3. Basic Imaging and Photography

Obtaining an Image

The easiest way to get an image is to use the instant picture function. Simply press the INST button on the control panel and wait a few seconds. If you don't get an image, press the button again. The instant picture uses secondary electron mode ( SEI) by default. To adjust the contrast and brightness contrast use the two knobs on the far right of the control panel. To use backscatter mode press the VIEW button on the upper right of the control panel until the word COMP is displayed on the lower left corner of the CRT. Brightness and contrast of backscattered images can be adjusted by using the knobs under the CRTs. Usually the fine contrast and coarse brightness are sufficient for most samples. If the image is still to bright, turn off the optical microscope illuminator by pressing the OMTV button on the top row of the control panel (next to the INST button).

The MAGNIFICATION knob is used to adjust the magnification (d'uh). The minimum magnification is 40 x and the maximum is 300,000 x. For most samples the practical limit of magnification is ~ 5000 x. The FOCUS knob adjusts the focus. For magnifications under 1000 x the coarse setting will suffice, but for magnifications greater than 1000 x, the fine focus must be used. First get the best focus possible using the coarse setting (FINE button dark), the press the FINE button and use the focus knob to adjust the focus.

The MODE button cycles among imaging modes. The most useful is the crosshair mode in which a crosshair on the left CRT indicates the beam position (more or less, if you need exact positioning see lab staff). Simply press the button until the crosshair appears. To get rid of the crosshair, press the PIC button.

Photography

Thermal Prints. This type of image is best suited for locating analysis areas. The resolution is lower than that of a photograph, and image quality degrades through time. Press the SLOW button, adjust the brightness and contrast to your liking, and press the PRINT button. The crosshair will not be on the print.  If necessary you can adjust the brightness and contrast on the front panel of the video printer.

Polaroid Photographs. Polaroid prints are suitable for publication and long term storage.

1. Select which type of film you want to use:

• Polaroid 55 - This film should be used when you require a print and a negative. It must be coated to prevent image degradation, and the negatives must be washed and dried after exposing.
• Polaplan 400 - The film does not require coating, but does not produce negatives
• Polaplan 100 - Coaterless, and supplied in an eight exposure cartridge, making it easier to use.

1. Set the proper f - stop.

Film	f - stop
Polaroid 55	5.6
Polaplan 100	8
Polaplan 400	16

1. Make sure the proper holder is in place on the camera. Polaroid 55 and Polaplan 400 use the same holder (545I film back) while the Polaplan 100 has its own back.
2. Load the film according to the instructions on the holder or package. Make sure you remove the light shield from the Polaplan 100 holder.
3. Obtain an image and adjust the brightness and contrast to an appropriate level. Push the WFM button. You should get a display like this:

1. The dark line indicates the brightness and contrast of the line being scanned by the beam. Anything above the fifth line will be saturated (white) and anything below the second line will be black. Using the brightness and contrast knobs, adjust the image so that the areas of interest have a signal between the second and fifth bars. When the brightness and contrast are well adjusted, press the WFM button.
2. Check that the film is loaded properly, and press the RIGHT button.
3. When the exposure is finished, process the film according to the instructions on the film package.
4. The instructions for Polaroid 55 indicate that the negatives should be fixed in sodium sulphite, but experience has shown that this is not necessary.

Digital Images. Digital images of SEM images can also be acquired and downloaded to other computers. See Section 7.