scholarly journals Taurus Tunable Filter — Seven Years of Observing

2003 ◽  
Vol 20 (3) ◽  
pp. 242-251 ◽  
Author(s):  
J. Bland-Hawthorn ◽  
L. Kedziora-Chudczer
Keyword(s):  
Tunable Filters ◽  
Tunable Filter ◽  
To Come ◽  
William Herschel

AbstractThe Taurus Tunable Filter (TTF) has now been in regular use for seven years on the Anglo–Australian Telescope (AAT). The instrument was also used for three years (1996–1999) on the William Herschel Telescope (WHT). We present a brief review of the different applications in order to illustrate the versatility of tunable filters in optical/IR spectrophotometric imaging. Tunable filters are now either planned or under development for 6–10 m class telescopes which ensures their use for years to come.

scholarly journals A Technique for Tunable Filters with Low Insertion Loss and Narrow Bandwidth

2018 ◽  
Vol 38 ◽  
pp. 03039
Author(s):  
Chang Zhou ◽  
Chen Ji ◽  
Gen Ping Wu
Keyword(s):  
Insertion Loss ◽  
Return Loss ◽  
Tunable Filters ◽  
Tunable Filter ◽  
Center Frequency ◽  
Pin Diodes ◽  
Lc Filters ◽  
Narrow Bandwidth ◽  
Low Insertion Loss ◽  
Resonant Capacitor

A technique for tunable filters with low insertion loss and narrow bandwidth is proposed in the form of comb-line structure. Both resonant capacitor with pin-diodes and resonant inductance in the tunable filter were analyzed and the main source of insertion loss was obtained. A series of filters with same pin-diodes, center frequency, absolute bandwidth and low return loss was simulated. The results showed that, by changing the values of the resonant capacitor and inductance, insertion loss of the filter can be greatly restricted. This technique will allow the design of tunable LC filters with low insertion loss and narrow bandwidth.

A NOVEL SWEPT LASER SOURCE BASED ON COMBINED TUNABLE FILTERS FOR OCT

2011 ◽  
Vol 04 (01) ◽  
pp. 53-58 ◽  
Author(s):  
MINGHUI CHEN ◽  
ZHIHUA DING ◽  
LING WANG ◽  
TONG WU ◽  
YUANHAO TAO
Keyword(s):  
Line Width ◽  
Parallel Implementation ◽  
Mode Locking ◽  
Tunable Filters ◽  
Tunable Filter ◽  
Laser Source ◽  
Laser Resonator ◽  
Fourier Domain ◽  
Tunable Range ◽  
Light Amplification

A novel broad tunable bandwidth and narrow instantaneous line-width linear swept laser source using combined tunable filters working at 1,300 nm center wavelength is proposed. The combined filters consist of a fiber Fabry–Perot tunable filter and a tunable filter based on diffractive grating with scanning polygon mirror. In contrast to traditional method using single tunable filter, the trade-off between bandwidth and instantaneous line-width is alleviated. Parallel implementation of two semiconductor optical amplifiers with different wavelength range is adopted in the laser resonator for broadband light amplification. The Fourier domain mode locking swept laser source with combined tunable filters offers broadband tunable range with narrow instantaneous line-width, which is especially benefiting for high-quality optical frequency domain imaging. The proposed Fourier domain mode locking swept laser source provides a tuning range of 160 nm with instantaneous line-width of about 0.01 nm at sweeping rate of 15 kHz, a finesse of 16,000 is thus achieved.

scholarly journals Microring Mixers and Tunable Filters in Silicon Photonics (Project Report 1201308-Y3)

2021 ◽  
Author(s):  
Shayan Mookherjee
Keyword(s):  
Silicon Photonics ◽  
Tunable Filters ◽  
Tunable Filter ◽  
Integrated Photonics ◽  
Project Report ◽  
The Third ◽  
Funded Project ◽  
On Chip ◽  
Quantum Photonics ◽  
Photonics Devices

The main goal of this NSF-funded project [1201308 - Year 3] is to develop integrated photonics devices based on silicon photonics which can be used for compact and efficient nonlinear classical and quantum photonics applications. During the third year of this project, we demonstrated the combination of an on-chip ring mixer and a tunable filter.

