Internal ERF safety research

[AndiesHandyHandies]

Hi

1. Baader Dichroic UV-IR Luminance passes just visual band 400-700nm

2. Beloptic Dichroic UV-IR & KG3 starts cutting in the red but absorbs long IR the dielectrics pass.

3. Dichroic Red rgb passes 600-700nm

Passes about 13% of energy in the red of the total.

H&S on rear Telecentric / Quarks

UV-IR

Red 25a absorption, blocks blue and green which etalon leaks.

Seems safe enough and pretty standard.

Problem with Baader narrow band H-alpha is bright reflections. 35nm will reduce energy transmitted to about 4%.

Cheers. Andrew.

[AndiesHandyHandies]

Hi

Of course the Quark 1nm trim filter reduces the transmission to 0.12%.

And a 1A etalon comb tooth to 0.012%

I tried a search for melted PST etalon or Quark without a result.

Peter Drew uses a 6" PST Mod2 without additional ERFs which will work unless the PST ERF, Trim filter or Etalon fail 'clear'.

Cheers. Andrew.

[AndiesHandyHandies]

Hi

Someone else complained about red scatter in the LUNT ERF, IR block coating, Red 630, Anti-reflection coating. But good for imaging where can process out. For imaging have a UV-IR KG3 Beloptik in the diagonal.

There are two views of course, imaging and visual. First are worried about tube currents and second about eye safety.
And both worried about degrading blocking filters.

Lunt used to use blue glass for the ERF. But it passes less h-alpha than a KG3 which is better at blocking long IR.

I will compare gradual rejection against 35nm big bang and KG3 for visual.

Cheers. Andrew.

[AndiesHandyHandies]

Hi

A couple of sunny days for start of season messing about.

Focuser died again on Rumak180 F10 so need to sort that out.
In a pushed up tube in the focuser so in the bottom of the central baffle
1.25" UV-IR
1.25" Meade light Red rgb.

Some temperatures taken with IR thermometer.
Secondary front 30C

Light out of back of Meade 121C Black Body Equivalent BBE. Remove from Sun then back of Meade 24C.

Add 2" StL 40nm H-alpha
Light out of back 38C BBE and front 23C

1.25" UV-IR ES 2x TE
Light out of back 20C BBE


Moved to a 90mm TS Triplet F6.7.

2" UV-IR
2" KG3
1.25" True Technology Red rgb
Light out of back 146C BBE

Replace the Red rgb with a 2" StL 40nm
Light out of the back 84C BBE. Front 23C.

3x VK TE
Light out back 40C BBE
2x ES TE
Light out back 40C BBE, light cone not stopped down.

So I moved to all dialectric ERF pack in front of the diagonal. And no filters after to remove possible reflections.

2" UV-IR
2" KG3
2" StL 40nm

The Rumak still has the permanent UV-IR and Meade Red rgb in respect of the aperture.

Cheers. Andrew.

[AndiesHandyHandies]

Hi

More figures and some research.

Imagers report their cameras at 40C to 60.4C, presumably behind D-Erfs.

Rusted used a D-Erf on his 150mm F 10 and measured 120F 50C behind that. Adding a 2" BO UV-IR blocks 61% and the KG3 for 19% over 700nm and a Baader Red CCD 100nm pass, for Blue/Green suppression, he measured 55F 13C at ambient of 40F.

Using the 90mm F6.7:

After my Erf stack I measured BBE 52.3C looking up the back of the diagonal at the Sun , 62C on the 80mm F15.
The body of the filter stack 14.8C and inside the OTA 30.8C. Looking up 18.8C and down at the filter end 17.5C.

After the VK 3x TE 29.7 BBE and the ES 2x TE 24.8C looking up at the sun.

A red 20mm filter on the front of the Quark was 22C.

Looking up the Quark is just the oven temp at 37.3C.

Looking up the eyepiece 18.3C the rear lens temperature.

Solar Spectrum fit D-Erfs.

CV says light only heats mechanical parts, optical glass is pretty clear. So my Reverse Sun Block, diagonal on a stick before the OTA, at 90Deg, can send a converging beam of just the light we want into the scope. Need a bit of leeway in the baffles for prom imaging. Use dielectric filters to send unwanted heat back out the objective, which it has already gone through

Thomas says his Zeiss 63mm Quark mod is better than 60/90 Coranados. And a TMB 100 F8 equals a LUNT 150.

Mark W Says internal ERFs are smaller and cheaper. My point especially for set ups where UK seeing would allow full resolution. Use all of the clear aperture of the ERF filter. And he repaired melted delrin behind a RG610 Erf. At F35+ into the blocking filter no problem with hurting the filter without an Erf. He said I needed a KG3 for long IR on my PST Mod2, when I asked about getting more light through it.

