A system for measuring the topography of a surface including a carriage assembly and a base assembly. The carriage assembly comprising a plurality of displacement-measuring probes coupled to a carriage support structure. The base assembly positioned adjacent to the carriage assembly and comprising at least one reference object with an opening sized to receive a test object. At least one of the carriage assembly or the base assembly is configured to translate with respect to the other in at least two directions to enable at least one of the displacement-measuring probes to measure a displacement to a reference surface of the reference object and at least another one of the displacement-measuring probes to measure a displacement to a target surface of the target object whose topography is measured.

A scanning monochromatic spatial low-coherent interferometer (S-LCI) can be used to simultaneously measure geometric thickness and refractive index. The probe beam of the scanning S-LCI can be an off-axis converging single wavelength laser beam, and the decomposed incident angles of the beam on the sample can be accurately defined in the Fourier domain. The angle dependent phase shift of a plane parallel plate or other sample can be obtained in a single system measurement. From the angle dependent phase shift, the geometric thickness and refractive index of the sample can be simultaneously obtained. Additionally or alternatively, the S-LCI system can interrogate the sample to profile the location and refractive index of one or more layers within the sample using the disclosed techniques.

A grazing-incidence interferometer includes first and second spaced-apart diffractive optical elements with a generally planar object disposed therebetween. The first diffractive optical element forms sheared first-diffracted-order light beams that reflect from opposite first and second surfaces of the object at grazing-incidence angles, while a zero-diffracted-order light beam goes unreflected. The second diffractive optical element combines the unreflected zero-diffracted-order light beam and the sheared reflected beams to form a collimated, combined beam. A 1 double-telecentric relay system relays the combined beam to a folding optical system that forms first and second interference images on a diffusing screen located at an image plane. Digital images of the first and second interference images are obtained and processed to characterize the thickness variation of the object.

A grazing incidence interferometer is configured to measure a profile of a target surface using a measurement beam radiated on the target surface in a direction oblique to a normal line of the target surface and reflected on the target surface to cause an interference with a reference beam. The grazing incidence interferometer includes: a light source to emit light; a first polarization beam splitter that splits the light from the light source into the reference beam and the measurement beam; a ratio changer that changes a light amount ratio between the reference beam and the measurement beam; a second polarization beam splitter that synthesizes the measurement beam reflected on the target surface and the reference beam; and an image capturing camera that receives the synthesized beam of the reference beam and the measurement beam.

A displacement detecting device includes a light source that performs irradiation with light, a light-beam splitting section, a reflection/transmission section, a phase plate, a transmission-type diffraction grating, a light-beam combining section, a light-receiving section, and a relative position information output unit. The reflection/transmission section transmits or reflects a first light beam, and causes the beam to enter a member to be measured. Furthermore, the reflection/transmission section guides the first light beam to a specific position of the member to be measured in the case where the member to be measured is in a reference position. Moreover, an optical path of the first light beam reflected by the member to be measured again overlaps with an optical path of the first light beam reflected at a specific position of the member to be measured.