Fast Scanning Synchronous Luminescence Spectrometer Based on Acousto-Optic Tunable Filters

1995 ◽  
Vol 49 (11) ◽  
pp. 1624-1631 ◽  
Author(s):  
Dennis M. Hueber ◽  
Christopher L. Stevenson ◽  
Tuan Vo-Dinh
Keyword(s):  
Bandpass Filter ◽  
Tunable Filters ◽  
Tunable Filter ◽  
Portable Instrumentation ◽  
Mechanical Parts ◽  
Operating Range ◽  
Grating Monochromator ◽  
Electronically Tunable

A new luminescence spectrometer based on quartz-collinear acousto-optic tunable filters (AOTFs) and capable of synchronous scanning is described. An acousto-optic tunable filter is an electronically tunable optical bandpass filter. Unlike a tunable grating monochromator, an AOTF has no moving mechanical parts, and an AOTF can be tuned to any wavelength within its operating range in microseconds. These characteristics, combined with the small size of these devices, make AOTFs an important new alternative to conventional monochromators, especially for portable instrumentation. The relevant performance of the AOTFs (efficiency, bandwidth, rejection, etc.) is compared with that of typical small-grating monochromator.

APPLICATION OF PHOTOREFRACTIVE FIBER AND WAVEGUIDE GRATINGS TO FAST SPEED NARROW BAND TUNABLE FILTERS

1999 ◽  
Vol 08 (01) ◽  
pp. 147-158 ◽  
Author(s):  
SHIZHUO YIN
Keyword(s):  
Narrow Band ◽  
Grating Period ◽  
Tunable Filters ◽  
Tunable Filter ◽  
Bragg Grating ◽  
Diffraction Effect ◽  
Preliminary Results ◽  
Fast Speed ◽  
Electro Optic ◽  
Waveguide Gratings

In this paper, the progress of the application of photorefractive fiber and waveguide crystal gratings to a narrow band, fast speed, tunable filter is presented. This novel filter is based on tunable Bragg grating. It uses the diffraction effect of Bragg grating to select the wavelength and the electro-optic effect of the grating to tune the effective grating period. Several approaches of fabricating this type of tunable Bragg grating based filter are discussed and some preliminary results are provided. It is shown that the tuning speed of this type of filter can be in the ns range and the bandwidth can be as narrow as 0.01 nm.

scholarly journals Taurus Tunable Filter: A Flexible Approach to Narrowband Imaging

1998 ◽  
Vol 15 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Joss Bland-Hawthorn ◽  
D. Heath Jones
Keyword(s):  
Galactic Plane ◽  
Interference Filter ◽  
Tunable Filter ◽  
Narrowband Interference ◽  
Flexible Approach ◽  
Monochromatic Imaging ◽  
Narrowband Imaging ◽  
William Herschel

AbstractThe Taurus Tunable Filter (TTF) is a tunable narrowband interference filter covering wavelengths from 6300 Å to the sensitivity drop-off of conventional CCDs (∼9600 Å), although a blue ‘arm’ (4000–6500 Å) is to be added by the end of 1997. The TTF offers monochromatic imaging at the Cassegrain foci of both the Anglo-Australian and William Herschel Telescopes, with an adjustable passband of between 6 and 60 Å. In addition, frequency switching with the TTF can be synchronised with movement of charge (charge shuffling) on the CCD, which has important applications to many astrophysical problems. Here we review the different modes of TTF and suggest their use for follow-up narrowband imaging to the AAO/UKST Galactic Plane Hα Survey.

