<aside> 💡 Current Tradebooks of Slit Width Analysis:

Plots are found within tradebook Architect

</aside>

Description

Tasks

• [x] Peruse through the ‣ to determine what parameters are impacted by slit width (SNR, spectral resolution, maybe FOV)
• [x] Read on literature concering this tradeoff in hyperspectral systems
• [x] Architect figure out gaps in implementations
• [ ] Create tradebook for slit width v/s SNR & spectral resolution
• [ ] If optimal slit width (where both requirements are met) is not obvious, consider other requirements that impact SNR & spectral resolution
• [ ] Document trade and verdict in (Slit Width)

Artifacts

Notes

• Parameters impacted by slit width: [ ]

  • Signal-to-Noise > 30
    • Signal $s_{target}$ [electron] (signal from the target) ← $\epsilon$ [%] (fraction of light blocked by the slit)
      • Signal Sensor, Signal Optical
    • Noise ← $s_{target}(\lambda)$ [electron2] (signal level)
      • Shot Noise
  • Absolute Spatial Resolution ≤ 90m
  • Absolute Spectral Resolution ≤ 10nm
    • Optically-Limited Spectral Resolution,Resolvance
    • Sensor-Limited Spectral Resolution ← $n_{\text{bin}_{y}}$: Number of pixel binning operations in the along-track direction
  • Field of View ← $\vec{s} = \begin{bmatrix} s_x \\ s_y \end{bmatrix}$ [m] (lit dimensions in the across and along track directions)
  • Diffraction Efficiency
  • VPH Grism Diffraction Angle [empty] & Diffraction Angle & Diffraction Angle
  • Miscellaneous:
    • Undeviated Wavelength
    • Hyperspectral Datacube Size
    • Illuminated Slits
    • integration time (??)

• Slit width determines an optical system’s

  • optical resolution,
  • diffraction grating dispersion, and
  • number of detector pixels
  • “total jitter should not be larger than slit width” ??

• TRADEOFF:

  • Larger slit width increases throughput but decreases optical resolution
    • increases optical power available for analysis (thus reducing the time needed to acquire an accurate reading)
    • BUT increases minimum difference in wavelength that can be resolved
  • Smaller slitwidth increases optical resolution but decreases throughput
  • Must weigh both consequences

• Slits are available in a wide range of widths, ranging from 5 µm up to a maximum of 800 µm, and are typically between 1 mm and 2 mm in height, with a 1 mm height being the standard.

• Once a slit is selected, it is permanently mounted, so difficult and costly to install new one; make decision wisely.

Literature