function d17_he3corr,win,params,tol=tol

                LAMP function to correct polarization analysis data taken with the He3 filter

 NECESSARY VARIABLES:

                win=workspace with the data, must have the four polarization states as

                                [[I00],[I01],[I10],[I11]]

                params=the fitted parameters to phi and trans

                                This can be a 1 or 2D array,

                                                the second row in a 2D array is the error on the parameter                          

                                params[0]=initial time for filter (t0)

                                params[1]=initial polarization of 3He gas (P0He)

                                params[2]=decay time of cell (t1)

                                params[3]=polarizer inefficiency (p1)

                                params[4]=gas pressure ([3He])

                                params[5]=wavelength   (lambda)

                                params[6]=first flipper efficiency (f1)

                                params[7]=second flipper efficiency (f2)

                                Cell thickness is fixed at 10 cm

OPTIONAL VARIABLES:

                tol=the tolerance in the time for the measurement in seconds.

                                The correction requires a time of measurement for the 4 flipper states

                                This is taken as the average time of measurement.

                                There will be some variation on the calculated average,  normally +/- a second or two

                                If you have  problem, tol=2 should cover this and allow a proper correction to be made

                                If the data falls outside this tolerance, an error message will be sent

                                The default tolerance is 1e-7 seconds.

                e.g. w5=d17_he3corr(w4,p,tol=2)