The present invention relates to optical methods of observing, distinguishing andor visualizing grown or nascent crystals of biological material within a biological sample. A substrate has a display, a digital to analog converter, and a lookup table formed thereon. The active layer is formed of an organic semiconductor in a contact region between the source and the drain. When a level of the light received by the first optical amplifier changes by \u0394, the controller controls a level of the light received by the second optical amplifier to change by approximately \u2212\u0394. A second interlayer insulating layer having a relatively low dielectric constant is interposed between the conductive layer and the interconnections, which reduces the parasitic capacitance therebetween.