Re: [ATM] Accuracy of Ronchi grid

["Bob May" <rmay@nethere.com>]

For a Ronchi grid, you want to have the lines accurate.  If
you're going to be printing them out, you need to access the
native dot pitch of the printer and  print an equal number of
dots per line.  If you really want to, you can do lines of
different width from the spaces but I think that that really
won't work too well.  I do know that printing lines of different
widths on a grid won't work well.  I also know that most printers
can't control the edges of the line well enough to be able to
make fine grids as the width of a dot may vary by fifty percent.
In addition, the distance between dots will not be a straight
line but rather be some ragged dot edge.
As a little side note on Ronchi grids, it is best when you have
only one or two slots where the light comes out of the grid
rather than having many as the angles of the light coming back
will tend to mess things up in the viewed image.
Willmann-Bell sells some Ronchi grid transparencies for a very
cheap price that work well.  Also, Edmund Scientific does sell
some fairly inexpensive Ronchi gratings.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net


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