Now...what if the mask is a black spot at the center with the rest
    being clear?  It is a differential amplifier.  Do you know why?
    The development package provides much more information. So you can learn.

      Thus, the production of all sorts of useful photonic products may be 
    created by using the development tools provided in our development 
    package.  It remains only for the clever innovator, YOU, to organize 
    the components into useful products. 

      That is precisely why the development programs have been written as 
    a general purpose set...separating operations into individual programs 
    that can be rearranged in any order...for the production of any set 
    of holograms and masks...to be combined together into any type of  
    photonic transistor product. 

      Can you learn to do it?  YOU MOST CERTAINLY CAN!  With aid of the 
    development package tools, the publications we provide, and the many 
    new products that other developers add to the list of available tools, 
    you can become a precision workman in the brand new field of photonic 
    transistor engineering and design.  It's a new field, so everyone starts 
    out on an equal footing.