I have found a "Peak" optical tool.  Can you help identify it?  It grid lines and numbers and has a No.5 in it
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http://www.vicon.com/applications/posture.html
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possibly this site http://www.shepherdtool.com/antique_tools_store1.htm would have a picture of one, so that you'd at least know what it is, and from there you'd have more info to go on in looking up more info
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The number is a rating for the hardness of the lead/graphite.  Lower numbers are softer, higher numbers are harder.  The #2 is optimal for optical scan sheets and wear.
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Check out the following\nhttp://dyg2.tripod.com/id11.html
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Check at a site called neo (near earth objects)!!
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It's an optical instrument used to check for astigmatism.  Remember that thing at the eye doctor that shoots a puff of air into your eyeball?  That's it.\n\n*shiver*      those things
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It depends on what kind of mount you have, it seems you either have a German equitorial or an altazimuth mount.\nIf you are leveling & alighning on polaris and the blank end has a reference mark & 0 deg. north on the scale is in the center of two tripod legs the zero faces south.
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try this:\nhttp://www.hoyt.com/technical/bowmanuals.tpl
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you just need to clean it via cd lens cleaner available very cheap. and it will do the job. do not try open it coz there are very tiny parts in it . if u  need any further help contact me.
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If you live in AZ (possibly other states), The Magnifying Store. If not, try ebay.
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It's a FresnelC function.  Check out the link.
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I don't have a specific answer for you, but have you tried asking your local eye doctor or optician?  They have access to just about everything available and may be able to point you in the right direction.
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Take a professional to look at it
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www.tiff-counter.co.uk/tiff-tools/3.htm
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its a lens to a microscope
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While the answers above are correct, I will go a bit further.\n\nEstes rockets sells a nice tool for just this very job that will make your measurement fairly easy and accurate. It is called AltiTrak (TM).\n\nhttp://www.estesrockets.com/cgi-bin/products.cgi?view,296
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Try this link\nhttp://diode-lasers.globalspec.com/LearnMore/Optical_Components_Optics/Lasers/Diode_Lasers?se=gt