Who invented the brightdark field microscopy

Coherent imaging by digital holographic microscopy focusing capabilities and Real world objects capturing using in line digital holography, How to extend depth of focus in 3D imaging by Subscribe to Digital Library. Receive Erratum Email Alert. Erratum Email Alerts notify you when an article has been updated or the paper is withdrawn. Visit My Account to manage your email alerts. Email or Username Forgot your username?

Password Forgot your password? Keep me signed in. No SPIE account? Create an account Institutional Access:. The alert successfully saved. If light waves pass those structures, they experience a certain phase shift that corresponds to the respective optical path lengths.

The phase contrast technique is intended to convert such phase shifts into amplitude differences that are detectable by the human eye bright-dark-contrasts. Principle When light passes through an object that is more optically dense than its environment background , the wavefronts are retarded with respect to the unaffected, bypassing background light.

The idea behind visualization of phase shifts in the object light is to change the phase of the background light in such a manner that background and object light weaken or even cancel each other out when interfering in the primary image plane. Consequently, the object would appear dark against the background.

Schematic simplified assembly of a phase contrast microscope containing an annular aperture light ring in the condenser and an accordant phase ring in the objective. The background light is colored orange and the object light is rose. In order to do that, the background light must be influenced without affecting object light which is already phase shifted due to the object.

This is achieved by placing a annular aperture light ring in the front focal plane of the condenser and a matching phase ring in the back focal plane of the objective see figure on the left. Due to this alignment, the parallel light fronts leaving the annular aperture are focused by the objective directly onto the phase ring, i.

The reduction of the amplitude is necessary, because the object light is much less intense than the bright direct light. If an object is placed in the light path, the object light gets deflected, only slightly passing through the phase ring. Most object light passes by and remains unaffected as desired. For this reason, the properties of the phase ring must take into account the most frequent refractive index and the thickness of the samples.

Starting at a certain thickness, phase contrast objects show light or dark "halos" along their edges and simulate a kind of 3D effect.

This is due to the fact that a small part of the diffracted object light passes through the phase ring as well and interferes at the image plane.