synospec.etc.detector module

Detector class

class synospec.etc.detector.Detector(shape=None, pixelsize=15.0, binning=1, rn=1.0, dark=0.0, cic=0.0, gain=1.0, fullwell=10000.0, nonlinear=1.0, qe=0.9, em_fac=1.0, em_gain=1.0, fps=1.0)[source]

Bases: synospec.etc.efficiency.Efficiency

Define the detector technical properties.

Parameters

shape (tuple, optional) – Dimensions of the unbinned detector in number of pixels along the spectral axis and number of pixels along the spatial axis. Can be None, but limits use if it is.
pixelsize (float, optional) – The size of the unbinned (square) detector pixels in micron.
binning (int, optional) – The number of unbinned pixels along one axis included in a square binned pixel. I.e., if the binning is 4x4, this should be 4. Currently cannot accommodate binned that is not square.
rn (float, optional) – Read-noise in electrons.
dark (float, optional) – Dark current in electrons per pixel per second.
cic (float, optional) – Clock-induced charge in electrons per pixel.
gain (float, optional) – Gain of detector amplifier in electrons per ADU.
fullwell (float, optional) – The full well of the pixels in electrons.
nonlinear (float, optional) – The fraction of the fullwell above which the detector response is nonlinear.
qe (float, Efficiency, optional) – Detector quantum efficiency.
em_fac (float, optional) – For EMCCDs, this is the multiplicative noise factor due to the stochasticity in the gain at high gain. The theoretical value for this is \(\sqrt{2}\). Average values for EMCCDs is quoted as 1.3 by Hamamatsu. This should be 1 for a normal CCD.
em_gain (float, optional) – For EMCCDs, the readnoise can be provided as either the readnoise without electron multiplication or with multiplication. If provided with multiplication, this parameter should be set to 1 and the inclusion of the readnoise in the detector noise is identical to a normal CCD. If provided without electron multiplication, em_gain should provide the electron multiplication gain setting, and the readnoise term included in the error budget is then rn/em_gain.
fps (float, optional) – Readout time expressed in number of full-frame readouts per second.

count_rate(wave, photon_rate)[source]

Apply the quantum efficiency to convert a photon rate to an electron count rate.

Parameters

wave (float, array-like) – The wavelength for the incident photons.
photon_rate (float, array-like) – The photon flux in number per second at the provided wavelength.

Returns

Count rate.

Return type

float, numpy.ndarray

n_exp(t_exp, t_tot)[source]

Provided a total observing time and an integration time per exposure, calculate the maximum number of exposures that be performed given the detector readout time.

Parameters

t_exp (int) – Integration time per exposure.
t_tot (float) – Total observing allocation in seconds.

Returns

Number of exposures possible within the total observing allocation.

Return type

float

t_exp(n_exp, t_tot)[source]

Provided a total observing time and a number of exposures, calculate the maximum integration time per exposure given the detector readout time.

Parameters

n_exp (int) – Number of exposures.
t_tot (float) – Total observing allocation in seconds.

Returns

Integration time per exposure to fill to total observing allocation.

Return type

float

t_tot(n_exp, t_exp)[source]: Get the total observing time including readout overhead.

variance(count_rate, exptime=1.0)[source]

Compute the detector variance for a given count rate.

Parameters

count_rate (float, numpy.ndarray) – Number of counts per second. The quantum efficiency should already have been accounted for; see count_rate().
exptime (float, optional) – The exposure time in seconds.

Returns

The expected statistical error in the detector counts. Shape (and type) match photon_flux.

Return type

float, numpy.ndarray