Method and apparatus for detecting minute irregularities on the surface of an object

A method for inspecting a surface of an object for defects using an optical imaging device, comprising:

• imaging the surface to obtain brightness data for each of a plurality of pixels;
• defining a smallness region comprising plural pixels;
• shifting a location of the smallness region to produce plural smallness regions;
• calculating at the plural smallness regions respective horizontal fluctuation values along a horizontal direction of the brightness data obtained in the imaging step;
• calculating at the plural smallness regions respective vertical fluctuation values along a vertical direction of the brightness data obtained in the imaging step;
• adding each said horizontal fluctuation value to a respective of the vertical fluctuation values to obtain corresponding added fluctuation values;
• averaging selected combinations of the added fluctuation values obtained in the adding step;
• and
• detecting defects on the surface of the object based on a result of the averaging step.

A method for inspecting a surface of an object for defects using an optical imaging device, comprising:

• imaging the surface to obtain brightness data continuously;
• calculating at plural neighboring pixels respective horizontal fluctuation values along a horizontal direction of the brightness data obtained in the imaging step;
• calculating at the plural neighboring pixels respective vertical fluctuation values along a vertical direction of the brightness data obtained in the imaging step;
• adding each said horizontal fluctuation value to a respective of the vertical fluctuation values to obtain corresponding added fluctuation values;
• averaging selected combinations of the added fluctuation values obtained in the adding step;
• and
• detecting defects on the surface based on a result of the averaging step.

A method for inspecting a surface of an object for defects using an optical imaging device, comprising:

• imaging the surface to obtain brightness data continuously;
• generating a first signal having a high-peak defect portion corresponding to a defect portion of the surface of the object and a low-peak noise portion corresponding to a normal portion of the surface of the object, the normal portion neighboring the defect portion;
• generating a second signal having a smoothed wave shape derived from the first signal;
• and
• detecting defects on the surface of the object based on the second signal.

A method for inspecting a surface of an object for defects using an optical imaging device, comprising:

• transferring the object and the optical imaging device;
• imaging the surface to obtain brightness data continuously;
• setting a brightness area which configures brightness data along a horizontal direction and along a vertical direction;
• shifting the brightness area in synchronization with an imaging direction of the object to obtain plural transfer positions of the brightness area;
• calculating for the plural transfer positions respective horizontal fluctuation values along the horizontal direction of brightness data obtained in the imaging step;
• calculating for the plural transfer positions respective vertical fluctuation values along the vertical direction of the brightness data obtained in the imaging step;
• adding each said horizontal fluctuation value to a respective of the vertical fluctuation values to obtain corresponding added fluctuation values;
• setting up an addition value area, wherein the added fluctuation values are arranged in the horizontal direction and the vertical direction;
• averaging selected combinations of the added fluctuation values obtained in the adding step;
• and
• detecting defects on the surface of the object based on a result of the averaging step.

An apparatus for inspecting a surface of an object for defects, comprising:

• a lighting device configured to illuminate the surface of the object;
• an imaging device configured to produce brightness data corresponding to an image of the surface being illuminated by the lighting device;
• a horizontal fluctuation calculator configured to compute horizontal fluctuation values of the brightness data along a horizontal direction;
• a vertical fluctuation calculator configured to compute vertical fluctuation values of the brightness data along a vertical direction;
• an adder configured to add each said horizontal fluctuation value and a respective of the vertical fluctuation values to obtain corresponding added fluctuation values;
• an averaging device configured to average selected combinations of the added fluctuation values;
• and
• a defect detector configured to detect a defect on the surface oft he object, including a comparator configured to compare a predetermined threshold value with an output of the averaging device.