The basic optical system optical head and optical parts

The brightness of green ray laser pointer is really much higher compared with the yellow ray laser pointer .
The basic optical system optical head and optical parts of the income poor. DVD optical head is the most critical components of the system, its basic principle is as follows. Optical head is 1 rem lens, 2 collimating lens, 3. Polarizing prism, 4 prism, 5 mirrors, 6.1 / 4 wave plate, 7 focus error detection optical system and 8. Seek error detection optical system and other optical parts and optical systems, 9 focus control servo (F-ACT), 10. Seek control servo (T-ACT) and other servo-mechanical control parts, as well as semiconductor laser diodes, multi-split photodiode PD (photo diode) and other optical components consisting of.
General multi-mode LD RIN way lower, but the anti-reflective optical interference, without superimposed high-frequency drive current for the single mode light-emitting LD, a strong impact on the optical signal reflected light must be superimposed on the drive current frequency, generally about 500 ─ ─ 700MHZ range. LD to exert internal energy of incident light to maintain a certain, usually containing the photodiode PD, do APC (auto power control) with. Because DVD uses a laser wave length, so the light surface aberration demanding, so try to use the LD light in the middle part of that wave-front portion of income difference is small, but also consider the energy use efficiency. laser pointer works with 1 AAA battery.
So that with a regular CD with a different head. Need plastic prism, it is the role of the flat oval-shaped light, transformed into a circle parallel light (pictured), the role of polarizing prism. Is the light emitted from the LD of the reflected light from a separate CD, so that the first reflected light does not return to the laser cavity LD, resorted to shooting the laser does not produce noise, the second is that the reflected laser reflection with information beam can have a minimal loss, the first surface of the filter Q of P A linear polarized incident light than the ingredient, making it a pure linear polarization P, Q must also face the whole P linear polarizer Through, S linear polarized total reflection. Wavelength of laser pointer is 532nm.
The design of the lens material, must depend on the thickness of the disc, if the thickness of the disc does not match with the design values, will produce spherical aberration, the aggregation properties deteriorate, which is why for a DVD disc with 0.6mm thick of things 1.2mm thick lens can not read CD-ROM The CD-ROM signal grounds. General read-only type with less power, use of non-spherical optical resin can be injection, but with the power of a larger record type, generally with multiple sets of optical glass lens combination, the ministries of the imaging system aberration goods must be strictly controlled .