Wavelength calibration for hyperspectral microscopy
Wavelength calibration of hyperspectral microscopy systems should have taken place in the factory. However, after transportation, installation and time, wavelength accuracy can change.
From a day to day standpoint there will rarely be noticeable differences, however when data is compared with that acquired in other labs, on the same or different instruments, there may be significant discrepancies.
For those researchers building their own systems the question of wavelength accuracy has to be settled before work can start.
The MIDL lamp provides an eye-safe solution that comes in two formats; pencil and flat. Use the pencil lamp for upright and the flat version for inverted microscopes. The pencil lamp is shown in Figure 1.
The MIDL, wavelength calibration Multi-Ion Discharge, Lamp
The MIDL emits Hg+, Ar+ and inorganic fluorescence emission lines to provide an eye-safe absolute rather than a relative, wavelength line spectrum.
Bright emission lines occur 365, 405, 436, 546, 611, 695, 811 and 912-nm- among others! This enables effective wavelength accuracy validation over the same wavelength range. See Figure 2.
Use the MIDL wavelength calibration lamp with:
Any hyperspectral imaging microscope system.
Spectrometers and imaging spectrometers
Microscope mounted multispectral imaging systems based on AOTF, LCTF devices and interferometers
Note: Ar+ emission wavelengths fade rapidly above 650 nm. Requires a fast wavelength scan or a spectrograph that will acquire all wavelengths simultaneously