Ph.D

Yes, definitely you can study Ph.D in instrumentation technology after the completion of B.Tech in the same.
Candidates those who have completed their B.Tech degree course in instrumentation technology from a recognised university with a minimum of 55% of marks are eligible to opt for the Ph.D course in the same.
Candidates must have to qualify in the GATE examination for applying for the Ph.D course.
Eligibility criteria:
- The candidate should be Indian national.
- The candidate should have valid B.Tech degree from a recognized university.
- The candidate must score more than 55% of marks

There is no Ph.D in immunology at the University of Calcutta. However, there are M.Phil courses.
Eligibility for PhD in immunology at other institutes are as follows:
As a minimum criterion of eligibility, aspiring candidates need to meet the following minimum eligibility criteria:
Postgraduate degree in a relevant discipline, completed from a recognized university.
A minimum aggregate score of 55% (50% for SC/ST candidates) at the level of post-graduation.
At least 5 years of teaching/ industry/ administrative/ professional experience at a senior level.

Check this link to know all about the WILP programme offered by BITS: http://www.bits-pilani.ac.in/university/wilp/wilpoverview.

Hi Sushila,
You should try applying abroad, it will give you a very good opportunity to gain international exposure and better career prospects at this stage. Give a try. You will have access to many global opportunities.

Apply on different sites of universities, even for abroad. Apply now.

If one of your degree is through correspondence, then there's no issue!
Make sure B.Ed through correspondence is recognised by the NCTE. Now, as far PhD. is concerned, U.G.C has stopped recognizing any PhD through correspondence mode.