Will a windshield repair kit fix a dinged condenser lens?

Will a windshield repair kit fix a dinged condenser lens?

I accidentally dinged the flat side of a condenser lens with the edge
of another lens, made a small gouge probably a couple of 1/1000ths "
deep give or take - I can feel it with a fingernail - and it's quite
visible when projecting an image through it.

Will one of these windshield repair kits with a sunlight hardened resin
make the ding optically invisible - i.e. so that it doesn't cast a
shadow when projecting through it, or is pointless to try? Don't want
to spend the $11 if it's not going to work. Is there any kind of repair
material for this kind of thing?

If that method isn't going to work, it's my understanding DIY lens
grinding is possible. Do you think it would be possible to grind down
the flat side of the lens past the point of the damage? Any links to
directions on how to do it? Where's a good place to get materials to do
this?

I know, the lenses aren't expensive but I hate to waste an otherwise
good one. I assume it would change its focal length slightly but it's
probably not crucial for my purposes.

Thanks for all input.

Re: Will a windshield repair kit fix a dinged condenser lens?

Doc wrote:
> I accidentally dinged the flat side of a condenser lens with the edge
> of another lens, made a small gouge probably a couple of 1/1000ths "
> deep give or take - I can feel it with a fingernail - and it's quite
> visible when projecting an image through it.
>
> Will one of these windshield repair kits with a sunlight hardened resin
> make the ding optically invisible - i.e. so that it doesn't cast a
> shadow when projecting through it, or is pointless to try? Don't want
> to spend the $11 if it's not going to work. Is there any kind of repair
> material for this kind of thing?
>
> If that method isn't going to work, it's my understanding DIY lens
> grinding is possible. Do you think it would be possible to grind down
> the flat side of the lens past the point of the damage? Any links to
> directions on how to do it? Where's a good place to get materials to do
> this?
>
> I know, the lenses aren't expensive but I hate to waste an otherwise
> good one. I assume it would change its focal length slightly but it's
> probably not crucial for my purposes.
>
> Thanks for all input.
>
It's doubtful that the acrylic resin will have the same optical
characteristics as the glass; even though it appears the same color the
refraction and dispersion is bound to be different. That translates to
image distortion for the rays that pass through the resin.

Grinding a new flat surface won't change the focal length significantly,
but it will be a lot of work, hours and hours, and then checking for
optical flatness is not simple. Far better to junk it and get another.

Colin D.

--
Posted via a free Usenet account from * w w w .teranews . com

Re: Will a windshield repair kit fix a dinged condenser lens?

Colin D <nospam@127.0.0.1> writes:

> Doc wrote:
>> I accidentally dinged the flat side of a condenser lens with the edge
>> of another lens, made a small gouge probably a couple of 1/1000ths "
>> deep give or take - I can feel it with a fingernail - and it's quite
>> visible when projecting an image through it.
>> Will one of these windshield repair kits with a sunlight hardened
>> resin
>> make the ding optically invisible - i.e. so that it doesn't cast a
>> shadow when projecting through it, or is pointless to try? Don't want
>> to spend the $11 if it's not going to work. Is there any kind of repair
>> material for this kind of thing?
>> If that method isn't going to work, it's my understanding DIY lens
>> grinding is possible. Do you think it would be possible to grind down
>> the flat side of the lens past the point of the damage? Any links to
>> directions on how to do it? Where's a good place to get materials to do
>> this?
>> I know, the lenses aren't expensive but I hate to waste an otherwise
>> good one. I assume it would change its focal length slightly but it's
>> probably not crucial for my purposes.
>> Thanks for all input.
>>
> It's doubtful that the acrylic resin will have the same optical
> characteristics as the glass; even though it appears the same color
> the refraction and dispersion is bound to be different. That
> translates to image distortion for the rays that pass through the
> resin.

It might be less visible than the scratch he has now though.

> Grinding a new flat surface won't change the focal length
> significantly, but it will be a lot of work, hours and hours, and
> then checking for optical flatness is not simple. Far better to
> junk it and get another.

Grinding will also remove any coating from that surface. Probably not
a good idea.

--
Måns Rullgård
mru@inprovide . com

Re: Will a windshield repair kit fix a dinged condenser lens?

In sci.optics Doc <docsavage20@yahoo . com > wrote:
> I accidentally dinged the flat side of a condenser lens with the edge
> of another lens, made a small gouge probably a couple of 1/1000ths "
> deep give or take - I can feel it with a fingernail - and it's quite
> visible when projecting an image through it.

Colour it in with black marker.

Re: Will a windshield repair kit fix a dinged condenser lens?


Ian Stirling wrote:

> Colour it in with black marker.

Clear varnish is better. Instead, if it is one of a pair of identical
lenses (convex sides inwards) just reverse the two to get the damaged
surface away from the focal plane.

Brian
Ancient and Modern Optics

Re: Will a windshield repair kit fix a dinged condenser lens?


Ian Stirling wrote:

> Colour it in with black marker.

Clear varnish is better. Instead, if it is one of a pair of identical
lenses (convex sides inwards) just reverse the two to get the damaged
surface away from the focal plane.

Brian
Ancient and Modern Optics

Re: Will a windshield repair kit fix a dinged condenser lens?

Actually works but something a little more opaque is better,
you can fill small scratches with India Ink and "dings"
with black brushing lacquer.
darkroommike

Ian Stirling wrote:
> In sci.optics Doc <docsavage20@yahoo . com > wrote:
>> I accidentally dinged the flat side of a condenser lens with the edge
>> of another lens, made a small gouge probably a couple of 1/1000ths "
>> deep give or take - I can feel it with a fingernail - and it's quite
>> visible when projecting an image through it.
>
> Colour it in with black marker.

Re: Will a windshield repair kit fix a dinged condenser lens?

You might want to try Canada Balsam. It is used to
glue lens elements together as it has the same
refractive index as glass.

Also used to mount microscope specimens on slides
and a scientific store would be the place to start looking.
Be warned it ain't cheap. Maybe you know someone
who works in a lab doing pathology?

Murray

Doc wrote:
> I accidentally dinged the flat side of a condenser lens with the edge
> of another lens, made a small gouge probably a couple of 1/1000ths "
> deep give or take - I can feel it with a fingernail - and it's quite
> visible when projecting an image through it.
>
> Will one of these windshield repair kits with a sunlight hardened resin
> make the ding optically invisible - i.e. so that it doesn't cast a
> shadow when projecting through it, or is pointless to try? Don't want
> to spend the $11 if it's not going to work. Is there any kind of repair
> material for this kind of thing?
>
> If that method isn't going to work, it's my understanding DIY lens
> grinding is possible. Do you think it would be possible to grind down
> the flat side of the lens past the point of the damage? Any links to
> directions on how to do it? Where's a good place to get materials to do
> this?
>
> I know, the lenses aren't expensive but I hate to waste an otherwise
> good one. I assume it would change its focal length slightly but it's
> probably not crucial for my purposes.
>
> Thanks for all input.
>