The most complex aperture that we shined our laser through was a grating surface made out of squares arranged offset from each other like bricks in a wall with sides measuring 0.62 mm.  In order to block all of the arms in our Fraunhoffer plane we turned the grating forty-five degrees.  That is why the image in GR#1 doesn't appear to have vertical and horizontal wires.

Image GR#1


Image GR#2                                                                        Image GR#3

The plot profile of GR#1 doesn't show much because it depends on the section of light you are measuring.  What you can see in GR#2 is the very square like nature of the image for one of the squares.  It appears very similar to the plot profile in SS#2, as you would expect.  The FFT created by ImageJ (see Single Slit for reference of ImageJ), shows that our Fraunhofer has four arms of light in vertical and horizontal directions.

Image GR#4

Here is our Fraunhofer plane picture which looks very similar to GR#3 and the expected theoretical results.  Notice the vertical and horizontal arms of light at the Fraunhofer plane.

Grating with the Center Blocked at the Fraunhofer Plane

Image GR#5


Image GR#6                                                                            GR#7

In order to block the center information we had to tilt the grating so that the arms on the Fraunhofer plane were in a diagonal cross.  We then used a thin strip to block the center information.  GR#7 still shows the vertical and horizontal arms, but the center is much more dim than before.  This is also true in GR#6.  You can see how the missing center information affects the resultant image.  GR#6 looks similar to DS#2 but because the image is two dimensional then you can only measure two sides at a time.

Grating with Horizontal Arms Blocked at the Fraunhofer Plane

Image GR#8


Image GR#9                                                                                    Image GR#10

For this alteration we turned the grating back to where the wires were vertical and horizontal.  We then blocked the horizontal arms.  As mentioned in the Pinhole discussion by blocking the horizontal information you are affecting the vertical components of the image.  In this case the vertical components are the vertical wires in the grating.  They become smudged out and the grating appears as horizontal stripes.  The FFT in GR#10 shows the horizontal arms blocked in the Fraunhofer plane, but the vertical components remain.

Grating with Vertical Arms Blocked in the Fraunhofer Plane

Image GR#11


Image GR#12                                                                        Image GR#13

This is the same case as mentioned above except that we blocked the vertical components in the Fraunhofer plane.   You can see what the resultant plane looked like in GR#13, where only the horizontal information got through.  GR#11 is similar to GR#8 except the stripes are vertical instead of horizontal.

Grating with All Sides Blocked at the Fraunhofer Plane

Image GR#14


Image GR#15                                                                                    Image GR#16

In this case we again rotated the grating to allow use to block all four arms at the same time.  You can see in GR#16 what our Fraunhofer plane looked like.  The major comparison is between GR#2 and GR#15.  In the former the edges of the separate squares were sharp and distinct.  Here they are blurred and mixed together.  The image in GR#14 almost looks as if it were a large dot, due to the absense of vertical and horizontal lines.  We were unable to fully block all of the arms and still leave the center untouched and that is why you can still see where the wires are supposed to be (as in GR#1).