Fabrication of petal-shaped masks for suppression of the on-axis poisson spot in telescope systems

Abstract

Aspects of the present disclosure involve a system and method for suppressing a Poisson spot. A Poisson spot is a bright spot in the geometrical shadow of circular/spherical shapes. A broad class of telescopes that involve simultaneous transmit and receive require suppression of the reflected light from the secondary mirror on the detector. In one embodiment, coronagraphy petal-shaped masks are fabricated using photolithography and wire-EDM for the suppression of the Poisson spot. The petal-shaped masks can be designed and fabricated to operate at varying Fresnel numbers and petal tip radius-of-curvature (ROC).

What is claimed is: 
     
         1 . A method comprising:
 transmitting, to a detector, a reflected beam from a mirror of a telescopic instrument obstructed by a symmetrical object, to yield a transmitted and reflected beam, wherein a Poisson spot is formed on the detector;   fabricating a petal shaped mask on a surface of the mirror using one of a photolithography process and stand alone electrical machining process; and   suppressing by the petal shaped mask the Poisson spot created by the transmitted and reflected beam.   
     
     
         2 . The method of  claim 1 , wherein the reflected beam is from a secondary mirror of the telescopic instrument. 
     
     
         3 . The method of  claim 1 , wherein the telescopic instrument is a space antenna. 
     
     
         4 . The method of  claim 1 , wherein the petal shaped mask is fabricated using the photolithography process and wherein the photolithography processes uses a chromium substrate. 
     
     
         5 . The method of  claim 1 , wherein the petal shaped mask is fabricated using the electrical machining process and wherein the electrical machining process uses thin single-strand metal wire in conjunction with deionized water. 
     
     
         6 . The method of  claim 1 , wherein the petal shaped mask is between 2 mm and 50 mm in diameter. 
     
     
         7 . The method of  claim 1 , wherein the petal shaped mask suppresses an intensity of the Poisson spot along an optical axis of the telescopic instrument with a Fresnel number between 4.7 and 120. 
     
     
         8 . The method of  claim 4 , wherein the petal shaped mask includes a 2 μm petal tip. 
     
     
         9 . A system comprising:
 a source device, the source device configured to transmit a laser beam in a direction of a mirror and wherein the mirror receives the laser beam, reflects the laser beam in a direction of a device, wherein the laser beam reflected in the direction of the device creates a Poisson spot; and   a controller that positions a petal shaped mask in proximity to the mirror, wherein the petal shaped mask is fabricated using one of a photolithography process and an electrical machining process, wherein the petal shaped mask is configured to suppress the Poisson spot created by the reflected laser beam.   
     
     
         10 . The system of  claim 9 , wherein the system is a space antenna. 
     
     
         11 . The system of  claim 9 , wherein the petal shaped mask is fabricated using the photolithography process and wherein the photolithography processes uses a chromium substrate. 
     
     
         12 . The system of  claim 9 , wherein the petal shaped mask is fabricated using the electrical machining process and wherein the electrical machining process uses thin single-strand metal wire in conjunction with deionized water. 
     
     
         13 . The system of  claim 9 , wherein the petal shaped mask is between 2 mm and 50 mm in diameter. 
     
     
         14 . The system of  claim 9 , wherein the petal shaped mask suppresses an intensity of the Poisson spot along an optical axis of a telescopic instrument with a Fresnel number between 4.7 and 120. 
     
     
         15 . The system of  claim 11 , wherein the petal shaped mask includes a 2 μm petal tip. 
     
     
         16 . A method comprising:
 transmitting, by a light source, a coherent light beam;   receiving a reflected beam associated with the coherent light beam from a mirror at a device, wherein the reflected beam creates a Poisson spot;   attaching, by a controller, a petal shaped mask in proximity to the mirror, wherein the petal shaped mask is fabricated using one of a photolithography process and an electrical machining process; and   suppressing, by the petal shaped mask, the Poisson spot created by the reflected beam.   
     
     
         17 . The method of  claim 16 , wherein the petal shaped mask is fabricated using the photolithography process and wherein the photolithography processes uses a chromium substrate. 
     
     
         18 . The method of  claim 16 , wherein the petal shaped mask is fabricated using the electrical machining process and wherein the electrical machining process uses thin single-strand metal wire. 
     
     
         19 . The method of  claim 16 , wherein the petal shaped mask is between 2 mm and 50 mm in diameter. 
     
     
         20 . The method of  claim 17 , wherein the petal shaped mask includes a 2 μm petal tip.