Mold with hydrogenated amorphous carbon film for molding an optical element

This specification discloses a mold for use for press-molding an optical element, characterized in that at least the molding surface of a mold base material is coated with an a-C:H film containing 5-40 atom % of hydrogen therein and having a film density of 1.5 g/cm.sup.3 or more. Other mold coating films also disclosed are a hydrogenated amorphous carbon film with an intermediate carbide layer between the film and the molding surface, and a hard carbon film containing 0-5 atom % of hydrogen therein and having a spin density of 1.times.10.sup.18 spin/cm.sup.3 or less and a film densisy of 1.5 g/cm.sup.3 or more.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a mold used to manufacture an optical element 
formed of glass such as a lens or a prism by press-molding of a glass 
material, a method of manufacturing said mold, and a molding method using 
said mold. 
2. Related Background Art 
The technique of manufacturing a lens by press-molding of a glass material 
without requiring a polishing process has eliminated the complicated steps 
heretofore required in the manufacture of a lens and has made it possible 
to make a lens simply and inexpensively, and has recently been used in the 
manufacture of not only a lens but also other optical elements formed of 
glass such as prisms. 
As the characteristics required of a mold used for the press-molding of 
such an optical element of glass, mention may be made of the excellence in 
hardness, heat resisting property, parting property, mirror surface 
workability, etc. Heretofore, numerous materials such as metals, ceramics 
and materials coated therewith have been proposed as mold of this type. 
Mentioning some examples, Japanese Laid-Open Patent Application No. 
49-51112 proposes 13 Cr martensite steel, Japanese Laid-Open Patent 
Application No. 52-45613 proposes SiC and Si.sub.3 N.sub.4, and Japanese 
Laid-Open Patent Application No. 60-246230 proposed a super-hard alloy 
coated with a precious metal. 
Also, a method using a mold material consisting of carbon is proposed in 
Japanese Laid-Open Patent Application No. 49-81419, and methods using a 
mold material coated with carbon are proposed in Japanese Patent 
Publication No. 55-11624, Japanese Laid-Open Patent Application No. 
63-203222, Japanese Laid-Open Patent Application No. 61-183134, Japanese 
Laid-Open Patent Application No. 61-281030 and Japanese Laid-Open Patent 
Application No. 64-83529. 
However 13 Cr martensite steel suffers from the disadvantages that it is 
ready to be oxidized and that Fe is diffused in glass at a high 
temperature to thereby color the glass. SiC and Si.sub.3 N.sub.4 are 
generally regarded as being difficult to be oxidized, but still suffers 
from the disadvantage that it is also oxidized at a high temperature and a 
film of SiO.sub.2 is formed on the surface thereof and therefore fusion 
with glass is caused and further the workability of the mold itself is 
very bad due to the high hardness. The material coated with a precious 
metal is difficult to be fused, but it is very soft, and this leads to the 
disadvantage that it is ready to be injured and also ready to be deformed. 
Also, the glassy carbon shown in Japanese Laid-Open Patent Application No. 
49-81419 is weak in structural strength and therefore suffers from the 
disadvantage that during press molding, the shape of the mold surface is 
distorted or the deterioration of the surface roughness by flaws or the 
like occurs. 
On the other hand, a mold coated with a carbon film has been proposed, 
whereas the carbon film is not limited to one kind, but from the viewpoint 
of crystal structure, it can be divided broadly into: (i) a diamond 
polycrystalline film; (ii) a graphite film or a glassy carbon film having 
a crystalline property; (iii) a diamond-like carbon film comprising a 
diamond crystallite phase and an amorphous phase; and (iv) a carbon film 
of high hardness composed of amorphous or microcrystal (an aggregate of 
crystallites) comprising SP.sup.2 and SP.sup.3 -hybrided carbon. 
The diamond polycrystal film mentioned under item (i) above is high in 
surface hardness and free of fusion with molded glass as well as low in 
reactiveness, but has the disadvantage that due to its being a 
polycrystalline film, it is inferior in surface roughness and the process 
of polishing the mold is difficult. The graphite film or the glassy carbon 
film mentioned under item (ii) above is low in hardness and structural 
strength and is inferior in the anti-oxidation property at high 
temperatures and the surface accuracy or the surface roughness is 
deteriorated, and this is not preferable. 
Also, the diamond-like carbon film disclosed in Japanese Laid-Open Patent 
Application No. 63-203222 is made into a film by the use of the plasma 
chemical vapor deposition (=PCVD) method under a condition of relatively 
high substrate temperature, and is the diamond-like carbon film of item 
(iii) containing a diamond crystal phase. Therefore, the film is of 
inhomogeneous quality and it is difficult to obtain a smooth film which is 
high in the surface accuracy Further, in the repetitive molding process, 
the mold surface is oxidized little by little, but the film of 
inhomogeneous quality is not generally uniformly oxidized and therefore 
has the disadvantage that the deterioration of the surface roughness is 
keen. In addition, the crystallization of the film is ready to progress 
due to molding at high temperature, and this leads to the disadvantage 
that the quality of the film is deteriorated and the hardness and adhesion 
are deteriorated. 
A method using a diamond-like carbon film is disclosed in Japanese 
Laid-Open Patent Application No. 61-183134, but an amorphous film of this 
kind comprises SP.sup.2 carbon and SP.sup.3 carbon, and is difficult to 
clearly distinguish from a glassy carbon film or an amorphous carbon film 
chiefly comprising SP.sup.2 carbon. So, hereinafter, as regards the carbon 
of high hardness composed of amorphous or micro crystal comprising 
SP.sup.2 and SP.sup.3 -hybrided carbon, a film containing a small amount 
of hydrogen in its composition will be referred to as a hard carbon film, 
and a film containing hydrogen to a certain concentration or greater will 
be referred to as a hydrogenated amorphous carbon film (a-C:H film). 
The hard carbon film disclosed in Japanese Laid-Open Patent Application No. 
1-83529 is sputtered at a relatively low substrate temperature and 
therefore is presumed to be an aggregate of diamond-like and graphite-like 
hyperfine particles. and is considered to be classified into the hard 
carbon film of item (iv) containing amorphous or microcrystal. 
This film, when made, has no hydrogen atom contained therein and therefore 
is high in the homogeneity of film, but has the tendency that the better 
the surface smoothness, the greater the film stress becomes. This leads to 
the disadvantage that in the molding process, due to the release of the 
stress, the film is ready to peel off in a minute area or generally with 
the polishing flaw of the mold base material, the remaining polishing 
agent, dust, or the grain boundary or the partiality of composition of the 
mold base material as an occasion. 
In addition, this film is not terminated by hydrogen atoms and therefore, 
much dangling bond is ready to be contained therein, and this leads to the 
disadvantage that the film reacts to glass and is fused thereto or causes 
a component in the glass to be reduced and deposited on the surface of the 
glass to thereby reduce the optical characteristic or the readiness with 
which it reacts to the oxygen in the atmosphere is liable to reduce the 
hardness and the adhesion by the deterioration resulting from oxidation. 
SUMMARY OF THE INVENTION 
It is the first object of the present invention to provide an optical 
element molding mold for heating and pressing a glass blank and 
press-molding it and in which at least the molding surface of the mold is 
coated with a carbon film, and a method of manufacturing such mold. 
The present invention further proposes a method of molding an optical 
element by the use of said mold. 
Particularly, to achieve the above first object, there are provided: (i) a 
mold used for press-molding an optical element, characterized in that at 
least the molding surface of the mold is coated with an a-C:H film 
containing 5-40 atom % of hydrogen and having a film density of 1.5 
g/cm.sup.3 or more; (ii) mold used for press-molding an optical element, 
characterized in that at least the molding surface of the mold is coated 
with a hard carbon film containing 0-5 atom % of hydrogen and having a 
spin density of 1.times.10.sup.18 spin/cm.sup.3 or less and a film density 
of 1.5 g/cm.sup.3 or more; (iii) a method of manufacturing the mold of 
said item (i), characterized in that at least the molding surface of the 
mold is coated with a-C:H film by the plasma sputter deposition method or 
the plasma ion plating method made of a solid carbon source and in an 
atmosphere containing at least hydrogen; (iv) a method of manufacturing 
the optical element molding mold of said item (i), characterized in that 
at least the molding surface of the mold base material is coated with 
a-C:H film by the electron cyclotron resonance PCVD method or the ion beam 
deposition method; (v) a method of manufacturing the mold of said item 
(ii), characterized in that the heat treatment/annealing is carried out 
after a-C:H film is made; (vi) a method of manufacturing the mold of said 
item (v), characterized in that a-C:H film having a hydrogen content of 
5-40 atom % and having a film density of 1.5 g/cm.sup.3 or more is 
heat-treated; and (vii) an optical element molding method characterized by 
molding an optical element by the use of mold of said item (i) or (ii). 
It is the second object of the present invention to propose mold 
characterized by being coated with an a-C:H film decreased in hydrogen 
content from the interface of the mold base material and film toward the 
surface. 
In accordance with the present invention, there is provided an optical 
element molding mold used for press-molding an optical element formed of 
glass, characterized in that at least the molding surface of the mold base 
material is coated with a-C:H film decreased in hydrogen content from the 
interface of the mold base material and film toward the surface, and 
wherein the a-C:H film decreased in hydrogen content from the interface of 
the mold base material and film toward the surface is constructed of two 
layers of films differing in hydrogen content. 
The present invention forms, on at least the molding surface of the mold 
base material, a-C:H film which is relatively great in hydrogen content 
and low in hardness, and gradually decreases the hydrogen content to 
thereby obtain an inactive a-C:H film which is high in hardness, smooth 
and small in coefficient of friction on the surface side (the side of the 
surface of contact with glass) and which does not react the lead or alkali 
element in a high temperature state. Here, the film portion of the 
interface of the mold and the film which is great in hydrogen content has 
the action of absorbing the internal stress of the film and the difference 
between the coefficients of thermal expansion of the mold and the film, 
thereby improving the mechanical strength typified by the sticking 
property of the a-C:H film formed on the mold. 
As regards the a-C:H film, it is preferable that the hydrogen content in 
the interface of the film with the mold base material be 60 atom % or 
less. If the hydrogen content exceeds 60 atom %, there is the tendency 
that it becomes difficult to construct C-C network of the film. (If the 
hydrogen content exceeds 66 atom % (C:H=1:2), it is impossible to 
construct the film.) Also, it is preferable that the hydrogen content in 
the surface be 5 atom % or more. If the hydrogen content is less than 5 
atom %. double bond increases within the film and therefore the film 
becomes a graphite-like film, and this leads to the tendency that the 
hardness of the film becomes low and the problem that the lead oxide in 
the glass component is reduced arises. 
Also, where the a-C:H film is constructed of two layers of films differing 
in hydrogen content, the film thickness of the layer greater in hydrogen 
content (40-60 atom %) serves to absorb the internal stress of the film 
and the difference between the coefficients of thermal expansion of the 
mold and the film to thereby improve the adhesion of the film, but if the 
film thickness is too great, the characteristics (for example, the 
hardness) of the film greater in hydrogen content will become strong and 
therefore, it is preferable that the film thickness be 500-1000 .ANG.. It 
is preferable that the film thickness of the layer smaller in hydrogen 
content (5-40 atom %) be 4000 .ANG. or more to keep the film high in 
hardness and smooth, and if the film thickness of said layer exceeds 8000 
.ANG., the influence of the internal stress of the film and the difference 
between the coefficients of thermal expansion of the mold and the film 
will become great and therefore, it is preferable that said film thickness 
be 4000-8000 .ANG.. 
As the base material of the optical element molding mold, mention may be 
made of ceramics excellent in mirror surface property and heat resisting 
property, besides super-hard alloy. 
As a method of coating at least the molding surface of the mold base 
material with a-C:H film, mention may be made of the plasma chemical vapor 
deposition method (the PCVD method), the ion beam deposition method, the 
plasma sputter deposition method, the plasma ion plating method, the 
electron cyclotron resonance PCVD method or the like. 
It is the third object of the present invention to propose a molding mold 
in which the molding surface of the mold base material is coated with an 
a-C:H film containing one or more kinds of elements selected from nitrogen 
and oxygen, in addition to hydrogen atoms. 
Generally, some of films of a-Si (amorphous silicon) and amorphous carbon 
films have a great deal of dangling bond in the film. If there is much of 
such dangling bond in the amorphous carbon film formed on the mold base 
material, there will occur an active site which will cause reaction to 
lead oxide and alkali elements contained in molded glass during molding, 
and this will cause deposition of lead or the like. AccordinglY, a slight 
amount of hydrogen or other element is added to decrease such dangling 
bond and is terminated to such dangling bond, whereby the dangling bond 
can be decreased. 
Further, in connection with the above third object, the present invention 
proposes a mold in which the a-C:H film contain at least one kind of inert 
gas element selected from among He, Ne, Ar, Kr and Xe, instead of at least 
one kind of element selected from nitrogen and oxygen. 
Furthermore, the present invention proposes a mold in which the a-C:H film 
contains at least one kind of halogen element selected from among F, Cl, 
Br and I, instead of at least one kind of element selected from nitrogen 
and oxygen. 
In accordance with the present invention, there are provided: (1) a mold 
used for press-molding an optical element formed of glass, characterized 
in that at least the molding surface of the mold base material is coated 
with a-C:H film containing 5-40 atom % of hydrogen and carbon as the 
remainder and further, at least one kind of element selected from nitrogen 
and oxygen; (2) said mold in which the a-C:H film contains at least one 
kind of inert gas element selected from among He, Ne, Ar, Kr and Xe, 
instead of at least one kind of element selected from nitrogen and oxygen; 
(3) said mold in which the a-C:H film contains at least one kind of 
halogen element selected from among F, Cl, Br and I, instead of at least 
one kind of element selected from nitrogen and oxygen; and (4) said mold 
in which the a-C:H film contains at least one kind of element selected 
from among He, Ne, Ar, Kr and Xe, in addition to at least one kind of 
element selected from nitrogen and oxygen. 
As the base material of the mold, mention may be made of ceramics excellent 
in mirror surface property and heat resisting property, besides super-hard 
alloy. 
At least that surface of the mold base material which is in contact with a 
glass blank. i.e., the molding surface, is coated with the a-C:H film. 
The composition of this a-C:H is 5-40 atom % of hydrogen and carbon as the 
remainder. 
Here, it is for the following reason that the hydrogen content has been 
limited. The relations as shown in FIGS. 1 and 2 of the accompanying 
drawings are obtained between the hydrogen content in a-C:H and the 
hardness of the film and the roughness of the surface. As seen from FIG. 
1, as hydrogen content increases, the hardness is reduced, and if the 
hydrogen content exceeds 40 atom %, Knoop hardness becomes less than 800 
kg/mm.sup.2 and desired film hardness becomes unobtainable. Also, as seen 
from FIG. 2, as the hydrogen content decreases, the roughness of the 
surface increases, and for less than 5 atom %, the roughness of the 
surface exceeds 0.05 .mu.m at Rmax and a desired mirror surface property 
becomes unobtainable. The increase or decrease in the amount of hydrogen 
for obtaining the relations of FIGS. 1 and 2 has been effected by the use 
of the deposition apparatus of FIG. 5 of the accompanying drawings and 
with the acceleration voltage 500 V and the substrate temperature 
300.degree. C., among the conditions of making film, being constant and 
with the gas flow rate of CH.sub.4 and H.sub.2 changed. 
It is preferable that the amount of nitrogen and oxygen contained in the 
a-C:H film of item (1) containing at least one kind of element selected 
from nitrogen and oxygen be within the range of 100-50,000 atom ppm. If it 
is outside the range of 100-50,000 atom ppm, the effect of improving the 
durability of the mold will decrease. This is considered to be 
attributable to the fact that within the range of 100-50,000 atom ppm, 
nitrogen and oxygen atoms contribute to the stabilization of the structure 
of the a-C:H film, but outside this range; part of the structure is 
destroyed or it becomes difficult to accept the distortion of the 
amorphous structure. The Knoop hardness of said film is of the order of 
800-2000 kg/mm.sup.2. 
It is preferable that the amount of inert gas element contained in the 
a-C:H film of item (2) containing at least one kind of inert gas element 
selected from among He, Ne, Ar, Kr and Xe be within the range of 100-5,000 
atom ppm. If it is outside the range of 100-5,000 atom ppm, the effect of 
improving the durability and wear resistance of the mold will decrease. 
