Methods and apparatus to improve detection of defects in photomask blanks

A non-transitory machine readable storage medium comprising instructions to cause programmable circuitry to at least:

• identify a first potential defect in a photomask blank based on an intensity value not satisfying a first threshold but satisfying a second threshold, the intensity value based on pixel data associated with a first type of inspection of the photomask blank;
• and
• designate the first potential defect as a detected defect based on first coordinates for the first potential defect being within a threshold distance of second coordinates for a second potential defect, the second potential defect identified based on a second type of inspection of the photomask blank.

A method comprising:

• identifying a first potential defect in a photomask blank based on an intensity value not satisfying a first threshold but satisfying a second threshold, the intensity value based on pixel data associated with a first type of inspection data for the photomask blank;
• and
• designating, by executing instructions with programmable circuitry, the first potential defect as a detected defect based on first coordinates for the first potential defect being within a threshold distance of second coordinates for a second potential defect, the second potential defect identified based on a second type of inspection data for the photomask blank.