I have just been onto a site and basically :
It is the presence of estrogen in the saliva which increases and fern like crystal patterns will become visible.
During infertile times of the month the result on the lens will show small spots and line like patterns - this is a non fertile restult.
As you approach ovulation incipient (sp?) ferning patterns will begin to appear - this is a transitional result.
At the onset of ovulation heavier ferning crystal patterns will appear in the sample, these patterns will indicate that ovulation is occuring or about to take place - this is a +ve or fertile result. The duratin of your most fertile time will last for 4 days pre-ovulation and 24hrs post-ovulation.
I have checked another site and it says that to get a correct reading you must take the saliva from under your tongue - is this where we are going wron?
I have done a post on o microscopes now, feel free to add anything to it.
Hope this is of some help, i am still researching so if i find out anything else i may feel of use i will pass it on to you