If you type these commands:
f = midigui() tag = 'hd107446' oir1dcompressdata,f,getenv('prismhmask'),tag d = getoirdata(tag+'.compressed.fits') plot,d[500:900].data1[100]
You will get this:
You can subtract the data in the two interferometric channels:
plot,d[500:900].data1[100] - d[500:900].data2[100]
The result looks like this: