Influence of Tilting Angle on Temperature Measurements of Different Object Sizes Using Fiber-Optic Pyrometers.

Area of Science:

• Optical Engineering
• Metrology
• Thermal Measurement

Background:

• Accurate temperature measurement using fiber-optic pyrometers is crucial in various industrial applications.
• Existing models often do not fully account for the impact of misalignment, such as tilting angles, between the pyrometer and the target surface.
• Understanding these geometric factors is essential for reliable non-contact thermometry.

Purpose of the Study:

• To develop and validate a new model for optical power collection in fiber-optic pyrometers considering tilting angles.
• To investigate the influence of fiber specifications and object parameters on collected optical power under misalignment.
• To provide equations for determining optimal tilting angles and distances to maximize power collection and minimize temperature errors.

Main Methods:

• Development of a new theoretical model for optical power transfer.
• Numerical simulations using the developed model with varying parameters (fiber diameter, NA, object size, emissivity, tilting angle, distance).
• Validation of the model against existing pyrometer simulations in literature (without tilting).

Main Results:

• The model demonstrates that increasing the tilting angle between the fiber axis and the surface normal reduces collected optical power.
• Maximum power is collected when the fiber's field of view fully encompasses the target object.
• The study quantifies the relationship between tilting angle, distance, object size, fiber NA, and collected power.

Conclusions:

• The developed model accurately predicts optical power collection in fiber-optic pyrometers, including the effects of tilting.
• Misalignment significantly impacts temperature measurement accuracy, necessitating careful consideration of tilting angles and distances.
• The derived equations aid in optimizing pyrometer setup to ensure maximum signal and minimize measurement errors, especially for objects smaller than the field of view.