This is considered to be attributable to the fact that particularly within 
the range of 100- 5,000 atom ppm, the inert gas element differs in atomic 
diameter from carbon and oxygen atoms, whereby it accepts the distortion 
of the amorphous structure and contributes to the stabilization of the 
structure of the a-C:H film, and thus contributes to the improvement in 
the hardness of the film. The Knoop hardness of said film is of the order 
of 1000-3000 kg/mm.sup.2. 
The a-C:H film of item (3) containing at least one kind of halogen element 
selected from among F, Cl, Br and I reduces the wettability with respect 
to glass by its containing the halogen and therefore. the parting property 
during molding is improved, and during repetitive molding, the changes in 
the composition and structure of the a-C:H film are suppressed, and this 
leads to the improved durability of the mold. 
It is preferable that the halogen content in the a-C:H film of item (3) be 
within the range of 100-50,000 atom ppm. If the halogen content is less 
than 100 atom ppm, the effect or improving the wettability tends to become 
low, and if the amount of halogen element exceeds 50,000 ppm, the halogen 
content which is not bonded in the film tends to increase and thereby 
spoil the durability of the film. The Knoop hardness of said film is 800 
kg/mm.sup.2 or more. 
The halogen element may be distributed locally on the surface of the a-C:H 
film or may be uniformly distributed over the entire film. 
The amount of nitrogen and oxygen contained in the a-C:H film of item (4) 
containing at least one kind of inert gas element selected from among He, 
Ne, Ar, Kr and Xe, in addition to at least one kind of element selected 
from nitrogen and oxygen, may preferably be within the range of 100-50,000 
atom ppm, and the amount of inert gas element contained in said film may 
preferably be within the range of 100-5,000 atom ppm. 
The a-C:H films of items (1)-(4) may contain not only amorphous structure, 
but also a small amount of crystallite. However, this crystallite can be a 
minute diamond grain of the order of 0.01-0.1 .mu.m, but a crystallite 
whose diamond crystal surface appears clearly on the surface of the film 
is not preferable Also, it is preferable that the crystallite do not 
contain graphite and multiple bond as far as possible, but the graphite 
and multiple bond may contain them if in a small amount. 
It is preferable that the film thickness of the a-C:H film be 0.05-0.5 
.mu.m. If the film thickness is less than 0.05 .mu.m, the component 
element of the mold base material will dissolve into glass during molding 
and the durability of the molding mold will tend to be reduced, and if the 
film thickness exceeds 0.5 .mu.m, the distortion in the film will become 
great and the peeling-off of the film will become readily to occur. 
It is the fourth object of the present invention to provide the mold 
characterized in that at least the molding surface of the mold base 
material is coated with a-C:H film through an intermediate layer 
comprising a carbide of the base material component or an intermediate 
layer comprising the base material component and a-C:H. 
In the molding process involving a heat shock, a-C:H film through the 
intermediate layer according to the present invention is made in order to 
prevent the stress of the a-C:H film and the difference between the 
coefficients of thermal expansion of the mold base material and the a-C:H 
film and prevent the grain boundary of said mold base material or a binder 
metal distributed in the grain boundary from causing the peeling-off of 
the a-C:H film made thereon. 
Also, a-C:H film through the intermediate layer according to the present 
invention is made in order to prevent the binder metal as described above 
from being diffused in the a-C:H film and reacting to the metal and alkali 
component in glass to thereby cause them to be reduction and deposited or 
fused with the glass. 
As the mold base material, a material containing a component element 
capable of producing a carbide is preferable, and mention may be made, for 
example, of super-hard alloy (containing WC as a chief component). SiC, 
AlN, cermet or the like. 
The a-C:H film applied to at least the molding surface of the mold base 
material, i.e., the surface which contacts with glass, is formed with (1) 
an intermediate layer formed of a carbide of the base material component 
or (2) an intermediate layer formed of the base material component and 
a-C:H interposed between it and the mold base material. In the present 
invention, it is to be understood that the intermediate layers mentioned 
under items (1) and (2) above include, besides a layer whose boundary with 
the a-C:H film is clear, a layer which continuously varies in composition 
and structure and therefore whose boundary with the a-C:H film is not 
always clear. 
The a-C:H layer may or may not contain diamond crystal, but does not 
contain a graphite crystal layer, and is a carbon film which is excellent 
in hardness, thermal stability and chemical stability as compared with 
glassy carbon and polymerized film, and includes a film generally called 
i-carbon film. 
The layer thickness of said intermediate layer may preferably be of the 
order of 10-10,000 .ANG. to improve the property of intimate contact 
between the mold and the film. Also, the film thickness of the a-C:H film, 
if less than 50 .ANG., tends to reduce the surface accuracy, and if it 
exceeds 5,000 .ANG., the distortion of the film will increase and the 
property of adhesion/adherence will tend to be reduced and therefore, the 
film thickness may preferably be of the order of 50-5,000 .ANG.. 
As a method of coating at least the molding surface of the mold base 
material with said intermediate layer and said a-C:H film, use can be made 
of one of various PVD methods and CVD methods such as the plasma 
deposition method, the ion beam deposition method, the plasma sputter 
deposition method, the plasma ion plating method and the electron 
cyclotron resonance PCVD method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
1) Description of a First Invention 
Description will first be made of a-C:H film containing 5-40 atom % of 
hydrogen and having a film density of 1.5 g/cm.sup.3 or more. 
Here, it is for the following reason that the amount of hydrogen has been 
limited. The relations shown in FIGS. 1 and 2 are obtained among the 
amount of hydrogen content in a-C:H and the hardness of the film and the 
roughness of the surface. It is seen from FIG. 1 that if the hydrogen 
content increases, the hardness is reduced and if the amount of hydrogen 
exceeds 40 atom %, Knoop hardness becomes less than 800 kg/mm.sup.2 and 
desired film hardness becomes unobtainable Also, it is seen from FIG. 2 
that if the hydrogen content decreases, the roughness of the surface 
increases and for less than 5 atom %, the roughness of the surface exceeds 
0.05 .mu.m at Rmax and a desired mirror surface property becomes 
unobtainable. The increase and decrease in the hydrogen content for 
obtaining the relations of FIGS. 1 and 2 have been effected by the use of 
the film making apparatus of FIG. 5 with the acceleration voltage 500 V 
and the substrate temperature 300.degree. C. among the conditions of 
making a film being constant and with the ratio of CH.sub.4 /H.sub.2 gas 
flow rate being changed. 
The reason why the film density has been limited is that if the film 
density is less than 1.5 g/cm.sup.3, graphite crystallization is ready to 
occur during molding and the deterioration of the roughness of the surface 
and the hardness is quick and inferiority in durability occurs. 
It is preferable that the film hardness be greater than the degree which 
will not cause scratches, plastic deformation during the molding with a 
glass blank, and basically it is preferable that the film hardness be 
equal to or greater than the hardness 800 kg/mm.sup.2 of the glass blank 
itself. 
Also, to hold the sufficient adhesion/adherence and mechanical strength of 
the mold base material and the film under the temperature condition during 
molding, it is preferable that the coefficient of thermal expansion 
.alpha. of the film be within the range of 1.times.10.sup.-6 
.ltoreq..alpha..ltoreq.1.times.10.sup.-5 [K.sup.-1 ]. 
Further, it is preferable that the film thickness of the a-C:H film be 
0.05-0.5 .mu.m. If the film thickness is less than 0.05 .mu.m, the 
component element of the mold base material tends to dissolve into glass 
and reduce the durability of the mold, and if the film thickness exceeds 
0.5 .mu.m, the distortion in the film becomes great and the peeling-off of 
the film becomes ready to occur. 
Description will now be made of a method of manufacturing a mold which is 
coated with a-C:H film. 
As a method of coating at least the molding surface of the mold with a hard 
carbon film, mention may be made of the plasma deposition method, the ion 
beam deposition method, the plasma sputter deposition method, the plasma 
ion plating method, the electron cyclotron resonance PCVD method or the 
like. 
According to the plasma sputter method or the plasma ion plating method, as 
compared with the ion beam sputter method of Japanese Laid-Open Patent 
Application No 61-183134, the deposition rate is high (in the ion beam 
sputter method, the deposition rate is 0.1-0.2 .mu.m/hr. whereas in the 
present method, the deposition rate is 1 .mu.m/hr or higher) and moreover, 
a film can be made at a uniform thickness over a wide area Further, in the 
electron cyclotron resonance PCVD method, the deposition rate as high as 
10 .mu.m/hr. Also, the ion beam deposition method can adjust the hydrogen 
content by changing the acceleration voltage of an ion beam. 
Description will now be made of a hard carbon film containing 0-5 atom % of 
hydrogen and having a spin density of 1.times.10.sup.18 spin/cm.sup.3 or 
less and a film density of 1.5 g/cm.sup.3 or higher. 
Where molding is effected at a high temperature, or where in the molding 
process, glass containing an element such as lead which is ready to be 
reduced and deposited is used in the interface between the molded glass 
and the mold, or where molding is effected under a condition in which 
reduction and deposition are ready to occur, a hard carbon film containing 
5 atom % or less of hydrogen in the film or containing no hydrogen in the 
film and having a spin density of 1.times.10.sup.18 spin/cm.sup.3 or less 
is preferable. If the hydrogen content exceeds 5 atom %, the surface of 
the molded glass will become cloudy due to a reduced metal particularly 
during the several first moldings, and this is not preferable from the 
viewpoints of the optical characteristic and the appearances. If the spin 
density exceeds 1.times.10.sup.18 spin/cm.sup.3, peeling-off of the film 
will occur due to the heat shock resulting from molding, and this is not 
preferable. 
The film density of said hard carbon film is 1.5 g/cm.sup.3 or higher. If 
the film density is less than 1.5 g/cm.sup.3, deterioration of the 
hardness and the roughness of the surface will occur due to repetitive 
molding, and this will result in inferior durability. 
Said hard carbon film does not contain the diamond and graphite crystal of 
the size which can be detected by the X-ray diffraction method. 
Said hard carbon film may contain a slight amount of one or more kinds of 
elements of other elements than hydrogen, such as N, 0, He, Ne, Ar, Kr, 
Xe, F, Cl, Br and I. 
Also, the roughness of the surface of said hard carbon film may preferably 
be Rmax 0.05 .mu.m or less, and if it exceeds Rmax 0.05 .mu.m, the surface 
accuracy of the molded glass will become low and the durability of the 
mold will become low, and this is not preferable. 
The film thickness of said hard carbon film may preferably be 100 
.ANG.-20000 .ANG., and if the film thickness is less than 100 .ANG., the 
reactivity to glass will occur, and if the film thickness exceeds 20000 
.ANG., peeling-off of the film will occur, and this is not preferable. 
The film hardness of said hard carbon film may be higher than the hardness 
of the molded glass, and may preferably be 800 kg/mm.sup.2 or more. If the 
film hardness is less than 800 kg/mm.sup.2, the surface accuracy of the 
molded glass will tend to become insufficient, and this is not preferable. 
Description will now be made of a method of manufacturing the mold of the 
present invention which is coated with the hard carbon film. 
Said hard carbon film can be produced by heat-treating the aforementioned 
a-C:H film containing 5-40 atom % of hydrogen and having a film density of 
1.5 g/cm.sup.3 or more. 
The reason why it is preferable to use a-C:H film containing 5-40 atom % of 
hydrogen in the heat treatment will hereinafter be described. 
Generally in a hard carbon film, the film hardness is high and the degree 
of cross-link of the carbon-carbon network is high, and in a smooth 
amorphous film, the stress is high, and a film in which the stress is too 
high becomes the cause of the film peeling off in the whole surface or a 
minute area with the polishing flaw of the base material, the grain 
boundary, the dust or the like having adhesion to the film before film 
making as an occasion. If the peeling-off of the film is such that the 
film peels off in a minute area of the order of several tens to several 
hundred .mu.m, if not in the whole surface, due to a reduced adhesion, the 
roughness of the surface of the molded glass will increase though locally, 
and this will become the cause of the molded glass becoming cloudy and 
thus will pose a problem in terms of the optical characteristic and 
appearances. So, even if the degree of cross-rink of the carbon-carbon 
network is controlled with a view to control the stress, if unbonded hands 
which could not be bonded to carbon are present in the form of dangling 
bond in the film, the effect of alleviating the stress will be small and 
also, this will provide an active site for reacting to oxygen, and this is 
not preferable. 
That is, a film in which hydrogen has been made into a film to 0-5 atom % 
immediately after the making of the film generally has much dangling bond, 
and when the film is removed from a chamber for preservation after the 
making of the film or is heated, the film is liable to peel off or be 
oxidinized and deteriorated, and this is not preferable. 
Also, if a film in which hydrogen is 0-5 atom % and the stress has been 
alleviated is formed in the film making process, the film will become 
inhomogeneous in quality and crystallized and will exhibit a tendency 
toward the reduced roughness of the surface and the reduced structural 
strength of the film, and this is not preferable. 
So, even if the hydrogen content is increased to terminate the dangling 
bond, if the hydrogen content exceeds 40 atom %, the degree of cross-link 
of the carbon-carbon network will be reduced too much and particularly at 
the molding temperature, the hardness of the film and the roughness of the 
surface of the film will be reduced or glass will be fused, and this is 
not preferable. 
If a-C:H film having a film density of less than 1.5 g/cm.sup.2 is used in 
the heat treatment, graphite crystallization is ready to occur during the 
heat treatment and the deterioration of the roughness of the surface and 
the hardness of the hard carbon film obtained is quick and the film is 
inferior in durability, and this is not preferable. 
Also, due to the heat treatment, the roughness of the surface exhibits a 
tendency toward an increase and therefore, to obtain a mold material of 
good surface roughness having moldability sufficiently, it is preferable 
that the roughness of the surface of the a-C:H film before the heat 
treatment be less than Rmax 0.05 .mu.m. 
Also, such a-C:H film in which the hydrogen content has an inclination in 
the direction of thickness can be subjected to heat treatment to thereby 
form said hard carbon film. 
The a-C:H film used in the heat treatment can be made by the conventional 
PCVD method, ion plating method, ion beam deposition method, sputter 
deposition method or the like, and the control of the hydrogen content can 
be accomplished by adjusting the mixture ratio of carbon gas source and 
hydrogen gas source, substrate temperature, pressure, the kinetic energy 
of the ion flow concerned in film making. There are also methods using 
hydrogen plasma assist and hydrogen ion beam assist. 
The heat treatment conditions differ depending on the kind of the glass to 
be molded, the molding temperature and the qualities of film such as film 
density and the hydrogen content, and the lower limit of the heat 
treatment temperature may preferably be 400.degree. C. or the upper limit 
of the molding temperature may preferably be 750.degree. C. If the heat 
treatment temperature is less than 400.degree. C., the effect of 
dehydrogenation and the effect of obtaining good molded glass from the 
first molding will be difficult to obtain. If the heat treatment 
temperature exceeds 750.degree. C., deterioration such as the oxidation of 
the a-C:H film and graphite crystallization will progress and the 
structural strength of the hard carbon film will be deteriorated, and this 
is not preferable. More preferably, the heat treatment temperature is 
above 500.degree. C. and below 650.degree. C. 
The heat treatment atmosphere may preferably be inactive or inert gas such 
as He, Ne, Ar, Kr, Xe or the like or of N.sub.2 or H.sub.2 gas or a 
mixture of two or more kinds of gases of these gases or in a reduced 
pressure thereof, and the partial pressure of oxygen in the atmosphere may 
preferably be 1.times.10.sup.-1 Torr or less. If the partial pressure 
exceeds 1.times.10.sup.-1 Torr, the a-C:H film will be oxidinized and the 
thickness of the hard carbon film will decrease too much or the hardness 
of the film and the structural strength of the film will be reduced, and 
this is not preferable. 
The heat treatment can be carried out in the same film deposition apparatus 
subsequently to film deposition or can be carried out in the molding 
apparatus before molding. As a further alternative, the heat treatment may 
be carried out in another heat treatment furnace after film making. 
As the mold base material of the mold, mention may be made of super-hard 
alloy or ceramic materials excellent in mirror surface property and heat 
resisting property. 
