it's the STAGE
The light diaphragm
it controls the amount of light let into the slide.
The iris opens and closes its aperture or "hole" to let in the correct amount of light. Mechanical irises were used for a long, long time in pre-digital film camers.
There are many materials that light can not travel through which are called opaque objects.
The iris is the coloured membrane in the eye that controls the amount of light entering the eye by expanding and contracting. The pupil is a hole in the centre of the iris. By expanding, more light will enter the pupil and by contracting less light will enter the pupil.http://en.wikipedia.org/wiki/Iris_(anatomy)
The stage
i think its i a microscope love.
the glory hole, duhhhComment: It's not the 'glory hole' so 'duhhh' to you too!
The stage in a microscope holds the specimen, usually on a slide, and has an opening in it to permit light to come up through the stage and through the specimen and further on up to the optics.
A Light stereoscope microscope; this type of microscope is used to see three dimensional views of objects too thick to let light pass through.
A Light stereoscope microscope; this type of microscope is used to see three dimensional views of objects too thick to let light pass through.
A Light stereoscope microscope; this type of microscope is used to see three dimensional views of objects too thick to let light pass through.
Any organic substance or sample thin enough to let light through.
Any organic substance or sample thin enough to let light through.
Why can't light pass through what? To first contributer, don't say that. Say light cannot pass through solid, opaque objects at times.
The light diaphragm
it controls the amount of light let into the slide.