In 1965 the " Fence " system was modernized with the operating frequency doubled to "'216.98 MHz "'( just above Channel 13 in the VHF TV broadcast band ) to obtain higher resolution and to locate smaller objects.
32.
Potassium titanyl phosphate or KTP is a versatile nonlinear optical material, originally designed to frequency doubling red lasers to green for bloodless laser eye surgery; it now find additional application in urological surgery and hand-held green laser pointers.
33.
Blue lasers can also be fabricated directly with InGaN semiconductors, which produce blue light without frequency doubling . 450 nm ( 447 nm plus / minus 5 nm ) blue laser diodes are currently available on the open market.
34.
In practice what this means is that in highly oblique texturing situations a 4 : 1 filter will be twice as sharp as a 2 : 1 filter ( it will display frequencies double that of the 2 : 1 filter ).
35.
The crystal is mounted on a copper block, acting as a heat sink; its 1064 nm output is fed into a crystal of potassium titanyl phosphate ( KTP ), mounted on a heat sink in the laser frequency doubler and halves the wavelength to the desired 532 nm.
36.
Finally, and omitting the many Laser sources which are always needed in such a laboratory, the LMOPS can rely on heavy equipment far actual material fabrication, such as ovens using the Czochralski process to grow bulk non linear crystals which are to be used for laser frequency doubling, as well as MOVPE equipments for the deposition of thin layers of semi-conductors.
