ppops.detector
==============

.. py:module:: ppops.detector

.. autoapi-nested-parse::

   detector.py
   ------------
   Handles detector signal and noise calculations.

   This module includes functions to compute the expected signal and noise
   levels for a detector based on the hardware specifications.

   Constants:
   - ELEMENTARY_CHARGE: Electron charge (C)
   - ANODE_RADIANT_SENSITIVITY: Anode radiant sensitivity (A/W)
   - DARK_CURRENT: Dark current noise (A)
   - BANDWIDTH: Bandwidth (Hz)
   - INPUT_CURRENT_NOISE: Preamplifier input current noise (A/√Hz)

   Functions:
   - laser_power_density(laser_power, beam_major, beam_minor): Computes
   the laser power density at the aerosol stream.
   - estimate_signal_noise(truncated_csca, laser_power): Estimates signal
   and noise levels for a given truncated scattering cross section and
   laser power.

   Citations:
   - Gao, R.S., et al. 2016. A light-weight, high-sensitivity particle
   spectrometer for PM2.5 aerosol measurements. Aerosol Science and
   Technology 50, 88-99. https://doi.org/10.1080/02786826.2015.1131809
   - Thor Labs. TIA60 Transimpedance Amplifier Datasheet. https://www.thorlabs.com/drawings/c627bb63fbc792f9-BE0A1D53-FE71-D4E9-369F32E2683F2FB6/TIA60-SpecSheet.pdf
   - Hamamatsu Photonics. H10720 Series Photomultiplier Tube Datasheet. https://www.hamamatsu.com/content/dam/hamamatsu-photonics/sites/documents/99_SALES_LIBRARY/etd/H10720_H10721_TPMO1062E.pdf



Attributes
----------

.. autoapisummary::

   ppops.detector.ELEMENTARY_CHARGE
   ppops.detector.H10720_110_CATHODE_RADIANT_SENSITIVITY
   ppops.detector.H10720_110_GAIN_SLOPE
   ppops.detector.H10720_110_GAIN_INTERCEPT
   ppops.detector.H10720_110_DARK_CURRENT
   ppops.detector.BANDWIDTH
   ppops.detector.TIA60_INPUT_CURRENT_NOISE


Functions
---------

.. autoapisummary::

   ppops.detector.anode_radiant_sensitivity
   ppops.detector.laser_peak_power_density
   ppops.detector.estimate_signal_noise


Module Contents
---------------

.. py:data:: ELEMENTARY_CHARGE
   :value: 1.602176634e-19


.. py:data:: H10720_110_CATHODE_RADIANT_SENSITIVITY
   :value: 110


.. py:data:: H10720_110_GAIN_SLOPE
   :value: 8.645


.. py:data:: H10720_110_GAIN_INTERCEPT
   :value: 6.299


.. py:data:: H10720_110_DARK_CURRENT
   :value: 1e-09


.. py:data:: BANDWIDTH
   :value: 4000000.0


.. py:data:: TIA60_INPUT_CURRENT_NOISE
   :value: 4.8e-12


.. py:function:: anode_radiant_sensitivity(PMT_control_voltage)

   Return the anode radiant sensitivity of the PMT in A/W.

   :param PMT_control_voltage: Control voltage of the PMT in volts.
   :type PMT_control_voltage: float

   :returns: Anode radiant sensitivity in A/W.
   :rtype: float


.. py:function:: laser_peak_power_density(laser_power, beam_major = 6, beam_minor = 0.054)

   Return the laser peak power density at the aerosol stream.
   Assumes a Gaussian beam profile and that the beam is focused at the
   aerosol stream. Also assumes that the aerosol passes through the
   center of the beam where the power density is highest.

   The initial beam dimensions are taken from Gao et al. 2016 and the
   beam waist at the aerosol stream is estimated below assuming a
   Gaussian beam profile. The laser power density is then calculated as
   the laser power divided by the beam area at the aerosol stream.

   Horizontal beam waist at aerosol stream:
   spot_diameter = 4M² * λ * L / (π * w_initial) = 0.054 mm
   where λ = 405 nm, L = 75 mm, w_initial_horizontal = 1 mm, M² = 1.4
   (assumed).

   Vertical beam waist at aerosol stream:
   spot_diameter = 2M² * λ * L / (π * w_initial)
   where L = 25 mm, w_initial_vertical = 3 mm.
   DOF = 2 * π * (spot_diameter / 2)² / (M² * λ)
   beam_diameter = spot_diameter
   * sqrt(1 + (distance_from_lens - L)² / (DOF/2)²) = 6 mm

   :param laser_power: Laser power in mW.
   :type laser_power: float
   :param beam_major: Length of major axis of the oval laser beam at the aerosol
                      stream in millimeters. Default is 6.
   :type beam_major: float, optional
   :param beam_minor: Length of minor axis of the oval laser beam at the aerosol
                      stream in millimeters. Default is 0.054.
   :type beam_minor: float, optional

   :returns: **power_density** -- Optical power density (W/µm^2).
   :rtype: float

   .. rubric:: References

   Gao, R.S., et al. 2016. A light-weight, high-sensitivity particle
   spectrometer for PM2.5 aerosol measurements. Aerosol Science and
   Technology 50, 88-99. https://doi.org/10.1080/02786826.2015.1131809

   Laser spot size and beam waist calculator and formulas. Gentec.
   (n.d.).
   https://www.gentec-eo.com/laser-calculators/beam-waist-spot-size


.. py:function:: estimate_signal_noise(ops, truncated_csca)

   Return signal and noise estimates.

   Computes signal and noise estimates for a given truncated single
   scattering cross section and laser power. This function uses the
   maximum gain settings for the PMT and preamplifier. This is expected
   to be larger than the actual signal and noise levels in typical
   operation, but provides a useful upper bound.

   :param ops: Instance of the OpticalParticleSpectrometer class.
   :type ops: OpticalParticleSpectrometer
   :param truncated_csca: Truncated scattering cross section in units of µm².
   :type truncated_csca: float or np.ndarray

   :returns: * **signal** (*float or ndarray*) -- Estimated signal current (A).
             * **noise** (*float or ndarray*) -- Estimated noise (A).