For example, mention may be made of superhard alloy obtained by sintering 
WC by the use of a binder such as Co, Ni, TiN, TiC or TaC, or cermet of 
the TiC-Ni line, the TiC-Co line, the Al.sub.2 O.sub.3 -Fe line or the 
like, or ceramics such as Si.sub.3 N.sub.4, SiC and Al.sub.2 O.sub.3. 
Specific embodiments of the present invention will hereinafter be described 
with reference to the drawings. 
FIGS. 3 and 4 show an embodiment of the mold according to the present 
invention. 
FIG. 3 shows the state before the press-molding of an optical element, and 
FIG. 4 shows the state after the press-molding of the optical element. In 
FIG. 3, the reference numerals 1 and 2 designate mold base materials, the 
reference characters 1-a and 2-a denote a-C:H films or hard carbon films 
formed on the molding surfaces of the mold base materials which contact 
with a glass blank, and the reference numeral designates the glass blank, 
and in FIG. 4, the reference numeral 4 denotes the optical element. 
By press-molding the glass blank placed between the molds as shown in FIG. 
3, the optical element 4 such as a lens is molded as shown in FIG. 4. 
Embodiment 1 
The ion beam deposition method has been used as a method of forming the 
a-C:H film. An deposition apparatus used in the present embodiment is 
shown in FIG. 5. 
In FIG. 5, the reference numeral 11 designates a vacuum chamber, the 
reference numeral 12 denotes an ion beam apparatus, the reference numeral 
13 designates an ionization chamber, the reference numeral 14 denotes a 
gas inlet port, the reference numeral 15 designates an ion extractive 
grid, the reference numeral 16 denotes an ion beam, the reference numeral 
17 designates a mold substrate, the reference numeral 18 denotes a 
substrate holder and a heater, and the reference numeral 19 designates an 
exhaust outlet. When the a-C:H film is to be formed, the mold base 
material 17 having its surface cleaned by an organic solvent is installed 
on the holder 18 and the air is exhausted through the exhaust outlet 19 to 
thereby make the interior of the chamber 11 vacuum. The mold base material 
17 is heated to 300.degree. C. and a source gas of CH.sub.2 +H.sub.2 is 
introduced into the chamber through the gas inlet port 14 (CH.sub.4 
/H.sub.2 =0.1). The source gas is ionized in the ionization chamber 13 of 
the ion beam apparatus 12, and a voltage of 300 V is applied to the ion 
extractive grid 15 to thereby draw out an ion beam, which is applied to 
the base material 17 to a predetermined film thickness. In the manner 
described above, a mold coated with a-C:H film was manufactured. 
An example in which press-molding of a glass lens has been effected by the 
mold according to the present invention will now be described in detail. 
Table 1 below shows the kinds of the mold material used in the experiment. 
TABLE 1 
______________________________________ 
No. Coating material 
Base material 
______________________________________ 
1 None WC (90%) + Co (10%) 
2 None SiC 
3 SiC WC (90%) + Co (10%) 
4 a-C:H WC (90%) + Co (10%) 
5 a-C:H SiC 
______________________________________ 
Nos. 1-3 are comparative materials, and Nos. 4-5 are materials proposed by 
the present invention. Super-hard alloy WC(90%)+Co(10%) and sintered SiC 
were used as the base material. A lens molding apparatus used in the 
above-described example is shown in FIG. 9. 
In FIG. 9, the reference numeral 51 designates a vacuum chamber, reference 
numeral 52 denotes the lid thereof, the reference numeral 53 designates an 
upper mold for molding an optical element, the reference numeral 54 
denotes a lower mold, the reference numeral 55 designates an upper mold 
keeper for holding down the upper mold, the reference numeral 56 denotes a 
mold holder, the reference numeral 57 designates a mold holder, the 
reference numeral 58 denotes a heater, the reference numeral 59 designates 
a thrust-up bar for thrusting up the lower mold, the reference numeral 60 
denotes an air cylinder for operating the thrust-up bar, the reference 
numeral 61 designates a rotary oil pump, the reference numerals 62, 63 and 
64 denote valves, the reference numeral 65 designates an inert gas inlet 
pipe, the reference numeral 66 denotes a valve, the reference numeral 67 
designates a vent pipe, the reference numeral 68 denotes a valve, the 
reference numeral 69 designates a thermocouples, the reference numeral 70 
denotes a water cooling pipe, and the reference numeral 71 designates a 
base plate for supporting the vacuum chamber. 
The process of making a lens will now be described. 
The base material of the mold is first worked into a predetermined shape, 
and the lens molding surface thereof is polished into a mirror surface. A 
coating of SiC is then formed by the ion plating method. Also, a coating 
of a-C:H film containing 40 atom % of hydrogen is constructed by the ion 
beam chamber method. The film thickness was 0.1 .mu.m. Optical glass of 
the flint line (SF14) is then regulated to a predetermined amount, and a 
glass blank made into a spherical shape is placed in the cavity of the 
mold and is installed in the apparatus. 
The mold in which the glass blank is placed is installed in the apparatus, 
and then the lid 52 of the vacuum chamber 51 is closed, and water is 
flowed into the water cooling pipe 70 and an electric current is supplied 
to the heater 58. At this time, the valve 66 for nitrogen gas and the vent 
valve 68 are closed and the exhaust system valves 62, 63 and 64 are also 
closed. The oil rotary pump 61 is rotating at all times. 
The valve 62 is opened to start exhaust, and when 10.sup.-2 Torr or less is 
reached, the valve 62 is closed, and the valve 66 is opened to introduce 
nitrogen gas from a bomb into the vacuum chamber. When a predetermined 
temperature is reached, the air cylinder 60 is operated to press at a 
pressure of 10 kg/cm.sup.2 for five minutes. After the pressure is 
removed, cooling is effected until the cooling speed becomes less than the 
transition point at -5.degree. C./min, whereafter cooling is effected at a 
speed above -20.degree. C./min. and when the temperature falls to 
200.degree. C. or less, the valve 66 is closed and the vent valve 63 is 
opened to introduce air into the vacuum chamber 51. The lid 52 is then 
opened, the upper mold keeper is removed and the molded article is taken 
out. 
In the manner described above, the lens 4 shown in FIG. 4 was molded by the 
use of optical glass SF14 of the flint line (softening point 
Sp=586.degree. C. and transition point Tg=485.degree. C.). The then 
molding condition, i.e., the time-temperature relation, is shown in FIG. 
11. 
Subsequently, the roughness of the surface of the molded lens and the 
roughness of the surface of the mold before and after molding were 
measured. The result is shown in Table 2 below. 
TABLE 2 
__________________________________________________________________________ 
Roughness of surface Rmax (.mu.m) 
Parting 
No. 
Coating 
Base material 
Lens 
Mold (before molding) 
Mold (after molding) 
property 
__________________________________________________________________________ 
1 None WC (90%) + Co (10%) 
0.04 
0.02 0.03 Good 
2 None SiC -- 0.04 -- Fused 
3 SiC WC (90%) + Co (10%) 
-- 0.02 -- Fused 
4 a-C:H 
WC (90%) + Co (10%) 
0.03 
0.02 0.02 Good 
5 a-C:H 
SiC 0.05 
0.04 0.04 Good 
__________________________________________________________________________ 
Subsequently, with respect to Nos. 1, 4 and which did not cause fusion, 
molding was effected times by the use of the same mold, whereafter the 
roughness of the surface was measured. The result is shown in Table 3 
below. 
TABLE 3 
______________________________________ 
Roughness of surface Rmax (.mu.m) 
No. Lens Mold (after 200 times) 
______________________________________ 
1 0.14 0.15 
4 0.03 0.02 
5 0.05 0.04 
______________________________________ 
As is apparent from the results shown in Tables 2 and 3 above, the mold 
material according to the present invention is excellent in the parting 
property with respect to glass, and even if it is repetitively used, 
deterioration of the surface is very little as compared with the 
conventional mold material. 
Embodiment 2 
Film making was done by the use of the same deposition apparatus as that in 
Embodiment 1 and with the deposition conditions changed. With the ratio of 
the mixed gases being CH.sub.4 /H.sub.2 =1 and the substrate temperature 
being 500.degree. C. and the extractive voltage being 250 V, there was 
obtained a-C:H film containing 15 atom % of hydrogen and having a film 
thickness of 0.5 .mu.m. 
An example in which press-molding of a glass lens was effected by the 
above-described mold will now be described in detail. 
In FIG. 10, the reference numeral 102 designates a molding apparatus, the 
reference numeral 104 denotes a replacement chamber for taking-in, the 
reference numeral 106 designates a molding chamber, the reference numeral 
108 denotes an evaporation chamber, and the reference numeral 110 
designates a replacement chamber for taking-out. The reference numerals 
112, 114 and 116 denote gate valves, the reference numeral 118 designates 
a rail, and the reference numeral 120 denotes a pallet conveyed on the 
rail 118 in the direction of arrow A. The reference numerals 124, 138, 140 
and 150 designate cylinders, and the reference numerals 126 and 152 denote 
valves. The reference numeral 128 designates heaters arranged in the 
molding chamber 106 along the rail 118. 
The interior of the molding chamber 106 is divided into a heating zone 
106-1, a press zone 106-2 and a gradually cooling zone 106-3 along the 
direction of conveyance of the pallet. In the press zone 106-2, an upper 
mold member 130 for molding is fixed to the lower end of the rod 134 of 
the cylinder 138 and a lower mold member 132 for molding is fixed to the 
upper end of the rod 136 of the cylinder 140. These upper and lower mold 
members 130 and 132 are the mold members of FIG. 3 according to the 
present invention. A container 142 containing an evaporation materials 146 
therein and heaters 144 for heating this container are disposed in the 
evaporation chamber 108. 
Optical glass of the flint line (SF14, the softening point Sp=586.degree. 
C., the glass transition point Tg=485.degree. C.) was roughly worked into 
a predetermined shape and dimensions, whereby a blank for molding was 
obtained. 
The glass blank was mounted on the pallet 120, and was placed at a position 
120-1 in the replacement chamber 104 for taking-in, and the pallet at this 
position was pushed in the direction of arrow A by the rod 122 of the 
cylinder 124 and was conveyed to a position 120-2 in the molding chamber 
106 beyond the gate valve 112, whereafter in the same manner, pallets were 
newly successively placed into the replacement chamber 104 for taking-in 
at predetermined timing, and each time, the pallets were successively 
conveyed to positions 120-2.fwdarw. . . . .fwdarw.120-8 in the molding 
chamber 106. In the meantime, in the heating zone 106-1, the glass blank 
was gradually heated by the heaters 128 and was rendered to the softening 
point or above at the position 120-4, whereafter it was conveyed to the 
press zone 106-2, whereupon the cylinders 138 and 140 were operated and 
the glass blank was pressed by the upper mold member 130 and the lower 
mold member 132 with a pressure of 10 kg/cm.sup.2 for five minutes, 
whereafter the pressing force was released and the glass blank was cooled 
to the glass transition point or below, whereafter the cylinders 138 and 
140 were operated to thereby part the upper mold member 130 and the lower 
mold member 132 from the molded glass article. During said pressing, the 
pallet was utilized as a side mold member for molding. Thereafter, the 
molded glass article was gradually cooled in the gradually cooling zone 
106-3. The molding chamber 106 was filled with inert gas. 
The pallet which arrived at the position 120-8 in the molding chamber 106 
was then conveyed to a position 120-9 in the evaporation chamber 108 
beyond the gate valve 114. Although usually vacuum evaporation is effected 
here, such evaporation was not effected in the present embodiment. In the 
next cycle of conveyance, the pallet was conveyed to a position 120-10 in 
the replacement chamber 110 for taking-out beyond the gate valve 116. In 
the next cycle of conveyance, the cylinder 150 was operated and the molded 
glass article was taken out of the molding apparatus 102 by the rod 148. 
The roughness of the molding surfaces of the mold members 130 and 132 
before and after the press-molding as described above, the roughness of 
the optical surface of the molded optical element and the parting property 
of the molded optical element with respect to the mold members 130 and 132 
are shown in Table 4 below. 
TABLE 4 
__________________________________________________________________________ 
Roughness of surface Rmax (.mu.m) 
Parting 
No. 
Coating 
Base material 
Lens 
Mold (before molding) 
Mold (after molding) 
property 
__________________________________________________________________________ 
1 None WC (90%) + Co (10%) 
0.04 
0.02 0.03 Good 
2 None SiC -- 0.04 -- Fused 
3 SiC WC (90%) + Co (10%) 
-- 0.02 -- Fused 
4 a-C:H 
WC (90%) + Co (10%) 
0.03 
0.03 0.03 Good 
5 a-C:H 
SiC 0.05 
0.04 0.04 Good 
__________________________________________________________________________ 
Subsequently, with respect to Nos. 1, 4 and 5 which did not cause fusion, 
press-molding was effected 10,000 times or end by the use of the same mold 
members. The roughness of the molding surfaces of the mold members 130 and 
132 in this case and the roughness of the optical surface of the molded 
optical element are shown in Table 5 below. 
TABLE 5 
______________________________________ 
Number Roughness of surface Rmax .mu.m 
No. of molding Lens Mold 
______________________________________ 
1 200 0.14 0.15 
1000 0.20 0.21 
5000 0.23 0.24 
10000 0.26 0.27 
4 200 0.03 0.03 
1000 0.03 0.03 
5000 0.03 0.03 
10000 0.04 0.03 
5 200 0.05 0.04 
1000 0.05 0.04 
5000 0.05 0.04 
10000 0.05 0.05 
______________________________________ 
As described above, in the present embodiment, even the repetitive use of 
the mold for press-molding could maintain good surface accuracy 
sufficiently and an optical element of good surface accuracy could be 
molded without causing fusion. 
Embodiment 3, Comparative Example 
a-C:H films having a film thickness of 0.03-0.60 .mu.m were heaped up on 
the surface of a mold base material comprising WC 90% and Co 10% by the 
ECR-PCVD method. The ECR-PCVD apparatus is of the cavity type shown in 
FIG. 6, and a magnetic field is applied to a cavity 21 by an electromagnet 
22, and a microwave is introduced from a microwave introduction window 24 
through a waveguide tube 23 and gas is introduced from a gas inlet port 27 
into the cavity, and the gas is excited. 
The magnitude of the magnetic field was set so as to be 2000 gauss at the 
microwave introduction window and 875 gauss on the surface of the mold. A 
mold 26 supported on a mold holder 25 was installed outside the cavity, as 
shown in FIG. 6. Ethylene (5 SCCM) and hydrogen (20 SCCM) were introduced 
from the gas inlet port 27 into the ECR-PCVD apparatus, and the pressure, 
the microwave power and the mold surface temperature were set to 
2.times.10.sup.-3 Torr, 500 W and 300.degree. C., respectively. When under 
such conditions, deposition was effected for three minutes, four minutes, 
seven minutes, ten minutes, twenty minutes and twenty-five minutes, 
respectively, a-C:H films having film thickness of 0.03, 0.05, 0.10, 0.22, 
0.50 and 0.60 .mu.m, respectively, were formed on the surface of the mold 
base material. When the hydrogen content in these films was measured by 
combustion analysis, it was 30 atom %. The Knoop hardness was 1500 
kg/mm.sup.2. 
Subsequently, by the use of molds coated with the a-C:H films, 
respectively, having the six kinds of film thicknesses described above, 
press-molding of glass lenses was effected in the same manner as in 
Embodiment 1. After molding was effected, once, the roughness of the 
surface was measured. The result is shown in Table 6 below. 
TABLE 6 
______________________________________ 
Film Roughness of surface Rmax (.mu.m) 
thickness Mold Mold 
No. (.mu.m) Lens (before molding) 
(after molding) 
______________________________________ 
6 0.03 0.08 0.02 0.08 
7 0.05 0.03 0.02 0.02 
8 0.10 0.03 0.02 0.02 
9 0.22 0.03 0.02 0.02 
10 0.50 0.03 0.02 0.02 
11 0.60 0.03 0.02 0.02 
______________________________________ 
Subsequently, with respect to the respective molds having film thicknesses 
of 0.05-0.60 .mu.m, molding was effected 10,000 times in the same manner 
as in Embodiment 2, whereafter the roughness of the surface was measured. 
