|
Formula 6 Airy Disk Full Width Half Maximum (FWHM) Linear Diameter
FWHM LD = 1.02 * Lambda * FR
Where:
- FWHM LD is the Full Width Half Maximum Linear Diameter of the Airy disk
- 1.02 is a constant
- Lambda is the wavelength of the light
- FR is the Focal Ratio of the telescope.
Example: What is the linear diameter of the Airy Disk to its Full Width Half Maximum in a 5 inch f/8 telescope for light at a wavelength of 550nm.
FWHM LD = 1.02 * Lambda * FR
FWHM LD = 1.02 * 550nm * 8
Where 550nm = 0.00055 millimeters
FWHM LD = 1.02 * 0.00055 * 8
FWHM LD = .004488 mm
where 1 micron = 0.001 mm
FWHM LD = 4.5 microns
The FWHM linear diameter of the Airy Disk in a 5 inch f/8 telescope for light at 550nm is 4.5 microns.
|