Disclosed herein are spectral imaging systems having an internally folded prism, which can have four different refracting surfaces. A first angle defines the spatial relationship between the first and second refracting surfaces. The first angle can have a range between 45-95 degrees. In some embodiments, the first angle can be 70 degrees. The spatial relationship of the third and fourth refracting surfaces can be defined by a second angle, which can be the same as the first angle. Finally, the spatial relationship of the second and third refracting surfaces can be defined by a third angle, which can have a range between 90-145 degrees. The prism index of refraction, the first, second, and third angles are selected such that TIR is achieved at two of the refracting surfaces. Additionally, these prism parameters are selected such that a 180 degrees fold of the optical path is achieved entirely within the prism.

An apparatus includes a six-axis correction stage, an auto-collimation measurement device, a light splitter, a telecentric image measurement device, and a controller. The six-axis correction stage carries a device under test; the auto-collimation measurement device is arranged above the six-axis correction stage along a measurement optical axis; the light splitter is arranged on the measurement optical axis and is interposed between the six-axis correction stage and the auto-collimation measurement device. A method controls the six-axis correction stage to correct rotation errors in at least two degrees of freedom of the device under test according to a measurement result of the auto-collimation measurement device, and controls the six-axis correction stage to correct translation and yaw errors in at least three degrees of freedom of the device under test according to a measurement result of the telecentric image measurement device by means of the controller.

An apparatus includes a six-axis correction stage, an auto-collimation measurement device, a light splitter, a telecentric image measurement device, and a controller. The six-axis correction stage carries a device under test; the auto-collimation measurement device is arranged above the six-axis correction stage along a measurement optical axis; the light splitter is arranged on the measurement optical axis and is interposed between the six-axis correction stage and the auto-collimation measurement device. A method controls the six-axis correction stage to correct rotation errors in at least two degrees of freedom of the device under test according to a measurement result of the auto-collimation measurement device, and controls the six-axis correction stage to correct translation and yaw errors in at least three degrees of freedom of the device under test according to a measurement result of the telecentric image measurement device by means of the controller.

The present invention is a multi-spectral digital autocollimator system featuring a diverse range of capabilities. It comprises a multi-spectral light source spanning from deep UV to Far-IR (8-12 microns), a collimating mirror, a unique optical beam splitting lens, and an imaging device designed to detect the light deviation caused by the multi-spectral light source. The system projects the light through a specially designed cross target, generating visible light, and this cross target can be heated or cooled to create a high-quality black body cross. The resulting light is then reflected back from an examined reflective object and captured by the imaging device. An appropriate thermal camera is strategically positioned after the optical beam splitting lens to analyze the thermal properties of the black body cross. The primary objective of this invention is to offer a precise and multi-spectral digital autocollimator capable of facilitating optical alignment with different spectral devices.