Optical Feedback Control (OFC) Developer Guide

Important classes:

• BaseOFCData a python data class that contains the static data for the ofc operation.

• OFCData a data container class that inherits BaseOFCData and handles the dynamic data for ofc operations. This includes reading and storing data from files and higher level data manipulation.

• SensitivityMatrix calculates the sensitivity matrix at the given sensors and camera rotation angle.

• StateEstimator contains facilities to estimate the state of the system.

• OFCController calculates the degrees of freedom (DoF) offset by minimizing the cost function.

• OFC is the main class of the system, responsible for managing the conversion of wavefront errors into corrections.

Figure 1 OFC Class diagram.

Control Algorithm

• Control Algorithm in Optical Feedback Control
• Camera Rotation with Double Zernikes
  • Rotation of the sensor
  • Rotation of the field angle
• Camera Rotation and Degree of Freedom
  • Mirror Bending Mode
  • Hexapod Position

For more additional details about the algorithm see [Angeli2014], [Angeli2016a], [Angeli2016b] and [Xin2021].

Python API reference

lsst.ts.ofc Package

Classes

BendModeToForce(component, ofc_data)	Transform Bend mode to forces.
Correction(*args)	Container for corrections.
OFC(ofc_data[, log])	Optical Feedback Control.
OFCController(ofc_data[, log])	Optical Feedback Control Controller.
OFCData([name, config_dir, log])	Optical Feedback Control Data.
SensitivityMatrix(ofc_data)	Class to handle the sensitivity matrix.
StateEstimator(ofc_data[, rcond, log])	(Optical) State Estimator.

lsst.ts.ofc.ofc_data Package

Functions

default_eff_wavelenght()

Default effective wavelenght.

Classes

BaseOFCData(y2_filename_root, ...)	Base Optical Feedback Control Data.
OFCData([name, config_dir, log])	Optical Feedback Control Data.

lsst.ts.ofc.utils Package

Functions

get_config_dir()	Return the path to the policy dir within this package.
get_pkg_root()	Return the root directory of this package.
rot_1d_array(array, rot_mat)	Rotate 1D array from one basis to another.

Classes

CorrectionType(value[, names, module, ...])

Contributing

lsst.ts.ofc is developed at https://github.com/lsst-ts/ts_ofc.

References

Angeli2014

Angeli, George Z. et al., Real time wavefront control system for the Large Synoptic Survey Telescope (LSST). Proc. SPIE 9150, Modeling, Systems Engineering, and Project Management for Astronomy VI, 91500H (2014).

Angeli2016a

Angeli, George Z. et al., An integrated modeling framework for the Large Synoptic Survey Telescope (LSST). Proc. SPIE 9911, Modeling, Systems Engineering, and Project Management for Astronomy VI, 991118 (2016).

Angeli2016b

Angeli, George Z. and Xin, Bo, Normalized Point Source Sensitivity for LSST. document-17242.

Xin2021

Xin, Bo, SITCOMTN-003: Coordinate Transformations within the Rubin Active Optics System. sticomtn-003