A digital microscope apparatus includes a first imaging unit including a first imaging device and a first optical system including an objective lens configured to enlarge first and second images of a preparation that holds a sample, the first image being formed on the first device through the first system, a second imaging unit including a second optical system that is branched from the first system and has a depth of field larger than the first system and a second imaging device on which the second image is formed through the second system, and a controller configured to calculate a provisional in-focus position of the lens based on the second image, determine an area of the first device, from which the first image is read, and search for, based on the read image, an in-focus position of the lens in a predetermined range based on the provisional in-focus position.

A method refocuses on an optical assembly target surface, using at least one beam originating from a short-pulse optical source, having at least one optical system for focusing the beam on the surface. Refocusing occurs after learning reference conditions for which the assembly is considered as focused. A focusing signal is detected representing a time overlap of pulses between a beam reflected and a reference beam not reflected by the surface, one of the beams delayed by a delay line. The optical path on which the delay line is placed is varied, on the basis of the reference conditions, to cause the focusing signal to reach or exceed a predetermined threshold. The focus is adjusted on the basis of the path variation between the reference conditions and the conditions for which the focusing signal reaches or exceeds the threshold.

A digital microscope apparatus includes a first imaging unit including a first imaging device and a first optical system including an objective lens configured to enlarge first and second images of a preparation that holds a sample, the first image being formed on the first device through the first system, a second imaging unit including a second optical system that is branched from the first system and has a depth of field larger than the first system and a second imaging device on which the second image is formed through the second system, and a controller configured to calculate a provisional in-focus position of the lens based on the second image, determine an area of the first device, from which the first image is read, and search for, based on the read image, an in-focus position of the lens in a predetermined range based on the provisional in-focus position.

A focus monitoring arrangement (1000) is provided for a scatterometer or other optical system. A first focus sensor (510) provides a first focus signal (S1-S2) indicating focus relative to a first reference distance (z1). A second focus sensor (1510) for providing a second focus signal (C1-C2) indicating focus relative to a second reference distance (z2). A processor (1530) calculates a third focus signal by combining the first focus signal and the second focus signal. By varying the proportions of the first and second focus signals in calculating the third focus signal, an effective focus offset can be varied electronically, without moving elements.

An automatic focus system for an optical microscope that facilitates faster focusing by using at least two offset focusing cameras. Each offset focusing camera can be positioned on a different side of an image forming conjugate plane so that their sharpness curves intersect at the image forming conjugate plane. Focus of a specimen can be adjusted by using sharpness values determined from images taken by the offset focusing cameras.

An optical microscope and method for detecting lens immersion in optical microscopy includes an ultrasound circuit acoustically coupled to both an objective lens and a sample of an optical microscope, the ultrasound circuit comprising an ultrasound transmitter and an ultrasound receiver. The optical microscope and method includes transmitting an ultrasound pulse from the ultrasound transmitter to the ultrasound receiver, determining that a transit time of the ultrasound pulse is less than a threshold time, and providing an output signal from the pulse discriminator indicating that the ultrasound pulse is less than the threshold time.

A focus monitoring arrangement (1000) is provided for a scatterometer or other optical system. A first focus sensor (510) provides a first focus signal (S1-S2) indicating focus relative to a first reference distance (z1). A second focus sensor (1510) for providing a second focus signal (C1-C2) indicating focus relative to a second reference distance (z2). A processor (1530) calculates a third focus signal by combining the first focus signal and the second focus signal. By varying the proportions of the first and second focus signals in calculating the third focus signal, an effective focus offset can be varied electronically, without moving elements.

An optical microscope and method for detecting lens immersion in optical microscopy includes an ultrasound circuit acoustically coupled to both an objective lens and a sample of an optical microscope, the ultrasound circuit comprising an ultrasound transmitter and an ultrasound receiver. The optical microscope and method includes transmitting an ultrasound pulse from the ultrasound transmitter to the ultrasound receiver, determining that a transit time of the ultrasound pulse is less than a threshold time, and providing an output signal from the pulse discriminator indicating that the ultrasound pulse is less than the threshold time.

An autofocus mechanism includes a light source emitting light through an objective lens at a work piece; a first detector detecting a portion of light reflected by the work piece and generating a first signal; a second detector detecting a portion of the reflected light and generating a second signal; a first amplifier amplifying the first signal and generating a first amplified signal; a second amplifier amplifying the second signal and generating a second amplified signal; an amplification rate definer defining an amplification rate of each of the first amplifier and the second amplifier based on the first amplified signal and the second amplified signal, respectively; and a calculator identifying a focal position of the objective lens based on the first amplified signal and the second amplified signal.

An optical microscope and method for detecting lens immersion in optical microscopy includes an ultrasound circuit acoustically coupled to both an objective lens and a sample slide of an optical microscope, the ultrasound circuit comprising an ultrasound transmitter and an ultrasound receiver. The optical microscope and method includes transmitting an ultrasound pulse from the ultrasound transmitter to the ultrasound receiver, determining that a transit time of the ultrasound pulse is less than a threshold time, and providing an output signal from the pulse discriminator indicating that the ultrasound pulse is less than the threshold time.