I want to select non-contact infrared temperature sensor for measuring temperature I have following question regarding its selection:

  1. My basic doubt is whether i am using Glass-container or metal container will it give me different reading of temp. ? Though the same material in both the container

2.Can anybody give me a hint/idea that which parameter's i should keep in mind in selecting this sensor to detect the temperature of the material kept inside either Glass/Metal container of different thickness with non-contact distance of 2cm.

  1. My last question is does the emissivity of metal body or glass body changes while change in their thickness ?
  • \$\begingroup\$ You must greatly expand your question. The equation is 1 = reflectance + emissivity + transmission. You say nothing about the wavelength you are considering. Pretty much everything affects all of those. A flat surface will have lower emissivity than a roughened surface, so shape and texture and a lot of other things matter, too. Thickness certainly matters, but how thick and how much depends on the material, wavelength, shape, texture, etc. Wavelength matters. Observation angle and acceptance angle matters. You provide nothing to go on, at all. \$\endgroup\$
    – jonk
    Sep 12, 2016 at 4:56

1 Answer 1


Surface Material - Emissivity Coefficient, ε

  • Glass, Pyrex 0.85 - 0.95 W/m2
  • SS, polished 0.075 W/m2

  • q = ε σ T^4 A

    • q = heat transfer per unit time (W)
    • T = absolute temperature in Kelvin (K)
    • A = area of the emitting body (m2)

The thickness will affect heat loss to ambient while container heats up to inside temp and will have a temperature gradient across thickness dependent on rate of lost heat (W/s).


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