Home page of the microscope service parts, repair and spare parts online catalog - Sermik-Oplatek Mikroskopservice Dresden f.n.n.Z

Description of this part for the microscope.

PhA (negative, anoptral, yellow stripe*), PhS (positive, gray stripe), and A (amplitude phase contrast, brown stripe).
Condenser: Compatible with PZO K3Ph, K3Ph1, KS and K4Ph condensers. Not compatible with PZO K3Phz, KFF, and KFL condensers.
It also fits the PZO KS condenser (from the PZO MB30S microscope) after installing the appropriate polarizers.

The PZO phase contrast kit can be used with any microscope from any manufacturer that accepts a 39.5 mm condenser, although the top lens can be replaced with a 37 mm lens.

*Note: The yellow stripe on PZO PhA phase contrast objectives sometimes turns orange over time.

Description of this part for the microscope.

PhA (negative, anoptral, yellow stripe*), PhS (positive, gray stripe), and A (amplitude phase contrast, brown stripe).
Condenser: Compatible with PZO K3Ph, K3Ph1, KS and K4Ph condensers. Not compatible with PZO K3Phz, KFF, and KFL condensers.
It also fits the PZO KS condenser (from the PZO MB30S microscope) after installing the appropriate polarizers.

The PZO phase contrast kit can be used with any microscope from any manufacturer that accepts a 39.5 mm condenser, although the top lens can be replaced with a 37 mm lens.

*Note: The yellow stripe on PZO PhA phase contrast objectives sometimes turns orange over time.

Description of this part for the microscope.

Length: 45 mm
Cover Glass: 0.17 mm
Immersion: Yes, oil immersion
Thread: RMS
Info: PhS = positive phase contrast (gray bar).

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

This objective lens is in excellent condition, with no signs of use. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=45 mm.

Description of this part for the microscope.

45 mm
Cover Glass: 0.17 mm
Immersion: no
Thread: RMS
Info: PhS = positive phase contrast (gray bar).

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

This objective lens is in excellent condition. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=45 mm.

Description of this part for the microscope.

mm
Cover Glass: 0.17 mm
Immersion: no
Thread: RMS
Info: PhA = negative (anoptral) phase contrast (yellow bar).

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

This objective lens is in excellent condition. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=33 mm.

After installing the 12 mm adapter, this objective lens will have FL = 45 mm.

Description of this part for the microscope.

mm
Cover Glass: no
Immersion: no
Thread: RMS
Info: Ph = Zernike phase contrast (green bar).

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

Info: Ph (Zernike) objectives produce an exceptionally nice image with a bluish background when used with KS phase contrast condensers from the PZO MB-30S microscope.

This objective lens is in excellent condition. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=45 mm.

Description of this part for the microscope.

40
Tube Length: 160 mm
Focal Length: 45 mm
Cover Glass: 0.17 mm
Immersion: no
Thread: RMS
Info: PhA = anoptral phase contrast (gray band).

Note: The yellow band sometimes turns orange over time.

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

This objective lens is in excellent condition. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=45 mm.

Description of this part for the microscope.

40
Tube Length: 160 mm
Focal Length: 45 mm
Cover Glass: 0.17 mm
Immersion: no
Thread: RMS
Info: PhA = anoptral phase contrast (gray band).

Note: The yellow band sometimes turns orange over time.

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

This objective lens is in excellent condition. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=45 mm.

Description of this part for the microscope.

24
Tube Length: 160 mm
Focal Length: 45 mm
Cover Glass: nein (-)
Immersion: no
Thread: RMS
Info: PhA = anoptral phase contrast (gray band).

Note: The yellow band sometimes turns orange over time.

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

This objective lens is in excellent condition. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=45 mm.

Description of this part for the microscope.

0,24
Tube Length: 160 mm
Focal Length: 45 mm
Cover Glass: nein (0)
Immersion: no
Thread: RMS
Info: PhA = anoptral phase contrast (gray band).

Note: The yellow band sometimes turns orange over time.

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

This objective lens is in excellent condition. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=45 mm.

Description of this part for the microscope.

Length: 45 mm
Cover Glass: 0.17 mm
Immersion: Yes, oil immersion
Thread: RMS
Info: PhA = anoptral phase contrast (gray band).

