Abstract
High-precision optical measurements depend on the optical sensor's stability. Light source's intensity fluctuations are the dominant cause for output instability of the sensor. In order to address this issue, we have developed an optical sensor for reducing influence of the intensity fluctuations on the output stability. The sensor comprises a light source generating smoothly modulated intensity, a measuring channel, a reference channel, and a beam splitter dividing the light source intensity between the channels. The reference channel opens the measuring channel when the light source intensity equals a specific value and the measuring channel converts the input intensity into the output of the sensor. The sensor was designed and studied experimentally at a wave- length of 635 nm and a modulation frequency of 285 Hz. With the sensor, the influence of the intensity fluctua- tions on the output stability was reduced 110 times and the relative rms instability of 4.5 × 10 −5 was obtained. Techniques to achieve the instability of 1.0 × 10 −5 are also shown.©TheAuthors.PublishedbySPIEunderaCreativeCommons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its
Highlights
Technologies utilized in current laser gyroscopes, microelectromechanical systems, and cavity ring-down techniques require mirrors with a reflectance of ∼0.9999.1–3 Such reflectance can be achieved in multilayer dielectric mirrors manufactured with direct monitoring.[4]
The long-term output instability of the optical sensor was characterized by the ΔU relative instability calculated from Eq (7) and the σU relative rms instability calculated from the relation[26]
Downloaded From: https://www.spiedigitallibrary.org/journals/Optical-Engineering on 08 Nov 2021 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use the output of the optical sensor was varied almost 18-fold, (1) the σU∕ΔU ratios remained close to 0.4 and (2) the output stability of the optical sensor did not depend on the light intensity in the measuring channel
Summary
Technologies utilized in current laser gyroscopes, microelectromechanical systems, and cavity ring-down techniques require mirrors with a reflectance of ∼0.9999.1–3 Such reflectance can be achieved in multilayer dielectric mirrors manufactured with direct monitoring.[4] During the process of manufacturing, in situ measurements are taken to calculate optical properties of the layer deposited on the substrate. This allows to compensate for the manufacturing errors in the current layer with the subsequent one. The compensation channel of the sensors based on the feedback methods controls either the intensity of the light source[6,7,8,9,10] or the sensitivity of the measuring channel.[11,12,13,14] In the sensors based on the ratio method, the compensation channel defines the output of the optical
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