optics_table

  OPTICS_TABLE - Look up values from a table based on wavelength in nm

   [Y,UNITS_STR,DESC_STR] = OPTICS_TABLE(WAVELENGTHS, FILENAME)

   Reads in a table from the text file FILENAME.  If no path is provided,
   it is assume that FILENAME sits in the same directory as OPTICS_TABLE.  

   The table should have 2 or more columns.  The first column is assumed to
   have the wavelengths in units of nanometers, and columns 2-N have the
   units to be returned.

   Each of the N-1 dimensions is interpolated from the table using linear interpolation in INTERP1.
   Entries for wavelengths that are outside the bounds provided in the table are 0.

   If there are files FILENAME_units.txt and FILENAME_desc.txt in the same directory as
   FILENAME, then units and a description are read.
     UNITS_STR is a string that gives human-readable units.
     DESC_STR is a human-readable description string.
   If these files are not present, then UNITS_STR and DESC_STR are empty strings.


   Example:  Read in the intensity emissions from the NP510 projector:

      WAVES = [380:770]';
      [NP510,NP510_units,NP510_desc]=optics_table(WAVES,'NP510.txt');

      figure;
      plot(WAVES,NP510(:,1),'r');
      hold on;
      plot(WAVES,NP510(:,2),'g');
      plot(WAVES,NP510(:,3),'b');
      xlabel('Wavelength (nm)');
      ylabel('Intensity (abitrary units)');