Pupil phase apodization for achromatic imaging of extra-solar planets

Direct imaging of extra-solar planets in the visible and infrared region has generated great interest among scientists and the general public as well. However, this is a challenging problem. Diffculties of detecting a planet (faint source) are caused, mostly, by two factors: sidelobes caused by starlight diffraction from the edge of the pupil and the randomly scattered starlight caused by the phase errors from the imperfections in the optical system. While the latter diffculty can be corrected by high density active deformable mirrors with advanced phase sensing and control technology, the optimized strategy for suppressing the diffraction sidelobes is still an open question. In this thesis, I present a new approach to the sidelobe reduction problem: pupil phase apodization. It is based on a discovery that an anti-symmetric spatial phase modulation pattern imposed over a pupil or a relay plane causes diffracted starlight suppression sufficient for imaging of extra-solar planets. Numerical simulations with specific square pupil (side D) phase functions, such as ... demonstrate annulling in at least one quadrant of the diffraction plane to the contrast level of better than 10^12 with an inner working angle down to 3.5L/D (with a = 3 and e = 10^3). Furthermore, our computer experiments show that phase apodization remains effective throughout a broad spectrum (60% of the central wavelength) covering the entire visible light range. In addition to the specific phase functions that can yield deep sidelobe reduction on one quadrant, we also found that a modified Gerchberg-Saxton algorithm can help to find small sized (101 x 101 element) discrete phase functions if regional sidelobe reduction is desired. Our simulation shows that a 101x101 segmented but gapless active mirror can also generate a dark region with Inner Working Distance about 2.8L/D in one quadrant. Phase-only modulation has the additional appeal of potential implementation via active segmented or deformable mirrors, thereby combining compensation of random phase aberrations and diffraction halo removal in a single optical element.

Geology and Ore Deposits of the Butte-Highland Gold Mine.

The Butte-Highland mine is situated at the head of Basin Creek, in the Highland mining district, Silver Bow County, about 14 miles south of Butte. The tunnel portal and present surface plant are at an elevation of about 7350 feet above sea level, facing westward across the head of Basin Creek valley. The "ghost" mining town of Highland lies a mile to the east, near the forks of Fish Creek. Access to the mine is obtained at present from Beaudine's siding, 12 miles west. The property may also be reached, with difficulty, over poor roads from Limekiln hill, or from Moose Creek.

The General Geology of the Cardwell Mining District

The Cardwell Mining District is part of the greater Whitehall Mining District. The district is situated about four miles to the east and northeast of Whitehall in the southern end of the Bull Mountains which are near the Continental Divide. The first reported production was in 1896 after the dis­covery of the Mayflower Mine. Mining has been carried on in­termittently and on a small scale since that time.

The Geology of Lost Creek Canyon with Special Reference to Igneous Activity

This investigation was undertaken primarily as a problem in geologic mapping, coupled with a study of stratigraphy, glaciation, igneous phenomena, and structure. The area is admirably suited to a study of geology and geologic events. Because it is small in extent, the area was studied in some detail during the time which was devoted to field work. The record of igneous activity of past geological ages is re­markably well exposed, since Lost Creek Canyon was carved through the roof of a stock or batholith by the glaciers of the Pleistocene epoch.

Geology of some Gold Deposits of Montana

Gold is one of the rarer metals in nature, and chemically it is one of the most inactive. Gold forms stable, natural compounds with few other elements, and only with metals.

Geology and Ore Deposits of the Golden Era and Goldfinch Mines, Argenta Mining District, Montana.

This report includes the results of geological investigation of a small area in the northern part of the Argenta mining district. Approximately two square miles were mapped. The underground working of the three mines only were accessible: the Goldfinch. Golden Era, and Mayday mines.

Geology and Ore Deposits of the Golden Messenger MIne, Lewis and Clark County, Helena, Montana.

The Golden Messenger Mine which is approximately twenty-three miles northeast of Helena, Montana, near York, on Trout Creek, has long presented several problems of both theoretical and practical interest.

The Geology of the Southern Central Portion of the Morrison Cave Area.

Morrison Cave is located about 50 miles southeast of Butte, Montana. It was named after the man who discovered it. Later it was taken over by the State and renamed Morrison Cave State Park. Recently the government with the aid of the Civilian Conservation Corps has built a new road to the cave and has made the interior more accessible. The name of the cave is now Lewis and Clark Cavern National Monument.

The Geology and Ore Deposits of Jardine, Montana

The subject to be covered by this paper is based upon field study made during a six week stay at Jardine. The work began on June 19, 1937 and ended on July 31 of the same year.

Geology of a Portion of the Bull Mountain Range Jefferson County, Montana

Work was first done on a known section, the south Boulder Section, in order to familiarize the student with the formations. Most of the area was mapped by plane table and telescopic alidade, general features being surveyed by automobile traverse and a pacing traverse.

Geology of the Golden Sunlight Mine and Vicinity

The Golden Sunlight Mine is in the northern part of the Cardwell mining district on the eastern slope of a small range that rises by a series of benches to an elevation of 7,200 at a point five miles east of the town of Whitehall in Jefferson County.