Compact optical microscope, metrology device comprising the optical microscope and a wafer positioning metrology apparatus comprising the metrology device

A metrology device comprising

• an optical microscope configured to provide an image in an image plane of an object in an object plane, the optical microscope comprising in an order along an optical axis from the object plane to mage plane,
• a first lens having a first lens surface at the side of the object plane and a second lens surface at a side of image plane;
• second lens having a third lens surface at the side of the object plane and a fourth lens surface at a side of the image plane;
• and
• a third lens having a fifth lens surface at the side of the object plane and a sixth lens surface at a side of the image plane,
• wherein the first lens surface has a first semi-reflective coating a sixth lens surface as a second semi-reflective coating;
• a digital camera arranged in the image plane of the optical microscope to issue a digital image signal representative for an image in the image plane of the optical microscope, and
• a digital image processing device to process the digital image signal and to issue an image feature position signal indicative for a position of an image feature in the image.

A wafer positioning metrology apparatus comprising:

• a positioning device for positioning a wafer;
• an optical microscope configured to provide an image in an image plane of the wafer in an object plane, wherein the optical microscope comprises in an order along an optical axis from the object plane to the image plane,
• a first lens having a first lens surface at the side of the object plane and a second lens surface at a side of the image plane;
• a second lens having a third lens surface at the side of the object plane and a fourth lens ace at a side of the image plane;
• and
• a third lens having a fifth lens surface at the side of the object plane and a sixth lens surface at a side of the image plane,
• wherein the first lens surface has a semi-reflective coating and the sixth lens surface has a second se reflective coating,
• a digital camera arranged in the image plane of the of the optical microscope to issue a digital image signal representative for an image in the image plane of the optical microscope;
• and
• a digital image processing device to process the digital image signal and to issue an image feature position signal indicative for a position of an image feature in the image,
• wherein the image feature is an image of a marker on the wafer, and the positioning device is configured to use the image feature position signal to position the wafer.