Two-dimensional UV compatible programmable spatial filter

An optical inspection system for detecting anomalies on a sample, comprising:

• a light source for directing an incident light beam having a wavelength between about 340 nanometers and 400 nanometers onto a sample;
• a programmable spatial filter (PSF arranged in a path of light emanating from the sample in response to the incident light beam, wherein the PSF comprises:
• a pair of plates formed from a material that substantially transmits ultraviolet light and are sized to cover an aperture of the emanating light, the plates being arranged parallel to each other;
• a first indium tin oxide (ITO) layer deposed on a first one of the plates, the first ITO layer being divided into a plurality of first portions along a first direction;
• a second ITO layer deposed on a second one of the plates, wherein the first and second ITO layer are positioned between the plates, the first ITO layer being divided into a plurality of fit portions along a second direction that differs from the fist direction;
• liquid crystal layer arranged between the first ITO layer and second ITO layer portions, the liquid crystal layer being formed from a bi-stable material;
• and
• a controller configured for selectively applying a voltage potential difference between at least a pair of first and second ITO layer portions so that an adjacent portion of the liquid crystal layer are configured to inhibit or transmit one or more first portions of the emanating light;
• a detector arranged within the path of the emanating light so that the portions of the emanating light that are transmitted by the PSF impinge on the detector to thereby form an image of at least a portion of the sample;
• and
• an analyzer for receiving the image and determining whether there are any defects present on the sample portion by analyzing the received image.

A method of detecting anomalies on a sample, the method comprising:

• directing an incident light beam having a wavelength between about 340 nanometers and 400 nanometers onto a sample;
• selectively transmitting a first spatial portion of a emanating light beam through a programmable spatial filter (PSF), which results from the incident light beam hitting the sample, to a detector positioned within an image plane of such emanating light beam so that the first spatial portion has a minimum transmission value of about 40 percent wherein the first spatial portion is transmitted by applying a first voltage potential difference between a first row and a first column of the programmable spatial filter (PSF) having a plurality of addressable rows and columns;
• and
• inhibiting a second spatial portion of the emanating light beam through the PSF to the detector so that the second spatial portion(s) have a minimum extinction value of about 400:1.