KEYWORDS: Calibration, Sensors, High power lasers, Laser systems engineering, Measurement uncertainty, Power meters, Optical alignment, Metrology, Design, Sensor calibration
This paper will present the newly developed high-power laser calibration system and alignment at the National Metrology Institute Thailand (NIMT). The system is composed of a high stability, high-power fiber laser with a wavelength of 1080 nm, as a laser source for calibration. Due to this wavelength is not visible to human eyes, the laser is equipped with a built-in red alignment laser and an automatic shutter that can be used for the routine alignment of the whole optical path. The method of calibration is in direct comparison using 2 beam samplers and 2 monitor power meters, for better accuracy. Two beam expanders are used to adjust the laser beam diameter. The reference power meter for calibration is a thermopile sensor. The optical characterization results of the reference power meter such as power non-linearity and detector surface non-uniformity, to be performed at the National Metrology Institute of Germany (PTB), will also be present.
At present, the medium power calibration system at the National Institute of Metrology (Thailand), which has a CO2 laser as a laser source, can be used to calibrate customers’ laser power sensors from 100 mW-10 W. This power range of CO2 laser offers various applications, such as cutting of wood, paper, fabric, rubber, metals, and ceramics. CO2 lasers are also used widely as medical lasers for surgeries and cosmetic purposes such as removing mold and facial resurfacing. Originally, the calibration system of the CO2 laser has a measurement uncertainty of 4.0 % at a 95 % confidence level. This uncertainty level is considered high for medium laser measurement and sensors’ accuracy. One of the reasons is the high power linearity error of the detector, which is taken from manufacturing specifications. Other reasons are overestimation of the uncertainty of the non-uniformity of the detector, and the large uncertainty from the calibration certificate of the standard. Several efforts have been made to reduce the total uncertainty of the system. First, by reducing the uniformity and positioning error of the standard detector and unit under the calibration detector, and second by reducing the power linearity error of the monitor detector of the calibration system. This paper discusses how to experimentally determine the uniformity and positioning error of the detector and the power linearity error of the detector. The new uncertainty of the system is then determined and adjusted from 4.0 % to 1.1 %.
Due to an exponential growth of utilizing laser, light, and RF for medical and medical dermatology, there have been many issues regarding the use of those technologies. Modern devices are straightforward to use, but they are very powerful and are capable of considerable damage when used incorrectly, especially pulse laser, with high intensity. Since there has been an increasing use of pulse laser in medical and cosmetic applications in Thailand, and the laser pulse power and energy are needed to be calibrated. National Institute of Metrology, Thailand (NIMT) has set up a laser energy system and provide calibration service to customers. The service supports calibration of low-level laser pulse at wavelength of Nd-YAG laser at 1064 and 532 nm and at energy range 1 mJ-100 mJ. The laser energy standard was calibrated by National Metrology Institute of Japan (NMIJ) and compared with National Metrology Institute of Germany (PTB) measurement system under scientific collaboration MOU between NIMT & PTB.
Up to date, fiber optics laser systems are the most efficient way to carry information and very important in the field of telecommunication in Thailand. Typical optical fiber systems composed of laser sources, optical fibers as the transmission mediums, and detectors as receivers, where the most basic measurement necessary is optical power. To maintain quality and standard of information transmission, optical power measurement calibration is very important. The objective of this research was to design and development of InGaAs detectors, to use as an optical power transfer standard in the wavelengths where the optical fiber communication systems are operated. The design and development of the transfer standard under scientific collaboration between the national institute of metrology Thailand (NIMT) and Germany (PTB) will be presented.
The carbon dioxide laser (CO2 laser) is one of the most useful and is the highest CW laser at the present. The laser produces infrared light at 10.6 um. Due to its high power, CO2 lasers are usually used in industrial applications such as cutting and welding, or for engraving at less power. CO2 lasers are also used widely in medical applications, such as laser surgery, skin resurfacing, and removing mold, due to water (biological tissue) absorb light at this wavelength very well. CO2 lasers are also used as LIDAR laser source for military range finding applications because of the transparency of the atmosphere to infrared light. Due to the increasing use of CO2 lasers laser in industrial and medical applications in Thailand, the National Institute of Metrology (Thailand) has set up a CO2 laser power calibration system and provide calibration service to customers this year. The service support calibration of medium-level laser power at wavelength of 10.6 um and at power range 100 mW-10W. The design and development of the calibration system will be presented.
In light of the growing interest in spin-related phenomena and devices, there is now a renewed interest in the
science and engineering of narrow gap semiconductors. They offer several scientifically unique electronic features such
as a small effective mass, a large g-factor, a high intrinsic mobility, and large spin-orbit coupling effects. Our studies
have been focused on probing and controlling the coherent and quantum states in InSb quantum wells and InMnAs
ferromagnetic semiconductors. Our observations are providing new information regarding the optical control of carriers
and spins in these material systems. We demonstrated the generation of spin polarized photo-current in an InSb QW
where a non-equilibrium spin population has been achieved by using circularly polarized radiation. In addition, the
differential transmission measurements in InSb QWs demonstrated that the initial distribution function strongly
influences the carrier relaxation dynamics. We employed the polarization-resolved differential transmission as well as
the MOKE measurements to provide information on the spin relaxation dynamics in MOVPE grown InMnAs. Our
measured T1 is comparable to the reported measurements in MBE grown InMnAs and several time resolved
measurements on InAs.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.