Feb 20, 2021 15:00:00

A 'laser scanning microscope' can be created using parts that read DVDs.

A confocal laser scanning microscope is a type of microscope that acquires an image by scanning an object with a laser beam. Urs Gaudenz, a lecturer in product innovation at the Lucerne University of Applied Sciences and Arts in Switzerland, created a confocal laser scanning microscope using optical parts and optical pickups that reproduce information from optical disc media such as CDs and DVDs.

Welcome to »DVD Laser Scanner Microscope
https://www.gaudi.ch/GaudiLabs/?page_id=652

The mechanism of a confocal laser scanning microscope is to irradiate an object with a laser beam emitted from a light source, scan the entire object in two directions, the X-axis and the Y-axis, and detect the fluorescence returned from the object. An image is acquired by combining the light captured by a device and converted into an electrical signal with software. The advantage of a confocal laser scanning microscope is that it captures only the fluorescence emitted from the in-focus position, so even thick samples can obtain clearer images than other microscopes.

On the other hand, an optical pickup irradiates an optical disk medium such as a CD or DVD with a laser beam, processes the reflected light, and converts it into an electric signal to extract information. Since the optical pickup contains optical parts such as a semiconductor laser, an objective lens, and a light receiving element, Gaudenz challenged to make a confocal laser microscope from the optical pickup.

The resolution of a confocal laser scanning microscope is defined by the number of lines that scan the X and Y axes, and is basically dependent on the wavelength of the objective lens and laser. It is also possible to supplement the resolution by using a highly sensitive photodetector or increasing the intensity of the laser.

In addition, the sensitivity of the optical pickup used as a part of a confocal laser scanning microscope depends on the type of disc to be read. The unevenness on the surface of the optical disk medium is finer in the order of CD] DVD] HD DVD] Blu-ray, and the corresponding optical pickup is also said to have higher sensitivity in this order.

The optical pickup used by Gaudenz is a type called 'PHR-803T' that is installed in the initial model of the external HD DVD drive and

Xbox 360 HD DVD player that is used by connecting to the Xbox 360 via USB. In Alibaba, each one was sold for $ 5 (about 530 yen).

Laser Lens for Xbox 360 phr-803t Hd-dvd, Optical Pickup --Buy Laser Lens Phr-803t, Laser Lens Phr-803t, Laser Lens Phr-803t Product on Alibaba.com
https://japanese.alibaba.com/product-detail/laser-lens-phr-803t-hd-dvd-for-xbox360-optical-pickup-598096494.html

Since a confocal laser scanning microscope scans an object in two directions, the X-axis and the Y-axis, Gaudenz combines two optical pickups and uses a one-board microcomputer Arduino Micro to control the laser and lens movable coil. ) Is created. I removed the photodetector on the PHR-803T and replaced it with a simple photodiode .

The detected light is processed by software written in Processing , a programming language for electronic art and visual design. This software not only reads the acquired information to compose an image, but also can change parameters such as laser wavelength and intensity, scanning position, and resolution.

This is a confocal laser scanning microscope that actually created Mr. Gaudenz and used an optical pickup.

When I shoot a silicon chip, it looks like this.

You can clearly shoot the unevenness on the surface of the CD.

It is also possible to photograph yeast cells.

The schematics, printed circuit boards, and processing software used in Gaudenz's confocal laser scanning microscope are available on the GitHub page below.

GitHub --GaudiLabs / OpenLaserScanningMicroscope: Open Source Laser Scanning Microscope
https://github.com/GaudiLabs/OpenLaserScanningMicroscope