Re: [ATM] Tester question

["Francis J. O'Reilly" <foreilly@bestweb.net>]

Ben,

It's nice to hear from you. Thank you for taking the time to respond to my
query.

As I remember, you are working on an eight inch f/6, is that correct? How is
it going?

Best regards,

Francis J. O'Reilly
----- Original Message ----- 
From: "Ben McIlwain" <cydeweys@gmail.com>
Cc: <atm@atmlist.net>
Sent: Saturday, November 24, 2007 1:46 PM
Subject: Re: [ATM] Tester question


> Francis J. O'Reilly wrote:
>> Guy,
>>
>> I am very impressed with your combination tester, perhaps the most
>> interesting part was the optical alignment function, that is the
>> light which is reflected back to the tester light source to assure
>> that the apparatus is properly aligned. My weakest area in testing
>> has always been setting up the tester. Your idea makes the alignment
>> a sure hit every time.
>>
>> To that end I am making a tester that is similar to yours for my
>> home. Can you advise me as to the type of light source that you use
>> for the alignment light? I'd also like to know where it was purchased
>> if you remember.
>>
>> Thank you and best regards to you and yours for a blessed holiday
>> season.
>
> Well, I've used the Ronchi tester at the workshop enough to know how it
> works, so here you go.  The alignment light is nothing more than an
> off-the-shelf red laser pointer, which you should be able to get easily
> for less than $10 at many stores.  We use a clothes pin on the power
> button to keep it turned on.
>
> The laser pointer fits into an appropriate diameter hole cut into the
> end of a roughly ruler-proportioned piece of wood.  The other end of the
> wood is secured with a rotating mount, so the laser pointer can be swung
> into position to point through the top opening in the diffraction
> grating for alignment, then rotated out of the way so you can look
> through the grating for the Ronchi test itself.  It's a nice and simple
> setup that works very well.
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