RGB BF illumination unit

 

 

Following chapter summarizes the information about principles and construction of brightfield illumination in scan paths of Pannoramic scanners.

 

The described unit is momentarily used in Pannoramic Confocal, DESK_II, MIDI_II and SCAN_II type scanners.

 

In SMD_II-type scanners, the software version 1.21 or higher is required and is implemented since summer 2016.

 

 

 

 

 

                         RGB BF illumination principle

 

The construction of the BF optical path uses only a monochrome camera, so only monochrome images can be produced.

  • Monochrome cameras have an important advantage in relation to color cameras, today, the pixel size is the possible smallest.

 

To create color information of the tissue with a monochrome camera, we illuminate the tissue with monochrome light.

 

If the tissue is illuminated by blue light, and we are making an image of the Field of view, the gray scaled camera image contains the intensity of the blue parts in the tissue.

 

Because the pixel resolution of the camera is very high and the resolution of the image's gray scale is 10bit per pixel or higher (depending on the used camera), very detailed information of the blue part in the FOV, related to the appropriate pixel can be reached.

 

If we repeating the procedure with the colors Green and Red, 3 images of the same FOV are produced (a Red, Green and Blue image) and so, the software knows detailed color information about each pixel of the Field Of View.

 

By using the software coloring method the true color information of each pixel is found.

 

By using cameras with a large image sensor low shutter time and high pixel resolution (small pixel size), the scan time of the tissue can be held in acceptable boundaries and the result is an image with high resolution and high color fidelity.

 

 

 

 

Remark

In SCAN_II the Illumination mirror is not required; it is replaced by the illumination tube.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Illumination unit consists of:

 

 

Housing

            Used filters

            Working principle

 

Power LED module

Illumination tube

Illumination module

Mirror and diffuser

Connections

 

 

Watch video:            RGB BF Illumination unit

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                   Housing with:

 

·     two dichroic beamsplitters to route the light rays of Red, Green and Blue to the BF illumination mirror

·    Dichroic beamsplitters are mounted in an angle of 45º in relation to the light sources

·    the mounting of illumination modules

·    Illumination mirror with diffuser

·    Mountings to the scanner plate of the PCON; see image above

·    Electronics (power supply and control of the LEDs; not shown here)

 

 

 

·    The illumination components are mounted to the Illumination unit housing by bolts!

·    Adjustments are not required.

·    Maintenance is not required.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Used beamsplitters

 

·         The Dichroic beamsplitters are always mounted in an angle of 45º in relation to the light sources and the optical axis

 

 

Dichroic beamsplitter 1;     580nm

 

·         All light wavelengths above 580nm (the red and orange part of the visible light) passing thru the dichroic beamsplitter; all wavelengths below 580nm, the yellow, green, blue and violet light, will be reflected.

 

       In other words:

·         The lower wavelengths, below 580nm are always reflected while the higher wavelengths, above 580nm pass through the beamsplitter!

 

Part Number: FF580-FDi01-25x36

 

 

 

 

 

 

 

 

 

 

 

 

Dichroic beamsplitter 2;    488nm

·      All light wavelengths above 488nm (the red, yellow and green light) passing thru the dichroic beamsplitter all wavelengths below 488nm, the blue and violet light, will be reflected.

 

 

                        In other words:

·      The lower wavelengths, below 488nm are always reflected while the higher wavelengths, above 488nm pass through the beamsplitter!

 

 

Part Number: Di02-R488-25x36

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                   Working principle

 

By using the dichroic beamsplitters the required wavelengths for the colors Red, Green and Blue can be filtered from the white light, emitted by the LED.

 

·      Also important in this construction is the emitted wavelength spectrum of the white power LED.

·      The violet light, in the range from 390 ~ 420nm does practically not exist.

·      The visible white light is defined in the range of approximately 400 ~ 700nm.

