Wavelength standard at 543 nm and the corresponding ^127I_2 hyperfine transitions

Cheng, Wang-Yau; Shy, Jow−Tsong

doi:10.1364/josab.18.000363

Cited by 15 publications

(6 citation statements)

References 28 publications

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“…In previous works, the high-frequency stability of LD sources by locking them to I 2 hyperfine transitions was proposed [15][16][17][18][19]. To lock the frequency of LDs, their frequencies must be modulated and turned around the frequency transition of I 2 .…”

Section: Introductionmentioning

confidence: 99%

A Displacement Measuring Interferometer Based on a Frequency-Locked Laser Diode with High Modulation Frequency

Hoang

et al. 2020

Applied Sciences

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Laser interferometers can achieve a nanometer-order uncertainty of measurements when their frequencies are locked to the reference frequencies of the atom or molecule transitions. There are three types of displacement-measuring interferometers: homodyne, heterodyne, and frequency modulation (FM) interferometers. Among these types of interferometer, the FM interferometer has many advantageous features. The interference signal is a series of time-dependent harmonics of modulation frequency, so the phase shift can be detected accurately using the synchronous detection method. Moreover, the FM interferometer is the most suitable for combination with a frequency-locked laser because both require frequency modulation. In previous research, low modulation frequencies at some tens of kHz have been used to lock the frequency of laser diodes (LDs). The low modulation frequency for the laser source means that the maximum measurement speed of the FM interferometers is limited. This paper proposes a novel contribution regarding the application of a high-frequency modulation for an LD to improve both the frequency stability of the laser source and the measurement speed of the FM interferometer. The frequency of the LD was locked to an I2 hyperfine component at 1 MHz modulation frequency. A high bandwidth lock-in amplifier was utilized to detect the saturated absorption signals of the I2 hyperfine structure and induce the signal to lock the frequency of the LD. The locked LD was then used for an FM displacement measuring interferometer. Moreover, a suitable modulation amplitude that affected the signal-to-noise ratio of both the I2 absorption signal and the harmonic intensity of the interference signal was determined. In order to verify the measurement resolution of the proposed interferometer, the displacement induced by a piezo electric actuator was concurrently measured by the interferometer and a capacitive sensor. The difference of the displacement results was less than 20 nm. To evaluate the measurement speed, the interferometer was used to measure the axial error of a high-speed spindle at 500 rpm. The main conclusion of this study is that a stable displacement interferometer with high accuracy and a high measurement speed can be achieved using an LD frequency locked to an I2 hyperfine transition at a high modulation frequency.

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Section: Introductionmentioning

confidence: 99%

A Displacement Measuring Interferometer Based on a Frequency-Locked Laser Diode with High Modulation Frequency

Hoang

et al. 2020

Applied Sciences

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“…Iodine-stabilized 543 nm He-Ne laser systems have been the subject of extensive research [7][8][9][10][11][12][13][14] since strong 543 nm absorption was observed in 1986. 15 In 1992, the iodinestabilized 543 nm laser system was recommended to serve as one of the primary length-standard lasers, 16 and some intercomparisons were held thereafter.…”

Section: Introductionmentioning

confidence: 99%

Portable 543 nm length standard and magnetic-induced zero-crossing shift on length standard transition

Cheng

Shy

2005

Review of Scientific Instruments

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This study reports on the development of a portable iodine-stabilized 543 nm ͑green͒ length-standard laser, which is low cost and robust. All the needed optics and electronics were integrated into one box which measured 36 cm in length, 30 cm in width, and 15 cm in height. Simple circuits for third harmonic locking are presented and the laser's frequency instability could be as small as 2 ϫ 10 −12 , normalized to one hertz bandwidth. The influence of the magnetic field to the locking point of the 543 nm length-standard transitions was investigated.

