An optical element may include {TAIL ~ a first diffractive structure} having a radially symmetric amplitude function and a second diffractive structure having {HEAD ~ a phase function} 
An optical element may include { TAIL ~ a first diffractive structure } having a radially symmetric amplitude function and a second diffractive structure having { HEAD ~ a phase function }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD