David Charles Dayton

On the use of dual frequency nematic material for adaptive optics systems: first results of a closed -loop experiment.

The use of liquid crystal devices for wavefront control has been suggested and implemented by several authors. In this paper we report some preliminary results on the use of Nematic based liquid crystal devices. Several experimental efforts have been carried out in the past few months. One of the main aims was to characterize a new device that uses dual frequency nematic material in a closed loop arrangement.

Demonstration of new technology MEMS and liquid crystal adaptive optics on bright astronomical objects and satellites

We present here results using two novel adaptive optic elements, an electro-static membrane mirror, and a dual frequency nematic liquid crystal. These devices have the advantage of low cost, low power consumption, and compact size. Possible applications of the devices are astronomical adaptive optics, laser beam control, laser cavity mode control, and real time holography. Field experiments were performed on the Air Force Research Laboratory, Directed Energy Directorates 3.67 meter AMOS telescope on Maui, Hawaii.

Laboratory and field demonstration of a low cost membrane mirror adaptive optics system

Abstract We present here results of laboratory and field experiments using the OKO technologies membrane mirror as an adaptive optics device. The device can be operated at high temporal bandwidths from a low cost PC based control system. We have constructed a complete adaptive optics system costing less than twenty thousand dollars. In this paper we present results from this system used both in laboratory tests and on a one meter telescope located at Apache Point, New Mexico.

Long-range laser illuminated imaging: analysis and experimental demonstrations

David DaytonApplied Technology Associates1900 Randolph SEAlbuquerque, New Mexico 87106E-mail: dayton@aptec.comSteve BrowneThe Optical Sciences Company1341 S. Sunkist Ave.Anaheim, California 92806John GonglewskiAir Force Research LaboratoryDirected Energy DirectorateKirtland AFB, New Mexico 87117Steve SandvenApplied Technology Associates1900 Randolph SEAlbuquerque, New Mexico 87106Joe GallegosBoeing North AmericaKirtland AFB, New Mexico 87117Mike ShilkoITT Advanced Engineering Division6400 Uptown Blvd.Albuquerque, New Mexico 87110Abstract. We demonstrate the utility of laser-illuminated imaging forhigh-resolution clandestine nighttime surveillance from a simulated air-borne platform at standoff ranges in excess of 20 km. In order to reducethe necessary per-pulse laser energy required for illumination at suchlong ranges, and to mitigate atmospheric turbulence effects on imageresolution, we have investigated a unique multiframe postprocessingtechnique. It is shown that in the presence of atmospheric turbulenceand coherent speckle effects, this approach can produce superior resultsto conventional scene flood illumination.

Adaptive optics using a liquid crystal phase modulator in conjunction with a Shack-Hartmann wave-front sensor and zonal control algorithm

Multi-segment liquid crystal spatial light modulators have received much attention recently for use as high-precision wavefront control devices for use in astronomical and non-astronomical applications. They act much like piston only segmented deformable mirrors. In this paper we investigate the use of these devices in conjunction with a Shack-Hartmann wave-front sensor. Previous investigators have considered Zernike modal control algorithms. In this paper we consider a zonal algorithm in order to take advantage of high speed matrix multiply hardware which we have in hand.

Liquid crystal technology for adaptive optics: an update

The idea of using liquid crystal devices as an adaptive optics component has been proposed by several authors. In recent years a vigorous research effort has been carried out, and it is still flourishing, in several countries. Mainly the research and experimental work has been concentrated in the USA, U.K. and Russia. There are several reasons why liquid crystals may represent a valid alternative to the traditional deformable mirror technology that has been used for the past two decades or so. The main attractiveness of LC resides in the cost. Current deformable mirror technology has a range of price going from

Novel spatial light modulators for active and adaptive optics

2K to

Passive SWIR airglow illuminated imaging compared with NIR-visible for low-light nighttime observations

15K per channel. LC technology promises to be at least a couple of orders of magnitude cheaper. Other reasons are connected with reliability, low power consumption and with a huge technological momentum based on a wide variety of industrial applications. In this paper we present some preliminary characterizations of a new, large format device. Such devices have the potential for extremely high-resolution wave-front control due to the over 10,000 corrective elements. The characterization of the device, so far, consists of measurements of the overall optical quality and of the phase control relationship

Novel micromachined membrane mirror characterization and closed-loop demonstration

We present here results of laboratory and field experiments using two novel active optic elements, a membrane mirror, and a dual frequency nematic liquid crystal. These devices have the advantage of low cost, low power consumption, and compact size. Possible applications of the devices are astronomical adaptive optics, laser beam control, laser cavity mode control, and real time holography.

MEMS adaptive optics for high-resolution imaging of low Earth-orbit satellites

It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band with wavelength between 0.9 and 1.7 μm. By examining images in an urban and a rural setting, we investigate the correlation between the appearances of passive dark of night images in the SWIR with NIR- visible. The experimental setup consists of two sensors, a NIR-visible CCD and an InGaAs array sensitive in the SWIR, both colocated on an AZ-EL mount, and both co-boresighted so that different viewing angles of the sky and terrestrial scenes are possible. By making corrections for focal length and pixel size, the visible and SWIR data can be compared. After taking several nights of data in the urban environment of Albuquerque, NM, the entire system was then re-located to a rural location on the island of Kauai in a rural setting with very low ambient light. It is shown that under most conditions the SWIR sensor produces significantly better imagery using the airglow illumination source.