sinusoidal grating 28 the distance from the valley grating 30 to a peak 32 of the grating surface is defined in this example as a value x dotted line 34 illustrates a situation where signal generator controller 22 has increased the voltage supplied to the patterned electrodes of electrode configuration 20 in this situation the valley 36 to peak 38 difference is x a controller 22 may also decrease the voltage applied to electrodes of electrode configuration 20 in this situation the valley to peak difference is decreased 0038 fig1 a and 1c illustrate that deformable layer 16 will form into a surface relief pattern dependent upon the patterned electrode configuration 20 and as a varying signal is applied to the electrode configuration 20 the height of the peaks formed in the deformable layer will vary when no variable voltage is supplied from controller 22 reflective surface 18 acts as a mirror and displacement of an impinging light is at substantially zero displacement as the voltage to electrode configuration 20 is increased by the controller 22 displacement or diffraction of the light is increased when the surface reliefpattern is displaced by a quarter wavelength the light reflected from the two surfaces is 180 u00b0 out of phase and destructive interference occurs at this point the light is totally diffracted and none is reflected therefore by the described design analog control of the light e g from a zero state.