Process and devices for optically sensing a specimen with a large depth of field

A laser scanning microscope, with a laser source to produce a laser beam, in an arrangement where an optical instrument is placed downstream for the linear focusing of the laser beam onto or into a sample, and a scan module to move the laser beam transverse to the extension direction of the line focus above the sample, wherein a periodic intensity distribution is imposed on the laser beam by means of an amplitude grating, arranged in the illumination beam path, in the extension direction of its line focus and the amplitude grating in the microscope is so designed that it is moved back and forth along the extension direction of the line focus to produce a time phase change of the intensity distribution,

• characterized in that:
• a detection module is provided, which has a local resolution detection range, which records the sample area, with several recording pixels, two with evaluation channels that connect the recording pixels, and an evaluation unit connected to the two evaluation channels, and a control unit is provided, which during the measurement time of each recording pixel, synchronous in time with the phase of the detected sample light, alternatingly connects to the two evaluation channels, so that the detected sample light is divided into two fractions, which exhibit a phase shift with respect to one another, and is conducted to the two evaluation channels,
• wherein each recording pixel has two subpixels, wherein one of the subpixels can be connected only to the first of the two evaluation channels and the other subpixel only to the second evaluation channel.