| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical filter which exhibits stable and excellent performance even under severe usage conditions.SOLUTION: There is provided an optical filter which satisfies the following conditional expressions, when the thickness of a substrate is defined as a (μm), the Young's modulus of the substrate is defined as b (kgf/mm), the humidity expansion coefficient of the substrate is defined as c(%RH), the temperature expansion coefficient is defined as d(°C), the thickness of the inorganic multilayer film on both sides is defined as e1 and e2(μm), a larger value of the thickness e1 and e2 is e(μm), the temperature of a guaranteed environment of the optical filter is defined as f(°C), the humidity is defined as g (%RH), the substrate temperature during film formation is defined as h(°C) and the breakdown limit stress of the optical filter is defined as i (kgf/mm): [c×g+d(f-h)]×(a/2×b)/i<e (1), 0.9<e1/e2<1.1 (2), a<200 (3), b<500 (4) and i≤40 (5). |