The result is shown in Table 7 below. 
TABLE 7 
______________________________________ 
Film thickness Roughness of surface Rmax (.mu.m) 
No. (.mu.m) Lens Mold 
______________________________________ 
7 0.05 0.05 0.04 
8 0.10 0.04 0.03 
9 0.22 0.04 0.03 
10 0.50 0.04 0.03 
11 0.60 -- Film peeled. 
______________________________________ 
Embodiment 4 
A method of manufacturing a mold by the plasma sputter deposition method 
will hereinafter be described with reference to FIG. 7. 
FIG. 7 shows a RF sputtering apparatus used in the present embodiment. The 
reference numeral 31 designates a vacuum chamber, the reference numeral 32 
denotes a mold base material comprising super-hard alloy and a substrate 
holder, the reference numeral 33 designates the target of a solid carbon 
source (usually graphite), and the reference numeral 34 denotes a target 
holder which is cooled by cooling water passing through inlet and outlet 
ports 35. The reference numeral 36 designates a RF power supply for 
applying a RF (or rf) to the target holder and a matching device. The 
reference numeral 37 denotes a gas inlet port, and the reference numeral 
38 designates an exhaust port connected to an exhaust apparatus, not 
shown. It is to be understood that the atmosphere in which the a-C:H film 
is formed is such that hydrogen gas is introduced and the pressure is 
adjusted to 1.times.10.sup.-3 Torr to the order of 1 Torr. The hydrogen 
gas introduced at this time may be hydrogen 100%, but may also be mixed 
with inert gas such as argon, neon or helium for the stabilization of 
discharge. The mold base material is heated by a heater, not shown, in the 
substrate holder. The optimum substrate temperature differs depending on 
the conditions under which the mold is used for press-molding and the 
quality of the glass, but generally is 200.degree.-400.degree. C. By a RF 
(usually a frequency of 13.56 MHz) being applied to the target and the 
target holder, the carbon source of the target is sputtered and carbon 
films are deposited on the mold base material. In this manner, the mold 
base material is coated with a-C:H film having a film thickness of the 
order of 0.2-1.5 .mu.m. 
Although the RF sputtering method has been described above as the 
sputtering method, the present invention is not restricted thereto, but 
use may also be made of the RF magnetron sputtering method, the DC 
sputtering method or the like. Again in these methods, the conditions of 
film making such as pressure and substrate temperature may be 
substantially the same as those in the RF sputtering method. 
By the use of the film deposition apparatus shown in FIG. 7, a-C:H film was 
formed on the mold base material comprising WC(90%) and Co(10%). 10 SCCM 
of Ar and 10 SCCM of H.sub.2 were first introduced, and a valve, not 
shown, was adjusted to render the pressure to 0.1 Torr. The mold base 
material was heated to 300.degree. C. by a heater, whereafter a RF power 
source of 350 W was applied thereto and deposition was started. By 
approximately one hour of film deposition, a-C:H film having a film 
thickness of 0.5 .mu.m was formed on the mold base material. The mold thus 
obtained is referred to as No. 12. When the hydrogen content in this film 
was measured by combustion analysis, it was 24 atom %. 
By the use of the deposition apparatus of FIG. 7 and with the conditions of 
deposition changed in the following manner, a-C:H film was deposited on 
the mold base material comprising WC(90%) and Co(10%). 20 SCCM of Ar and 5 
SCCM of H.sub.2 were first introduced, and a valve, not shown, was 
adjusted to render the pressure to 1.times.10.sup.-2 Torr. The mold base 
material was heated to 350.degree. C. and a RF power of 300 W was applied 
thereto. By approximately one hour of deposition, a-C:H film of 0.4 .mu.m 
was formed. The mold thus obtained is referred to as No. 13. When the 
hydrogen content in this film was measured by combustion analysis, it was 
12 atom %. 
By the use of each mold coated with the a-C:H film, molding was effected 
200 times in the same manner as in Embodiment 1, whereafter the roughness 
of the surface was measured. The result is shown in Table 8 below. 
TABLE 8 
______________________________________ 
Roughness of surface Rmax (.mu.m) 
No. Lens Mold 
______________________________________ 
12 0.03 0.02 
13 0.03 0.02 
______________________________________ 
By the use of each mold coated with the a-C:H film, molding was effected 
10,000 times in the same manner as in Embodiment 2, whereafter the 
roughness of the surface was measured. The result is shown in Table 9 
below. 
TABLE 9 
______________________________________ 
Number Roughness of surface Rmax (.mu.m) 
No. of molding Lens Mold 
______________________________________ 
12 200 0.03 0.03 
1000 0.03 0.03 
5000 0.03 0.03 
10000 0.04 0.03 
13 200 0.03 0.03 
1000 0.03 0.03 
5000 0.03 0.03 
10000 0.04 0.03 
______________________________________ 
Embodiment 5 
A method of manufacturing a mold by the plasma ion plating method will 
hereinafter be described with reference to FIG. 8. 
FIG. 8 shows an ion plating apparatus used in the present embodiment. The 
reference numeral 41 designates a vacuum chamber, the reference numeral 42 
denotes a mold base material comprising super-hard alloy and a substrate 
holder, the reference numeral 43 designates a DC power supply, the 
reference numeral 44 denotes a RF coil, the reference numeral 45 
designates a RF power supply and a matching box, the reference numeral 46 
denotes an electron gun, the reference numeral 47 designates a solid 
carbon source, the reference numeral 48 denotes a gas inlet port, and the 
reference numeral 49 designates an exhaust port connected to an exhaust 
system, not shown. 
It is to be understood that the atmosphere in which a-C:H film is formed in 
such that a mixture of hydrogen gas and inert gas is introduced and the 
pressure is regulated to the order of 1.times.10.sup.-5 -1.times.10.sup.-3 
Torr. With hydrogen gas alone, discharge becomes unstable and therefore, 
mixing inert gas (such as helium, neon or argon) therewith is desirable. 
The mold base material is heated by the use of a heater, not shown. The 
substrate temperature may generally be of the order of 
200.degree.-400.degree. C. The carbon source is provided by evaporating 
solid graphite or the like by the use of an electron gun. At this time, 
the introduced gases are made into plasma by the use of the RF coil 
(usually a frequency of 13.56 MHz) and further, a bias 50-1000 V of 
negative voltage is applied to the mold base material and ions are applied 
to the mold base material, thereby forming a-C:H film having a film 
thickness of the order of 0.2-1.5 .mu.m on the mold base material, whereby 
the mold of the present invention is manufactured. 
By the use of the deposition apparatus shown in FIG. 8, a-C:H film was 
formed on the mold base material comprising WC(90%) and Co(10%). 10 SCCM 
of Ar gas and 10 SCCM of H.sub.2 gas were introduced to render the 
pressure to 2.times.10.sup.-4 Torr. The mold base material was heated to 
250.degree. C., and a bias of -250 V was applied thereto. Further, a RF of 
300 W was applied to the RF coil and graphite was evaporated by the 
electron gun, whereby a-C:H film of 0.5 .mu.m was formed on the mold base 
material. The mold thus obtained is referred to as No. 14. 
With the conditions of deposition changed in the following manner, a-C:H 
film was formed on the mold base material comprising WC(90%) and Co(10%). 
7 SCCM of Ar gas and 20 SCCM of H.sub.2 gas were introduced, the pressure 
was rendered to 1.5.times.10.sup.4 Torr, and the mold base material was 
heated to 300.degree. C., and a bias of -400 V was applied thereto. 
Further, a RF power of 250 W was applied to the RF coil, and graphite was 
evaporated by the electron gun, whereby a-C:H film of 0.5 .mu.m was formed 
on the mold base mateiral. The molding mold thus obtained is referred to 
as No. 15. 
By the use of each mold coated with the a-C:H film, molding was effected 
200 times in the same manner as in Embodiment 1, whereafter the roughness 
of the surface was measured. The result is shown in Table 10 below. 
TABLE 10 
______________________________________ 
Roughness of surface Rmax (.mu.m) 
No. Lens Mold 
______________________________________ 
14 0.03 0.02 
15 0.03 0.02 
______________________________________ 
By the use of each mold coated with the a-C:H film, molding was effected 
10,000 times in the same manner as in Embodiment 2, whereafter the 
roughness of the surface was measured. The result is shown in Table 11 
below. 
TABLE 11 
______________________________________ 
Number Roughness of surface Rmax (.mu.m) 
No. of molding Lens Mold 
______________________________________ 
14 200 0.03 0.03 
1000 0.03 0.03 
5000 0.03 0.03 
10000 0.04 0.03 
15 200 0.03 0.03 
1000 0.03 0.03 
5000 0.03 0.03 
10000 0.04 0.03 
______________________________________ 
Embodiment 6 
a-C:H film and hard carbon film were made by the ECR-PCVD apparatus shown 
in FIG. 6. A magnetic field is applied to the cavity 21 by the 
electromagnet 22, a microwave is introduced from the microwave 
introduction window 24 through the waveguide tube 23, and gas is 
introduced from the gas inlet port 27 into the cavity to thereby exist the 
gas. 
The magnitude of the magnetic field was set so as to be 900 gauss at the 
microwave introduction port and 400 gauss on the surface of the mold. The 
mold 26 supported on the mold holder 25 was installed outside the cavity, 
as shown in FIG. 6. Mixed gases of benzene/hydrogen=1/1 were introduced 
from the gas introduction port 27 into the ECR-PCVD apparatus, and the 
microwave power was set to 100 W. The mold holder was set so that it was 
insulated from the chamber and a bias potential could be applied to the 
mold. 
The other conditions, together with the result, are shown in Table 12 
below. 
As the substrate, use was made of a substrate obtained by making an SiC 
film of 100 .mu.m on sintered SiC by the thermal CVD method, and 
thereafter polishing the surface thereof to the roughness of surface Rmax 
0.01 .mu.m. Each sample was made at a deposition rate of 100-1000 
.ANG./min so that the film thickness was 5000 .ANG.. 
The spin density was analyzed by the electron spin resonance (ESR) method, 
and the hardness of the film was measured by a Knoop hardness meter. The 
hydrogen content and the density were measured by using rock salt as the 
substrate, depositing a film under the same conditions as those shown in 
Table 12 below, and thereafter water-dissolving and removing the rock 
salt, and isolating the film. The hydrogen content was quantified by the 
combustion analysis method. Subsequently, the determination of Hydrogen 
content was effected with respect to the samples by the FT-IR, with the 
detected analytical line of the combustion analysis result and the peak 
intensity of FT-IR spectra. 
The density was measured by the method using a pycnometer. 
The results are shown in Table 12. 
TABLE 12 
__________________________________________________________________________ 
Spin Film Film Roughness 
Sample 
Pressure 
Substrate 
Substrate 
density 
H content 
density 
hardness 
of surface 
No. (Torr) 
temp. (.degree.C.) 
bias (V) 
(spin/cm.sup.3) 
(atom %) 
(g/cm.sup.3) 
(kg/mm.sup.2) 
(Rmax .mu.m) 
__________________________________________________________________________ 
16 1 .times. 10.sup.-2 
150 0 1 .times. 10.sup.17 
60 1.3 400 0.02 
17 1 .times. 10.sup.-2 
300 0 2 .times. 10.sup.17 
40 1.5 1000 0.03 
18 1 .times. 10.sup.-4 
150 -400 5 .times. 10.sup.18 
10 1.8 1600 0.01 
19 1 .times. 10.sup.-4 
150 -500 5 .times. 10.sup.18 
5 1.8 1800 0.01 
20 1 .times. 10.sup.-4 
150 -1000 
1 .times. 10.sup.20 
2 2.0 1800 0.01 
21 1 .times. 10.sup.-4 
450 -500 2 .times. 10.sup.18 
2 1.5 800 0.06 
__________________________________________________________________________ 
Nos. 16, 20 and 21 show comparative examples. 
Subsequently, by the use of the mold of Nos. 16-21, a molding test was 
carried out by the molding apparatus shown in FIG. 10. 
In FIG. 10, the upper mold member 130 and the lower mold member 132 are 
ones having a-C:H film and hard carbon film, respectively, formed on mold 
base materials manufactured by the above-described method. 
First, low melting point glass of a glass transition point 292.degree. C. 
and a yield point 319.degree. C. (glass of a softening point of about 
342.degree.-370.degree. C. disclosed in Japanese Laid-Open Patent 
Application No. 63-170241) was roughly worked into a predetermined shape 
and dimensions, whereby there was obtained a blank for molding. 
Subsequently, a molding test was carried out in the same manner as in 
Embodiment 2. 
However, the temperature of the glass blank at a position 120-4 was 
rendered to 320.degree.-335.degree. C., whereafter the temperatures of the 
upper mold member 130 and the lower mold member 132 were rendered to 
335.degree. C., and the glass blank was pressed with a pressure of 100 
kg/cm.sup.2 for one minute, whereafter the pressure force was released and 
the glass blank was cooled to 230.degree. C. and parted from the mold. 
After such press-molding was carried out 50 times, the mold was removed 
from the molding apparatus to examine the hardness of the film and the 
peeling-off state of the film. Here, judgment as to the peeling-off state 
of the film is such that a case where peeling-off by 0.1 .mu.m or more is 
not found when examined by a scanning electron microscope (SEM) is judged 
as there being no peeling-off and a case where peeling-off by 1 .mu.m or 
more is found when examined by an optical microscope and a case where 
peeling-off by 0.1 .mu.m or more is found when examined by the SEM are 
judged as there being peeling-off (this also holds true hereinafter). The 
result is shown in Table 13 below. 
TABLE 13 
______________________________________ 
Number Film hardness 
Peeling-off 
No. of molding (kg/mm.sup.2) 
of film 
______________________________________ 
16 1st time -- Fusion of glass 
17 50th time 700 None 
18 50th time 1600 None 
19 50th time 1800 None 
20 12th time -- Peeling-off (3 .mu.m) 
21 20th time less than 100 
Peeling-off (10 .mu.m) 
Fusion of glass 
______________________________________ 
As shown above, the molds coated with the a-C:H film and hard carbon film 
of the present invention did not cause peeling-off of the film and 
exhibited a good molding property. 
Embodiment 7 
By the use of the RF sputtering apparatus of FIG. 7, a mold was 
manufactured by the plasma sputter deposition method in the same manner as 
in Embodiment 4. 
By the use of the deposition apparatus of FIG. 7, the conditions of 
deposition were set as follows, and a hard carbon film was formed on a 
mold base material comprising WC(90%) and Co(10%) and having surface 
roughness Rmax 0.02 .mu.m. First, 10 SCCM of Ar and 10 SCCM of H.sub.2 
were introduced, and a valve, not shown, was adjusted to render the 
pressure to 5.times.10.sup.-2 Torr. The mold base material was heated to 
150.degree. C., and an RF power of 300 W was applied thereto. By 
approximately one hour of deposition, a-C:H film having a film thickness 
of 5000 .ANG. was formed. The mold thus obtained is referred to as No. 22. 
This film hard a hydrogen content of 12 atom %, a density of 1.8 
g/cm.sup.3, surface roughness Rmax 0.02 .mu.m and a spin density of 
5.times.10.sup.18 spin/cm.sup.3. 
On the other hand, a mold on which a film was deposited under the same 
conditions as No. 22 with the exception that the introduced gas was 
changed to 20 SCCM of Ar gas is referred to as No. 23. The film of this 
mold contained very little hydrogen and had a density of 2.1 g/cm.sup.3, 
surface roughness Rmax 0.01 .mu.m and a spin density of 5.times.10.sup.19 
spin/cm.sup.3. 
A molding test was carried out by the use of the molds Nos. 22 and 23 and a 
molding apparatus similar to that used in Embodiment 6. 
By the use of glass of a glass transition point 365.degree. C. and a yield 
point 397.degree. C. (glass of an American softening point of about 
390.degree.-435.degree. C. disclosed in Japanese Laid-Open Patent 
Application No. 55-154343), molding was effected at a molding temperature 
of 415.degree. C. and a molding pressure of 100 kg/cm.sup.2 and for a 
pressing time of one minute. 
The mold of No. 23, after the 21st molding, exhibited much peeling-off of a 
minute area of several tens to several hundred .mu.m in diameter at the 
marginal portion of the surface of the mold, and became cloudy at 
locations corresponding to the portions of the molded glass surface in 
which the film peeled off, and had surface roughness of Rmax 0.1 .mu.m. 
