Method for testing curved reflective surfaces
AssigneeRaytheon Company
InventorsMegan Cheney, David J. Markason, Christopher Janich
Life of this patent
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Abstract
Methods and systems for calculating a reflectance value of a reflective coating on a curved surface of an optical element include calculating the reflectance value by taking a series of photon count measurements of an extended radiation source over a range of values of emitted radiation reflected from the curved surface into a detector. A combination of the measurements and a known value of accepted or conforming reflectance for the reflective coating is used to calculate the reflectance value of the reflective coating on the curved surface.
Claims20
A method for calculating a reflectance value, the method comprising the steps of:
- emitting, by an extended radiation source, first radiation at a first intensity along a first optical axis;
- reflecting, along a second optical axis separated from the first optical axis by a predetermined angle, the first radiation from a region of a curved surface of an optical element having a reflective coating;
- receiving, by a detector, the reflected first radiation;
- determining a first count from the received first radiation;
- emitting, by the radiation source, second radiation at a second intensity along the first optical axis;
- reflecting, along the second optical axis, the second radiation from the region of the curved surface;
- receiving, by the detector, the reflected second radiation;
- determining a second count from the received second radiation;
- and
- calculating the reflectance value based on a difference between the first count and the second count and a difference between a first irradiance value and a second irradiance value.
A system for calculating a reflectance value comprising:
- a radiation source configured to emit first radiation at a first intensity along a first optical axis and emit second radiation at a second intensity along the first optical axis;
- an optical element including a curved surface having a reflective coating;
- a region of the curved surface configured to reflect the first radiation along a second optical axis separated from the first optical axis by a predetermined angle, and reflect the second radiation along the second optical axis;
- a detector configured to receive the reflected first radiation and receive the reflected second radiation;
- and
- a controller configured to determine a first count from the received first radiation, determine a second count from the received second radiation, and calculate the reflectance value based on a difference between the first count and the second count and a difference between a first irradiance value and a second irradiance value.
Dependencies are inferred from the claim text.