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“…[3], scheme on figure 1). Polarization of laser radiation can be selected by half-wave plate (V2); laser is isolated from residual back-reflections by optical isolator (ISO).…”

Section: Introductionmentioning

confidence: 99%

“…Lasers 543 am use internal mirror He-Ne tubes: Siemens in PLG1 (22Ne) and REO in PLG2 (20Ne); Single longitudinal mode operation is selected and kept for one linear polarization by permanent magnetic field in similar way as e.g. in [3].The lasers frequencies are modulated, tumed and stabilized by PZTs (for 543nm tubes PZT compresses/extends the tube with tuning range about 100 MHz). After locking the laser frequency by PZT the voltage is maintained constant by additional slow feedback controlling the laser temperature (this enables us to keep the frequency locked for arbitrary long time without the risk of loosing the lock due to reaching PZT voltage limits).…”

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Iodine Frequency Stabilized Lasers in CMI

Balling

Křen

2004

2004 Conference on Precision Electromagnetic Measurements

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The paper describes recent development and improvement of optical frequency standards used in CMI for length metrologyiodine stabilized lasers 543nm and 532nm. The iodine cells, experimental set-up, operating parameters and results of comparisons are summarized together with absolute frequency measurements of these lasers and 633nm standard. Introduction Frequency stabilized lasers represent standards that provide traceability in length measurements. Since 1978 CMI developed several iodine stabilized He-Ne lasers 633nm, 612nm, 543nm and SHG Nd:YAG laser 532am. These wavelength standards were studied for optimization of stability and reproducibility and were successfully internationally compared for many times, values and repeatability always safely fall within the CCL recommended [1] ones. We present design of external iodine cells, set-up and properties of lasers with external cell and absolute measurements of laser frequencies. Status of 1542nm standard development is briefly mentioned. Cells Except of 633nm lasers we use 50cm long external iodine cells made and filled in ISI Brno. These cells have perpendicular windows with broadband AR coatings from inside and outside and aperture about 2cm. Double-stage TE (Peltier) cooler was selected to reach temperatures -15'C reliably. According to advice of L. Vitushkin [2] the TE cooler is soldered both to radiator and copper cap for cell finger by low-melting point Wood metal. We extended this approach even to contact copper cup to glass finger itself instead of using traditional paste. PU mounting foam prevents water condensation and insulates the TE cooler and central part (40%) of cell wall. We can reach cell finger temperature below -30°C temporarily and steadily to about -20°C at room temperature enviroament.The cell finger temperature stability is in the order of 1OmK, but the total uncertainty is about lOOmK due to residual gradient in copper cup. The purity of iodine cells was measured in BIPM 2001 and both cells CMI-ISI-7 and CMI-ISI-9 were found very pure (Stern-Volmer factor ko=l.04 and 1.23 respectively).13xperimental setup For locking 532 am and 543 am lasers we use sub-Doppler spectroscopy arrangement with isolation by changing the sense of circular polarization (similar to e.g. [3], scheme on figure 1). Polarization of laser radiation can be selected by half-wave plate (V2); laser is isolated from residual back-reflections by optical isolator (ISO). Laser beam is deflected by mirrors and passes through polarizing beam-splitter (P). By means of quarter-wave plate (V4) polarization changes to circular and beam passes through cell and part of it also back as probe. The returning probe beam polarization is converted to linear rotated by 90°and signal beam is thus reflected to detector (D).We use 532 nm Nd:YAG laser Prometheus 20 from INNOLIGHT (CMI YAGI). Lasers 543 am use internal mirror He-Ne tubes: Siemens in PLG1 (22Ne) and REO in PLG2 (20Ne); Single longitudinal mode operation is selected and kept for one linear polarization by permanent magnetic field...

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Wavelength standard at 543 nm and the corresponding ^127I_2 hyperfine transitions

Cited by 15 publications

References 28 publications

A Displacement Measuring Interferometer Based on a Frequency-Locked Laser Diode with High Modulation Frequency

A Displacement Measuring Interferometer Based on a Frequency-Locked Laser Diode with High Modulation Frequency

Portable 543 nm length standard and magnetic-induced zero-crossing shift on length standard transition

Iodine Frequency Stabilized Lasers in CMI

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