No. 22 did not cause such peeling-off of the film, but could be molded up 
to the 50th time. 
As described above, good molding free of peeling-off of the film could be 
accomplished by using the mold coated with the a-C:H film according to the 
present invention. 
Embodiment 8 (Heating Process for Dehydrogenation) 
A hard carbon film was made by the ion beam deposition apparatus shown in 
FIG. 5. 
When a hard carbon film is to be formed, a mold base material 17 having its 
surface cleaned by an organic solvent and comprising WC(95%) and Co(5%) 
(surface roughness of Rmax 0.02 .mu.m) is installed on a holder 18, and 
the air is exhausted from an exhaust port 19 to render the internal 
pressure of a chamber 11 to 5.times.10.sup.-7 Torr. 
Subsequently, from a gas inlet port 14, a mixture of gases CH.sub.4 and Ar 
is introduced at a mixture ratio CH.sub.4 /Ar=1/1 to render the interior 
of a chamber 11 to 1.times.10.sup.-4 Torr. The raw material gases are 
ionized by the ionization chamber 13 of an ion gun 12, and a voltage of 
500 V is applied to an ion beam extractive grid 15 and an ion beam is 
applied to a draw-out base material 17 to thereby deposite. At this time, 
the ion beam current was 0.6 mA/cm.sup.2, and the heating of the substrate 
was not specially done. 
The film thickness was 10000 .ANG., the roughness of the surface was Rmax 
0.01-0.02 .mu.m, the film density was 1.8 g/cm.sup.3, and the hardness was 
1400-1600 kg/mm.sup.2. 
The heating process was carried out for two hours in an atmosphere in which 
the partial pressure of oxygen which is an impurity in N.sub.2 has of 1.2 
atmospheric pressure was 5.times.10.sup.-3 Torr or less. 
Thereafter, a molding test was carried out by the use of an apparatus 
similar to that used in Embodiment 6. 
By the use of glass of the SF8 flint line (made of OHARA, having a 
transition point 444.degree. C. and a yield point 476.degree. C. and 
containing lead element), press-molding was effected at a molding 
temperature of 520.degree. C. and a molding pressure of 100 kg/cm.sup.2 
for one minute. 
The heat treatment temperature, the quality of film before molding, the 
state of the mold material after molding and the amount of lead deposited 
on the surface of the molded glass are shown in Table 14 below. The amount 
of lead was detected from the peak intensity of lead measured by the X-ray 
diffraction method. 
Glass molded by the mold materials of Nos. 26-31 were usable without being 
finally polished thereafter. 
TABLE 14 
__________________________________________________________________________ 
Mold Pb peak 
member After heating process (before molding) intensity 
heat Spin of molded 
treatment Surface density 
H After molding 
glass 
Sample 
temp. 
Hardness 
roughness 
Density 
(spin/ 
content 
Peeling-off 
Hardness 
surface 
No. (.degree.C.) 
(kg/mm.sup.2) 
Rmax (.mu.m) 
(g/cm.sup.3) 
cm.sup.3) 
(atom %) 
of film 
(kg/mm.sup.2) 
(cps) 
__________________________________________________________________________ 
24 No 1600 0.01 1.8 5 .times. 10.sup.18 
13 o 1400 350 
process 
25 350 1500 0.01 1.8 1 .times. 10.sup.19 
6 o 1500 330 
26 400 1600 0.01 1.8 2 .times. 10.sup.17 
4 o 1500 180 
27 500 1400 0.02 1.9 2 .times. 10.sup.17 
1 o 1400 40 
28 550 1500 0.01 1.9 less than 
1 o 1400 0 
10.sup.17 
29 600 1500 0.02 1.9 less than 
0 o 1500 0 
10.sup. 17 
30 650 1300 0.02 1.9 less than 
0 o 1200 0 
10.sup.17 
31 750 800 0.05 1.8 less than 
0 .DELTA. 
800 0 
10.sup.17 
32 850 less than 
0.08 1.7 less than 
0 x -- -- 
500 10.sup.17 
__________________________________________________________________________ 
o: no peelingoff of film 
x: generally peelingoff 
.DELTA.: peelingoff in minute areas 
No. 24 shows a comparative example. 
Embodiment 9 (Heat treatment for Dehydrogenation) 
By the use of a mold base material similar to that in Embodiment 8, a hard 
carbon film was made to a film thickness of 12000 .ANG. on the molding 
surface in a similar manner, whereby a mold member was made. The heat 
treatment was carried out at 520.degree. C. for one hour in an atmosphere 
in which the partial pressure of oxygen was controlled and the total 
pressure was rendered to 1.2 atmospheric pressure by introducing a mixture 
of {O.sub.2 (1%)+Ar(99%)} gas and Ar gas. Glass was press-molded by an 
apparatus similar to and under conditions similar to Embodiment 8. The 
partial pressure of oxygen during the heating process and the result of 
molding are collectively shown in Table 15 below. 
The hardness before the heat treatment was 1400-1600 kg/mm.sup.2. The mark 
x in the column of the molding property shows that the deterioration of 
the film hardness and the structural strength during the heating process 
was keen and fusion of glass and the film and peeling-off of the film 
occurred and molding could not be accomplished, the mark .DELTA. shows 
that molding could be accomplished, but the surface accuracy of the molded 
glass surface was insufficient due to the peeling-off of the film of the 
mold, and the mark o shows that molding was good. 
TABLE 15 
______________________________________ 
Partial pressure 
Hardness of 
of oxygen during 
mold after 
heat treatment heat treatment 
Molding 
No. (Torr) (kg/mm.sup.2) 
property 
______________________________________ 
33 5 .times. 10.sup.-1 
less than 500 
x 
34 1 .times. 10.sup.-1 
800 .DELTA. 
35 1 .times. 10.sup.-2 
1200 o 
36 5 .times. 10.sup.-3 
1500 o 
37 less than 1 .times. 10.sup.-3 
1400 o 
______________________________________ 
Embodiment 10 (Heat treatment for Dehydrogenation) 
a-C:H film and hard carbon film were made by the use of an apparatus shown 
in FIG. 12. 
In FIG. 12, the reference numeral 11 designates a vacuum chamber, the 
reference numeral 12 denotes an ion gun, the reference numeral 13 
designates an ionization chamber, the reference numeral 14 denotes a gas 
inlet port, the reference numeral 15 designates an ion beam extractive 
grid, the reference numeral 16 denotes an ion beam, the reference numeral 
17 designates a mold base material, the reference numeral 18 denotes a 
substrate holder a heater, the reference numeral 19 designates an exhaust 
hole, the reference numeral 46 denotes an electron gun, and the reference 
numeral 47 designates a solid carbon source. 
Use was made of the mold base material 17 comprising WC(84%) - TiC(8%) - 
TaC(8%) and having surface roughness of Rmax 0.02 .mu.m, and the surface 
thereof was cleaned by an organic solvent, whereafter the mold base 
material was installed on the holder 18, and the air is exhausted from the 
exhaust port 19 to render the interior of the chamber 11 to 
5.times.10.sup.-7 Torr. 
The mold base material was heated to a desired temperature by the use of a 
heater, not shown. 
Subsequently, a mixture of assist gas H.sub.2 and Ar gas was introduced 
from the gas inlet port 14 to render the interior of the chamber 11 to 
2.times.10.sup.-4 Torr. The assist gas was ionized in the ionization 
chamber 13 of the ion gun 12, and was drawn out into the ion beam 
extractive grid 15, and a voltage was applied thereto and an ion beam was 
extracted and applied to the mold base material 17. 
On the other hand, the carbon source 47 such as solid graphite or glassy 
carbon was deposited by the use of the electron gun 46. 
A film was deposited a film thickness of 2000 .ANG. while ion beam assist 
was effected in this manner. 
The detailed conditions of deposition, the hydrogen content in the film, 
the density of the film, the roughness of the surface and the result after 
the heat treatment are collectively shown in Table 16 below. 
The heat treatment was carried out in an Ar gas atmosphere of 1.2 
atmospheric pressure (the partial pressure of oxygen 1.times.10.sup.-2 
Torr or less) at 600.degree. C. for two hours. 
Any of the films of Nos. 38-43 contained very little hydrogen after the 
heat treatment, and had a spin density of 1.times.10.sup.18 spin/cm.sup.3 
or less. 
Subsequently, a molding test was carried out with respect to Nos. 38-41 
having sufficient hardness after the heat treatment. The molding apparatus 
and the molding method were similar to those adopted in Embodiment 8, that 
is, by the use of SF8 (the flint line produced by OHARA), molding was 
effected at a molding temperature of 520.degree. C. and a molding pressure 
of 100 Kg/cm.sup.2 for one minute. 
As regards Nos. 38-40, even after 50 times of molding, deterioration of the 
roughness of the surface and the hardness was not found, nor the 
peeling-off of the film was found even by the SEM. 
No. 41 began to present peeling-off of the film by several tens to several 
hundred .mu.m after the 14th molding, and at the 20th time, deterioration 
of the roughness of the surface of the molded glass and the surface 
accuracy thereof was severe and molding was discontinued. 
As described above, the mold coated with the a-C:H film according to the 
present invention and the mold material coated with a hard carbon film 
provided by heating the a-C:H film after it was made are remarkably 
improved in durability. 
TABLE 16 
__________________________________________________________________________ 
Conditions of deposition 
Assist gas 
Extrac- Before heat treatment 
After heat treatment 
mixture 
tion H Film Surface 
Film Surface 
Sample 
ratio 
voltage 
Substrate 
content 
density 
roughness 
density 
roughness 
Hardness 
No. H.sub.2 /Ar 
(V) temp. (.degree.C.) 
(atom %) 
(g/cm.sup.3) 
(Rmax .mu.m) 
(g/cm.sup.3) 
(Rmax .mu.m) 
(kg/mm.sup.2) 
__________________________________________________________________________ 
38 1/1 500 150 5 1.9 0.01 1.9 0.02 1600 
39 H.sub.2 only 
300 150 16 1.9 0.01 1.9 0.01 1200 
40 1/1 400 300 8 1.7 0.02 1.7 0.02 2000 
41 Ar only 
300 300 0 2.0 0.02 1.6 0.02 1200 
42 Ar only 
250 500 0 1.5 0.04 1.1 0.08 100 
43 H.sub.2 only 
1000 
150 5 1.3 0.05 1.2 0.08 200 
__________________________________________________________________________ 
Embodiment 11 (Heat treatment for Dehydrogenation) 
By the use of a mold base material similar to that used in Embodiment 8, 
a-C:H film was formed to a film thickness of 5000 .ANG. on the molding 
surface in a similar manner to thereby make mold members. These mold 
members were heat-treated at 590.degree. C. for two hours with the 
pressure reduced to 5.times.10.sup.-6 Torr, whereby the a-C:H film was 
changed into a hard carbon film, and this was used as Sample No. 44. What 
was not heat-treated was used as Sample No. 45. Glass was molded by the 
same apparatus and under the same conditions as those in Embodiment 8. 
Molding was effected 50 times on end with the mold members 38 and 39 
mounted on the cylinders 138 and 140, and the amount of lead on the 
surface of each molded glass was detected by the X-ray diffraction method. 
The result is shown in Table 17 below. 
TABLE 17 
______________________________________ 
Pb peak intensity of surface of 
molded glass (cps) 
No. 44 No. 45 
Number subjected to heat 
not subjected to 
of molding treatment heat treatment 
______________________________________ 
1 0 300 
2 0 280 
4 0 150 
8 0 100 
15 0 40 
25 0 0 
50 0 0 
______________________________________ 
As shown above, by effecting the heat treatment, good molded glass could be 
obtained from the first molding even if final polishing was not effected. 
Embodiment 12 
A carbon film was formed on the surface of a mold base material polished to 
surface roughness Rmax 0.01 .mu.m similar to that in Embodiment 6, by the 
apparatus shown in FIG. 6. 
The mold base material 26 was installed on the holder 25 and the internal 
pressure of the apparatus was reduced to 1.times.10.sup.-6 Torr, 
whereafter benzene and hydrogen gas were introduced into the apparatus to 
provide a desired pressure The mold base material was heated and kept at a 
desired temperature, whereafter a magnetic field was applied thereto by 
the electromagnet 22, a bias voltage was applied to the mold base material 
and a microwave was introduced to thereby deposite films to 10000 .ANG. 
each. The mold base material No. 46 was subjected to the heat treatment 
after a carbon film was made thereon. The conditions were: an N.sub.2 gas 
atmosphere of 1.2 atmospheric pressure (the partial pressure of oxygen 
being 5.times.10.sup.-3 Torr or less), 600.degree. C. and the heating time 
of one hour. 
The conditions of deposition and the characteristics of the film before 
molding, together with the result of a molding test, are collectively 
shown in Table 18 below. 
The crystalline property was measured by the X-ray diffraction method. 
The molding test was carried out by the same apparatus and under the same 
conditions and by the use of the same gas as those in Embodiment 8, and 
molding was effected 50 times on end. 
The mark o shows that after molding, peeling off of the film by 10 .mu.m or 
more was not found by an optical microscope, and the mark x shows that 
peeling-off of the film by 10 .mu.m or more was found. 
As described above, films containing a crystal component therein are 
remarkable in peeling-off of the film and deterioration of the roughness 
of the surface and are not preferable. 
TABLE 18 
______________________________________ 
No. 46 No. 47 No. 48 
______________________________________ 
Conditions of deposition 
Intensity of magnetic 
400 400 875 
field at the sub- 
strate (Gauss) 
Benzene/H.sub.2 ratio 
3/1 3/1 1/9 
Pressure (Torr) 
1 .times. 10.sup.4 
5 .times. 10.sup.4 
0.5 
Temperature of mold 
300 500 600 
base material (.degree.C.) 
Microwave power (W) 
200 200 1000 
Bias of mold base 
-500 -250 +50 
material (V) 
Film characteristics 
before molding 
Crystalline property 
amorphous graphite diamond 
(X-ray crystal 
diffraction) 
H content 2 2 7 
(atom %) 
Spin density 1 .times. 10.sup.18 
5 .times. 10.sup.18 
1 .times. 10.sup.19 
(spin/cm.sup.3) 
Film density (g/cm.sup.3) 
1.8 1.7 2.2 
Surface roughness 
0.01 0.02 0.05 
Rmax (.mu.m) 
After 
molding 
Peeling-off of film 
o x o 
Surface roughness 
0.01 -- 0.11 
Rmax (.mu.m) 
______________________________________ 
Embodiment 13 
Carbon films as shown in Table 16 were made on respective mold base 
materials by the same apparatus and under the same condition as Samples 
Nos. 38-41 in Embodiment 10. 
A molding test was carried out by the same apparatus and under the same 
conditions and by the use of the same glass as those in Embodiment 6. 
However, the molding temperature was 335.degree. C., the molding pressure 
was 100 kg/cm.sup.2, the pressing time was one minute, and molding was 
effected 100 times on end. 
With regard to the mold of Nos. 38, 39 and 40, peeling-off of the film by 3 
.mu.m or more was not found after molding, nor deterioration of hardness 
was found. 
With regard to the glass molded by the mold of No. 41, deterioration of the 
roughness of the surface and the accuracy of the surface was found after 
the 62nd molding, and on the surface of the mold after the 100th molding, 
peeling-off of the film by 3 .mu.m was found much particularly in the 
marginal portion. 
As described above, by coating the mold base material with a-C:H film 
containing 40 atom % of hydrogen therein and having a film density of 1.5 
g/cm.sup.3 or more, peeling-off of the film does not occur and the 
durability of the mold is improved. Also, by using a mold coated with a 
hard carbon film containing 0-5 atom % of hydrogen therein and having a 
spin density of 1.times.10.sup.18 spin/cm.sup.3 or less and a film density 
of 1.5 g/cm.sup.3 or more, there can be molded a good optical element 
which is low in reactiveness to glass and which does not require final 
polishing. 
Further, said hard carbon film which is low in reactivity to glass is 
heat-treated and manufactured after a hard carbon film containing 5-40 
atom % of hydrogen therein is made, whereby peeling-off of the film does 
not occur and the durability of the mold is improved and a stable film can 
be provided with good reproducibility by the heat treatment. 
