Abstract: A closed-track optical delay module, a terahertz system, and a photoelectric system are provided. The closed-track optical delay module comprises a first constraint component with a closed-track line structure, a second constraint component with a straight line groove, a third constraint component with a positioning convex, a light conversion device, a housing, and a driving control device. The positioning convex forms a constraint fit relationship with the closed curve groove and straight line groove. One of the first, second, and third constraint components is connected with the driving control device, the other is fixedly disposed, a next one is connected with the light conversion device and moves parallel to the straight line groove. A light input interface is used for an incident light to be irradiated onto the light conversion device. A light output interface is used for a delayed beam to be emitted from the housing.

Abstract: A closed-track optical delay module, a terahertz system, and a photoelectric system are provided. The closed-track optical delay module comprises a first constraint component with a closed-track line structure, a second constraint component with a straight line groove, a third constraint component with a positioning convex, a light conversion device, a housing, and a driving control device. The positioning convex forms a constraint fit relationship with the closed curve groove and straight line groove. One of the first, second, and third constraint components is connected with the driving control device, the other is fixedly disposed, a next one is connected with the light conversion device and moves parallel to the straight line groove. A light input interface is used for an incident light to be irradiated onto the light conversion device. A light output interface is used for a delayed beam to be emitted from the housing.

Abstract: A method for measuring thickness or defect depth by pulsed infrared thermal wave technology is described. The method includes heating a measured object by pulsed heating devices, and at the same time, obtaining a thermal image sequence on the surface of the measured object by an infrared thermography device, and storing the thermal image sequence in a general-purpose memory. The method also includes multiplying a temperature-time curve at every point of the thermal image sequence by a corresponding time, thereby obtaining a new curve. The method also includes calculating a first-order differential and obtaining a peak time thereof. The method also includes use of one or more formulas to thereby determine the thickness or the defect depth of the measured object.