subroutine focus_ele(ele,x,y,t,field)

use bmad
use parameters_bmad
implicit none
type(ele_struct) ele
TYPE(em_field_struct) field
real(rp) x,y,t
real(rp) gradient,width,start, omega, phase
integer:: save, lun
logical :: first = .true.
logical err
!if(first)then
!  lun=lunget()
!  open(unit=lun,file='focus_ele_out.dat')
!  first=.false.
!endif

width = value_of_attribute(ele, 'KICK_WIDTH', err)
start = value_of_attribute (ele, 'X_ANGLE', err) ! for square pulse <start> = start time in ns. For sinusoidal pulse, start = <phase>
omega = width
phase = start
  field%E(1:3) = 0.
  field%B(1:3) = 0.
if(abs(value_of_attribute(ele, 'FIELD_INDEX')) > 100.) then !must be voltage
  gradient = value_of_attribute(ele, 'FIELD_INDEX')/(0.05)**2 * 2  * cos(omega * t + start)
 field%E(1) = -gradient * x
 field%E(2) = gradient * y
 else
  gradient = value_of_attribute(ele, 'FIELD_INDEX') * cos(omega * t + start)
 field%B(1) = gradient * y
 field%B(2) = gradient * x
endif

!if(t > start .and. t < start+width)then
 write(113, '(8(a13,1x,es12.4))')' gradient = ',gradient,' width=',width,'start=',start,'t=',t,' x =',x,' y =',y,' field%B(1) =', field%B(1),' field%B(2) =', field%B(2)
!endif
return
end