Slit Image Test

Slit Image Test
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Computations

In the Spreadsheet (Spreadsheet.xls):
	(The examples are that of a 22" f/4.75 mirror.)
	Input:
		CCD:
			G2 = The E-300 CCD cell size in microns (=0.00003937 inches)[2]
			F2 = The E-300 Lens mount to CCD spacing [3]
			E2 = Slit to lens mount distance - Figure 13 and 14
			J2 = The E-300 CCD glass thickness [2]
			K2 = The E-300 CCD glass index of refraction [2]
		FILM:
			D2 = Slit to image plane (usually zero).
			H2 = Scanned DPI.
		A2 = Mirror optical diameter.
		B2 = ROC initially to +/- 1/8". Then refined from Sixtests results.
		B4:B12 = Zone h's (linked to 'router mask'!D12:D18)
			Accuracy of hole positions is refined by flatbed scanning the mask (direction of scan is most accurate), and then processed in 'router mask' B23:C30 & B33:C40. The hole positions are then adjusted, using Solver to compensate for parallax i.e., rays are not at right angels to the mask.
			Solve for the h's - Cells D12:D18 of 'router mask' 12.
				Tools->Solver can only solve for one at a time:
					First: F12 value of 0, By Changing D12
					..........................................................
					Last: F18 value of 0, By Changing D18
		Y_pix's As measured in Photoshop.
			D5:D11 left side.
			E5:E11 right side
			D4 = Center.
				Used to check if the mask was properly centered. If any of the pixel differences, F5:F11 are greater than +/- 9, the mask needs to be re-centered and the test done again.
	Solve for l (C14) - Figure 11 and 12
		Tools->Solver (computations are relative to the edge zone)
			Target Cell = D14, value of 0
			By Changing Cell C14
	Solve for the Foucault's - Cells F18:F23.
		Tools->Solver can only solve for one at a time:
			First: E18 value of 0, By Changing F18
			..........................................................
			Last: E23 value of 0, By Changing F23
		Note:	Because the calculations are relative to the edge, the outer zones s' (F24) is h²/(2R) (using the outer zones h).


Figure 8 Spreadsheet

Sixtests.exe http://home.earthlink.net/~burrjaw/atm/odyframe.htm
		Using Notepad type (paste) the following info from the spreadsheet to create file Sixtests_input.txt - Figure 9

Figure 9 Sixtests_input.txt

Note: A program to replace the spreadsheet, and generate Sixtests_input.txt file is underdevelopment.

In Sixtests.exe
	*File->Open setup*
		Navigate to file *Sixtest_input.txt*
		Click Open
	Click *Surface* getting - Figure 10:

Figure 10 Sixtests output

	Note: The Glass Surface Plot is invaluable when figuring. With the exception of interferometry, the rest of the tests measure the derivatives of the glass surface. Conjuring the surface from the derivatives e.g., Foucault is not intuitively obvious and is best left to programs like Sixtests.

Equations:

Figure 11 Fixed Source-LWT

		Y_diff is the pixel distance between slit pairs i.e., Y_pix right D5:D11 - Y_pix left E5:E11 - Figure 8.
		Y_i = (Y_diff/pixels per inch)/2 i.e., a negative value.

Foucault:
	Given the Y_i's (G5:G10), the spreadsheet Solver tool is used to work the equation Y_i=w(Y_n-h)+h, backwards to obtaining the s' (F18:F23) - Figure 8 and 11.
	Note: Because the calculations are relative to the edge, the outer zones s' (F24) is h²/(2R).
		Y_l = Y_i when q = l (Figure 11).
		Y_l is approximately 2h(s-l)/R

Figure 12 Using Solver

Figure 13 Camera Spacer

Figure 14 Spacer Parts

References

[1]	Karine and Jean-MarcLecleire, A Manual for Amateur Telescope Making. http://www.willbell.com/tm/atmmanual/index.htm
[2]	Kodak Spec KAF-8300CE
[3]	E-300 Lens mount to CCD spacing http://www.markerink.org/WJM/HTML/mounts.htm
[4]	Mirror Math Jim Burrows http://home.earthlink.net/~burrjaw/atm/atm_math.lwp/atm_math.htm
[5]	Foucault Test by Leon Foucault 1858 http://bobmay.astronomy.net/foucault/leontop.htm
[6]	Lateral Wire Test (LWT) http://hometown.aol.com/julesfran/index.html

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