By using the mold according to the present invention, there can be obtained 
molded glass which does not require final polishing. 
The film disclosed in Japanese Laid-Open Patent Application No. 61-183134 
is a film of unclear classification and characteristic called DLC, whereas 
the present invention has realized a particular film which is rich in 
practicability. 
In the film disclosed in Japanese Laid-Open Patent Application No. 
61-281030, the surface of the formed film is not smooth and requires 
surface treatment after the making of the film. Further, it contains a 
crystal component therein and therefore is of inhomogeneous, and the 
durability is reduced by the roughing of the film. 
The film disclosed in Japanese Laid-Open patent Application No. 64-83529 
does not contain hydrogen therein during the making of the film and 
therefore has high internal stress which leads to the readiness with which 
the film peels off. 
2) Description of a Second Invention 
Description will now be made of some embodiments of the mold of the 
aforedescribed second object which is coated with an a-C:H film decreased 
in the hydrogen content from the interface of the film with the mold base 
material toward the surface of the film thereof. 
Embodiment 14 
FIGS. 13 and 14 show one form of the mold according to the present 
embodiment. 
FIG. 13 shows the state before the press-molding of an optical element, and 
FIG. 14 shows the state after the press-molding of the optical element. In 
FIG. 13, the reference numeral 201 designates a mold base material, the 
reference numeral 202 denotes a-C:H film formed on the molding surface of 
the mold base material which is contacted by a glass blank, and the 
reference numeral 203 designates the glass blank, and in FIG. 14, the 
reference numeral 204 denotes the optical element. By press-molding the 
glass blank 203 placed between the molds as shown in FIG. 13, the optical 
element 204 such as a lens is molded as shown in FIG. 14. 
As a method of coating the mold base material 201 with the a-C:H film of 
the present invention as described above, use was made of the PCVD method. 
In FIG. 15, there is shown a plainner type RF-PCVD type (hereinafter 
abbreviated as RF-PCVD) apparatus used for the formation of the film. In 
FIG. 15, the reference numeral 211 designates a vacuum chamber the 
reference numeral 212 denotes a gas supply system, the reference numeral 
213 designates a RF power supply, the reference numeral 214 denotes an 
exhaust system. and the reference numeral 215 designates a mold base 
material. 
First, the mold base material 215 was worked into a predetermined shape, 
and the lens molding surface thereof was polished into a mirror surface. 
Subsequently, by the RF-PCVD apparatus, CH.sub.4 is supplied through the 
gas supply system 212 at a flow rate of 10 SCCM and at a gas pressure of 
0.2 Torr, and 50 W was applied by the RF power of 13.56 MHz, and at room 
temperature, a film was deposited to a film thickness of 1000 .ANG. on the 
mold base material (substrate), whereafter film deposition was effected 
while the substrate temperature was gradually increased. The final 
substrate temperature was 400.degree. C., and the final film thickness was 
5000 .ANG.. The film (thickness 1000 .ANG.) on the surface of contact with 
the mold base material was chemically analyzed with a result that the 
hydrogen content was about 50 atom % and the hardness of the film was 800 
kg/mm.sup.2 in terms of Knoop hardness. On the other hand, the film on the 
surface of contact with glass was chemically analyzed with a result that 
the hydrogen content was about 20 atom %, the hardness of the film was 
2000 kg/mm.sup.2 in terms of Knoop hardness, the roughness of the surface 
was Rmax 0.02 .mu.m or less and the coefficient of friction was 0.2 or 
less and thus, the film obtained was a smooth film of high hardness. 
Also, when analysis of said film in the direction of depth thereof was 
effected by an ion microanalyzer, it was confirmed that the hydrogen 
content was decreased from the surface of contact with the mold base 
material toward the surface. 
Subsequently, the press-molding test of the optical element was carried out 
by the use of the above-described press-molding mold and other molds and 
by the use of the aforedescribed apparatus of FIG. 9. 
Next, a glass blank provided by adjusting optical glass of the flint line 
(SF14) to a predetermined amount and making it into a spherical shape is 
placed in the cavity of the mold, and this is installed in the apparatus 
shown in FIG. 9. 
After the mold in which the glass blank is placed is installed in the 
apparatus, the lid 52 of a vacuum chamber 51 is closed, and water flows 
into a water cooling pipe 70 and an electric current is supplied to 
heaters 58. At this time, valve for 66 and vent valves 68 nitrogen are 
closed and exhaust system valves 62, 63 and 64 are also closed. An oil 
rotating pump 61 is rotating at all times. 
The valve 62 is opened to begin exhaust, and when the pressure becomes 
10.sup.-2 Torr or less, the valve 62 is closed and the valve 66 is opened 
to thereby introduce nitrogen gas from a cylinder into the vacuum chamber. 
When a predetermined temperature is reached, an air cylinder 60 is 
operated to press the glass blank with a pressure of 10 kg/cm.sup.2 for 
five minutes. After the pressure is released, the glass blank is cooled to 
the transition point or below at a cooling speed of -5.degree. C./min, 
whereafter it is cooled at a cooling speed of -20.degree. C./min or 
higher, and when the temperature of the glass blank lowers to 200.degree. 
C. or below, the valve 66 is closed and the vent valve 63 is opened to 
thereby introduce air into the vacuum chamber 51. The lid 52 is then 
opened and the upper mold keeper is removed, and then the molded article 
is taken out. 
In the manner described above, a lens 204 shown in FIG. 14 was formed by 
the use of the optical glass SF14 of the flint line (the softening point 
Sp=586.degree. C. and the transition point Tg=485.degree. C.). The then 
conditions of deposition, i.e., the time-temperature relation, in the same 
temperature graph as the graph shown in FIG. 11. 
Subsequently, the roughness of the surface of the molded lens and the 
roughness of the surface of the mold before and after molding were 
measured. The result is shown in Table 19 below. 
Also, after with respect to Nos. 49, 52 and 53 which did not cause fusion, 
molding was effected 200 times by the use of the same mold, the roughness 
of the surface was measured. The result is shown in Table 20 below. 
TABLE 19 
__________________________________________________________________________ 
Roughness of surface Rmax (.mu.m) 
Sample Mold Mold Parting 
No. Coating 
Base material 
Lens 
(before molding) 
(after molding) 
Property 
__________________________________________________________________________ 
49 None WC (90%) + Co (10%) 
0.04 
0.02 0.03 Good 
50 None SiC -- 0.04 -- Fused 
51 SiC WC (90%) + Co (10%) 
-- 0.02 -- Fused 
52 a-C:H 
WC (90%) + Co (10%) 
0.03 
0.02 0.02 Good 
53 a-C:H 
SiC 0.05 
0.04 0.04 Good 
__________________________________________________________________________ 
TABLE 20 
______________________________________ 
Roughness of surface Rmax (.mu.m) 
No. Lens Mold (after 200 times) 
______________________________________ 
49 0.14 0.15 
52 0.03 0.02 
53 0.05 0.04 
______________________________________ 
As is apparent from Tables 19 and 20, the mold having the a-C:H film of the 
present invention formed on the surface thereof could press-mold optical 
elements of high accuracy which were good in the quality of image 
formation. 
From the foregoing, it is seen that the a-C:H film is excellent in working 
accuracy and heat resisting propertY and is fit to every material of every 
press-molding mold which is good in the adhesion/adherence with respect to 
the a-C:H film. 
Embodiment 15 
Use was made of the RF-PCVD apparatus used in Embodiment 14, the mold base 
material (substrate) was provided on the RF electrode side, the degree of 
vacuum was 0.03 Torr, and the substrate temperature was room temperature 
and the flow rate of CH.sub.4 was 15 SCCM. and first, the RF power was 50 
W and a film was formed to a film thickness of 1000 .ANG.. This film had 
Knoop hardness 800 kg/mm.sup.2 and contained 60 atom % of hydrogen 
therein. Thereafter, the RF power was changed to 100 W, and a film was 
made to a film thickness of 4000 .ANG.. This film had Knoop hardness 2200 
kg/mm.sup.2 and contained about 10 atom % of hydrogen therein, and the 
roughness of the surface thereof was Rmax 0.03 .mu.m or less and the 
coefficient of friction thereof was 0.2 or less. By the use of the mold on 
which this a-C:H film was formed, a press-molding test was carried out by 
the apparatus shown in FIG. 10. 
Optical glass of the flint line (SF14, the softening point Sp=586.degree. 
C. and the glass transition point Tg=485.degree. C.) was roughly worked 
into a predetermined shape and dimensions, whereby there was obtained a 
blank for molding. 
The glass blank was placed on the pallet 120, and then was placed in the 
position 120-1 in the taking-in replacement chamber 104, and the pallet in 
this position was pushed in the direction of arrow A by the rod 122 of the 
cylinder 124 and was conveyed to the position 120-2 in the molding chamber 
106 beyond the gate valve 112, whereafter in the same manner, pallets were 
newly successively placed into the taking-in replacement chamber 104 at 
predetermined timing, and each time, the pallets were successively 
conveyed to positions 120-2.fwdarw. . . . .fwdarw.120-8 in the molding 
chamber 106. In the meantime, in the heating zone 106 - 1, the glass blank 
was gradually heated by the heaters 128 and was rendered to the softening 
point or about at the position 120 - 4, whereafter it was conveyed to the 
press zone 106-2, where the cylinders 138 and 140 were operated to press 
the glass blank with a pressure of 10 kg/cm.sup.2 for five minutes by the 
upper mold member 130 and the lower mold member 132, whereafter the 
pressure was released and the glass blank was cooled to the glass 
transition point or below, and thereafter the cylinders 138 and 140 were 
operated to part the upper mold member 130 and the lower mold member 132 
from the molded glass article. During this press, said pallet was utilized 
as a side mold member for molding. Thereafter, the molded glass article 
was gradually cooled in the gradually cooling zone 106-3. The molding 
chamber 106 was dilled with inert gas. 
The pallet which arrived at the position 120-8 in the molding chamber 106 
was then conveyed to the position 120-9 in the evaporation chamber 108 
beyond the gate valve 114. Usually, vacuum evaporation is effected here, 
but in the present embodiment, such evaporation was not effected. In the 
next cycle of conveyance, the pallet was conveyed to the position 120-10 
in the taking-out replacement chamber 110 beyond the gate valve 116. 
During the next cycle of conveyance, the cylinder 150 was operated and the 
molded glass article was taken out of the molding apparatus 102 by the rod 
148. 
The roughness of the molding surfaces of the mold members 130 and 132 
before and after the press-molding as described above, the roughness of 
the optical surface of the molded optical element and the parting property 
of the molded optical element with respect to the mold members 130 and 132 
are shown in Table 21 below. 
TABLE 21 
__________________________________________________________________________ 
Roughness of surface Rmax (.mu.m) 
Sample Mold Mold Parting 
No. Coating 
Base material 
Lens 
(before molding) 
(after molding) 
Property 
__________________________________________________________________________ 
54 None WC (90%) + Co (10%) 
0.04 
0.02 0.03 Good 
55 None SiC -- 0.04 -- Fused 
56 SiC WC (90%) + Co (10%) 
-- 0.02 -- Fused 
57 a-C:H 
WC (90%) + Co (10%) 
0.03 
0.03 0.03 Good 
58 a-C:H 
SiC 0.05 
0.04 0.04 Good 
__________________________________________________________________________ 
Subsequently, with respect to Nos. 54, 57 and 58 which did not cause 
fusion, press-molding was effected 10,000 times on end by the use of the 
same mold members. The roughness of the molding surfaces of the mold 
members in this case and the roughness of the optical surface of the 
molded optical element are shown in Table 22 below. 
TABLE 22 
______________________________________ 
Number 
of Roughness of surface Rmax (.mu.m) 
No. molding Lens Mold 
______________________________________ 
54 200 0.14 0.15 
1000 0.20 0.21 
5000 0.23 0.24 
10000 0.26 0.27 
57 200 0.03 0.03 
1000 0.03 0.03 
5000 0.03 0.03 
10000 0.04 0.03 
58 200 0.05 0.04 
1000 0.05 0.04 
5000 0.05 0.04 
10000 0.05 0.05 
______________________________________ 
As shown above, in the present embodiment, even the repetitive use of the 
mold for press-molding could maintain good surface accuracy sufficiently 
and optical elements of good surface accuracy could be formed without 
causing fusion. 
Embodiment 16 
By a method similar to Embodiment 15, a film was first formed to a film 
thickness 1000 .ANG. at RF power 50 W. The RF power was then changed to 80 
W and the mold base material (substrate) was heated to 300.degree. C., 
whereafter the film was further formed to 6000 .ANG.. This film had Knoop 
hardness of 2400 kg/mm.sup.2, contained 20 atom % of hydrogen therein, and 
had surface roughness of Rmax 0.02 .mu.m or less and a coefficient of 
friction of 0.2 or less. Also, by the analysis in the direction of depth 
by an ion microanalyzer, it was confirmed that the hydrogen content in the 
film on that side contacting with the mold base material was 60 atom %, 
that hydrogen content in the film on the surface side was 20 atom % and 
that two layers of films were formed by the difference in the hydrogen 
content. By the use of this mold, a molding test and evaluation similar to 
those in Embodiment 1 were effected with a result that a mold equal to 
that of Embodiment 14 was obtained. 
a-C:H film in which the hydrogen content exceeds 40 atom % is softer than a 
film in which the amount of hydrogen content is 5-40 atom % and therefore, 
when a film containing 5-40 atom % of hydrogen therein is formed on the 
a-C:H film, the film thickness thereof exceeds 5000 .ANG. and even if the 
internal stress therein becomes great, the stress can be absorbed in this 
soft a-C:H film to reduce the stress of the entire film, whereby the 
adhesion/adherence thereof with respect to the mold base material is 
improved. Also, not only the stress but also the distortion in the film 
due to the difference in the coefficient of thermal expansion and to the 
mechanical deformation resulting from molding can be alleviated. 
The optical element molding mold of the present invention is excellent in 
the parting property with respect to glass and permits mirror surface 
polishing, and suffers very little from the deterioration of the surface 
as compared with the prior-art mold even if the mold is used repetitively. 
According to the present invention, a-C:H film which is great in the 
hydrogen content and low in hardness is formed on the molding surface of a 
mold base material, and by gradually decreasing the amount of hydrogen 
content, there can be obtain a molding mold which does not react to lead 
and alkali elements contained in glass in the high temperature state of 
the glass. 
Particularly, by the film containing much hydrogen being provided near the 
base material, the stress in the film can be alleviated and the 
adhesion/adherence between the base material and the amorphous film can be 
improved. 
3) Description of a Third Invention 
Description will now be made in detail of some embodiments of a molding 
mold coated with an a-C:H film containing hydrogen atoms and other 
elements therein which is the third object of the present invention. 
Embodiment 17 
The surface of a mold base material comprising WC(90%) and Co(10%) was 
coated with a-C:H film by the ECR-PCVD method (the ECR method). The 
ECR-PCVD plasma apparatus is of the cavity type shown in FIG. 6, that is, 
a magnetic field is applied to the cavity 21 by the electromagnet 22, a 
microwave is introduced from the microwave introduction window 24 through 
the waveguide tube 23, gas is introduced from the gas inlet port 27 into 
the cavity and the gas is excited. The magnitude of the magnetic field was 
set so as to be 2000 gauss in the microwave introduction port and 500 
gauss on the surface of the mold. The mold 26 supported on the mold holder 
25 was installed outside the cavity resonator as shown in FIG. 6. 
TABLE 23 
______________________________________ 
Mold No. CH.sub.4 CO H.sub.2 NH.sub.3 
N.sub.2 
______________________________________ 
59 10 20 1 
60 10 20 1 
61 10 1 
62 20 20 1 
63 15 1 
64 10 10 
65 10 20 
66 5 5 
67 10 1 5 
68 10 10 1 
69 10 10 10 1 
70 5 5 10 2 
71 10 10 
______________________________________ 
Subsequently, the gases shown in Table 23 above were introduced from the 
gas inlet port 27, the pressure was rendered to 5.times.10.sup.-2 Torr, 
and under constant conditions of microwave power 600 W and the mold 
surface temperature 300.degree. C., film making was effected for one hour, 
whereby molds Nos. 59-71 were obtained. 
