I’m quoting an emailed question by @kumarsumanth.m for the forum:
The OD calibration curve shows high sensitivity at OD of 2 to 4 which is quite high for our applications, ideally we work under OD 1. I was wondering if you regulate the LED intensity based on the working OD range.
Here are the fit values:
a : 35,286.23
b : 63,962.66
c : 2.822
d : –0.383
Responding to the question:
Sumanth is talking about the rate of change of ADC values as a function of OD, which should not matter too much after calibration. As you see, the min-eVOLVER should be able to distinguish between values up to OD ~5, when in OD 90 mode. It will simply get more noisy at higher ODs. However, it should actually be best in the 0.2 - 1.5 range due to less noise.
Depending on how accurate you want your ODs to be in the 0 - 0.2 range, you may want to switch it to OD 135 mode. Before doing so, double check that OD 90 won’t work for you by doing a calibration in the OD range that you want and excluding higher OD standards.
See here if you want to switch to OD 135 and check the figure above for how to make the swap. I’m not 100% sure you have photodiodes in the OD 135 positions, so double check that as well. Fair warning, OD 135 is currently less characterized than OD 90 in the min-eVOLVER.
Thank you, Nate. My working OD range is between 0 to 1. Are you saying that OD90 which generated the current calibration curve is good enough for it? otherwise I’ll try OD135.
Yeah try OD90 with standards from 0 to 1.
Sure, I’ll try that.
