Method for evaluating and controlling temperature influence on a homogeneity test for infrared optical materials

A method for evaluating and controlling temperature influence on a homogeneity test for infrared optical materials, comprising:

• 1) setting test precision requirements for the homogeneity test of refractive index as PΔn, a thickness of a sample as t0, the number of times that an infrared radiation flux passes through the sample as N, a wavefront distortion of reference waves corresponding to PΔn as ΔWP;
• wherein ΔWP is calculated according to:
• ΔWP=Nt0PΔn;
• (1)
• 2) when an ambient temperature in a test room changes, bringing a local temperature increment ΔT of the sample and a wavefront distortion ΔWΔT of the reference waves;
• setting a nominal refractive index of infrared optical materials of samples as n0, a thermo-optical coefficient of infrared optical materials as G, a thermal expansion coefficient of infrared optical materials of the samples as α, and a temperature gradient coefficient of refractive indexes of infrared optical materials of the samples as dn/dt;
• wherein the wavefront distortion of the reference waves brought by the local temperature increment ΔT of the sample is ΔWΔT, and ΔWΔT is calculated according to:
• Δ
• ⁢
• ⁢
• W
• Δ
• ⁢
• ⁢
• T
• =
• Nt
• 0
• ⁢
• Δ
• ⁢
• ⁢
• TG
• =
• Nt
• 0
• ⁢
• Δ
• ⁢
• ⁢
• T
• ⁢
• ⌊
• (
• n
• 0
• -
• 1
• )
• ⁢
• α
• +
• dn
• dt
• ⌋
• ;
• (
• 2
• )
• 3) enabling the test precision requirements of the homogeneity test for infrared optical materials to satisfy:
• ΔWΔT≤kΔWP;
• (3)
• wherein k is the precision control factor of the influence of temperature;
• and
• transforming formula (3) into formula (4):
• Δ
• ⁢
• ⁢
• T
• ≤
• k
• ⁢
• P
• Δ
• ⁢
• ⁢
• n
• G
• ;
• (
• 4
• )
• 4) determining a range of the test precision requirements PΔn of the samples of the infrared optical materials;
• 5) determining a range of the thermo-optical coefficient G of the infrared optical materials based on the formula (2);
• 6) according to the formula (4) in step 3, the range of the test precision requirements PΔn determined in step 4, and the range of the thermo-optical coefficient G of the infrared optical materials determined in step 5, establishing a temperature influence control numerical table corresponding to the test precision requirements of the homogeneity test for the infrared optical materials;
• and
• 7) controlling the ambient temperature in the test room during test using corresponding temperature control data in the temperature influence control numerical table according to the test precision requirements and materials of the samples.