Note: The yellow band sometimes turns orange over time.

Fits the following PZO phase contrast condensers:
- K4Ph
- K3Ph
- K3Ph1
- KS
- KFF 2
- KFL

This objective lens is in excellent condition, with no signs of use. It's difficult to find an objective of this quality on the used parts market.

It can be used with any microscope from any manufacturer, along with a compatible phase contrast condenser. Of course, the microscope must be compatible, i.e. support RMS objectives, TL=160 mm, FL=45 mm.

Description of this part for the microscope.

eyepiece contains two lines in the field of view used for adjusting DIC interference fringes, but this is the only difference compared to an otherwise identical eyepiece used for adjusting phase contrast. Therefore it can be used:
- for adjusting DIC
- for adjusting phase contrast
- for observing the iris diaphragm
- for observing the filament when setting illumination according to the Köhler standard

This is one of those microscope elements for which many different names are used. Among others:
- phase telescope
- phase contrast telescope
- phase alignment telescope
- phase adjustment telescope
- phase centering telescope
- phase contrast centering telescope
- phase contrast alignment telescope
- phase contrast adjustment telescope
- centering telescope
- condenser centering telescope
- condenser alignment telescope
- condenser adjustment telescope
- alignment telescope
- adjustment telescope
- inspection telescope
- aperture viewing telescope
- back focal plane viewing telescope
- auxiliary microscope
- phase contrast auxiliary microscope
- alignment auxiliary microscope
- centering auxiliary microscope
- adjustment auxiliary microscope
- auxiliary telescope
- centering scope
- alignment scope
- phase scope
- phase viewer
- phase contrast viewer
- phase centering eyepiece
- phase contrast eyepiece
- phase alignment eyepiece
- phase telescope eyepiece
- centering eyepiece
- condenser centering eyepiece
- adjustment eyepiece
- inspection eyepiece

Description of this part for the microscope.

thread

Fits condensers:
- PZO KPI-2 (Pluta / Nomarski DIC)
- PZO K4Ph (phase contrast Ph, PhA, PhS, A)
- PZO K3Ph (phase contrast Ph, PhA, PhS, A)
- PZO K3Ph1 (phase contrast Ph, PhA, PhS, A)
- PZO KFL (phase contrast / darkfield for fluorescence)
- PZO KFF
- PZO K3Phz (variable phase contrast Phz)

This upper lens allows conversion of the mounting standard from PZO 39.5 mm to the 37 mm standard and the use of PZO condensers on many other microscopes, e.g. Olympus BH / CH-2 or Lomo MBB

This microscope element can solve the following issues:
- How to mount PZO DIC on a Lomo microscope?
- Can I install a PZO DIC KPI2 condenser on an Olympus CH-2 microscope?
- Can I use PZO phase contrast on my non-PZO microscope?
- Does PZO phase contrast or DIC work on a microscope with a 37 mm condenser mount?

Description of this part for the microscope.

condenser fits microscopes from many manufacturers (e.g. Lomo, Carl Zeiss Jena, Olympus and many others) with a condenser holder diameter of 37 mm.

Description of this part for the microscope.

Lichteinstellupe (Centering / Focus telescope)
Mounting diameter: 23.2 mm + original 30 mm adapter

This centering telescope can be used for:
- DIC alignment (Differential Interference Contrast)
- Phase contrast alignment (centering phase rings)
- Aperture diaphragm inspection (iris diaphragm observation)Filament centering when setting up Köhler illumination

This is one of those microscope elements for which many different names are used. Among others:
- phase telescope
- phase contrast telescope
- phase alignment telescope
- phase adjustment telescope
- phase centering telescope
- phase contrast centering telescope
- phase contrast alignment telescope
- phase contrast adjustment telescope
- centering telescope
- condenser centering telescope
- condenser alignment telescope
- condenser adjustment telescope
- alignment telescope
- adjustment telescope
- inspection telescope
- aperture viewing telescope
- back focal plane viewing telescope
- auxiliary microscope
- phase contrast auxiliary microscope
- alignment auxiliary microscope
- centering auxiliary microscope
- adjustment auxiliary microscope
- auxiliary telescope
- centering scope
- alignment scope
- phase scope
- phase viewer
- phase contrast viewer
- phase centering eyepiece
- phase contrast eyepiece
- phase alignment eyepiece
- phase telescope eyepiece
- centering eyepiece
- condenser centering eyepiece
- adjustment eyepiece
- inspection eyepiece

Description of this part for the microscope.

