A collimation evaluation device includes a first reflection member, a second reflection member, a screen, and a housing. A first reflection surface of the first reflection member and a first reflection surface of the second reflection member face each other and are parallel to each other. Further, interference fringes are formed on the screen by light L.sub.12 reflected on the first reflection surface of the first reflection member and a second reflection surface of the second reflection member and light L.sub.21 reflected on a second reflection surface of the first reflection member and the first reflection surface of the second reflection member, and collimation of incident light is evaluated on the basis of a direction of the interference fringes.

A point diffraction interferometric wavefront aberration measuring device comprising an optical source, an optical splitter, a first light intensity and polarization regulator, a phase shifter, a second light intensity and polarization regulator, an ideal wavefront generator, an object precision adjusting stage, a measured optical system, an image wavefront detection unit, an image precision adjusting stage, and a data processing unit. The center distance between the first output port and the second output port of the ideal wavefront generator is smaller than the diameter of the isoplanatic region of the measured optical system and is greater than the ratio of the diameter of the image point dispersion speckle of the measured optical system over the amplification factor thereof. A method for detecting wavefront aberration of the optical system is also provided by using the device.

A device for measuring point diffraction interferometric wavefront aberration having an optical source, an optical splitter, a first light intensity and polarization regulator, a phase shifter, a second light intensity and polarization regulator, an ideal wavefront generator, an object precision adjusting stage, a measured optical system, an image wavefront detection unit, an image precision adjusting stage, and a data processing unit. A method for detecting wavefront aberration of the optical system by using the device is also disclosed.

Apparatuses and methods for investigating the inside of a tissue cell are disclosed. Embodiments include diffusely scattering light off a target sample, producing two crossing beams from the scattered light, and using a camera to create an image from the light. Some embodiments utilize a Fourier lens and a Fresnel biprism, and optionally include a long-coherence light source, a delay plate (which can be a polarization rotator or an optical flat), and/or a beam expander. Still further embodiments utilize a diffraction grating, a spatial filter (which may include two differently sized apertures), and a Fourier lens, and optionally include differently sized apertures in the spatial filter. Some embodiments include a transparent support and illuminating the target at an oblique angle through the transparent support. Still further embodiments utilize a low-coherence light source and/or immobilizing the sample tissue using surface bonding chemistry.