I did todays testing from 6-7pm looking through tree branches. I was pleased to see a black field with the sun just outside of the field.

Cheers. Andrew.

[AndiesHandyHandies]

Hi

I decided to have a session looking at the temperatures of the components in my 90mm F6.7 Triplet.

Also looking up at the Sun through that component last. All with a remote IR thermometer, for meat cooking and we are meat machines.

2" front extension tubes and components. 1.25" Baader T2 prism diagonal.

All the Back temperatures are with the sun moved out of the field.
Looking up at the Sun I assume is the Black Body equivalent of the thermometers sensitivity spectrum. BBE.

OTA and diagonal with no components and sun centred so only going through clear apertures.
Back of objective 28.1C
Front of diagonal 26.7C
OTA inside 23.4C

2" UV-IR. And then adding components of course.
Back 33C

2" 40nm Red Optolong
Back 34.9C

2" Beloptic UV-IR KG3
Back 24.4C
Looking up at the Sun 63C, a Black Body Equivalent for the thermometer

T2 Diagonal
Back 30.5C
Looking up at the Sun 100.7C near focus so higher energy intensity I presume

3x VK TE extender
Back 24.5C
Looking up at sun 57C

2x ES TE
Back 27.0C
Looking up at sun 52.6C

40mm Plossl. I used this here to have a hold on the temperature compared to heated etalon.
Back 31.2C
Looking up at sun 35.9C Near body temperature

Quark Chromo
Back 40.3C of course it is heated, central setting.

40mm Plossl
Back 35.6C

So all the components before the heated etalon are cooler than it.

And the light entering the Quark is at body temperature.

I did try visually with
UV-IR and Baader KG3

UV-IR, RED CCD 100nm, Baader KG3

UV-IR, RED 40nm, Baader KG3

and could see no difference in brightness at H-Alpha.

Try later with CCD camera.

Cheers. Andrew.

[marktownley]

So, what range of wavelengths do the meat thermometers measure?

[AndiesHandyHandies]

Hi

This is the model I am using.

https://www.ebay.co.uk/itm/234622489528 ... 04395c6164

It does not like looking up at the unfiltered sun, gives a warning.

Seems to work on various materials.

Specs show 0.2 to 20 microns for these type of thermometers.

Cheers. Andrew.

[AndiesHandyHandies]

Hi

I shortened the ERF stack a bit to ensure light cone stays inside front filter edges.

I seem to have a few variables:

UV
Red transmission, Blue and green suppression.
Short IR
Long IR Mark says the Quark will block this.

Sunny afternoon but seeing over town poor.

1. Quark Prominence on 4.2x.

As this has a small filter I used my full 2" ERF stack. UV-IR, 40nm Red, KG3. Silver front turned 20mm baffle and silver focus stop on 1.25" nosepiece on T2 to 28.5mm tube in front of the diagonal. The prom is very bright.

Shade 23.5C

Objective 20.4C
UV-UR front 23C

Sun looking up diagonal IR Remote Thermometer 137C

Bare Quark front 37.2C, with 20mm baffle 34.5C.

Sun up the Quark with 20mm baffle 54C.

Sun up the Quark with 10mm baffle. Black steel washer. 47.2C looking down.

Add 7nm with 20mm baffle. Front 7nm 30.3C, front Quark 29.6C. Up the 7nm 26.7C

With usual 10mm baffle. Front 7nm 21.8C, front Quark 21.5C. Up the 7nm 26.1C

Down on the 20mm Clave' eyepiece 30.1C, Sun up 27.4C.

So with full ERF, UV, Red 40nm and Sort IR and a Red 7nm can get low 20'sC on a sunny UK spring day on the Blocker.

--------------------------------------------
I went to the Combo Chromosphere and for a ( second measurement ) removed the 2" KG3 as working at F40 visually.

Look down on the eyepiece 28.2C (30.1C).

Look down on the Quark Blocker 27.3C (33.6C).

Replacing the Quark body with a 40mm Plossl with polariser looking up 25.6C Eyepiece glass temperature? and down 27.5C as blocker.

Look down on the 2X TE 23.6C (49.8C?).

Look down on the 3X TE 20.5C (25.5C).


Look up the Quark 43.7C (46.4C). Looking at heater and then Long IR extra?

Look up the 2X TE 49.7C (49.8).

Look up the 3x TE 86.6C (90.9C).

Look up the diagonal 112.3C (227C). Hand pointing so can vary. (Prominence 137C)

Will adding a Red 7nm help reduce the Blocker temperature?

Cheers. Andrew.

[AndiesHandyHandies]

Hi

Starting from a minimum of a UV-IR ERF filter I am looking at whats needed to hopefully on an average UK day get 23C at the blocking filter.

I did start today but as it was mostly cloudy so lots of moisture in the air to absorb long IR I was getting variable results. Need a calm clear day.

I started with a 2" UV-IR filter on a 2" extension tube stack. 24.4C and 35.3 on the front.

Inside the stack I put a cheap Chinese filter body, 20mm hole, with the front turned off to the silver alloy and a concave finish. Fortunately placed in the Bluelightning T2 to 28.5 passthrough it is just right as a baffle on the front of the T2 diagonal.

WIth that filter had 22.4C and 30.3C when it was sunnier at the blocker.

I added a 2" 40nm red h-alpha filter after the UV-IR. Looking up at the filter stack removed the 40nm was at 51.1C.

I tried a black 20mm stop on the Quark front but the temperatue increased, 33.4C and 36.5C, absorbing and transmitting energy?

I put a 20mm Chinese red filter on a short 1.25" extension on the Quark. The red filter was at 17.6C and the Quark blocker at 19.7C, 'single glazed'?.

I had found before that baffles can affect the temperature as well as filters.

Cheers. Andrew.

[AndiesHandyHandies]

Hi

Been having a play with the Quark Combo and 90mm.

After another set of tests today using just UV-IR, Baader 35nm and the Blocker filter mostly measures in the 30s'C so I think the Quark heater has most influence on its temperature. If thats so its 7-17C higher than the default specified temperature for Andover filters of 23C.

Have to try a 'Cold filter' substitute.

At Ha the standard blocker will move about .18Ang/C.

Say 12C higher than specification x 0.18 = 2.16Ang peak transmission. Will that be a noticable problem?

Cheers. Andrew.

[AndiesHandyHandies]

Hi

I looked at the blocker temperature with no filters in front and the Combo Quark cold.

It tops out at 35C.

So nowhere near 70C max operating temp.

Not seen over 39C with UV-IR and the Combo Quark heater on.

The 4.2x with smaller blocker but not by the heated etalon may be different.

Is the Blocker tilted as there seems to be an off-axis reflection off it?

Cheers. Andrew.

[AndiesHandyHandies]

Hi

The blocker front temperature is in the range 39-42C with the UV-IR filter and any red, Optolong 40nm, 35nm or Red CCD.

The UV-IR shows 32.4C on its front surface.

The Optolong looks like my Lunt ERF, Red glass IR block and maybe non-reflection back as well. It heats up to about 60C right after the UV-IR.

And keeps the image as sharp as with just the UV-IR.

If the Blocker is to a specification at 23C then it will have drifted higher on band by about **3.6A***. Is that significant?

Cheers. Andrew.

[AndiesHandyHandies]

Hi

Personally on even a 90mm I would add a Optolong 40nm after the UV-IR.

During testing after change to running just on the UV-IR and missing a 20mm baffle in front of a plastic Celestron/Skywatcher 1.25" Moonfilter holding a steel washer baffle I managed to slightly melt the plastic.

I did also briefly use the 100mm f5 with a Lunt ERF, IR block on red glass.

Not done that with any extra red filter.

Cheers. Andrew.

[AndiesHandyHandies]

Hi

The blocking filter peak is above the h-alpha line at its specified 23C.

http://astrosurf.com/viladrich/astro/in ... spaced.jpg

So moving the peak up about 3.6A will reduce the transmission.

Cheers. Andrew

[AndiesHandyHandies]

Hi

Been having another play with the Quarks looking at Blocker filter temperatures.

Both experience about 35C on the blocker. The default specified temperature is 23C. Maximum 70C.

Chromosphere.

I tried adding a 7nm from my PST mod but did not make much difference.

In the end adding a 0.3D was the only way to get around 23C on the blocker. No gain there.

Prominence.

Tried a stop and polariser on the nose piece but no help.

An aside:
However trying a polariser at both ends did tame the general brightness made the background a bit darker.
It is very bright.

So either the blockers have been custom made for say 35C or we are getting less light thru than could be the case.

Does anyone have a contact who would know?

Cheers. Andrew.

[AndiesHandyHandies]

Hi

I went to see 'Rod the White' today to pick up the Santel 180 with SH focuser replacing the worn out original.

He is already designing a blocker filter cooler.

I measured the earth temp under the deck and 10C so a fan and flexi hose might work.

I had a look at his new 6" F5 Celestron objective put in a Seben Newtonian tube.

Lovely sharp image with nice details.

I looked all round the telescope and down the tube and it was all white. Something about how the professionals do it.

Cheers. Andrew.

[marktownley]

Would have to be the correct type of white. There has been discussion about it for observatories too.