10x
Correction: Achromat
Numerical aperture N.A.: 0.24
Tube length: 160 mm
Parfocal length: 45 mm
Cover glass: not required, but may be used
Immersion: no
Thread: RMS
Info: Ph = Zernike phase contrast (green ring).

Compatible with the following phase contrast condensers:
- PZO K4Ph
- PZO K3Ph
- PZO K3Ph1
- PZO KS
- PZO KFF 2
- PZO KFL
- and even PZO K3PhZ

Here https://www.facebook.com/photo/?fbid=1262188377207557&set=a.462747092529893 you can see a very interesting test. It shows that if you use this PZO objective with the green ring (i.e. Zernike phase contrast) together with light-polarizing condensers (i.e. PZO KS or PZO K3PhZ), you will obtain an interesting blue background effect.

This objective can be used with any microscope from any manufacturer together with a compatible phase contrast condenser. Naturally, the microscope must support RMS objectives, TL=160 mm and FL=45 mm.

Description of this part for the microscope.

Achromat
Numerical aperture N.A.: 0.24
Tube length: 160 mm
Focal length: 45 mm
Cover glass: not required, but may be used
Immersion: no
Thread: RMS
Info: PhZ = variable phase contrast (white ring).

PZO PhZ objectives, designed for variable phase contrast, are intended to be used together with the PZO K3PhZ phase contrast condenser equipped with a rotating polarizer.

This objective can be used with any microscope from any manufacturer together with a compatible phase contrast condenser. Naturally, the microscope must support RMS objectives with a tube length of 160 mm and a parfocal length of 45 mm.

Description of this part for the microscope.

Achromat
Numerical aperture N.A.: 0.4
Tube length: 160 mm
Focal length: 45 mm
Cover glass: yes, 0,17 mm
Immersion: no
Thread: RMS
Info: PhZ = variable phase contrast (white ring).

PZO PhZ objectives, designed for variable phase contrast, are intended to be used together with the PZO K3PhZ phase contrast condenser equipped with a rotating polarizer.

This objective can be used with any microscope from any manufacturer together with a compatible phase contrast condenser. Naturally, the microscope must support RMS objectives with a tube length of 160 mm and a parfocal length of 45 mm.

Description of this part for the microscope.

Achromat
Numerical aperture N.A.: 1,3
Tube length: 160 mm
Focal length: 45 mm
Cover glass: yes, 0,17 mm
Immersion: yes, oil
Thread: RMS
Info: PhZ = variable phase contrast (white ring).

PZO PhZ objectives, designed for variable phase contrast, are intended to be used together with the PZO K3PhZ phase contrast condenser equipped with a rotating polarizer.

This objective can be used with any microscope from any manufacturer together with a compatible phase contrast condenser. Naturally, the microscope must support RMS objectives with a tube length of 160 mm and a parfocal length of 45 mm.

Description of this part for the microscope.

condensers:
- PZO K3Ph
- PZO K3Ph1
- PZO K4Ph
- PZO KS (this is the "stereo contrast" condenser sold with PZO MB30S microscopes. There are no(!) markings or numbers whatsoever on this condenser)

The diaphragm blades themselves, which are located inside this module, also fit the diaphragms installed in the following condensers:
- PZO K3PhZ (variable phase contrast)
- PZO KPI2 (condenser for Pluta DIC)

Mechanically, this diaphragm is screwed onto the lower part of the phase contrast condenser. The housing of the diaphragm module has a 32 mm male thread. The complete diaphragm with its housing has a diameter of 52 mm.

