APS File Read Settings

If you have turned on APS data file support, there is an entry "APS File Read Settings" in the "Extra" menu. It opens a small popup (see Fig. 5.20) which lets you set some parameters which are applied when opening an APS data file. Currently, only 2-ID-E files (*.mda and silicon detector data files (*.sdt) are supported in this popup window (2-ID-B files can still be read with fixed settings). The 2-ID-E section has the following entries:

Figure 5.20: The window which lets you set some file reading parameters for APS data files

Number of detector segments.

You should know in advance how many detector segments were recorded in the file you are opening (meaning, what kind of chip had been installed) because the data file holds no information about this. As long as you look at single segments only, having the wrong number won't be a huge problem (you'll either miss data or have a meaningless signal, which should be easy to see). Knowing the correct number (chip layout) is important, however, when displaying combinations of segments like differential phase contrast.

Read ADC channels.

If this box is checked, the program will attempt to read the ADC channels from the file besides the regular V2F channels (as default, we record the silicon detector signals through a voltage-to-frequency converter). If the ADC channels are not present, an informational (non-fatal) error message is printed to the IDL output log. Note that all predefined combinations (see Chap. 9) are made from the V2F data. If you want to make combinations from ADC data, you'll have to use custom display combinations (see Sec. 9.2.5).

Columns (l/r) to skip.

Here, you can enter a number of columns which should be skipped at the left and the right of the image when the file is read. Fly scans from 2-ID-E will always have very large (and meaningless) numbers in the first column which screws up the contrast when you do autoscaling ("Full Scale"). By skipping those columns, autoscaling (when the file is opened) will work better. Of course if you don't skip those columns, you can still adjust the contrast by playing with the min/max values or the histogram (see Sec. 5.5).

Below is a section which applies to both *.mda and *.sdt files:

Use ADC for disp. combinations:

At 2-ID-E, as of March 2006, we are reading the voltages from the silicon detector by default with a V2F (voltage to frequency converter) coupled to a scaler. In some scans, we have also read them additionally with the ADC, even though that hasn't worked very reliably so far. In cases where both have been recorded, you can use this checkbox to choose whether the V2F or the ADC signals should be used to calculate the predefined display combinations.