Each film formed was element-analyzed by the combustion method, and the 
Knoop hardness thereof was measured. The result is shown in Table 24 
below. 
TABLE 24 
______________________________________ 
Mold Element analysis value 
Knoop hardness 
No. C H N O (kg/mm.sup.2) 
______________________________________ 
59 1.5 1 1,000 -- 1800 
60 1.5 1 200 -- 1750 
61 19 1 20,000 -- 2100 
62 5 3 100 -- 1500 
63 19 1 300 -- 2000 
64 4 3 -- 1,000 2000 
65 1.5 1 -- 30,000 1650 
66 2 1 -- 500 1850 
67 2 1 -- 100 1900 
68 2 1.3 100 200 2000 
69 1.5 1 100 3,000 1950 
70 1.5 1 2,000 100 1750 
71 1.5 1 -- -- 700 
______________________________________ 
(The contents of C and H are in atom ratio, and the amounts of N and O are 
in atom ppm.) 
Description will now be made of an example in which by the use of molds 
coated with these thirteen kinds of films, press-molding of glass lenses 
was effected by the apparatus shown in FIG. 9. 
Optical glass of the flint line (SF14) is first adjusted to a predetermined 
amount, a glass blank made into a spherical shape is placed in the cavity 
of a mold, and this is installed in the apparatus. 
The mold in which the glass blank is placed is installed in the apparatus, 
and then the lid 52 of the vacuum chamber 51 is closed, and water flows 
into the water cooling pipe 70 and a current is supplied to the heaters 
58. At this time, the valve 66 for nitrogen gas and rent valve 68 are 
closed and the exhaust system valves 62, 63 and 64 are also closed. The 
rotary oil pump 61 is rotating at all times. 
The valve 62 is opened to begin exhaust, and when the pressure becomes 
10.sup.-2 Torr or less, the valve 62 is closed, and the valve 66 is opened 
to introduce nitrogen gas from a cylinder into the vacuum chamber. When a 
predetermined temperature is reached, the air cylinder 60 is operated to 
press the glass blank with a pressure of 10 kg/cm.sup.2 for five minutes. 
After the pressure is released, cooling is effected at a cooling speed of 
-5.degree. C./min until the transition point or below is reached, 
whereafter cooling is effected at a speed of -20.degree. C./min or higher, 
and when the temperature falls to 200.degree. C. or below, the valve 66 is 
closed and the leak valve 63 is opened to introduce air into the vacuum 
chamber 51. The lid 52 is then opened and the upper mold keeper is 
removed, whereafter the molded article is taken out. 
In the manner described above, a lens 4 was molded by the use of optical 
glass SF14 of the flint line (the softening point Sp=586.degree. C. and 
the transition point Tg=485.degree. C.). The condition of deposition at 
this time, i.e., the time-temperature relation, is the same as that shown 
in FIG. 11. 
Subsequently, after molding was effected 200 times by the use of the same 
mold, the roughness of the surfaces of the molded lenses and the roughness 
of the surface of the mold before and after molding were measured. The 
result is shown in Table 25 below. 
TABLE 25 
______________________________________ 
Mold Roughness of surface Rmax (.mu.m) 
No. Lens Mold (before molding) 
Mold (after molding) 
______________________________________ 
59 0.03 0.03 0.03 
60 0.03 0.03 0.03 
61 0.03 0.03 0.03 
62 0.03 0.03 0.03 
63 0.03 0.03 0.03 
64 0.03 0.03 0.03 
65 0.03 0.03 0.03 
66 0.03 0.03 0.03 
67 0.03 0.03 0.03 
68 0.03 0.03 0.03 
69 0.03 0.03 0.03 
70 0.03 0.03 0.03 
71 0.10 0.05 0.07 
______________________________________ 
Description will now be made in detail of an example in which by the use of 
the molds Nos. 59-71, press-molding of glass lenses was effected by the 
molding apparatus shown in FIG. 10. 
Optical glass of the flint line (SF14, the softening point Sp=586.degree. 
C. and the glass transition point Tg=485.degree. C.) was roughly worked 
into a predetermined shape and dimensions, whereby a blank for molding was 
obtained. 
The glass blank was placed on the pallet 120 and placed in the position 
120-1 in the taking-in replacement chamber 104, and the pallet in this 
position was pushed in the direction of arrow A by the rod 122 of the 
cylinder 124 and conveyed to the position 120-2 in the molding chamber 106 
beyond the gate valve 112, whereafter in the same manner, pallets were 
newly successively placed into the taking-in replacement chamber 104 at 
predetermined timing, and each time, the pallets were successively 
conveyed to the positions 120-2.fwdarw. . . . .fwdarw.120-8 in the molding 
chamber 106. In the meantime, in the heating zone 106-1, the glass blank 
was gradually heated by the heaters 128 and rendered to the softening 
point or above at the position 120-4, whereafter it was conveyed to the 
press zone 106-2, where the cylinders 138 and 140 were operated to press 
the glass blank with a pressure of 10 kg/cm.sup.2 for five minutes by the 
upper mold member 130 and the lower mold member 132, whereafter the 
pressure was released and the glass blank was cooled to the glass 
transition point or below, whereafter the cylinders 138 and 140 were 
operated to part the upper mold member 130 and the lower mold member 132 
from the molded glass article. During this pressing, said pallet was 
utilized as a side mold member for molding. Thereafter, in the gradually 
cooling zone 106-3, the molded glass article was gradually cooled. The 
molding chamber 106 was filled with inert gas. 
The pallet which arrived at the position 120-8 in the molding chamber 106 
was then conveyed to the position 120-9 in the evaporation chamber 108 
beyond the gate valve 114. Usually, vacuum evaporation is effected here, 
but in the present embodiment, such evaporation was not effected. In the 
next cycle of conveyance, the pallet was conveyed to the position 120-10 
in the taking-out replacement chamber 110 beyond the gate valve 116. 
During the next cycle of conveyance, the cylinder 150 was operated and the 
molded glass article was taken out of the molding apparatus 102 by the rod 
148. 
When 1,000, 5,000 and 10,000 durability tests were carried out, the mold 
No. 71 coated with a film which does not contain nitrogen and oxygen atoms 
therein had its coating film peeled off at the 800th-900th time. However, 
the other molds Nos. 59-70 exhibited lens surface roughness of Rmax 0.3 
.mu.m or less even after the 10,000th molding. The best was the mold No. 
69 which exhibited Rmax 0.02 .mu.m, and the worst was the mold No. 62 
which exhibited Rmax 0.03 .mu.m. 
Embodiment 18 
In the same manner as in Embodiment 17, by the use of the apparatus shown 
in FIG. 6 and by the ECR-PCVD method, the surface of a mold base material 
comprising WC 90% and Co 10% was coated with a-C:H film. However, the 
microwave power 600 W as changed to 700 W, and the magnitude 2000 gauss of 
the magnetic field in the microwave introduction port was changed to 2500 
gauss. The kinds and flow rates of gases used for deposition are shown in 
Table 26 below. 
TABLE 26 
______________________________________ 
Mold 
No. CH.sub.4 
CH.sub.3 OH 
He Ne Ar Xe Kr NH.sub.3 
CO H.sub.2 
______________________________________ 
72 10 2 
73 10 2 5 
74 10 2 
75 10 2 
76 10 2 
77 10 2 1 5 
78 2 10 5 
79 2 1 10 
______________________________________ 
(Unit: SCCM) 
The a-C:H film thus obtained was elementary analyzed by the combustion 
analysis and the atomic absorption analysis, and the Knoop hardness 
thereof was measured. The result is shown in Table 27 below. 
TABLE 27 
__________________________________________________________________________ 
Mold Hardness 
No. C H N O He Ne Ar Xe Kr (kg/mm.sup.2) 
__________________________________________________________________________ 
72 2 1 500 1,500 
73 1.5 
1 900 1,200 
74 3 1 4,000 2,500 
75 1.5 
1 100 1,300 
76 1.5 
1 100 
1,400 
77 2 1 10,000 500 1,700 
78 3 1 1,000 
3,000 2,600 
79 2 1 1,000 
1,000 1,000 1,800 
__________________________________________________________________________ 
(The contents of C and H are in atom ratio, and the others are in atom 
ppm.) 
Subsequently, by the ion beam deposition method shown in FIG. 16, the mold 
was coated with a film in the same manner as in the above-described 
example. In FIG. 16, the reference numeral 322 designates a vacuum 
chamber, the reference numerals 323 and 323' denote two ion gun, the 
reference numerals 324 and 324' designate ionization chambers, the 
reference numerals 325 and 325' denote ion beam extractive grids, the 
reference numerals 326 and 326' designate gas introduction ports, the 
reference numeral 327 denotes a mold base material, and the reference 
numeral 328 designates a mold holder. 
From the gas inlet port 326, a mixture of carbon-containing gas and 
hydrogen is introduced and ionized to create an ion beam, and in the gas 
inlet port 326', inert gas atoms are ionized and drawn out as an ion beam, 
and a film is formed on the mold base material 327. 
The back pressure of the vacuum chamber was 2.times.10.sup.-5 Torr, 
methane, hydrogen and helium were used as the film-making gases, and the 
gas flow rates thereof were fixed to 5 SCCM. At this time, the pressure 
became 3.times.10.sup.-4 Torr. 
The acceleration voltages of the ion beam of methane and hydrogen and the 
ion beam of helium were rendered such as shown in Table 28 below and a 
film was made without the substrate being specially heated. The substrate 
temperatures were as shown in Table 28 depending on the conditions of each 
ion beam. 
TABLE 28 
______________________________________ 
Acceleration voltage 
Ion beam of Substrate 
Mold methane and Ion beam of 
temperature 
No. hydrogen (kv) helium (kv) 
(.degree.C.) 
______________________________________ 
80 0.5 0.5 80 
81 0.8 0.5 100 
82 1.0 0.5 120 
83 5.0 0.5 150 
84 0.5 2 100 
85 0.8 2 130 
86 1.0 2 150 
87 5.0 2 180 
______________________________________ 
The component analysis and hardness of these films are shown in Table 29 
below. 
TABLE 29 
______________________________________ 
Mold No. C H He Hardness (kg/mm.sup.2) 
______________________________________ 
80 1 1 1,000 1500 
81 1 1 1,000 1400 
82 1 0.8 1,000 1800 
83 1 0.7 1,000 1850 
84 1 0.6 1,000 1900 
85 1 0.6 1,000 2000 
86 1 0.4 1,000 2300 
87 1 0.2 1,000 2900 
______________________________________ 
(The contents of C and H are in atom ratio, and the amount of He is in atom 
ppm.) 
Also, slight amounts of N and 0 were detected in these films. 
Subsequently, by the use of molds coated with these sixteen kinds of films 
and by the apparatus shown in FIG. 9, press-molding of glass lenses was 
effected. 
The roughness of the surfaces of the molded lenses and the roughness of the 
surfaces of the molds before and after molding were measured. The result 
is shown in Table 30 below. 
TABLE 30 
______________________________________ 
Roughness of surface Rmax (.mu.m) 
Mold Mold Mold Parting 
No. Lens (before molding) 
(after molding) 
property 
______________________________________ 
72 0.03 0.03 0.03 Good 
73 0.03 0.03 0.03 " 
74 0.03 0.03 0.03 " 
75 0.03 0.03 0.03 " 
76 0.03 0.03 0.03 " 
77 0.03 0.03 0.03 " 
78 0.03 0.03 0.03 " 
79 0.03 0.03 0.03 " 
80 0.03 0.03 0.03 " 
81 0.03 0.03 0.03 " 
82 0.03 0.03 0.03 " 
83 0.03 0.03 0.03 " 
84 0.03 0.03 0.03 " 
85 0.03 0.03 0.03 " 
86 0.03 0.03 0.03 " 
87 0.03 0.03 0.03 " 
______________________________________ 
Subsequently 1,000, 5,000 and 10,000 durability tests were carried out by 
the apparatus shown in FIG. 10. In all cases, the roughness of the 
surfaces of the lenses was Rmax 0.03 .mu.m or less. The best was the film 
of No. 87 which exhibited Rmax 0.02 .mu.m. 
Embodiment 19 
The mold base material was coated with a-C:H film by the use of an 
apparatus shown in FIG. 17. In FIG. 17, the reference numeral 341 
designates RF of 13.56 MHz, and this apparatus is a PCVD apparatus in 
which a substrate bias can be applied by a DC power supply 340. 
When a-C:H film is to be formed, the mold base material 337 having its 
surface cleaned by an organic solvent is installed on a holder 336, and 
the air is exhausted from an exhaust port 342 to thereby render the 
interior of a chamber 335 vacuum. The mold base material 337 is heated to 
300.degree. C., and source gas CH.sub.4 +CF.sub.4 is introduced at the 
ratio of CH.sub.4 /CH.sub.4 =2 from a gas inlet port 338. H.sub.2 gas is 
introduced by 10 SCCM from an introduction port 339. 
RF power 300 W and substrate bias -300 V were applied, the pressure was 
kept at 2.times.10.sup.-2 Torr and discharge was effected. The substrate 
temperature was held at 150.degree. C. and a film of 0.5 .mu.m was 
deposited. 30 atom % of hydrogen was contained in the thus produced film 
a-C:H:F and C-F bonding was confirmed by the surface analysis using ESCA. 
Embodiment 20 
In the same manner as in Embodiment 19, by the use of the apparatus of FIG. 
7, mixture gas of Ar/H.sub.2 =1 was introduced from the inlet port 339, 
CH.sub.4 gas was introduced from the inlet port 338, RF power 300 W and 
substrate bias -500 V were applied and a film of 0.5 .mu.m was deposited 
at a substrate temperature 200.degree. C. Thereafter, CF4 gas was 
introduced from the introduction port 339 and discharge was effected at RF 
power 200 W and substrate bias 0 V. 
The thus produced film contained 25 atom % of hydrogen therein and C-F 
bonding was confirmed by ESCA. 
The process of making a lens will now be described. 
First, a mold base material is worked into a predetermined shape, and the 
lens molding surface thereof is polished into a mirror surface. A coating 
of SiC is then formed by the ion plating method. Also, samples Nos. 91 and 
92 were coated with a-C:H film by the method of Embodiment 19, and sample 
No. 93 was coated with a-C:H film by the method of Embodiment 20. The 
thickness of each film was 0.1 .mu.m. Optical glass of the flint line 
(SF14) is then adjusted to a predetermined amount, and a glass blank made 
into a spherical shape is placed in the cavity of the mold, and this is 
installed in the apparatus. 
Description will now be made in detail of an example in which press-molding 
of a glass lens was effected by the mold according to the present 
invention. Table 31 below shows the kinds of the mold materials used in 
the experiment. 
TABLE 31 
______________________________________ 
No. Coating Material 
Base material 
______________________________________ 
88 None WC (90%) + Co (10%) 
89 None SiC 
90 SiC WC (90%) + Co (10%) 
91 a-C:H:F WC (90%) + Co (10%) 
92 a-C:H:F SiC 
93 a-C:H:F WC (90%) + Co (10%) 
______________________________________ 
Nos. 88-90 are comparative materials, and Nos. 91-93 are materials proposed 
by the present invention. Super-hard alloy WC (90%)+Co (10%) and sintered 
SiC were used as the base material. By the use of these molds, molding was 
effected by the apparatus of FIG. 9 in the same manner as in Embodiment 
17. 
Subsequently, the roughness of the surfaces of the molded lenses and the 
roughness of the surfaces of the molds before and after molding were 
measured. The result is shown in Table 32 below. 
TABLE 32 
__________________________________________________________________________ 
Roughness of surface Rmax (.mu.m) 
Mold Mold Parting 
No. 
Coating 
Base material 
lens 
(before molding) 
(after molding) 
property 
__________________________________________________________________________ 
88 None WC (90%) + Co (10%) 
0.04 
0.02 0.03 Good 
89 None SiC -- 0.04 -- Fused 
90 SiC WC (90%) + Co (10%) 
-- 0.02 -- Fused 
91 a-C:H:F 
WC (90%) + Co (10%) 
0.03 
0.02 0.02 Good 
92 a-C:H:F 
SiC 0.05 
0.04 0.04 Good 
93 a-C:H:F 
WC (90%) + Co (10%) 
0.03 
0.03 0.03 Good 
__________________________________________________________________________ 
Subsequently, with respect to Nos. 88, 91, 92 and 93 which did not cause 
fusion, press-molding was effected 10,000 times on end by the use of the 
same mold members and by the apparatus shown in FIG. 10. The roughness of 
the molding surfaces of the mold members at this time and the roughness of 
the optical surfaces of the molded optical elements are shown in Table 33 
below. 