Reconfigurable diplexer using hybrid couplers and perturbed TE012 cavities

2021 ◽  
pp. 1-11
Author(s):  
E. Laplanche ◽  
O. Tantot ◽  
N. Delhote ◽  
S. Verdeyme ◽  
A. Perigaud ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Design Process ◽  
Tunable Filters ◽  
Tunable Filter ◽  
Low Loss ◽  
Input Filter ◽  
Bandwidth Tuning ◽  
Linear Movement ◽  
Hybrid Coupler ◽  
Ku Band

Abstract A continuously tunable Ku-band waveguide diplexer is proposed in this paper. This diplexer is based on a hybrid coupler topology and is composed of an input filter centered at 11.9 GHz with a 200 MHz bandwidth, a pair of ladder-type hybrid couplers, and a pair of tunable filters. This diplexer can provide two bandpass channels (channels 1 and 2) that can continuously go from a state where the bandwidths of channels 1 and 2 are maximum (up to 140 MHz) and minimum (down to 40 MHz), respectively, to another configuration where the bandwidth of channel 1 is the largest and the bandwidth of channel 2 is the narrowest. We propose a tunable filter based on TE012 mode circular cavities that are perturbed by low-loss dielectric inserts to obtain such performance. The resonant frequency of these cavities can be continuously tuned between 11.8 and 12 GHz due to the linear movement of the dielectric perturber. The design process for these components is presented and a breadboard device has been manufactured and measured to prove the concept. Different measured configurations of the diplexer are demonstrated, showing that the 200 MHz operating bandpass between 11.8 and 12 GHz can be efficiently separated into two tunable channels. The measured bandwidth of channels 1 and 2 in the manufactured diplexer can be tuned from 135 to 40 MHz (and vice versa) while maintaining an average guard band between the channels of approximately 26 ± 7 MHz. The obtained bandwidth tuning ratios are 3.2 for the highest channel and 3.1 for the lowest channel.

scholarly journals Herschel and the Construction of the Heavens

1982 ◽  
Vol 60 ◽  
pp. 55-66
Author(s):  
Michael Hoskin
Keyword(s):  
Head Start ◽  
Old Age ◽  
Systematic Search ◽  
History Of Astronomy ◽  
Royal Family ◽  
Cape Of Good Hope ◽  
General Catalogue ◽  
History Of ◽  
To Come ◽  
William Herschel

The history of astronomy knows great telescope builders, great observers, and great theorists; but only William Herschel falls indisputably into all three categories. When he became a professional astronomer in the summer of 1782, he had already demonstrated his skills in the construction of big reflectors: the mounting of his 20ft still left much to be desired, but otherwise his mirrors, his eyepieces, and his mountings combined to give him a head start over any other astronomer in the examination of distant and therefore faint objects. And in little over a year after his arrival near Windsor Castle where he was to be available on occasion to show the heavens to the Royal Family, he completed one of the great telescopes of all time: his ‘large’ 20ft reflector, with mirrors of 18 inches diameter, and soon to be equipped with a stable ladder-type mounting so that telescope and observing platform could be rotated together by a single workman. This mounting he further improved and refined in the years to come, and meanwhile the telescope was his favourite instrument and in constant use during his twenty-year systematic search of the sky for nebulae. In his extreme old age it was refurbished under his direction by his son John, who resurveyed his father’s nebulae and then took the telescope to the Cape of Good Hope to extend the coverage to the southern skies. John’s General Catalogue of Nebulae and Clusters of Stars (1864) led to the New General Catalogue that astronomers use today.

Investor-State Dispute Settlement under NAFTA Chapter 11: The Shape of Things to Come?

1998 ◽  
Vol 35 ◽  
pp. 263-290
Author(s):  
J. Anthony VanDuzer
Keyword(s):  
Free Trade Agreement ◽  
Dispute Settlement ◽  
Trade Agreement ◽  
Minimum Standards ◽  
The North ◽  
State Behaviour ◽  
Nafta Chapter 11 ◽  
To Come ◽  
The Right

SummaryRecently, there has been a proliferation of international agreements imposing minimum standards on states in respect of their treatment of foreign investors and allowing investors to initiate dispute settlement proceedings where a state violates these standards. Of greatest significance to Canada is Chapter 11 of the North American Free Trade Agreement, which provides both standards for state behaviour and the right to initiate binding arbitration. Since 1996, four cases have been brought under Chapter 11. This note describes the Chapter 11 process and suggests some of the issues that may arise as it is increasingly resorted to by investors.

Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

1970 ◽  
Vol 28 ◽  
pp. 114-115
Author(s):  
P. A. Madden ◽  
W. R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Secondary Electron ◽  
Distilled Water ◽  
Freeze Dried ◽  
Silver Paint ◽  
To Come ◽  
Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

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