Comments

Author Comment Last activity Moderation
stoft " Yes, once the camera exposure is under control (and fixed value) then the linearity can be measured -- IF you have controlled means of adjusting t..." | Read more » over 1 year ago
stoft "From that link, I found a 'settings' file here: https://gitlab.com/bath_open_instrumentation_group/picamera_cra_compensation/blob/fdb98308149e686a..." | Read more » over 1 year ago
stoft " Right, the camera's do automate as much as possible, which works against the needs of spectrometers. If the AGC cannot be shut off, then it become..." | Read more » over 1 year ago
stoft " Good work and observations. Yes, I think HDR techniques can help extract additional dynamic range from these simple cameras. In reading through yo..." | Read more » over 1 year ago
stoft "Progress. Right, the likely alignment issue is grating to camera which is notoriously hard to do without having much mechanical control beyond tape..." | Read more » over 1 year ago
stoft " Right ... the optical distances are very small ;-) which is why mechanical rigidity is so important ... (think of the 'optical bench' which is mad..." | Read more » over 1 year ago
stoft " A while back I experimented with some 35mm 'slide-mount' holographic grating film (I believe it was 1200) vs the DVD (which is 740). The diffracti..." | Read more » over 1 year ago
stoft " Looks like a nice clean construction. The glue should help mechanical stability. I did notice the swap from DVD to what appears to be a film holog..." | Read more » over 1 year ago
stoft "Observation of some basic system parameters will help define the limits. 1) A single stable source (Solux and CFL) plus the PLab-class spectromete..." | Read more » over 1 year ago
stoft "With non steady-state sources, measurement error results from asynchronous data sampling. The 'fix' is either long integration time (assuming the s..." | Read more » over 1 year ago
stoft "Ok, the project concepts are taking shape which always prompts more thoughts. 1) By 2D mapping the light spectrum and relative intensity, you will..." | Read more » over 1 year ago
stoft "A few more thoughts... On absolute 'average' intensity - You could use a Solux source (at fixed distance and known orientation) as a transfer stan..." | Read more » over 1 year ago
stoft " Ah, I've seen the curve on the web but it was not attributed to the specific sensor. It's helpful to now have that information. It looks like the ..." | Read more » over 1 year ago
stoft " Jasmin, glad my previous notes were helpful. I did find one plot for the IMX219, but it was not from Sony and only covered to 700nm. The IMX265 c..." | Read more » over 1 year ago
stoft "Interesting project. I did not readily find spectral response curves from Sony on the IMX219 sensor though others in that family of devices appear..." | Read more » over 1 year ago
stoft " "The diffraction grating is not perfectly flat" would suggest you are using one of the readily available 35-mm laser holographic film gratings -- ..." | Read more » almost 2 years ago
stoft "The spectrum of most common halogen lamps is neither smooth nor flat and generally do not have published spectral data. You might consider the Solu..." | Read more » over 2 years ago
stoft "On using only raw data (eg. using the CSV 'avg' data): Yes, you could implement a simple linear mapping of pixel:nm with the data from a CFL spectr..." | Read more » over 2 years ago
stoft "I'll admit I'm not following your comparisons -- but a few thoughts anyway in case they will help. The second plot at least shows a CFL spectra; al..." | Read more » over 2 years ago
stoft "Also, 5 - Use 'absolute' measurement values when mathematically comparing amplitude of spectra -- where the only change between plots is the experi..." | Read more » over 2 years ago
stoft "Ok, visualizing the spectra helps. 1 - The calibration (wavelength calibration using a CFL source) does not require an amplitude change (though SWB..." | Read more » over 2 years ago
stoft "Could not find the actual spectra from the info provided. How about an explicit link or post the graphic? " | Read more » over 2 years ago
stoft "True, the physical layer aspect is one issue. The other fundamental issue is the 'line spacing' of the recording 'tracks' which form the diffractio..." | Read more » over 2 years ago
stoft "Pollution comes in many forms and many of the worst contaminants will not alter the appearance so visible light spectrometers (i.e. PLab types) wil..." | Read more » over 2 years ago