The down-loadable calibration spreadsheet is built using Microsoft Excel.
To use the spreadsheet, download it from here: Graticule calibration The spreadsheet provides four tables, one for each objective lens.
Calibrate the microscope in the usual manner, using the eyepiece graticule and stage micrometer. The readings obtained from the two scales are then entered into the appropriate blue cells on the spreadsheet for the objective lens being calibrated.
Stage micrometers are manufactured with different sized scales. Some stage micrometers have more than one size of scale included on the same slide. The size of the scale used for the calibration (usually printed on the micrometer) should be entered into the green cell.
Repeat the above process for each objective lens. The spreadsheet allows different scales to be used for each objective.
Once calibration is complete, the spreadsheet can be printed on a single A4 sheet. I find it useful to laminate the printed sheet and cut it into two A5 sized pieces which can be kept in the microscope box.