The iris diaphragm is damaged very often. Replacing it can solve the following problems:
- when the small lever used to open and close the diaphragm blades breaks off. This is a common failure, because this lever is a thin sheet made of a brittle alloy
- when the diaphragm blades get damaged, bent or broken. This is one of the most common faults in microscopes
- when the diaphragm blades jump out of their mounting grooves and you cannot reassemble them
- when the diaphragm stops opening and closing and is completely seized. This happens when the grease has dried out or rust has glued the blades together

The last photos in the gallery show the PZO KS condenser, with an arrow indicating where this diaphragm is located inside the condenser. This allows the component to be identified unambiguously.

PZO phase contrast condensers are often fitted in microscopes from manufacturers other than PZO, so the component presented here is not a repair part for one specific microscope model. This diaphragm will help to repair a phase contrast condenser - regardless of which microscope model and which manufacturer it works in.

Description of this part for the microscope.

condensers:
- PZO K3Ph
- PZO K3Ph1
- PZO K4Ph
- PZO K3PhZ (variable phase contrast)
- PZO KS (this is the "stereo contrast" condenser sold with PZO MB30S microscopes. There are no(!) markings or numbers whatsoever on this condenser)

These condensers contain phase annuli (also called phase rings) and each of them can be centred. They are centred by turning two screws with rectangular heads (different from the square heads in Carl Zeiss Jena condensers).
The condenser models listed above have a special centring module screwed to the housing of the turret, with two spring-loaded centring keys that fit these screws. Thanks to this, there is no need to keep the centring keys at hand and there is no risk of losing them.

Unfortunately, these centring keys protrude more than 40 mm beyond the outline of the condenser and often get bent. In addition, many users unscrew them from the housing for transport or when they store the condenser in non-original packaging - and this leads to the unscrewed centring keys being lost frequently. The solution to such a problem is then to buy separate centring keys or to replace the entire centring module.

Mechanically, this module is screwed to the housing of the PZO phase contrast condenser with two screws, which are additionally locked by two pins - all these elements are included with the centring module presented here.

The last photos in the gallery show the PZO K3Ph condenser, with an arrow indicating where this component for centring the phase annuli is located inside the condenser. This allows the component to be identified unambiguously. The video in the video gallery shows the movement of the moving parts, the action of the springs and how the centring keys rotate.

PZO phase contrast condensers are often fitted in microscopes from manufacturers other than PZO, so the component presented here is not a repair part for one specific microscope model. This module will help to repair a phase contrast condenser - regardless of which microscope model and which manufacturer it works in.

Description of this part for the microscope.

Basic parameters of this phase annulus:
Position in the condenser: phase annulus to be fitted in the "40x" position of a turret condenser, to be paired with the phase ring in a 40x phase contrast objective
Construction: disc with a phase annulus in a mount
Material: glass, colourless polarising film and printed black circles
Diameter of the glass disc with the printed annulus: 14 mm
Disc mount: metal, with a notch for the spring-loaded ejector pin
Spring cushioning: no - the mount of the 40x phase annulus has no spring cushioning
Other names: phase disc, phase glass, phase ring
Intended for: PZO KS condenser
Compatibility: PZO K3Ph, K3Ph1, K4Ph and K3PhZ phase contrast condensers
Important note on appearance: the black dots and lines visible in the photo are not a surface defect - this is how PZO phase rings normally look
Note on the polarising film: two pieces of polarising film are glued onto the annulus. The vertical line running through the middle of the annulus is where these two films meet - it is neither a defect nor a crack, even though it looks like one

Over the years the polarising film used on these phase annuli very often came unstuck (delamination), which often - though not always - caused it to lose its properties and made stereoscopic contrast completely unusable. In such a case you can either:
- peel off the old film, clean the surface of the glass disc and glue on a new one, keeping the polarisation angle
- or replace the whole disc with one like the one offered here.

The specific feature of the PZO KS is that the ring of every disc is divided into two equal halves by two polarisers set perpendicular to each other. By rotating the analyser you extinguish one half of the ring and brighten the other - smoothly, without moving anything in the optical path. The specimen is then illuminated from one side.

And this is exactly how the disc from the KS condenser differs from the discs of the PZO K3Ph, K3Ph1, K4Ph and K3PhZ condensers. Mechanically it is the same insert, 14 mm in diameter, and it fits those condensers. The difference lies solely in the polarisation of the ring itself, described above. That is why a KS disc used in an ordinary phase condenser still gives correct phase contrast with no loss of quality, but once an analyser is placed in the optical path (for example under the head) it can produce interesting, unexpected effects.

