Whiskbroom Scanners

Pushbroom Scanners