TABLE 33 
______________________________________ 
Roughness of 
Number surface Rmax (.mu.m) 
No. of molding Lens Mold 
______________________________________ 
88 200 0.14 0.15 
1000 0.20 0.21 
10000 0.26 0.27 
91 200 0.03 0.03 
1000 0.03 0.03 
10000 0.04 0.03 
92 200 0.04 0.04 
1000 0.05 0.04 
10000 0.05 0.04 
93 200 0.03 0.03 
1000 0.03 0.03 
10000 0.03 0.03 
______________________________________ 
The mold of the present invention is excellent in the parting property with 
respect to glass and permits mirror surface polishing, and even if it is 
repetitively used, it suffers very little from the deterioration of its 
surface as compared with the prior-art mold. 
According to the present invention, as described previously with respect to 
the third object thereof, stabilization of the structure of the amorphous 
film could be achieved. That is, the present invention could provide a 
mold which could preclude the activation of dangling bond and could 
prevent the reaction to lead or the like contained in glass. 
4) Description of the Fourth Invention 
Description will now be made of some embodiments of the mold having the 
molding surface thereof coated with an amorphous carbon film having an 
intermediate layer comprising a carbide of the base material component or 
an intermediate layer comprising the base material component and an a-C:H. 
Embodiment 21 
FIGS. 18 and 19 shown an embodiment of the mold according to the present 
invention. 
FIG. 18 shows the state before the press-molding of an optical element, and 
FIG. 19 shows the state after the molding of the optical element. In FIG. 
18, the reference numeral 401 designates a mold base material, the 
reference numerals 402 and 405 denote a-C:H film and an intermediate layer 
formed on the molding surfaces of the mold base material which contact 
with a glass blank, and the reference numeral 403 designates the glass 
blank, and in FIG. 19, the reference numeral 404 denotes the optical 
element. By press-molding the glass blank 403 placed between the molds as 
shown in FIG. 18, the optical element 404 such as a lens is molded as 
shown in FIG. 19. 
Description will now be made in detail of an example of the manufacture of 
the mold of the present invention. The apparatus used to form the a-C:H 
film and the intermediate layer is schematically shown in FIG. 20. 
In FIG. 20, the reference numeral 411 designates a vacuum chamber, the 
reference numeral 412 denotes an ion gun, the reference numeral 413 
designates a gas inlet port, the reference numeral 414 denotes a 
substrate, the reference numeral 415 designates an exhaust port, the 
reference numeral 416 denotes tungsten, and the reference numeral 417 
designates an electron gun. 
WC(90%)+Co(10%) was used as the mold base material. The internal pressure 
of the vacuum chamber 411 was reduced to 1.times.10.sup.-6 Torr, 
whereafter Ar gas was introduced from the gas introduction port 413 into 
the ion gun 412 and was thereby made into an Ar.sup.+ ion beam, which was 
applied to the surface of the substrate (base material) 414 to clean the 
same. 
Thereafter, the intermediate layer was produced. Methane gas was introduced 
from the gas introduction port into the ion gun, and an acceleration 
voltage 100 V and an ion current 0.05 mA/cm.sup.2 were applied to thereby 
make the gas into an ion beam while, on the other hand, an electron beam 
(9 KV, 1A) was applied from the electron gun 417 to the tungsten 416 of 
high purity (99.99%) and at the same time, evaporation was effected. The 
substrate temperature was held at 300.degree. C., and the pressure in the 
vacuum chamber was 4.times.10.sup.-4 Torr. The produced intermediate layer 
had a thickness of 1,000 .ANG.. 
The a-C:H film was then formed. Mixture gas of a ratio of CH.sub.4 /H.sub.2 
=1/2 was introduced into the ion gun, an acceleration voltage 600 V was 
applied, and an ion beam of ion current 0.85 mA/cm.sup.2 was applied onto 
the substrate (base material+intermediate layer) held at a substrate 
temperature 150.degree. C. 
The pressure was 2.times.10.sup.-4 Torr, and the film thickness of the 
a-C:H film was 5,000 .ANG.. 
Description will now be made in detail of an example in which press-molding 
of a glass lens was effected by the optical element mold according to the 
present invention. Table 34 below shows the kinds of the base materials 
used in the experiment. 
TABLE 34 
______________________________________ 
No. Coating material 
Base material 
______________________________________ 
94 None WC (90%) + Co (10%) 
95 None SiC 
96 SiC WC (90%) + Co (10%) 
97 a-C:H (having WC (90%) + Co (10%) 
intermediate layer) 
______________________________________ 
Nos 94-96 are comparative materials, and No. 97 is the material proposed by 
the present invention. The lens molding apparatus used in the same as the 
apparatus shown in FIG. 9. 
First, optical glass of the flint line (SF14) is adjusted to a 
predetermined amount, a glass blank made into a spherical shape is placed 
in the cavity of the mold, and this is installed in the apparatus. 
The mold in which the glass blank is placed is installed in the apparatus, 
and then the lid 52 of the vacuum chamber 51 is closed, and water flows 
into the water cooling pipe 70 and an electric current is supplied to the 
heaters 58. At this time, the valve 66 for nitrogen gas and vent valve 68 
are closed and the exhaust system valves 62, 63 and 64 are also closed. 
The oil rotating pump 61 is rotating at all times. 
The valve 62 is opened to begin exhaust and when the pressure reaches 
10.sup.-2 Torr or less, the valve 62 is closed and the valve 66 is opened 
to introduce nitrogen gas from a cylinder into the vacuum chamber. When a 
predetermined temperature is reached, the air cylinder 60 is operated to 
press the glass blank with a pressure of 10 kg/cm.sup.2 for five minutes. 
After the pressure is released, cooling is effected at a cooling speed of 
-5.degree. C./min until the transition point or below is reached, 
whereafter cooling is effected at a speed of -20.degree. C./min or higher, 
and when the temperature falls to 200.degree. C. or below, the valve 66 is 
closed and the vent valve 63 is opened to introduce air into the vacuum 
chamber 51. The lid 52 is then opened, the upper mold keeper is removed 
and the molded article is taken out. 
In the manner described above, the lens 404 shown in FIG. 19 was molded by 
the use of optical glass SF148 of the flint line (the softening point 
Sp=586.degree. C. and the transition point Tg=485.degree. C.). The 
condition of molding at this time, i.e., the time-temperature relation, is 
the same as FIG. 11. 
Subsequently, the roughness of the surfaces of the molded lenses and the 
roughness of the surface of the mold before and after molding were 
measured. The result is shown in Table 35 below. 
TABLE 35 
__________________________________________________________________________ 
Roughness of surface Rmax (.mu.m) 
Mold Mold Parting 
No. 
Coating 
Base material 
Lens 
(before molding) 
(after molding) 
property 
__________________________________________________________________________ 
94 None WC (90%) + Co (10%) 
0.04 
0.02 0.03 Good 
95 None SiC -- 0.04 -- Fused 
96 SiC WC (90%) + Co (10%) 
-- 0.02 -- Fused 
97 a-C:H WC (90%) + Co (10%) 
0.03 
0.02 0.02 Good 
(having 
intermediate 
layer) 
__________________________________________________________________________ 
With respect to Nos. 94 and 97 which did not cause fusion, the roughness of 
the surface was measured after molding was effected 200 times by the use 
of the same mold. The result is shown in Table 36 below. 
TABLE 36 
______________________________________ 
Roughness of surface Rmax (.mu.m) 
No. Lens Mold (after 200 times) 
______________________________________ 
94 0.14 0.15 
97 0.03 0.02 
______________________________________ 
As is apparent from the results shown in Tables 35 and 36 above, the mold 
material according to the present invention is excellent in the parting 
property with respect to glass, and even if it is repetitively used, it 
suffers very little from the deterioration of its surface as compared with 
the prior-art mold material. 
Embodiment 22 
Use was made of a mold base material and an apparatus similar to those used 
in Embodiment 21. In a similar manner, cleaning of the substrate was 
effected, whereafter the pressure and the substrate temperature were kept 
at 4.times.10.sup.-4 Torr and 150.degree. C., respectively, and methane 
gas was introduced into the ion gun and an ion beam was applied and at the 
same time, evaporation of tungsten was effected. The then acceleration 
voltage of the ion gun and the current value of the ion beam for 
deposition were varied as shown in FIG. 21, and the intermediate layer and 
the a-C:H layer were continuously formed into a film of 6,000 .ANG. as a 
whole. 
Description will now be made in detail of an example in which by the use of 
the apparatus shown in FIG. 10, press-molding of a glass lens was effected 
by the above-described mold. 
Optical glass of the flint line (SF14, the softening point Sp=586.degree. 
C. and the glass transition point Tg=485.degree. C.) was roughly worked 
into a predetermined shape and dimensions, whereby a blank for molding was 
obtained. 
The glass blank was installed in the pallet 120 and placed in the position 
120-1 in the taking-in replacement chamber 104, and the pallet in this 
position was pushed in the direction of arrow A by the rod 122 of the 
cylinder 124 and conveyed to the position 120-2 in the molding chamber 106 
beyond the gate valve 112, whereafter in a similar manner, pallets were 
newly successively placed in the taking-in replacement chamber 104 at 
predetermined timing, and each time, the pallets were successively 
conveyed to the positions 120-2.fwdarw. . . . .fwdarw.120-8 in the molding 
chamber 106. In the meantime, in the heating zone 106-1, the glass blank 
was gradually heated by the heater 128 and was rendered to the softening 
point or below at the position 120-4, whereafter it was conveyed to the 
press zone 106-2, where the cylinders 138 and 140 were operated to press 
the glass blank with a pressure of 10 kg/cm.sup.2 for five minutes by the 
upper mold member 130 and the lower mold member 132, whereafter the 
pressure was released and the glass blank was cooled to the glass 
transition point or below, and thereafter the cylinders 138 and 140 were 
operated to part the upper mold member 130 and the lower mold member 132 
from the molded glass article. During said pressing, said pallet was 
utilized as a side mold member for molding, whereafter the molded glass 
article was gradually cooled in the gradually cooling zone 106-3. The 
molding chamber 106 was filled with inert gas. 
The pallet which arrived at the position 120-8 in the molding chamber 106 
was then conveyed to the position 120-9 in the deposition chamber 108 
beyond the gate valve 114. Usually, vacuum evaporation is effected here, 
but in the present embodiment, such evaporation was not effected. In the 
next cycle of conveyance, the pallet was conveyed to the position 120-10 
in the taking-out replacement chamber 110 beyond the gate valve 116. 
During the next cycle of conveyance, the cylinder 150 was operated and the 
molded glass article was taken out of the molding apparatus 102 by the rod 
148. 
The roughness of the molding surfaces of the mold 130 and 132 before and 
after the press-molding as described above, the roughness of the optical 
surface of the molded optical element and the parting property of the mold 
130 and 132 with respect to the molded optical element are shown in Table 
37 below. 
TABLE 37 
__________________________________________________________________________ 
Roughness of surface Rmax (.mu.m) 
Mold Mold Parting 
No. 
Coating 
Base material 
Lens 
(before molding) 
(after molding) 
property 
__________________________________________________________________________ 
98 
None WC (90%) + Co (10%) 
0.04 
0.02 0.03 Good 
99 
None SiC -- 0.04 -- Fused 
100 
SiC WC (90%) + Co (10%) 
-- 0.02 -- Fused 
101 
a-C:H WC (90%) + Co (10%) 
0.03 
0.03 0.03 Good 
(having 
intermediate 
layer) 
__________________________________________________________________________ 
Subsequently, with respect to Nos. 98 and 101 which did not cause fusion, 
press-molding was effected 10,000 times on end by the use of the same 
mold. The roughness of the molding surfaces of the mold 130 and 132 at 
this time and the roughness of the optical surface of the molded optical 
element are shown in Table 38 below. 
TABLE 38 
______________________________________ 
Roughness of 
Number surface Rmax (.mu.m) 
No. of molding Lens Mold 
______________________________________ 
98 200 0.14 0.15 
1000 0.20 0.21 
5000 0.23 0.24 
10000 0.26 0.27 
101 200 0.03 0.03 
1000 0.03 0.03 
5000 0.03 0.03 
10000 0.04 0.03 
______________________________________ 
As shown above, in the present embodiment, even if the mold was 
repetitively used for press-molding, good surface accuracy could be 
maintained sufficiently and optical elements of good surface accuracy 
could be molded without fusion being caused. 
Embodiment 23 
The apparatus used is schematically shown in FIG. 22. 
In FIG. 22, the reference numeral 421 designates a vacuum chamber, the 
reference numeral 422 denotes an ion gun, the reference numerals 423 and 
423' designate gas inlet ports, the reference numeral 424 denotes a 
substrate, the reference numeral 425 designates an exhaust port, the 
reference numeral 426 denotes tungsten, the reference numeral 427 
designates an electron gun, the reference numeral 428 denotes a matching 
box, and the reference numeral 429 designates an RF power supply. 
By the same mold base material as that used in Embodiment 21 and in a 
similar manner, the substrate (base material) 424 was cleaned by Ar.sup.+ 
ion beam. Thereafter, methane gas at 4.times.10.sup.-3 Torr was introduced 
from the gas inlet port 423 into the ion gun 422 and an ion beam was 
applied to the substrate at an acceleration voltage 100 V and ion current 
0.05 mA/cm.sup.2. At the same time, argon gas at 4.times.10.sup.-4 Torr 
was introduced from the gas inlet port 423' into the vicinity of the 
tungsten 426 of high purity 99.99%, and an RF of 13.56 MHz and output 1 KW 
was applied to the tungsten, whereby sputter deposition of the tungsten 
was effected. The substrate temperature was 150.degree. C. and an 
intermediate layer was formed to a thickness of 1,000 .ANG.. 
Subsequently, a-C:H film was deposited in the same manner as in Embodiment 
21, and the film thickness of the whole including the intermediate layer 
was rendered to 6,000 .ANG.. 
When a molding test was carried out by the use of the thus obtained mold 
and by the use of the apparatus of FIG. 9 as in Embodiment 21, a good 
result was obtained similarly to the mold No. 97 in Embodiment 21. 
Embodiment 24 
The same mold base material apparatus as that used in Embodiment 23 was 
used and cleaning of the substrate was effected in a similar manner. 
Thereafter, methane gas was introduced into the ion gun and made into an 
ion beam, which was applied, and at the same time, sputtering of the 
tungsten was effected, but the RF output power and the ion gun 
acceleration voltage were varied as shown in FIG. 23, and a film was made 
continuously. The thickness of the entire film was 5,500 .ANG.. The 
substrate temperature was 150.degree. C., the Ar gas was at 
4.times.10.sup.-3 Torr.fwdarw.0 Torr, the RF (1356 MHz) output power was 1 
KW.fwdarw.0 W, the methane gas was at 4.times.10.sup.-4 Torr, and the 
acceleration voltage was 50 V.fwdarw.500 V. 
When a molding test was carried out by the use of the thus obtained mold 
and by the use of the apparatus of FIG. 11 as in Embodiment 22, a good 
result was obtained similarly to the mold No. 101 in Embodiment 22. 
The optical element molding mold of the present invention is excellent in 
the parting property with respect to glass and permits mirror surface 
polishing, and even if it is repetitively used, it suffers very little 
from the deterioration of its surface as compared with the prior-art mold. 
Where the mold base material is super-hard alloy (WC-Co), Cobalt Co in 
WC-Co reacts to lead in glass and peeling-off of films occurs during the 
molding operation. 
According to the present invention, the surface of WC-Co is coated with a 
film intermediate of tungsten (W') and carbon (C). 
Particularly, if the rate of tungsten is made great in the lower layer of 
the intermediate layer and the rate of carbon is made great in the upper 
layer of the intermediate layer, the reaction of Co in WC-Co of the base 
material to glass is suppressed by tungsten and therefore, there could be 
provided a mold which did not cause the reaction to glass.