For DIY enthusiasts looking for new, unusual visual effects in microscopy, an interesting option is to fit this polarising phase annulus into a different phase contrast condenser. You can then explore the unusual behaviour of various objectives in partially polarised light.
Here is an example: a Zernike-type phase contrast objective (PZO Ph with a green stripe) combined with the phase annulus from the PZO KS condenser gives an unusual, bluish background colour (https://www.facebook.com/photo?fbid=1262188377207557&set=a.462747092529893). And here you can see PZO microscope objectives for six types of phase contrast: https://www.facebook.com/MikroskopyPZO/photos/por%C3%B3wnanie-obiektyw%C3%B3w-pzo-20x-do-kontrastu-fazowego-pier%C5%9Bcienie-zielony-ph-kf-do/1259433520816376/.

The PZO KS condenser was fitted to PZO MB-30S microscopes and was an essential part of a special phase contrast method called "Stereoscopic Contrast" (KS). This condenser is characterised by carrying no markings at all - and that is how you recognise it.

Fastest way to recognise the PZO KS condenser:
PZO KS condenser: no serial number, no manufacturer name or logo, no model designation
Other PZO phase contrast condensers: at least a printed model designation (for example KFF, KFL, K3Ph, K3Ph1, K4Ph, K3PhZ, or KPI 2 in the case of the DIC condenser)

Description of this part for the microscope.

Basic parameters of this phase annulus:
Position in the condenser: phase annulus to be fitted in the "10x" position of a turret condenser, to be paired with the phase ring in a 10x phase contrast objective
Construction: disc with a phase annulus in a mount
Material: glass, colourless polarising film and printed black circles
Diameter of the glass disc with the printed annulus: 14 mm
Disc mount: metal, with a notch for the spring-loaded ejector pin
Spring cushioning: yes - inside the mount, underneath the glass with the phase annulus, there is a spring cushioning
Other names: phase disc, phase glass, phase ring
Intended for: PZO KS condenser
Compatibility: PZO K3Ph, K3Ph1, K4Ph and K3PhZ phase contrast condensers
Important note on appearance: the black dots and lines visible in the photo are not a surface defect - this is how PZO phase rings normally look
Note on the polarising film: two pieces of polarising film are glued onto the annulus. The vertical line running through the middle of the annulus is where these two films meet - it is neither a defect nor a crack, even though it looks like one

Over the years the polarising film used on these phase annuli very often came unstuck (delamination), which often - though not always - caused it to lose its properties and made stereoscopic contrast completely unusable. In such a case you can either:
- peel off the old film, clean the surface of the glass disc and glue on a new one, keeping the polarisation angle
- or replace the whole disc with one like the one offered here.

The specific feature of the PZO KS is that the ring of every disc is divided into two equal halves by two polarisers set perpendicular to each other. By rotating the analyser you extinguish one half of the ring and brighten the other - smoothly, without moving anything in the optical path. The specimen is then illuminated from one side.

And this is exactly how the disc from the KS condenser differs from the discs of the PZO K3Ph, K3Ph1, K4Ph and K3PhZ condensers. Mechanically it is the same insert, 14 mm in diameter, and it fits those condensers. The difference lies solely in the polarisation of the ring itself, described above. That is why a KS disc used in an ordinary phase condenser still gives correct phase contrast with no loss of quality, but once an analyser is placed in the optical path (for example under the head) it can produce interesting, unexpected effects.

For DIY enthusiasts looking for new, unusual visual effects in microscopy, an interesting option is to fit this polarising phase annulus into a different phase contrast condenser. You can then explore the unusual behaviour of various objectives in partially polarised light.
Here is an example: a Zernike-type phase contrast objective (PZO Ph with a green stripe) combined with the phase annulus from the PZO KS condenser gives an unusual, bluish background colour (https://www.facebook.com/photo?fbid=1262188377207557&set=a.462747092529893). And here you can see PZO microscope objectives for six types of phase contrast: https://www.facebook.com/MikroskopyPZO/photos/por%C3%B3wnanie-obiektyw%C3%B3w-pzo-20x-do-kontrastu-fazowego-pier%C5%9Bcienie-zielony-ph-kf-do/1259433520816376/.

