The analysis done only for the 2nd hydrogel (the one which was measured after the first one broke). The point with force 0N is omitted, since the actual 0N should be the point of start of seeing the force change. The birefringence was measured at 2 points

Fig1:Birefringence vs Force of point 1

Fig 2: Diattenuation vs Force  of point 1

Fig 3:Birefringence vs Force of point 2

Fig 4: Diattenuation vs Force  of point 2

The number plotted is the median obtained from the data at each force value.

Update 1: I changed the plot becauase I had previously overconverted rad to rad, assuming it was degrees.

Update 2: Added Error bar to fitted data