This work presents the progress made in primary level photometric measurements at the National Metrology Institute of Turkey (UME). A Cryogenic Radiometer (Oxford Instruments Radiox) was employed in the optics laboratory as an absolute primary standard. Temperature-controlled filter radiometer constructed from three-element silicon trap detector, band-pass filters and precision aperture. Filter radiometers were calibrated using the cryogenic radiometer at discrete laser wavelengths of vertically polarized tuneable Ar+, fixed He-Ne and Nd: YAG (with second harmonic) laser sources. Luminous intensity unit of candela was realized with an expanded uncertainty of 2.88x10-3 and photometric scale was re-established depending on this detector-based realization. Candela realization was performed on optical bench using traditional Osram Wi41/G type incandescent light source and an absolute filter radiometer. Other derived units of photometry that are luminous flux, illuminance, color temperature and luminance are derived from candela through various photometric measurements including some homemade devices of laboratory.
We will use InGaAs and Ge based reflection type trap detectors as a detecting element and lasers as light sources to realize the absolute power and responsivity scales in the near infrared region. The output of lasers should be stabilized in order to make measurements on the metrological level. Therefore, we have established a home made laser intensity stabilization optics in the laboratory. The intensity stability of infrared lasers was reached to a level of 5x10-5 with this system. We have employed a spatial filter, which consists of a 10X objective, a 25 μm pinhole and a Plano convex lens in order to generate a clean beam with the desired dimension Circular power distributions and Gaussian properties of the beams were analysed by using a CCD beam profiler.
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.