raghavsol
8-Jul-2008, 02:55
Hi,
I would like to start this new thread as I did not find any satisfactory information related to this topic except something in Wikepedia. Hence I needed help of experts so I came here. My question is very basic: What are the uses of Ground Glass?
In wikepedia it says: Ground glass is a glass whose surface has been ground to produce a flat but rough (matte) finish. A sheet of ground glass is used for the manual focusing of both still and motion picture cameras.For further details see go to this link- http://en.wikipedia.org/wiki/Ground-glass. Here, I would like to know how ground glass helps in focusing?
Apart from that: recently I came to know an optical design which was using a ground glass plate just before the image plane (which is quadrant detector). This optical design is not an "Imaging Optics" rather I can call it "Collecting optics or Tracking Optics" as the spot made on the image plane was huge in size (5mm). It is basically collecting the light from an infinte distance object and focusing it on the quadrant detector in an 5mm spot. The position of the spot on the detector tells about the position of the object, that why i called it tracking optics. Any way, here I would like to know why the ground glass plate has been used before the detector/image plane? Obviously in this case it is not for the purpose of focusing...then for what?....may be to achieve a uniform energy distribution (illumination) in the spot.
Thanks in advance
raghav
I would like to start this new thread as I did not find any satisfactory information related to this topic except something in Wikepedia. Hence I needed help of experts so I came here. My question is very basic: What are the uses of Ground Glass?
In wikepedia it says: Ground glass is a glass whose surface has been ground to produce a flat but rough (matte) finish. A sheet of ground glass is used for the manual focusing of both still and motion picture cameras.For further details see go to this link- http://en.wikipedia.org/wiki/Ground-glass. Here, I would like to know how ground glass helps in focusing?
Apart from that: recently I came to know an optical design which was using a ground glass plate just before the image plane (which is quadrant detector). This optical design is not an "Imaging Optics" rather I can call it "Collecting optics or Tracking Optics" as the spot made on the image plane was huge in size (5mm). It is basically collecting the light from an infinte distance object and focusing it on the quadrant detector in an 5mm spot. The position of the spot on the detector tells about the position of the object, that why i called it tracking optics. Any way, here I would like to know why the ground glass plate has been used before the detector/image plane? Obviously in this case it is not for the purpose of focusing...then for what?....may be to achieve a uniform energy distribution (illumination) in the spot.
Thanks in advance
raghav