Extended depth of field through wave-front coding

Abstract

We designed an optical-digital system that delivers near-diffraction-limited imaging performance with a large depth of field. This system is the standard incoherent optical system modified by a phase mask with digital processing of the resulting intermediate image. The phase mask alters or codes the received incoherent wave front in such a way that the point-spread function and the optical transfer function do not change appreciably as a function of misfocus. Focus-independent digital filtering of the intermediate image is used to produce a combined optical-digital system that has a nearly diffraction limited point-spread function. This high-resolution extended depth of field is obtained through the expense of an increased dynamic range of the incoherent system. We use both the ambiguity function and the stationary-phase method to design these phase masks.

Extended depth of field imaging for high speed cell analysis

“…The deformation causes light from different focal positions from a single lateral position in object space to be imaged on the detector plane simultaneously. This method can be applied to both TDI and frame-based detection techniques and is referred to as Wavefront Coded TM (WFC) by its developer, CDM Optics (Boulder, CO) (13). A third method involves imparting spherical aberration in the wavefront by inserting a coverglass of specific thickness between the object and the objective lens.…”

Analytical model for effect of temperature variation on PSF consistency in wavefront coding infrared imaging system

“…A larger amount of aberrations purposely introduced by an optical phase mask tend to achieve better PSF consistency [16]. As shown in Table 4, an OP caused by temperature variation of a Gematerial CPM is great larger than an OP caused by temperature variation of a ZnSe-material CPM.…”

“…The wavefront coding imaging system performs the wavefront modulation of the incident rays by mounting a purposely designed phase mask in a pupil and then a decoded image is obtained by reconstructing a coded blurred image [16]. For the athermalization of a wavefront coding infrared imaging system, the form parameters of the optical phase mask are purposely designed to keep the PSFs proximately consistent over a wide range of environmental temperatures.…”

“…1 illustrates the procedure of a wavefront coding infrared imaging system. The wavefront coding technique performs the wavefront modulation of the incident rays by mounting a purposely designed optical phase mask in the pupil of an optical system, and then the coded blurred image are digitally decoded to output a decoded image with sharpness [16].…”

Endoscopic Application of a Compact Compound-Eye Camera

“…It is well known that depth estimation with a multi-baseline stereo method, where more than two cameras are used, improves accuracy of estimation. Furthermore, multi-lens design allows systems to acquire multi-dimensional optical information such as multispectral images [9] that provide information of tissues or blood vessels, and polarization [10] for controlling the observable depth.…”