How bright are my PIV particles?

This little calculator allows an estimate of the brightness of small particles illuminated by laser light, as seen by a camera with a rated ISO or a rated amp gain/quantum efficiency.
See PIV post for more details on how each method calculates the saturation exposure.
Values in bold are inputs.


Saturation Photons Calculation - Known Camera ISO
ISO Film Speed or EI (S)
Exposure for 18% gray (H18) [lux-s]
Exposure for 100% gray (H100) [lux-s]
Wavelength (λ) [nm]
Photon energy (εph) [J]
Photopic luminous efficiency V(λ)
Saturation exposure energy per pixel (h100,e) [J]
Saturation exposure energy per pixel (h100,ph) [photons]
Saturation Photons Calculation - Known Quantum Efficiency
Wavelength (λ) [nm]
Photon energy (εph) [J]
Sensor quantum efficiency [%]
Saturation electrons
Saturation exposure energy per pixel (h100,e) [J]
Saturation exposure energy per pixel (h100,ph) [photons]
Saturation Photons Inputted Directly
Wavelength (λ) [nm]
Photon energy (εph) [J]
Saturation exposure energy per pixel (h100,ph) [photons]
Saturation exposure energy per pixel (h100,e) [J]
Camera Optics Setup
Pixel size (wpx) [μm]
Lens focal distance (f) [mm]
Distance from particle to lens (i) [mm]
Lens f-number (N)
Gaussian particle image std. dev. [px]
Camera view angle (0deg=looking at laser)
Illumination Parameters
Laser pulse energy (Qlaser) [J]
Laser pulse time (t) [ns]
Laser beam width (wbeam) [mm]
Laser beam length (lbeam) [mm]
Laser irradiance (Elaser) [W/m2]
Particle Radius (r) [μm]
Particle IOR, real part (nRe)
Particle IOR, imaginary part (nIm)
Medium IOR (nmedium, Re)
Radiant flux emitted by particle (Φe) [W]
Photons/pixel at the camera, perp. [photons]
Photons/pixel at the camera, par. [photons]



How do I know if my polarization is perpendicular or parallel?

It's very simple: use the plane in space formed by the three points: (1) light source, (2) particle and (3) camera; or the two vectors (A) incident light and (B) scattered light. If the electric field polarization vector is parallel to this plane, then use the "parallel" polarization curve. If it is perpendicular to the plane, then use the "perpendicular" polarization curve. Note that your laser light could be polarized at any arbitrary angle with respect to this plane, so the actual brightness will be somewhere in between these two numbers, in practice. See picture below for a graphical explanation.


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