TOMOGRAPHY SOFTWARE
There are four versions of the
tomography software on the disk. Two of
the versions (HardScanXL and SoftScanXL) require that the user have Microsoft's
Excel spreadsheet program on the computer.
The other versions (HardScan and SoftScan) do not require Excel. Two of the versions (SoftScan and
SoftScanXL) do not require any other materials. The programs simply demonstrate the manner in which a tomographic
scan proceeds. Two of the versions
(HardScan and HardScanXL) require the user to create a text file (.txt) for
input. The numbers for the text file
are generated either by 1) a scanning procedure using a laser and
photoresistor; or 2) a scanning procedure using transparencies.
The file vbrun300.dll used to link the
Visual Basic programs is on the disk.
Also on the disk are two text files (test1.txt and test2.txt) which
represent sample data to be used with the programs HardScan and HardScanXL
SoftScan and SoftScanXL
1. Double click the appropriate icon to begin
the program.
2. Moving the mouse over the grid, click
anywhere you wish to place an object.
That square of the grid will be blackened.
3. When you have placed as many objects in
the grid as you would like, click Scan Grid.
4. The software will step across the grid
for a number of angles, registering the absorption along each line. The absorptions are stored internally in an
array.
5. When the scan is completed, click
Recreate Grid. The software will draw
an image of those locations where an object was placed.
6. When the grid is recreated, you can also
view a three dimensional version of the results. Click on Draw Result.
7. If you are using SoftScan, you can rotate
the image with the slider bars on the side and bottom of the picture.
8. If you are using SoftScanXL, you will
have to select the array which appears in the application by highlighting it.
9. Then using the chart toolbar, you can
create a three dimensional plot of the data.
10. Using the Excel chart options, you can
change various features of the way in which the three dimensional plot is
displayed.
HardScan and HardScanXL
1. Double click the appropriate icon to
begin the program.
2. Click the Scan Grid button.
3. The program will prompt you for the name
of the text file from which the data is to be read. This text file must be in the same directory as that from which
either HardScan or HardScanXL is running.
Otherwise the program will not be able to find the file.
4. Enter the name of the file. Do not add the
extension .txt. The program will do
that automatically.
5. Once the program has read the text file,
it will notify you.
6. Click Recreate Grid. The software will draw an image of those
locations where an object was placed.
7. When the grid is recreated, you can also
view a three dimensional version of the results. Click on Draw Result.
8. If you are using SoftScan, you can rotate
the image with the slider bars on the side and bottom of the picture.
9. If you are using SoftScanXL, you will have
to select the array which appears in the application by highlighting it.
10. Then using the chart toolbar, you can
create a three dimensional plot of the data.
11. Using the Excel chart options, you can
change various features of the way in which the three dimensional plot is
displayed.
Scan Simulation with Laser and
Photoresistor.
1. On a sheet of paper, create an array with
18 rows and 21 columns. The rows
correspond to scan angles. The columns correspond to scan lines. This array will hold the recorded
absorptions.
2. The rows should be marked beginning from
5 degrees and going up to 175 degrees in 10 degree increments.
3. The columns should be numbered from 0 to
20.
4. Place pegs which represent the objects to
be scanned anywhere in the wooden grid.
5. Place the wooden grid so that its center
line (Line 10) is aligned with the 5 degree line.
6. Turn on the power to the laser and the
photoresistor.
7. Place the laser-photoresistor pair along
Line 0.
8. Record the transmitted light in the array
for Row 5 degrees, Line 0 as measured by the ammeter connected to the
photoresistor.
9. Move the laser-photoresistor pair to Line
1.
10. Record the transmitted light in the
array for Row 15 degrees, Line 1 as measured by the ammeter connected to the
photoresistor.
11. Continue this procedure until all 21
lines have been scanned at 5 degrees.
12. Rotate the wooden grid by 10 degrees so
that its center line aligns with 15 degrees.
13. Repeat the procedure of measuring the
transmitted light as recorded by the ammeter for each of the 21 lines.
14. Continue rotating the grid and scanning
the pegs until all lines have been covered at each of the angles.
15. Since the array holds transmitted
values, it is necessary to convert these to absorption values. Simply find the largest transmitted value in
the array. Call it tmax.
16. To create the absorption array, subtract
each value in the transmission array from tmax. These values represent the amount of light absorbed.
17. The data must now be entered into a text
file.
18. The numbers can simply be entered
sequentially with a carriage return into any text editor. The program WordPad works fine. The numbers should be entered reading across
each row, before proceeding to the next.
19. Alternately if one has a spreadsheet
program available, one can enter the numbers into the rows and columns of the
spreadsheet. The data must be saved as
a text file.
20. The file can be given any name, but the
user must remember to place it in the same directory as either HardScan or
HardScanXL.
21. Running the software should recreate the
pattern of pegs in the grid.
Scan Simulation Using Transparencies.
1. On a sheet of paper, create an array with
18 rows and 21 columns. The rows
correspond to scan angles. The columns correspond to scan lines. This array will hold the recorded
absorptions.
2. The rows should be marked beginning from
5 degrees and going up to 175 degrees in 10 degree increments.
3. The columns should be numbered from 0 to
20.
4.On a grid which is not more than 8 cm by 8
cm, blacken one or more locations which represent the location of an
object. A sheet of quadrille paper cut
to the appropriate size is easy to use.
5. Place the first transparency with angles
marked from 5 degrees to 175 degrees on top of the grid. The grid should be centered at the middle of
the first transparency. The grid should
be attached to this transparency either with scotch tape or with paper clips at
the edges of the two sheets.
6. Lay the first transparency with grid
attached flat on the table.
7. Place the second transparency with lines
marked from 0 through 21 on top of the these two sheets.
8. Align the center line of the second
transparency (number 10) with the 5 degree line of the first transparency.
9. Look along Line 0. The absorption along Line 0 is determined
simply by inspecting how many times Line 0 crosses one of the objects in the
grid which you created. For example, if
Line 0 intesects none of the objects which are drawn on the grid, enter a zero
into the array for Row 5 degrees, Line 0.
If Line 0 intersects one object in the grid, enter a one into the array
for Row 5 degrees, Line 0. If Line 0 intersects two objects in the
grid, enter a two into the array for
Row 5 degrees, Line 0, and so on.
10. Look along Line 1. The absorption for Line 1 and each of the
subsequent rows is found by the same procedure as above. Simply inspect how many times Line 1 crosses
the objects in the grid. Record that
number in Row 5 degrees, Line 1.
11. Continue inspecting each of the
lines. For each line, record in the
array the number of intersections with the objects in the grid.
12. Once you have completed all 21 lines for
the 5 degree angle, you rotate the second transparency with the lines by 10
degrees until Line 10 is aligned with 10 degree line of the first transparency.
13. You repeat the procedure of inspecting
each line and recording in Row 15 degrees and the appropriate column the number
of intersections for each of the 21 lines.
14. The procedure is repeated for each of
the angles until you have reached the 175 degree angle. The absorption array will now be filled.
15. The data must now be entered into a text
file.
16. The numbers can simply be entered
sequentially with a carriage return into any text editor. The program WordPad works fine. The numbers should be entered reading across
each row, before proceeding to the next.
17. Alternately if one has a spreadsheet
program available, one can enter the numbers into the rows and columns of the
spreadsheet. The data must be saved as
a text file.
18. The file can be given any name, but the
user must remember to place it in the same directory as either HardScan or
HardScanXL.
19. Running the software should recreate the
gird underneath the transparency.