The PZO KS condenser was fitted to PZO MB-30S microscopes and was an essential part of a special phase contrast method called "Stereoscopic Contrast" (KS). This condenser is characterised by carrying no markings at all - and that is how you recognise it.

Fastest way to recognise the PZO KS condenser:
PZO KS condenser: no serial number, no manufacturer name or logo, no model designation
Other PZO phase contrast condensers: at least a printed model designation (for example KFF, KFL, K3Ph, K3Ph1, K4Ph, K3PhZ, or KPI 2 in the case of the DIC condenser)

Description of this part for the microscope.

Basic parameters of this phase annulus:
Position in the condenser: phase annulus to be fitted in the "20x" position of a turret condenser, to be paired with the phase ring in a 20x phase contrast objective
Construction: disc with a phase annulus in a mount
Material: glass, colourless polarising film and printed black circles
Diameter of the glass disc with the printed annulus: 14 mm
Disc mount: metal, with a notch for the spring-loaded ejector pin
Spring cushioning: yes - inside the mount, underneath the glass with the phase annulus, there is a spring cushioning
Other names: phase disc, phase glass, phase ring
Intended for: PZO KS condenser
Compatibility: PZO K3Ph, K3Ph1, K4Ph and K3PhZ phase contrast condensers
Important note on appearance: the black dots and lines visible in the photo are not a surface defect - this is how PZO phase rings normally look
Note on the polarising film: two pieces of polarising film are glued onto the annulus. The vertical line running through the middle of the annulus is where these two films meet - it is neither a defect nor a crack, even though it looks like one

Over the years the polarising film used on these phase annuli very often came unstuck (delamination), which often - though not always - caused it to lose its properties and made stereoscopic contrast completely unusable. In such a case you can either:
- peel off the old film, clean the surface of the glass disc and glue on a new one, keeping the polarisation angle
- or replace the whole disc with one like the one offered here.

The specific feature of the PZO KS is that the ring of every disc is divided into two equal halves by two polarisers set perpendicular to each other. By rotating the analyser you extinguish one half of the ring and brighten the other - smoothly, without moving anything in the optical path. The specimen is then illuminated from one side.

And this is exactly how the disc from the KS condenser differs from the discs of the PZO K3Ph, K3Ph1, K4Ph and K3PhZ condensers. Mechanically it is the same insert, 14 mm in diameter, and it fits those condensers. The difference lies solely in the polarisation of the ring itself, described above. That is why a KS disc used in an ordinary phase condenser still gives correct phase contrast with no loss of quality, but once an analyser is placed in the optical path (for example under the head) it can produce interesting, unexpected effects.

For DIY enthusiasts looking for new, unusual visual effects in microscopy, an interesting option is to fit this polarising phase annulus into a different phase contrast condenser. You can then explore the unusual behaviour of various objectives in partially polarised light.
Here is an example: a Zernike-type phase contrast objective (PZO Ph with a green stripe) combined with the phase annulus from the PZO KS condenser gives an unusual, bluish background colour (https://www.facebook.com/photo?fbid=1262188377207557&set=a.462747092529893). And here you can see PZO microscope objectives for six types of phase contrast: https://www.facebook.com/MikroskopyPZO/photos/por%C3%B3wnanie-obiektyw%C3%B3w-pzo-20x-do-kontrastu-fazowego-pier%C5%9Bcienie-zielony-ph-kf-do/1259433520816376/.

The PZO KS condenser was fitted to PZO MB-30S microscopes and was an essential part of a special phase contrast method called "Stereoscopic Contrast" (KS). This condenser is characterised by carrying no markings at all - and that is how you recognise it.

Fastest way to recognise the PZO KS condenser:
PZO KS condenser: no serial number, no manufacturer name or logo, no model designation
Other PZO phase contrast condensers: at least a printed model designation (for example KFF, KFL, K3Ph, K3Ph1, K4Ph, K3PhZ, or KPI 2 in the case of the DIC condenser)