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Optics / Re: chromatic aberration at different wavelengths for two-color simultaneous imaging
« on: May 02, 2017, 04:13:01 PM »
Disclaimer: I am an engineer working on microscope systems at Doric Lenses.
In our case, we decided to correct the chromatic aberration by using 2 CMOS sensors, because we believe that this is the most robust solution that allows for two-color simultaneous imaging. As mentioned above, the trade-off is the increase of the weight on the animal. The weight of Doric’s two-color systems are 3.5 g for the model L (with GRIN), compared with 2.2 g for Doric’s single color microscopes. The 2-color model L was tested in one of our collaborators labs for more than 2 days straight. With a trained mouse, he told us that the mouse was moving fairly unimpaired in its cage even after wearing the microscope for 2-3 days.
You are right though that even when using 2 CMOS, one optical path adjustment will be valid for one specific GRIN lens length (actually the number of pitches). That is because the chromatic focal shift is proportional to the number of pitches of the GRIN lens. Two lenses having the same number of pitches will introduce about the same level of chromatic aberration, even if they are coming from different lot of the same glass with slightly different lengths.
Using a GRIN lens with a microscope body optimized for a different number of pitches will introduce a substantial chromatic shift. That is why we ultimately developed different microscope bodies, optimized for the different GRIN lengths.
In our case, we decided to correct the chromatic aberration by using 2 CMOS sensors, because we believe that this is the most robust solution that allows for two-color simultaneous imaging. As mentioned above, the trade-off is the increase of the weight on the animal. The weight of Doric’s two-color systems are 3.5 g for the model L (with GRIN), compared with 2.2 g for Doric’s single color microscopes. The 2-color model L was tested in one of our collaborators labs for more than 2 days straight. With a trained mouse, he told us that the mouse was moving fairly unimpaired in its cage even after wearing the microscope for 2-3 days.
You are right though that even when using 2 CMOS, one optical path adjustment will be valid for one specific GRIN lens length (actually the number of pitches). That is because the chromatic focal shift is proportional to the number of pitches of the GRIN lens. Two lenses having the same number of pitches will introduce about the same level of chromatic aberration, even if they are coming from different lot of the same glass with slightly different lengths.
Using a GRIN lens with a microscope body optimized for a different number of pitches will introduce a substantial chromatic shift. That is why we ultimately developed different microscope bodies, optimized for the different GRIN lengths.