What is claimed is:
1. A magnetic recording medium being of evaporation-type and having a non-magnetic support and a magnetic layer comprising at least a magnetic metal thin film provided thereon, said magnetic metal thin film having a coercive force Hc of 100 to 115 kAm and a squareness ratio Rs of 0.79 or larger.
2. The magnetic recording medium as claimed in claim 1, wherein said non-magnetic support is a polyamide film.
3. The magnetic recording medium as claimed in claim 1 being in compliance with AIT3 format of a magnetic recording system.
4. A method of fabricating a magnetic recording medium, wherein:
a magnetic layer including at least a magnetic metal thin film is formed on a non-magnetic support by a vacuum evaporation process in which a magnetic metal material is deposited on said non-magnetic support, which is in continuous running, under supply of oxygen gas so as to have a coercive force Hc of 100 kAm to 115 kAm and a squareness ratio of 0.79 or larger, wherein:
said non-magnetic support has a running speed of 150 mmin to 200 mmin.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A center-adjustable optical lens system, comprising:
a first barrel, having a first lens disposing space and a first outer ring part surrounding the first lens disposing space, wherein the first outer ring part comprises a plurality of indentations;
a second barrel, having a second disposing space and a second outer ring part surrounding the second lens disposing space, wherein the second outer ring part comprises a plurality of protrusions, wherein the second outer ring part is engaged with the first outer ring part, and the protrusions and the indentations are engaged by loose fit;
a plurality of lenses, disposed in the first lens disposing space and the second lens disposing space; and
a plurality of fixing members, located on the first outer ring part and the second outer ring part to fix the first barrel and the second barrel.
2. The center-adjustable optical lens system of claim 1, wherein when the protrusions and the indentations of the first outer ring part and the second outer ring part are engaged, due to an effect of loose fit, the barrels can be relatively moved under an engaged state between the protrusions and the indentations, before fixing members are affixed to the first and the second outer ring parts.
3. The center-adjustable optical lens system of claim 1, wherein the fixing components include screws.
4. The center-adjustable optical lens system of claim 1, wherein the fixing components include bolts and nuts.
5. The center-adjustable optical lens system of claim 1, wherein an including angle between the adjacent two protrusions is 120 degree.
6. A center-adjustable assembly process for the optical lens system as recited in claim 1, the assembly process comprising:
providing a projection jig, the projection jig comprising a light source, a collecting module and a testing plate, wherein the collecting module is disposed at an optic path between the light source and the testing plate, a chart is formed on the testing plate, and the projection jig is used to project the chart onto a screen;
fixing the first barrel on the projection jig, and a portion of the lenses has been disposed in the first barrel already;
disposing the second barrel on the first barrel, and the other portion of the lenses has bee disposed in the second barrel already, wherein the protrusions are engaged with the indentations, respectively;
adjusting a relative position between the second barrel and the first barrel to make the chart be clearly projected onto the screen; and
using the fixing components to fix the relative position between the second barrel and the first barrel.
7. The center-adjustable assembly process of claim 6, wherein, after adjusting the relative position between the second barrel and the first barrel but before using the fixing components, further using a fixing glue to fix the first barrel and the second barrel.
8. The assembly process of claim 6, wherein the chart includes cross mark, rectangular mark or circle mark.