 

 

Significant colors can be assumed in the following wavelength ranges

 

Color

Range

Typical

[nm]

[nm]

Violet

390 ~ 430

410

Indigo

430 ~ 450

440

Blue

450 ~ 495

460

Green

500 ~ 560

535

Yellow

560 ~ 590

575

Orange

590 ~ 620

610

Red

620 ~ 700

660

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                   Illumination path

 

The illumination module creates always white light in the wavelength range of ~400 to 700nm.

 

·         The shown color of the illumination tube is only used to show the arrangement of the light sources in relation to the beamsplitters.

·         The illumination modules are switched on separately, so only 1 wavelength range will be created at a time.

 

·         Detailed information about the working principle will be shown in the following.

 

 

 

 

 

 

 

 

 

 

 

Remark

 

In SCAN_II the Illumination mirror is not required; it is replaced by the illumination tube.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Red light source emits light in the range of 400 ~ 700nm

 

·    The unwanted wavelength range from 400 ~ 580nm (yellow, green and blue) will be filtered out (reflected) by the dichroic beamsplitter with a nominal wavelength edge of 580nm.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Green light source emits light in the range of 400 ~ 700nm

 

·         The unwanted wavelength range from 590 – 700nm (yellow, orange and red) will be filtered out (passes thru) by the dichroic beamsplitter with a wavelength edge of 580nm.

·         The blue part will be filtered out (reflected) by the dichroic beamsplitter with a wavelength edge of 488nm.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Blue light source emits light in the range of 400 ~ 700nm

 

·    The dichroic beamsplitter would also reflecting violet light, but because the power LED emits only blue light (from about 420nm) in practice, the violet part does not exist.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                   Power LED module

The power led module creates white light and is used to illuminate the Field Of View (FOV) in the brightfield scan mode.

 

·                 Because the brightfield image is created from the colors RGB the module exists 3 times in the brightfield illumination unit; the wire color is used to find the appropriate connector easily.

 

 

The pulse frequency may be more than hundred Hz; it means, the scan camera can make more than 100 images /second.

 

 

To switch on the LED during the camera is ready; the led module is triggered (synchronized) by the scan camera with a trigger cable or software controlled together with the camera.

 

·         The LED module is inserted into the Illumination tube until it stops!

·         Adjustments are not required.

·         Maintenance is not required.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                   Illumination tube

 

In microscopes and scanners as well, correct illumination of the tissue is very important. The illumination tube contains the optics to produce light with a high density and coherent rays; so, the field of view can be illuminated evenly.

Because the brightfield image is created from the colors RGB the illumination tube exists 3 times in the brightfield illumination unit; there are no differences in the construction.

 

·         The illumination tube is mounted to the Illumination unit by 2 bolts!

·         Adjustments are not required.

·         Maintenance is not required.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

·         The white light, emitted by the LED will be collected by the aspheric lens and will be arranged to parallel light rays.

·         The light rays crossing the diffuser and are send to the dichroic beamsplitter.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                   Illumination module

 

An illumination module consists of the LED module and the illumination tube.

 

 

·      The Illumination module does not contain wavelength range filtering components!

 

 

 

·      Adjustments are not required.

·      Maintenance is not required.

 

Watch video:            Illumination module

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

·      To ensure, that the distance of the illumination module to the condenser is equal for all three colors, the light path of blue got a light path length equalization tube!

·      The construction does not contain wavelength range filtering components!

 

 

·      Adjustments are not required.

·      Maintenance is not required.

 

 

 

 

 

 

 

 

 

 

 

 

                   Mirror and diffuser

 

 

·      Adjustments are not required.

·      Maintenance is not required.

 

 

Watch video:            Illumination mirror

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Remark

 

In SCAN_II the Illumination mirror is not required; it is replaced by the illumination tube.

 

 

 

 

 

 

 

 

 

 

 

 

 

                   Connections

 

·      Connect the appropriate cable to the specified connector

 

 

 

 

 

See also:       S_II_Power and control” and “PCON_RGB BF scan illumination

                        M_II_Power and control”

                        D_II_USB_DC_Control