A calibration apparatus which estimates a calibration parameter of an image acquisition apparatus, comprises a calibration jig which includes at least two planes and in which calibration markers having known three-dimensional positions are arranged in each plane based on a predetermined rule. More particularly, it relates to filtering in a feedback control loop, for example in a sigma-delta modulator. The exposition of the flexible wires of the cooling device on the surface of the frame can be prevented so as to allow the wires to be able to be commonly used in all kinds of sizes of frames. A second well is formed in a second region deeper than the first well in the substrate, and the second well is in contact with some of the first wells. The degree of sintering of the second material is lower than the degree of sintering of the third material.